CN116671261A

CN116671261A - Flexible circuit and electrical communication assembly associated therewith

Info

Publication number: CN116671261A
Application number: CN202180088722.5A
Authority: CN
Inventors: 乔纳森·E·巴克; 马克·埃皮托
Original assignee: Samtec Inc
Current assignee: Samtec Inc
Priority date: 2020-11-02
Filing date: 2021-11-02
Publication date: 2023-08-29

Abstract

Flex circuit embodiments having higher signal conductor densities and higher signal integrity are provided. An electrical communication system is described that is disposed in electrical communication with a flexible circuit. An electrical communication system is described that includes an electrical connector that is selectively mateable with an electrical connector mounted to a flexible circuit and an electrical connector mounted to a substrate, such as a Printed Circuit Board (PCB).

Description

Flexible circuit and electrical communication assembly associated therewith

Cross Reference to Related Applications

The present application claims priority from U.S. patent application Ser. No. 63/108,871, filed 11/2/2020, and U.S. patent application Ser. No. 63/249,423, filed 9/28 2021, the disclosures of each of which are incorporated herein by reference as if fully set forth herein.

Background

High data rate connectivity and processing is drastically changing many aspects of human society. Connectivity and processing innovations are implemented by integrated circuits (integrated circuits, ICs) that can generate and process terabytes per second (Tbps) of information. Within an integrated circuit, information is transmitted through narrow (< 10 nm) conductive traces and is handled by thousands or millions of transistors. ICs are typically packaged in the form of IC dies that are mounted on a die package substrate to form a die package or IC package. In turn, the IC package is mounted to the host substrate. The primary substrate has electrical traces and these electrical traces can create undesirable parasitic insertion loss (parasitic insertion loss) and other undesirable signal transmission qualities.

An earlier approach to reducing the adverse and undesirable signal transmission loss in a host or circuit board substrate is disclosed in U.S. patent No. 6,971,887, which is incorporated herein by reference in its entirety. This patent discloses the use of an external substrate to couple a first socket member and a second socket member. The outer substrate has a dielectric having an electric loss tangent (electrical loss tangent value) lower than that of the dielectric constituting the circuit board substrate. The signal may be transmitted through the outer substrate at a rate of 12GT/s+ at a distance of about six inches. Generally, U.S. patent No. 6,971,887 teaches connecting an intermediate processing unit (CPU) socket to an external substrate such that high-rate signals bypass the main or circuit board substrate.

Another method of reducing adverse and undesirable signal transmission losses in a host substrate is described on pages 26 and 27 in the third edition of "flex circuit technology" (2006) published by Joseph Fjelstad, BR Publishing, inc. Mr. Fjelstad writing: while the historical role of flex circuits has been generally as a replacement for wire harnesses, this technology has far exceeded this common range of applications. Nowadays, flexible circuits are expanding their range of applications. Electronic packaging engineers worldwide are designing newer methods of using flexible circuits and expanding the fundamental prospect of this technology by developing more exotic but practical electronic interconnect structures. It is worth briefly discussing some of the unique capabilities of flex circuit technology to improve electronic circuit packaging density and performance in some of the many new applications being used or being developed. Some new applications and methods of use of flexible circuit technology further demonstrate the ability of the technology to increase circuit density in an unusual manner, such as in IC packages, where new package structures typically occupy a small portion of the volume of more conventional designs. High-speed flex circuit assemblies have proven to be viable alternatives for high-speed applications where flex circuits are directly integrated into connectors at data rates of up to 10Gbps with a maximum board-to-board distance of 75 millimeters (30 inches). An example is shown in fig. 2-14 (high speed flex cables may be directly connected from the package to the connector to avoid parasitics and avoid crosstalk problems associated with conventional interconnect designs.) for differential pair and single ended arrangements, the spacing of typical high speed flex circuit products may be as low as 0.5 millimeters (0.020 inches) or less. These types of flex circuit applications will become more and more important as data transmission speeds become higher and higher. The high-speed structure implemented by the high-speed cable will be discussed in more detail later. "

In summary, mr. Feier discloses the use of flexible circuit material to bypass the main substrate and set flexible cable connections for signaling up to 10Gbps between the differential signal pairs of the right angle backplane connector and the die package substrate, rather than providing jumpers between at least two CPUs or at least two CPU sockets.

U.S. patent No. 8,353,708 entitled "independent loading mechanism (Independent Loading Mechanism Facilitating Interconnections for Both CPU and Flexible Printed Cables) to facilitate interconnection of both a CPU and a flexible printed cable" generally discloses electrically connecting the CPU to a printed circuit board and enabling high speed signal transmission between the CPUs through the cable.

About five years further, U.S. patent publication number 2016/0218455, entitled "hybrid electrical connector for high frequency signals (Hybrid Electrical Connector For High-Frequency Signals)" filed by the applicant, discloses that electrical traces in a primary substrate have much higher losses than fiber optic cables or shielded cables and are more susceptible to interference and crosstalk. U.S. publication 2016/0218455 proposes shortening electrical traces in a host substrate to about 5 mm or 10 mm from an IC and connecting a dual-axis cable to the electrical traces in the host substrate.

U.S. patent publication 2021/0265785 entitled "Cable connector System (Cable Connector System)" filed by the applicant and incorporated herein by reference in its entirety discloses that "in general, a die package in the range of about 140 mm by 140 mm to about 280 mm by 280 mm can carry at least 1024 dual-axis pairs or 2048 individual cable conductors on both the first and second surfaces of the die package, which are routed to respective first electrical panel connectors … …"

Finally, U.S. patent publication No. 2021/0289617, entitled "alternate circuit arrangement for long host routing (Alternative Circuit Apparatus For Long Host Routing)" and incorporated by reference herein in its entirety, discloses a circuit assembly. The circuit assembly includes a package including a multi-layer BGA/chip carrier and a flexible circuit (package to board flex circuit) packaged to a board. The BGA/chip carrier comprises an IC, the IC comprises a first BGA mounted on a chip carrier/adapter plate, the chip carrier/adapter plate comprises a PCB or a substrate connected between the first BGA and a second BGA, and the first BGA and the second BGA are mounted on the multi-layer PCB through a first group of BGA chips formed on the upper layer of the multi-layer PCB through patterns. The left end of the flexible circuit is mounted on the top surface of the chip carrier through the BGA device, and the right end of the flexible circuit is mounted on the multi-layer PCB through a second group of BGA pieces formed on the upper layer of the PCB through patterns. The second set of pads is electrically connected to the connector through a layer of wiring. The high-speed data channel may have a bandwidth of at least 50 Gbps.

Disclosure of Invention

The present disclosure is generally directed to: improved flex circuits and related interconnects; routing at least 512 or at least 1024 differential signal pairs from a single surface of the IC die package, a single surface of the die package substrate, or a signal surface of the connectivity module; attaching a flexible circuit to at least two die package faces, at least three die package faces, or at least four die package faces of a die package substrate; and a hybrid cable assembly that includes one or more flex circuits and cables in combination, alone or in combination with an end-to-end electrical connector and/or an end-to-end electrical connector.

Brief description of the drawings

The foregoing summary, as well as the following detailed description of illustrative embodiments of the electrical communication system of the present disclosure, will be better understood when read in conjunction with the appended drawings. For the purpose of examples of the present disclosure, exemplary embodiments are shown in the drawings. It should be understood, however, that the present disclosure is not limited to the precise arrangements and instrumentalities shown. In the drawings:

FIG. 1A is a perspective view of a portion of a three-layer flex circuit including a single ground conductor disposed between adjacent differential signal pairs of signal conductors;

FIG. 1B is a cross-section of a portion of the flexible circuit shown in FIG. 1A;

FIG. 1C is a perspective view of the flexible circuit shown in FIG. 1A with a docking area at a first circuit end of the flexible circuit;

FIG. 1D is a cross-section of the portion of the flexible circuit shown in FIG. 1C that extends through the docking area at the first circuit end;

FIG. 1E is a cross-section of the portion of the flexible circuit shown in FIG. 1A that extends through the docking area at the second circuit end;

FIG. 1F is a graph plotting NEXT, FEXT, IR and RL as a function of the operating frequency of the flexible circuit of FIGS. 1A-1E;

FIG. 2A is a cross section of a portion of a three-layer flex circuit having two grounds between adjacent differential signal pairs;

FIG. 2B is a perspective view of the flexible circuit of FIG. 2A with a docking area at a first circuit end of the flexible circuit;

FIG. 2C is a cross-section of the portion of the flexible circuit shown in FIG. 2B through the docking area at the first circuit end;

FIG. 2D is a cross-section of the portion of the flexible circuit shown in FIG. 2A through the docking area at the second circuit end;

FIG. 2E is a graph plotting NEXT, FEXT, IR and RL as a function of the operating frequency of the flexible circuit of FIGS. 2A-2D;

FIG. 3A is a cross section of a portion of a flexible circuit having two layers;

FIG. 3B is a cross section of a portion of a flexible circuit having five layers;

FIG. 4A is a side view of an electrical communication assembly including a substrate, a flexible circuit having single-sided contacts, and an electrical connector mated to the flexible circuit and mounted to the substrate at an oblique angle;

FIG. 4B is a perspective view of the electrical communication assembly of FIG. 4A;

FIG. 4C is a side view of the electrical communication assembly similar to FIG. 4A, but showing a different angle between the flexible circuit and the substrate;

FIG. 4D is a side view of the electrical communication assembly similar to FIG. 4A, but showing a different angle between the flexible circuit and the substrate;

FIG. 5A is a perspective view of the electrical communication assembly similar to FIG. 4A, but showing the electrical connectors mated to a pair of flexible circuits;

FIG. 5B is another perspective view of the electrical communication assembly of FIG. 5A;

fig. 6A is a schematic top view of an IC die package 72 connected to a plurality of flex circuits;

fig. 6B is a schematic top view of an IC die package 72, the IC die package 72 having different die package footprints on different sides of the IC die package;

FIG. 6C is a perspective view of an electrical communication assembly in another example;

FIG. 6D is a cross-sectional side view of the electrical communication assembly of FIG. 6C;

fig. 6E is a perspective view of an electrical communication assembly similar to the assembly of fig. 6C, but showing a plurality of flexible circuits extending from the die package substrate to the corresponding communication modules;

Fig. 6F is a perspective view of the electrical communication assembly of fig. 6E showing termination of the first circuit end of the flex circuit to the die package substrate;

FIG. 6G is a perspective view of a portion of the electrical communication assembly of FIG. 6F showing termination of a second circuit end of the flexible circuit to the communication module;

FIG. 7A is a perspective view of another example electrical communication assembly including a substrate, a flexible circuit, an electrical edge card receptacle connector, and an electrical connector, wherein the electrical connector is configured to mount to the flexible circuit, the receptacle connector is configured to mount to the substrate, and the receptacle connector is configured to receive the electrical connector, thereby mating the receptacle connector to the electrical connector;

FIG. 7B is a side view of the electrical communication assembly of FIG. 7A;

FIG. 7C is an end view of the electrical communication assembly of FIG. 7B;

FIG. 7D is another side view of the electrical communication assembly of FIG. 7A;

FIG. 7E is a top view of the electrical communication assembly of FIG. 7A;

FIG. 8A is a perspective view of an electrical communication assembly in another example, partially removed for clarity, the electrical communication assembly including a first substrate and a second substrate, the edge card receptacle connector of FIG. 7A configured to mount to the first substrate, and a plug connector configured to mount to the second substrate and to interface with the receptacle connector;

Fig. 8B is a perspective view of the plug connector of fig. 8A;

FIG. 8C is a cross-sectional side view of the electrical communication assembly of FIG. 8A;

FIG. 8D is another perspective view of the electrical communication assembly of FIG. 8A;

FIG. 8E is a side view of the electrical communication assembly of FIG. 8A;

fig. 9 is a top perspective view of a high density interconnect attached to a die package substrate in another example;

FIG. 10A is a top perspective exploded view of the high density interconnect shown in FIG. 9 attached to one side of a die package substrate;

FIG. 10B is an enlarged top perspective view of the first circuit end of the high density interconnect shown in FIG. 10A;

FIG. 10C is an enlarged top perspective view of the second circuit end of the high density interconnect shown in FIG. 10A;

FIG. 11 is a perspective view of a high density interconnect attached to the die package substrate shown in FIG. 9, the high density interconnect further connected to an optical input/output module having an optical engine;

FIG. 12 is a schematic top view of a cable and flexible circuit subassembly;

FIG. 13A is a schematic top view of the cable and flex circuit subassembly of FIG. 12 with connectors on both ends of the subassembly; and is also provided with

Fig. 13B is a schematic side view of the cable and flex circuit subassembly of fig. 13A providing interconnection between an IC package and a panel.

Detailed Description

The present disclosure may be understood more readily by reference to the following detailed description taken in conjunction with the accompanying drawings and examples forming a part of this disclosure. It is to be understood that this disclosure is not limited to the particular devices, methods, applications, conditions or parameters described and/or shown herein, and that the terminology used herein is for the purpose of describing particular embodiments by way of example only and is not intended to limit the scope of the disclosure. Furthermore, references to plural, as used in the specification including the appended claims, include the singular "a," an, "" the, "and also include the" at least one. Furthermore, references to a particular numerical value in the specification, including the appended claims, include at least that particular numerical value unless the context clearly dictates otherwise.

The term "plurality" as used herein means more than one. When a range of values is expressed, the range extends from one particular value to another particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another example. All ranges are inclusive and combinable.

When used in describing dimensions, shapes, spatial relationships, distances, directions, and other similar parameters, the terms "substantially," "about," and derivatives thereof, and words of similar import, include the parameters and ranges up to 10% and up to 10% less, including up to 5% and up to 5% less, including up to 3% and including up to 1% and up to 1% less, than the parameters. If elements of the invention are compared or described using terms such as "equal," "perpendicular," or numerical values associated with a given dimension, these terms should be construed to refer to those terms within manufacturing tolerances.

In general, the flex circuit has a higher differential pair density than two coaxial cables or one co-extruded twin-core cable, all under the same conditions. However, flex circuits also perform electrically worse than coaxial waveguide cables, biaxial waveguide cables, or extruded waveguide cables of equal length. As the length of the flex circuit increases, signal integrity performance decreases faster than coaxial waveguide cables, biaxial waveguide cables, and waveguide cables. Thus, for applications transmitting signals at high speed or high data rates, such as 56G NRZ/112G PAM4 signaling or 112G NRZ/224G PAM4 signaling, many people have employed dual-axis cables rather than flexible circuits.

However, one problem with cables is density. For example, a 34AWG, 100 ohm two-axis cable with THV (thermoplastic elastomer ) jacket has a width of about 1.2 millimeters. The center-to-center spacing of two immediately adjacent differential pairs of cable conductors is at least 1.5 millimeters, which includes ground termination and mechanical tolerances. Thus, the simplified formula for calculating the number of 34AWG cables that can be attached to one of the four sides or edges of the die package substrate is approximately (side length-10 millimeters (held out))/1.5 millimeters/pair.

As shown in table 1: fitting to the number of 34AWG twin-axis cables on one of the four die package faces, it is almost impossible to attach the fully shielded 1024 coaxial cables to only one major surface of a 50 mm x 50 mm to 100 mm x 100 mm die package substrate that already carries an IC die. The biaxial cable is too thick. At best, without connectors, most of the two-axis cables that may be directly attached to a 100 mm x 100 mm die package substrate, also containing only one major surface of the IC die 70, are 240 two-axis cables permanently attached to each of the four die package faces, with a total of 960 differential signal pairs on one major surface of the IC die package, at four rows deep on each of the four die package faces.

Table 1: number of 34AWG biaxial cables adapted on one of four die package faces

Making the die package substrate larger to accommodate thicker wires is not always a practical solution because the more likely the die package substrate will deform (warp), "potato chip warp" or lose coplanarity during reflow as the die package substrate side becomes longer and as the die package main surface area increases.

Thus, a technical problem is how to make a die package substrate small enough to mitigate coplanarity problems, such as having the die package substrate approximately any one of the following dimensions: 50 mm x 50 mm or 55 mm x 55 mm or 60 mm x 60 mm or 65 mm x 65 mm or 70 mm x 70 mm or 75 mm x 75 mm or 80 mm x 80 mm or 85 mm x 85 mm or 90 mm x 90 mm or 95 mm x 95 mm, or even 100 mm x 100 mm or 105 mm x 105 mm, but still route or transmit at least 1024 high speed differential signal pairs from only one major surface of an IC die or IC die package or die package substrate to an electrical component, communication module or electrical connector, wherein the high speed is at least 28G NRZ, 56G PAM-4, e.g., 56G NRZ, 112G PAM-4 and 112G NRZ, 224G PAM-4. The first non-limiting solution is to have the flex circuit work well electrically. A second non-limiting solution is to take advantage of the density of flexible circuits and the better signal integrity advantage of dual-axis cables. These general solutions are now discussed.

Referring to fig. 1A, which shows a perspective view of a portion of a flexible circuit 20, fig. 1B shows a cross section of the same flexible circuit 20. The flexible circuit 20 may include a first flexible circuit surface 23A and a second flexible circuit surface 23B opposite the first flexible circuit surface 23A in the transverse direction T. The flexible circuit 20 may include first and second conductive layers 22 and 24, respectively, the first and second conductive layers 22 and 24 opposing each other along the transverse direction T and thus being spaced apart from each other. The flexible circuit 20 may also include a first electrical signal conductive layer 26A disposed between the first conductive layer 22 and the second conductive layer 24, the first electrical signal conductive layer 26A may include a flexible signal conductor 26.

As best shown in fig. 1B, the flexible circuit 20 may include a first outer dielectric layer 23, and the first outer dielectric layer 23 may be provided as an electrically insulating coating that may cover an outer surface of the first conductive layer 22 facing away from the plurality of flexible electrical conductors 26. The flexible circuit 20 may include a second outer dielectric layer 25, and the second outer dielectric layer 25 may be provided as an electrically insulating coating that may cover an outer surface of the second conductive layer 24 facing away from the plurality of flexible signal conductors 26. The first outer dielectric layer 23 and the second outer dielectric layer 25 may cover all surfaces of the first conductive layer 22 and the second conductive layer 24 as needed. The first conductive layer 22 and the second conductive layer 24 may set respective outermost conductive elements of the flexible circuit 20 with respect to the transverse direction T. The first outer dielectric layer 23 and the second outer dielectric layer 25 may set the respective outermost layers of the flexible circuit 20 with respect to the transverse direction T.

The flexible circuit 20 may also include a first inner dielectric layer 27 between the first conductive layer 22 and the plurality of flexible signal conductors 26. The flexible circuit 20 may also include a second inner dielectric layer 28 between the second conductive layer 24 and the plurality of flexible signal conductors 26. Further, an adhesive sheet 29 may be located between the first inner dielectric layer 27 and the plurality of flexible signal conductors 26. The adhesive sheet 29 may help adhesively connect the layers of the flexible circuit 20 together.

The first conductive layer 22, the second conductive layer 24, and the plurality of flexible signal conductors 26 may be made of copper. Patterning on these different layers may be formed by photolithography or some other method. The first and second outer dielectric layers 23 and 25 may be made of polyimide. The first and second inter-dielectric layers 27 and 28 may be made of a liquid crystal polymer. The liquid crystal polymer may have dielectric properties that are superior to polyimide and thus may be beneficial in the interior region of the flexible circuit 20 where an electric field is present during circuit operation. The liquid crystal polymer has a lower dielectric constant and a lower loss tangent than polyimide (dissipation factor). Further, unlike polyimide, the liquid crystal polymer does not absorb water, and thus its dielectric characteristics are not affected by the presence of water.

The flexible signal conductor 26 may include a plurality of flexible ground conductors 21, a plurality of flexible signal conductors 26, or both. The flexible signal conductors 26 may each be elongated along the longitudinal direction L. At least one of the flexible ground conductors 21 may be disposed between adjacent flexible differential signal pairs S1, S2 of the flexible signal conductors 26 along a lateral direction a that is perpendicular to each of the transverse direction T and the longitudinal direction L. One flexible ground conductor 21 may be disposed in a lateral direction between adjacent flexible differential signal pairs S1, S2 of flexible signal conductors 26. The flexible ground conductors 21 and the flexible signal conductors 26 may form a repeating arrangement (repeating pattern) of the G-S layout. The flexible differential signal pair S1, S2 of the flexible signal conductor 26 may be operated as a differential signal pair, which may provide some resistance to background electromagnetic noise that may be present in any operating system. Thus, each flexible differential signal pair S1, S2 of flexible signal conductors 26 may be isolated from each other by a respective flexible ground conductor 21. The flexible signal conductors 26 may be arranged such that immediately adjacent flexible signal conductors 26 may be spaced apart from each other in a transverse direction along a center-to-center conductor pitch that is in the range of about 0.3 millimeters to about 0.5 millimeters. For example, the conductor pitch may be about 0.35 millimeters. Thus, the pitch between the repeating patterned conductors is about 0.9 mm to about 1.5 mm. For example, the pitch between conductors laid out in a repeating pattern may be about 1.05 mm.

The flexible signal conductors 26 may be substantially coplanar with one another along a plane including the longitudinal direction L and the lateral direction a. Further, the shape of the flexible signal conductor 26 in the plane set by the transverse direction T and the lateral direction a may be rectangular or trapezoidal. The width of the flexible signal conductors 26 in the lateral direction a may be greater than their height in the transverse direction T. It should be appreciated that the transverse direction T, the longitudinal direction L, and the lateral direction a, as well as other spatial relationships, are described herein with the flexible circuit 20 in a flat position (flat position), where it should be appreciated that the flexible circuit 20 may bend (bent), twist (twisted), or otherwise twist (connected) during use.

The flexible ground conductor 21 may be in electrical communication with at least one of the first conductive layer 22 and the second conductive layer 24. For example, the first conductive layer 22 and the second conductive layer 24 may be electrically connected to the flexible ground conductor 21. In particular, the flexible circuit 20 may include a plurality of conductive ground vias 33, which plurality of conductive ground vias 33 may extend from the first conductive layer 22, through a respective one of the flexible ground conductors 21, and to the second conductive layer 24. The ground vias 33 may each extend through the first conductive layer 22 and the second conductive layer 24 along the transverse direction T. Alternatively, the ground vias 33 may extend to, but not through, one or both of the first conductive layer 22 and the second conductive layer 24. In another example, the ground vias 33 may extend from the first conductive layer 22 to the respective flexible ground conductors 21, and the ground vias 33 may each extend from the respective flexible ground conductors 21 to the second conductive layer 24. Thus, it can be said that the ground vias 33 may extend from the respective flexible ground conductors 21 to at least one or both of the first conductive layer 22 and the second conductive layer 24. A plurality of ground vias 33 (or pairs of first and second ground vias 33) may connect each flexible ground conductor 21 to the first and second conductive layers 22 and 24. Thus, the sets of ground vias 33 may extend to or through the respective flexible ground conductors 21 and may be spaced apart from each other along the respective lengths of the flexible ground conductors 21 in the longitudinal direction. In this regard, it should be appreciated that the first and second conductive layers 22 and 24, as well as the flexible ground conductor 21, may be in electrical communication with one another through the ground via 33.

The presence of the ground vias 33 may create undesirable resonances in the flexible circuit 20, so in alternative embodiments the flexible circuit 20 may have no ground vias 33, or only ground vias 33 at the first circuit end 134 or the second circuit end 136 (fig. 6A), with electrical signals entering and/or exiting the flexible circuit 20 at the first circuit end 134 or the second circuit end 136. In other words, the flex circuit 20 may have no ground vias 33, or only a small number of ground vias 33, such as less than 2, less than 4, less than 6, less than 8, or less than 10 ground vias 33 per flexible differential signal pair S1, S2.

The flex circuit 20 shown in fig. 1A and 1B may be referred to as a tri-layer flex circuit 20 because there are three layers of metal conductors separated by an electrically insulating dielectric layer. The flexible circuit 20 may be made by laminating one or more metal/dielectric sheets. Photolithography or some other means may be used to etch away the metal in the unwanted areas to pattern the metal of the metal/dielectric sheet. The metal may be copper and the flexible dielectric may be polyimide or a liquid crystal polymer. The thickness of the metal layer may be very thin (about >0 microns and <0.002 microns) to very thick (about >250 microns), and the dielectric thickness may vary from about 10 microns to 220 microns. The thickness of the various layers comprising the flex circuit 20 may be selected to optimize performance while maintaining sufficient flexibility. In some embodiments, the thickness of each layer of the three-layer flex circuit 20 may be less than about 0.15 millimeters, and the total thickness of the flex circuit may be less than about 0.4 millimeters. The filled conductive ground vias 33 or signal vias 34 between the different conductive layers may be made using mechanical drilling or laser drilling and well known electroplating processes. It should be noted that the flexible circuit 20 may be different from a flat cable made by an extrusion process.

The characteristic impedance of the flexible differential signal pair S1, S2 may be adjusted depending on the size and shape of the metal trace or flexible signal conductor 26, the relationship of the metal trace or flexible signal conductor 26 to, for example, the ground planes (ground planes) of the first and second conductive layers 22, 24, and the dielectric characteristics of the dielectric material coating the flexible signal conductor 26. The characteristic impedance may be adjusted to a range of about 85 + -5 ohms to about 100 + -10 ohms. In particular, the characteristic impedance may be 92.5±5 ohms. The flexible circuit 20 and the interconnections at the respective first and second circuit ends 134, 136 of the flexible circuit 20 where signals, such as coaxial signals or differential signals, enter and leave the flexible circuit 20, can be designed to maintain as uniform impedance as possible to minimize reflections and resonances in the transmission system. The pitch between flexible differential signal pairs in a common row, column, or linear array may be small, for example about 1.05 millimeters. This allows for high density interconnection of signals for flexible circuit 20 routing and routing from flexible circuit 20.

Fig. 1C and 1D show perspective and cross-sectional views of the flexible circuit 20 at the first circuit end 134 of the flexible circuit 20. The flexible circuit 20 may include a flexible docking region 19 on the first circuit end 134. Referring to fig. 4A and 4B as a background, the first circuit end 134 may be configured to interface with or mount to a complementary electrical component or connector, such as the first electrical connector 42. The first electrical connector 42 may be disposed mounted to or adjacent to the first major surface 200 of the first substrate 54 or the die package substrate 74. The first circuit end 134 may be referred to as a single-sided connection because all of the flexible signal sheets 30 may be positioned on one side of the first circuit end 134 of the flexible circuit 20, such as the first flexible circuit surface 23A of the flexible circuit 20 or the second flexible circuit surface 23B of the flexible circuit 20.

Referring again to fig. 1C and 1D, the flexible signal sheets 30 may each be electrically connected to a corresponding flexible signal conductor 26. In particular, the flex circuit 20 may include a plurality of signal vias 34, which plurality of signal vias 34 may each extend from the flexible signal sheet 30 to a corresponding flexible signal conductor 26. In particular, the flexible signal sheets 30 may be aligned with the respective flexible signal conductors 26 along the transverse direction T. The signal vias 34 may extend in the transverse direction T from the respective flexible signal sheets 30, from the aligned flexible signal conductors 26. In one example, each flexible signal sheet 30 may be connected to a respective single flexible signal conductor 26 by a single signal via 34, respectively, although it should be understood that the flexible signal sheet 30 may be connected to a single flexible signal conductor 26 by more than one signal via 34, if desired. If desired, one or more signal vias 34 may extend in the transverse direction T into, but not through, the respective flexible signal sheets 30 and the respective flexible signal conductors 26. Alternatively, the signal vias 34 may extend through each of the flexible signal sheet 30 and the flexible signal conductors 26 in the transverse direction T.

As shown in fig. 1D, the first circuit end 134 of the flexible circuit 20 may also include flexible ground pads 35, and the flexible ground pads 35 may each be defined by portions of the first conductive layer 22 that have not been removed to make a counter-pad (anti-pad) 32 around the flexible signal pad 30. The flexible ground sheet 35 may be at least partially or fully aligned with the flexible signal sheet 30 in the lateral direction a. The flex signal pads 30 may set the first differential flex signal pair pad 30A on the first flex circuit surface 23A or adjacent to the first flex circuit surface 23A. At least one flexible ground pad 35 may be positioned between the first differential flexible signal pair pads 30A.

Fig. 1E shows a cross-sectional view of the second circuit end 136 of the flexible circuit 20. Unlike the single-sided first circuit end 134 shown in fig. 1C and 1D, fig. 1E shows a double-sided connection in which the first flexible circuit surface 23A and the second flexible circuit surface 23B of the flexible circuit 20 can be electrically connected. The flex signal pads 30 may include a fourth differential flex signal pair pad 30D positioned on the first flex circuit surface 23A. The fourth differential flexible signal pair pad 30D may be substantially coplanar with the first conductive layer 22. The flex signal pads 30 may also include a second differential flex signal pair pad 30B positioned on the second flex circuit surface 23B. The second differential flex signal pair pad 30B may be substantially coplanar with the second conductive layer 24 to form a two-sided flex circuit. Thus, referring again to fig. 4A and 4B as a background, the respective first row of first electrical contacts 44 and second row of first electrical contacts 44 of the first electrical connector 42 may interface with the respective second differential flexible signal pair pad 30B and fourth differential flexible signal pair pad 30D and the respective flexible ground pad 35. Referring again to fig. 1E, the second differential flexible signal pair patches 30B in the first row may be offset from the fourth differential flexible signal pair patches 30D, which are sequentially adjacent and opposite in the second row, by less than one row pitch, or a distance greater than one row pitch in the lateral direction a. In this example, the counter plate 32 may be a first plurality of counter plates 32A that may separate and electrically isolate the fourth differential flexible signal pair plate 30D from the first conductive layer 22 and a second plurality of counter plates 32B that may separate and electrically isolate the second differential flexible signal pair plate 30B from the second conductive layer 24.

Each flexible signal pad 30 may be electrically connected to a corresponding flexible signal conductor 26. In particular, the flexible circuit 20 may include a plurality of conductive signal vias 34, which plurality of conductive signal vias 34 may each extend from a respective flexible signal sheet 30 to a respective flexible signal conductor 26. In particular, the flexible signal sheets 30 may be aligned with the respective flexible signal conductors 26 along the transverse direction T. The signal vias 34 may extend in the transverse direction T from the respective flexible signal sheets 30, from the aligned flexible signal conductors 26. In one example, each flexible signal sheet 30 may be connected to a corresponding single flexible signal conductor 26 by a single signal via 34, respectively, although it should be understood that the flexible signal sheet 30 may be connected to a single flexible signal conductor 26 by more than one signal via 34, if desired. If desired, the signal vias 34 may extend in the transverse direction T into but not through both the flexible signal sheet 30 and the flexible signal conductors 26. Alternatively, each signal via 34 may extend through a respective flexible signal sheet 30 and a respective flexible signal conductor 26, respectively, in the transverse direction T.

The flex circuit 20 may further include a flexible ground pad 35 that may be set by the first conductive layer 22 and may be at least partially or fully aligned with the flexible signal pad 30 or the fourth differential flexible signal pair pad 30D in the lateral direction a, and a flexible ground pad 35 that may be set by the second conductive layer 24 and may be at least partially or fully aligned with the flexible signal pad 30 or the second differential flexible signal pair pad 30B in the lateral direction a.

Although the cross-sectional views of fig. 1D and 1E show that all of the flexible signal sheet 30, the second differential flexible signal pair sheet 30B, the fourth differential flexible signal pair sheet 30D, and the flexible ground sheet 35 are located in a common plane set by the transverse direction and the lateral direction, these flexible signal sheet 30, the second differential flexible signal pair sheet 30B, the fourth differential flexible signal pair sheet 30D, and the flexible ground sheet 35 may be staggered (stacked) or offset in the longitudinal direction. For example, the flexible ground sheet 35 may be closer to the first circuit end 134 of the flexible circuit 20 than the flexible signal sheet 30. Further, the flexible signal sheets 30 may be arranged in rows that are offset in the longitudinal direction. There may be one, two, three, four, five, six, seven, eight or more rows of longitudinally offset flexible signal pads 30 and/or second and fourth differential flexible signal pair pads 30B, 30D.

Fig. 1F shows signal integrity model data for flex circuit 20 of fig. 1A-1E, including worst case multiple-active asynchronous far-end cross talk (FEXT), worst case multiple-active asynchronous near-end cross talk (NEXT), insertion Loss (IL), and Return Loss (RL) generated when signals are transmitted along respective flex signal conductors 26. Fig. 1F shows the values of these different parameters plotted against the frequency of the signal propagating along the flexible differential signal pair S1, S2 of the flexible signal conductor 26. The modeled flexible circuit with flexible signal sheet 30 was end-to-end and 3.65 millimeters in length. A second reference line 59 is shown to allow the propagation characteristics of the flex circuit 20 to be compared to other flex circuits 20 described below. A study of fig. 1F shows that at frequencies up to and including 60GHz, the modeled FEXT is a worst case multiple active asynchronous crosstalk of no more than about-55 dB, and the modeled NEXT is a worst case multiple active asynchronous crosstalk of no more than about-50 dB.

The flexible circuit 20 may be part of a digital connectivity system that transmits and/or receives digital information. Digital information may have various formats, but a common format is a non-return-to-zero (NRZ) format. For such a system, the information transmission rate, which may be expressed in gigabits per second (Gigabits per second, gbps), may be twice the transmission system bandwidth. For example, a system capable of transmitting signals at 50GHz may support an information transmission rate of approximately 100 Gabs. It should be appreciated that the flex circuit 20 may be used in different communication schemes, such as 112G PAM-4, and is not limited to use in the NRZ scheme.

If the-55 dB FEXT value and the-50 dB NEXT value are respectively acceptable in a connected system, flex circuit 20 can be used to transmit information at data transmission rates up to about 120 Gpbs. In particular, the flex circuit 20 may be part of a system in which the data transfer rate is at least about 12 gigabits per second (gigabits) or even about 112 gigabits per second, including about 15 gigabits per second, about 20 gigabits per second, about 25 gigabits per second, about 30 gigabits per second, about 35 gigabits per second, about 40 gigabits per second, about 45 gigabits per second, about 50 gigabits per second, about 55 gigabits per second, about 60 gigabits per second, about 65 gigabits per second, about 70 gigabits per second, about 75 gigabits per second, about 80 gigabits per second, about 85 gigabits per second, about 90 gigabits per second, about 95 gigabits per second, about 100 gigabits per second, about 105 gigabits per second, and about 110 gigabits per second.

Referring now to fig. 2A and 2B, fig. 2A shows a cross-section of the inflexible butt-joint region of the first circuit end 134 of a portion of the flexible circuit 20, and fig. 2B shows a perspective view of the same first circuit end 134 of the flexible circuit 20. Unlike the flex circuit 20 described with reference to fig. 1A-1F, fig. 2A and 2B illustrate a flex circuit 20 having a repeating G-S-G layout in the lateral direction a. Each pair of immediately adjacent flexible signal contacts 26 may set a flexible differential signal pair S1, S2 or a first differential flexible signal pair pad 30A. The flexible circuit 20 may include a flexible docking region 19 on the first circuit end 134, the flexible docking region 19 being configured to dock or mount to a complementary electrical component, such as any one selected from (all described below) the first electrical connector 42, the second electrical connector 60, the die package substrate 74, the third electrical connector 80, the package connector 138, or the package tab 162.

Fig. 2B shows a portion of the flexible circuit 20 that exposes the flexible docking region 19. In the flexible docking area 19, the first outer dielectric layer 23 may be removed, which exposes the first conductive layer 22. The flexible docking area 19 may include a plurality of flexible signal pads 30 in electrical communication with each flexible signal conductor 26. Each flexible ground tab 35 may be in electrical communication with a corresponding flexible ground conductor 21, respectively. At least some of the flexible signal sheets 30 may be substantially coplanar with the first conductive layer 22. In one example, all of the flexible signal sheets 30 may be coplanar with the first conductive layer 22 in a plane including the lateral direction a and the longitudinal direction L. Thus, referring again to fig. 4A and 4B as a background, a single row of first electrical contacts 44 may interface with all of the flexible signal sheets 30.

Fig. 2B shows that the flexible signal sheet 30 may be entirely coplanar with the first conductive layer 22. The flex circuit 20 may include a counter plate 32 or gap extending through the first conductive layer 22 in the transverse direction T to separate and electrically isolate at least some of the flex signal plates 30 or the first differential flex signal pair plates 30A from the first conductive layer 22. The flexible signal conductors 26 and flexible ground conductors 21 may be arranged such that a pair of immediately adjacent flexible ground conductors 21 are disposed between the first differential flexible signal pair plates 30A in the lateral direction a. Thus, the flexible circuit 20 can set a repeating G-S-G layout in the lateral direction a. The flexible signal conductors 26 may be arranged such that immediately adjacent flexible signal conductors 26 may be spaced apart from each other in a lateral direction along a center-to-center conductor pitch that is in the range of about 0.3 millimeters to about 0.5 millimeters. For example, the conductor pitch may be about 0.35 millimeters. For this exemplary conductor pitch, the pitch of the repeating pattern may be about 1.4 millimeters. Notably, for the same contact pitch, the repeated layout pitch of the G-S-G layout is greater than the G-S arrangement described with reference to fig. 1A-1F, due to the presence of additional flexible ground conductors G in the repeated layout, e.g., in the repeated G-S-G layout.

Fig. 2C shows a cross-sectional view of a portion of the flexible circuit 20 at the first circuit end 134 of the flexible circuit 20. The first circuit end 134 may be referred to as a single-sided connection because all electrical connections to the first circuit end 134 are made on one side of the flex circuit 20, such as the first flex circuit surface 23A or the second flex circuit surface 23. The signal contact pads 30 may be electrically connected to the respective flexible signal conductors 26. In particular, the flexible circuit 20 may include a plurality of conductive signal vias 34, which plurality of conductive signal vias 34 may each extend from one of the flexible signal sheets 30 to a corresponding flexible signal conductor 26. In particular, the flexible signal sheets 30 may be aligned with the respective flexible signal conductors 26 along the transverse direction T. The signal vias 34 may extend in the transverse direction T from the respective flexible signal sheets 30 from the aligned flexible signal conductor conductors 26. In one example, each flexible signal sheet 30 may be connected to a respective single flexible signal conductor 26 by a single signal via 34, respectively, although it should be understood that the flexible signal sheet 30 may be connected to a single flexible signal conductor 26 by more than one signal via 34, if desired. If desired, the signal vias 34 may extend in the transverse direction T into, but not through, each of the flexible signal sheets 30 and the flexible signal conductors 26. Alternatively, the signal vias 34 may extend through each of the flexible signal sheet 30 and the flexible signal conductors 26 in the transverse direction T.

Fig. 2D shows a cross-sectional view of the second circuit end 136 of the flexible circuit 20. Unlike the first circuit end 134 shown in fig. 2C, which illustrates a single-sided connection, fig. 2D illustrates a double-sided connection in which electrical connections can be established to both the first flexible circuit surface 23A and the second flexible circuit surface 23B. The fourth differential flexible signal pair sheet 30D may be substantially coplanar with the first conductive layer 22 and the second differential flexible signal pair sheet 30B may be substantially coplanar with the second conductive layer 24 to form a double sided flexible circuit. Further, the fourth differential flexible signal pair pad 30D may be offset in the lateral direction a relative to the sequentially adjacent and opposing second differential flexible signal pair pad 30B. In this example, the counter plate 32 may be a first plurality of counter plates 32A, and the first plurality of counter plates 32A may separate and electrically isolate the fourth differential flexible signal pair plate 30D from the first conductive layer 22. The flex circuit 20 may include a second plurality of opposing tabs 32B, and the second plurality of opposing tabs 32B may separate and electrically isolate the second differential flex signal pair tab 30B from the second conductive layer 24.

Fig. 2E shows modeled signal integrity data of the flex circuit 20 of fig. 2A-2D, including worst case multi-active asynchronous far-end cross talk (FEXT), worst case multi-active asynchronous near-end cross talk (NEXT), insertion Loss (IL), and Return Loss (RL) generated when signals are transmitted along the respective flex signal conductors 26. The flexible circuit 20 has an end-to-end length of 3.65 millimeters. The values of these parameters are plotted against the frequency of the signal propagating along flexible signal conductor 26. The reference line 59 is in the same position as previously described in fig. 1F.

As shown, the modeled flex circuit 20 may be configured to transmit data along the flex signal conductor 26 at frequencies up to about 80GHz while producing worst case multi-active asynchronous crosstalk of no more than about-60 dB. For example, the modeled flex circuit 20 may be configured to transmit data along the flex signal conductor 26 at frequencies up to about 55GHz while producing no more than about-65 dB of worst case multi-active asynchronous near-end crosstalk. Further, the modeled flex circuit 20 may be configured to transmit data along the flex signal conductor 26 at frequencies up to about 100GHz while producing no more than about-55 dB of worst case multi-active asynchronous crosstalk. At 60GHz, the FEXT value and the NEXT value are about-65 dB and-68 dB, respectively. In other examples, the modeled flex circuit 20 may be configured to transmit data along the flex signal conductor 26 at frequencies up to about 70GHz with return loss not exceeding about-15 dB. Comparison with reference line 59 helps illustrate that the cross-talk of a flex circuit having two ground conductors between the flexible differential signal pair S1, S2 is in the range of about 10dB to 15dB lower over most of the frequency range up to 100GHz as compared to flex circuit 20 having a single flexible ground conductor G between flexible differential signal pair S1, S2 (as shown in fig. 1F).

If the FEXT values of-65 dB and-68 dB and NEXT values, respectively, are acceptable in a connected system, the modeled flex circuit 20 can be used to transmit information at data transmission rates up to about 120 Gbps. Specifically, the flex circuit 20 may be part of a system in which the data transfer rate is at least about 12 gigabits per second (gigabits) or even about 112 gigabits per second, including about 15 gigabits per second, about 20 gigabits per second, about 25 gigabits per second, about 30 gigabits per second, about 35 gigabits per second, about 40 gigabits per second, about 45 gigabits per second, about 50 gigabits per second, about 55 gigabits per second, about 60 gigabits per second, about 65 gigabits per second, about 70 gigabits per second, about 75 gigabits per second, about 80 gigabits per second, about 85 gigabits per second, about 90 gigabits per second, about 95 gigabits per second, about 100 gigabits per second, about 105 gigabits per second, and about 110 gigabits per second.

Extrapolation (extrapolation) of the modeling results shown in fig. 2E to higher frequencies shows that the FEXT value and NEXT value at 130GHz will not exceed-45 dB. Thus, assuming-45 dB is an acceptable crosstalk limit in an electrical communication system, flex circuit 20 may be used to transmit signals to approximately 256Gbps.

Although fig. 1A-1F and their associated descriptions disclose a three-layer flex circuit 20 with a G-S repeating layout, and fig. 2A-2E and their associated descriptions disclose a three-layer flex circuit 20 with a G-S-G repeating layout, it should be understood that flex circuit 20 may be arranged with two types of repeating layouts. For example, it may be beneficial to add an additional flexible ground conductor 21 between the group of transmitting flexible differential signal pairs S1, S2 and the group of receiving flexible differential signal pairs S1, S2. Thus, most of the flexible differential signal pairs S1, S2 may be separated by a single flexible ground conductor 21, but some of the flexible differential signal pairs S1, S2 may be separated by two flexible ground conductors 21.

The flexible circuit 20 (G-S repeating pattern) of fig. 1A-1F may have a higher density of flexible signal conductors 26 than the flexible circuit 20 (G-S-G repeating pattern) of fig. 2A-2D; however, the G-S-G repeating pattern may provide better signal integrity, as indicated by lower FEXT values and NEXT values at the same frequency. Depending on the system requirements, a G-S-S repeating pattern, a G-S-S-G repeating pattern, or a mixture of the two repeating patterns may be beneficial. Alternatively, the flexible signal conductor 26 may be single ended, i.e. have a single flexible signal conductor 26 surrounded (surrouded) by a flexible ground conductor 21 or surrounded (flanked) on both sides by a flexible ground conductor 21. In this case, the repeating pattern may be a simple S-G.

Fig. 3A shows a portion of a cross section of the dual-layer flexible circuit 20 away from the first circuit end 134 and the second circuit end 136. Unlike the three-layer flex circuit 20 disclosed above, the flex circuit 20 of fig. 3A may have only two conductive layers, namely a first conductive layer 22 and a second conductive layer 24. Conductive layer 22 and conductive layer 24 may be separated by intermediate dielectric layer 18. The first conductive layer 22 may be covered by a first outer dielectric layer 23. Similarly, the second conductive layer 24 may be covered by a second outer dielectric layer 25. The outer surfaces of the first and second outer dielectric layers 23 and 25 may form first and second flexible circuit surfaces 23A and 23B of the flexible circuit 20 along the transverse direction T. Flexible signal conductors 26 may be formed in the first conductive layer 22 and the second conductive layer 24. An optional ground via 33 may connect the ground regions of both the first conductive layer 22 and the second conductive layer 24.

The dual-layer flex circuit 20 shown in fig. 3A may have adjacent flex differential signal pairs S1, S2 positioned on opposing first flex circuit face 23A and second flex circuit face 23B of the flex circuit 20. In other embodiments, all of the flex differential signal pairs S1, S2 may be positioned on a single face of flex circuit 20, either first flex circuit face 23A or second flex circuit face 23B. In other embodiments, all of the flexible differential signal pairs S1, S2 of the transmit signals may be on the first flexible circuit face 23A of the flexible circuit and all of the flexible differential signal pairs S1, S2 of the receive signals may be on the second flexible circuit face 23B.

For brevity, the first circuit end 134 and the second circuit end 136 of the flexible circuit 20 shown in fig. 3A are not shown, but the flexible signal sheet 30 and the flexible ground sheet 35 may be arranged as shown in fig. 1D, 1E, 2C, or 2D.

The use of two-layer flex circuit 20, rather than three-layer flex circuit, has several advantages and disadvantages. Advantageously, the two-layer flex circuit 20 may be cheaper and more flexible than the three-layer flex circuit 20. These advantages may be accompanied by potential drawbacks such as higher propagation loss and greater crosstalk.

Fig. 3B shows a portion of a cross-section of the five-layer flex circuit 20 away from the first circuit end 134 and the second circuit end 136. The five-layer flex circuit 20 shown in fig. 3B may have a repeating G-S-G layout, but any of the repeating layouts described above may be used with the five-layer flex circuit 20. The flex circuit 20 may have two opposing first flex circuit faces 23A and second flex circuit faces 23B. The opposing first and second flex circuit surfaces 23A and 23B may be covered by first and second outer dielectric layers 23 and 25, respectively. There may be three conductive layers, namely a first conductive layer 22, a second conductive layer 24 and a third conductive layer 17. The first conductive layer 22, the second conductive layer 24, and the third conductive layer 17 may serve as ground planes. Located between the first conductive layer 22 and the second conductive layer 24 may be a first electrical signal conductor layer 26A. Located between the second conductive layer 24 and the third conductive layer 17 may be a second electrical signal conductor layer 26B. Located between the first conductive layer 22 and the first electrical signal conductor layer 26A may be a first inter-dielectric layer 27 and a first adhesive sheet 29A. Located between the first electrical signal conductor layer 26A and the second conductive layer 24 may be a second inter-dielectric layer 28. Located between the second conductor layer 24 and the second electrical signal conductor layer 26B may be a third inter-dielectric layer 16 and a second adhesive sheet 29B. Located between the second electrical signal conductor layer 26B and the third conductive layer 17 may be a fourth inter-dielectric layer 15. The first adhesive sheet 29A and the second adhesive sheet 29B can help adhesively connect the layers of the flexible circuit 20 together. The ground vias 33 may extend between the flexible ground conductors 21 in the first conductive layer 22, the first electrical signal conductor layer 26a, the second conductive layer 24, the flexible ground conductors 21 in the second electrical signal conductor layer 26b, and the third conductive layer 17. As previously mentioned, in some embodiments, the ground vias 33 may be omitted or a different arrangement than shown in fig. 3B may be employed to minimize electrical resonance in the flexible circuit 20. Although fig. 3B shows an exemplary arrangement of five-layer flex circuit 20, in other embodiments, the arrangement of dielectric layers and adhesive sheets may be modified, and additional layers or sheets may be added or omitted.

Although not shown in fig. 3B, at the end regions of the five-layer flex circuit 20, signal vias 34 may route the first and second flexible signal conductors 26 to the flexible signal sheets 30 in the first and third conductive layers 22 and 17 in a manner similar to that described with reference to fig. 1C-1E and 2D and 2E. The flexible signal sheets 30 may be located entirely in the first conductive layer 22, entirely in the third conductive layer 17, or some flexible signal sheets 30 may be located in both the first conductive layer 22 and the third conductive layer 17.

Summarizing possible construction details of the flex circuit 20 described herein, the flex circuit 20 may include a first circuit end 134, an opposing second circuit end 136, a first flex circuit surface 23A, and an opposing second flex circuit surface 23B. The first conductive layer 22 may be positioned adjacent to the first flex circuit surface 23A. The second conductive layer 24 may be positioned opposite the first conductive layer 22 and adjacent to the second flexible circuit surface 23B. A plurality of flexible signal conductors 26 may be disposed between the first conductive layer 22 and the second conductive layer 24. A first plurality of flexible signal pads 30, which may include a first differential flexible signal pair pad 30A, may be positioned at the first circuit end 134. A second plurality of flexible signal pads 30, which may include a second differential flexible signal pair pad 30B, may be positioned at the second circuit end 136. The first plurality of flexible signal sheets 30 may be positioned entirely on the first flexible circuit surface 23A or adjacent to the first flexible circuit surface 23A, and the second plurality of flexible signal sheets 30 may be positioned entirely on the second flexible circuit surface 23B or adjacent to the second flexible circuit surface 23B.

The third plurality of flex signal pads 30, which may include a third differential flex signal pair pad 30C, may all be positioned at the first circuit end 134 and may all be positioned on the second flex circuit face 23B or adjacent to the second flex circuit face 23B. The first differential flexible signal pair pad 30A of the first plurality of flexible signal pads 30 may be offset from an adjacent opposing third differential flexible signal pair pad 30C of the second plurality of flexible signal pads 30 such that a line perpendicular to both the first and second flexible circuit surfaces passes through one of the flexible signal pads 30 of the first differential flexible signal pair pad 30A but not through any of the flexible signal pads 30 of the third differential flexible signal pair pad 30C. In other words, the sequentially adjacent and opposite first and third differential signal pair slices 30A, 30C may be offset by more than one row pitch. The sequentially adjacent and opposing first and third differential signal pair tiles 30A and 30C may also be offset by one row pitch, or by more than no offset but less than an entire row pitch. The sequentially adjacent and opposing second and fourth differential signal pair slices 30B, 30D may be offset by more than one row pitch. The sequentially adjacent and opposite second and fourth differential signal pair slices 30B, 30D may also be offset by one row pitch, or by more than no offset but less than an entire row pitch.

The first differential flexible signal pair sheets 30A, the third differential flexible signal pair sheets 30C, or both may be spaced apart from each other such that at least two hundred fifty-six first differential flexible signal pair sheets 30A, the third differential flexible signal pair sheets 30C, or both are contained within an area of about 500 square millimeters or about 550 square millimeters or about 600 square millimeters or about 650 square millimeters or about 700 square millimeters or about 750 square millimeters or about 800 square millimeters, whether on a single flexible circuit 20, or on more than one flexible circuit 20.

The first plurality of flexible signal sheets 30 may define first differential flexible signal pair sheets 30A, and the first differential flexible signal pair sheets 30A may be spaced apart from one another such that a row of at least sixty-four first differential flexible signal pair sheets 30A are received along the first die package face 178, the first die package face 178 having a length greater than 50 millimeters but no more than about 75 millimeters, or having a length greater than 55 millimeters but no more than about 80 millimeters, or having a length greater than 60 millimeters but no more than about 85 millimeters, or having a length greater than 65 millimeters but no more than about 90 millimeters, or having a length greater than 70 millimeters but no more than about 95 millimeters, or having a length greater than 75 millimeters but no more than about 100 millimeters, 105 millimeters, or 110 millimeters.

The fourth plurality of flexible signal pads 30D, which may include a fourth differential flexible signal pair pad 30D, may be all positioned at the second circuit end 136 and all positioned on the first flexible circuit face 23A. The third differential flexible signal pair pad 30C and the adjacent opposing fourth differential flexible signal pair pad 30D may be offset from each other such that a line perpendicular to both the first flexible circuit surface 23A and the second flexible circuit surface 23B passes through one flexible signal pad 30 of the second differential flexible signal pair pad 30B, but does not pass through any of the flexible signal pads 30 of the fourth differential flexible signal pair pad 30D. The second differential flexible signal pair pad 30B and the fourth differential flexible signal pair pad 30D may also be offset by one row pitch or more than no offset but less than one entire row pitch. A flexible electrical connector 172 may be attached to the second circuit end 136 and may be configured to receive a docking cable connector 174. The respective coaxial and/or biaxial cable 79 may be directly attached to the respective third differential flexible signal pair patch 30C, fourth differential flexible signal pair patch 30D, or both.

The flexible ground strip 35 may be positioned on the first flexible circuit surface 23A at the first circuit end 134. The flexible ground strip 35 may be positioned on the second flexible circuit surface 23B or adjacent to the second flexible circuit surface 23B at the second circuit end 136. The flexible ground strip 35 may be positioned on the second flexible circuit surface 23B or adjacent to the second flexible circuit surface 23B at the first circuit end 134. The flexible ground strip 35 may be positioned on the first flexible circuit surface 23A or adjacent to the first flexible circuit surface 23A at the second circuit end 136. The flexible signal sheet 30, the flexible ground sheet 35, or both may be devoid of fusible elements prior to and during use. The flexible circuit 20 may be made of a liquid crystal polymer (liquid crystal polymer, LCP) material. The flex circuit 20 may be configured to transmit data at frequencies up to 55GHz while producing worst case multi-active asynchronous crosstalk of no more than-60 dB. The flexible circuit may be configured to transmit data at frequencies up to 55GHz while producing worst case multi-active asynchronous near-end crosstalk of no more than-65 dB. The flex circuit may be configured to transmit data at frequencies up to 55GHz while producing worst case multi-active asynchronous far-end crosstalk of no more than-68 dB. The flex circuit may be configured to transmit data at frequencies up to 100GHz while producing worst case multi-active asynchronous crosstalk of no more than-50 dB.

The flexible circuit 20 may include a first circuit end 134 and a second circuit end 136. The first circuit end 134 may have at least two hundred fifty-six differential flexible signal pair slices. The first circuit end 134 may have a first flexible width d1 sized and shaped to be received on the first die package face 178 or the second die package face 180 or the third die package face 182 or the fourth die package face 184 of the die package substrate 74, the first die package face 178 or the second die package face 180 or the third die package face 182 or the fourth die package face 184 having a length of about 60 millimeters to about 100 millimeters, about 70 millimeters to about 90 millimeters, or about 75 millimeters to about 85 millimeters. The second circuit end 136 may be sized and shaped to receive at least 128 twinax cables 79 or at least 256 coaxial cables 79, the at least 128 twinax cables 79 or the at least 256 coaxial cables 79 each being 32AWG to 40AWG, or 32AWG to 36AWG, or 33AWG to 35AWG. The second circuit end 136 may have a second width d2 of between 95 millimeters and 120 millimeters.

The flex circuit 20 may include a first flex circuit surface 23A, an opposing second flex circuit surface 23B, and a plurality of flex signal pads 30. The flexible signal strips 30 may be arranged as first differential flexible signal pair strips 30A on the first flexible circuit face 23A or adjacent the first flexible circuit face 23A, adjacent the first circuit end 134. The third differential flex signal pair pad 30C may be disposed on the second flex circuit surface 23B or disposed adjacent to the second flex circuit surface 23B adjacent to the first circuit end 134. The first differential flexible signal pair pad 30A may be offset from a third differential flexible signal pair pad 30C that is sequentially adjacent and opposite by one row pitch, by more than one row pitch, or by less than one entire row pitch. The flex signal pads 30 may also be arranged as fourth differential flex signal pair pads 30D on the first flex circuit face 23A or adjacent the first flex circuit face 23A and adjacent the second circuit end 136. The second differential flex signal pair pad may be positioned on the second flex circuit surface 23B or adjacent to the second flex circuit surface 23B and adjacent to the second circuit end 136. The second differential flexible signal pair pad 30B may be offset from the fourth differential flexible signal pair pad 30D, which is adjacent and opposite in sequence, by one row pitch, by more than one row pitch, or by less than one entire row pitch.

Examples of the electrical communication assembly 40 will now be described in more detail. The signal integrity data shown and described is applicable to all such electrical communication systems including at least one flexible circuit 20, unless otherwise indicated.

Referring now to fig. 4A-4B, the electrical communication assembly 40 may include a first electrical connector 42, and the first electrical connector 42 may further include a plurality of first electrical contacts 44 and a dielectric or electrically insulating first connector housing 46 supporting the first electrical contacts 44, the plurality of first electrical contacts 44 including a first electrical ground contact 45 and a first electrical signal contact 47. The first electrical contacts 44 of the first electrical connector 42 may be configured to physically connect, electrically connect, or both physically connect and electrically connect with the flexible signal pad 30 and the flexible ground pad 35 of the flexible circuit 20. Accordingly, the first electrical signal contacts 47 of the first electrical connector 42 may be in electrical communication with the corresponding flexible signal conductors 26 of the flexible circuit 20, and the first electrical ground contacts 45 of the first electrical connector 42 may be in electrical communication with the corresponding flexible ground conductors 21 of the flexible circuit 20. In one example, the electrical connector 42 may be configured to interface with the flexible circuit 20, such as shown in fig. 2C, such that the first electrical contact 44 of the first electrical connector 42 is physically, electrically, or both physically and electrically connected with the corresponding flexible signal pad 30 and the corresponding flexible ground pad 35 of the flexible circuit 20 to set the separable interface.

The first electrical contact 44 may be profiled (contoured) to make. For example, profiling may mean that one or more first electrical contacts 44 may be stamped rather than rolled (formed). In other words, the first electrical contact 44 may be cut out of a metal sheet having a material thickness that sets the width of the first electrical contact 44 in the lateral direction a. In particular, the first electrical contact 44 may be cut out of sheet metal to have a profile that sets the size and shape of the first electrical contact 44 in a plane set by the longitudinal direction L and the transverse direction T. Thus, in one example, electrical contact 44 may remain unbent or not rolled after electrical contact 44 is cut from the sheet metal. Alternatively, the electrical contacts 44 may be stamped and rolled from sheet metal as desired. The first electrical contacts 44 may be arranged in a single row extending in the lateral direction a, such as the broadside-to-broadside arrangement shown or the edge-to-edge arrangement.

The first electrical connector 42 may define a slot or receptacle 48 that extends into the mating end of the first connector housing 46. The receptacle 48 may be configured to receive the flexible circuit 20 in a mating direction to mate the first electrical contact 44 with the corresponding flexible signal pad 30 and flexible ground pad 35. The first ground mating ends 51 of the first electrical ground contacts 45 of the first electrical connector 42 may be offset in the longitudinal direction L relative to the first signal mating ends 49 of the first electrical signal contacts 47. Alternatively, the first ground mating ends 51 of the first electrical ground contacts 45 and the first signal mating ends 49 of the first electrical signal contacts 47 may be collinear with each other in the lateral direction a. The first electrical connector 42 and the flexible circuit 20 may mate in a corresponding mating direction, which may be set by the longitudinal direction L. The first electrical contact 44 may define a surface facing the flexible circuit 20 in a first direction and the first connector housing 46 may define a cavity 50, the cavity 50 being alignable with the surface in a second direction opposite the first direction. The cavity 50 may be sized and shaped as desired for impedance matching purposes at, for example, a mating interface between the flexible circuit and the first electrical connector 42.

The first electrical contacts 44 may each define a respective first mounting end 52, the first mounting ends 52 being configured to mount to a complementary electrical component. The electrical communication assembly 40 may include complementary electrical components that may be in electrical communication with the flexible circuit 20 through the first electrical connector 42. The complementary electrical components may be provided as a first substrate 54, such as a Printed Circuit Board (PCB) or IC die package substrate. The first mounting end 52 may define a first mounting interface 53, and the first mounting interface 53 may face toward and abut against the first substrate 54. Thus, the first mounting interface 53 may be mounted on a major outer surface 55 of the first substrate 54 that is coplanar with the first mounting interface 53.

The first mounting interface 53 may be oriented such that a reference straight line 56 oriented perpendicular to the first mounting interface 53 sets an angle with respect to a plane including the lateral direction a and the longitudinal direction L of the flexible circuit 20, and thus the main outer surface 55 of the first substrate 54 sets an angle with respect to a plane including the lateral direction a and the longitudinal direction L of the flexible circuit 20. In one example, the angle may be set by fiducial line 56 and longitudinal direction L of flex circuit 20. The angle may be in the range of up to about 90 degrees. The angle shown in fig. 4A may be about 60 degrees. In another example shown in fig. 4C, the angle may be about 90 degrees. In another example shown in fig. 4D, the angle may be about 0 degrees such that fiducial line 56 may be oriented in the longitudinal direction.

Referring now to fig. 5A and 5B, the first electrical connector 42 may be arranged such that the first electrical contacts 44 are arranged in a first row and a second row. In one example, as shown, a first row of electrical contacts 44 may interface with a flexible signal sheet 30 corresponding to a first flexible circuit 20A of the flexible circuits 20, as described above, and a second row of first electrical contacts 44 may interface with a flexible signal sheet 30 corresponding to a second flexible circuit 20B of the flexible circuits 20, as described above. Docking may occur at each first circuit end 134 of a first flexible circuit 20A and a second flexible circuit 20B in the flexible circuits 20. Accordingly, all of the flexible signal sheets 30 of each of the first and second flexible circuits 20A, 20B of the flexible circuits 20 may be coplanar with the respective first conductive layers 22, and all of the flexible ground sheets 35 of each of the first and second flexible circuits 20A, 20B of the flexible circuits 20 may be set by the first conductive layers 22. The respective second conductive layers 24 of the first 20A and second 20B ones of the flexible circuits 20 may face each other. The first flexible circuit 20A and the second flexible circuit 20B of the flexible circuits may be a double-layer flexible circuit, a triple-layer flexible circuit, or the first flexible circuit 20A may be a double-layer flexible circuit and the second flexible circuit 20B may be a triple-layer flexible circuit. Each of the first flexible circuit 20A and the second flexible circuit 20B of the flexible circuits 20 may have a single-sided connection at the respective first circuit ends 134 of the first flexible circuit 20A and the second flexible circuit 20B.

Alternatively, the first flexible circuit 20A and the second flexible circuit 20B in the flexible circuit 20 may be combined into a single flexible circuit, such as the five-layer flexible circuit shown in fig. 3B, whereby the first plurality of flexible signal sheets 30 may be substantially coplanar with the first conductive layer 22 and the first plurality of flexible ground sheets 35 may be defined by the first conductive layer 22. The first row of first electrical contacts 44 may interface with the first plurality of flexible signal pads 30 and the first plurality of first flexible ground pads 35. Similarly, the second plurality of flexible signal sheets 30 may be substantially coplanar with the second conductive layer 24, and the second plurality of flexible ground sheets 35 may be defined by the second conductive layer 24. Thus, the second row of first electrical contacts 44 may interface with the second plurality of flexible signal pads 30 and the second plurality of first flexible ground pads 35. The single flex circuit 20 may have a double sided connection at each of the first flex circuit 20A and the second flex circuit 20B of the flex circuits 20 or at each of the second flex circuit ends 136 of the first flex circuit 20A and the second flex circuit 20B of the flex circuits 20.

The first electrical connector 42 may be configured to interface with at least one flexible circuit 20 or a first flexible circuit 20A and a second flexible circuit 20B of two or more stacks of flexible circuits 20. As shown in fig. 5B, the first electrical connector 42 may further include at least one latch 58, the at least one latch 58 being configured to move from a locked position to an unlocked position. The at least one latch 58 may be configured to retain the flexible circuit 20 in its mated position relative to the first electrical connector 42 when in the locked position. Thus, the engaged or closed or locked latch 58 resists the retractive force applied to the flexible circuit 20 in a direction opposite the mating direction. When the latch 58 is in the unlocked position, the flexible circuit 20 may be undocked and removed from the first electrical connector 42 in response to the retraction force. It can thus be said that the latch 58 is configured to releasably lock the at least one flexible circuit 20 in the mated position with the first electrical connector 42.

Fig. 6A is a schematic top view of IC die package 72. The IC die package 72 may include a die package substrate 74 and may include, for example, an IC die 70 mounted to the die package substrate centrally mounted to the die package substrate. IC die 70 may be a square of about 40 millimeters by 40 millimeters. The IC die 70 may be mounted to the die package substrate 74 by Surface Mount Technology (SMT), for example, by solder balls mounted to the die package substrate 74.IC die 70 may be mounted directly to first major surface 200 of die package substrate 74. The die package substrate 74 may have a width W and a length L. The width W and length L of the die package substrate 74 may be equal, i.e., the die package substrate 74 may be square. The width W and length L of the die package substrate 74 may be at least about 50 millimeters, such as at least about 70 millimeters, at least about 75 millimeters, at least about 80 millimeters, at least about 85 millimeters, at least about 90 millimeters, at least about 95 millimeters, at least about 100 millimeters, at least 105 millimeters, or at least 110 millimeters. The die package footprint 140 may be disposed adjacent to a first major surface 200 of the die package substrate 74, such as a surface of the die package substrate 74 that carries the IC die 70. The die package footprint 140 may be disposed adjacent to the second major surface 202 of the die package substrate 74. In some embodiments, both the first and second major surfaces 200, 202 may have die package footprints 140 such that electrical connections may be established to both the first and second major surfaces 200, 202 of the die package substrate 74. At least two, at least three, or at least four respective first die package faces 178, second die package faces 180, third die package faces 182, and fourth die package faces 184 of the die package substrate 74 may have adjacent die package footprints 140, as generally shown in fig. 6A. Each die package footprint 140 may define a die substrate docking area on the die package substrate 74 where electrical connections to corresponding die package contacts 210 may be established. Each die package footprint 140 may not be partitioned or may be divided into a plurality of spaced-apart die package footprints 141. For example, there may be one, two, three, four, five, or six die package footprints 141 on a respective one, two, three, or four of the first die package face 178, the second die package face 180, the third die package face 182, and the fourth die package face 184 of the die package substrate 74. All of the first die package face 178, the second die package face 180, the third die package face 182, and the fourth die package face 184 may have the same length or different lengths. Each die package footprint 140 may also have a single portion, respectively, i.e., the rows of package tabs 162 may be continuous along the length of the die package footprint 140. Each of the first die package face 178, the second die package face 180, the third die package face 182, and the fourth die package face 184 may have the same number of die package footprints 141, as shown in fig. 6A; however, in other embodiments, a different number of die package footprints 141 may be present on different first, second, third, and fourth die package faces 178, 180, 182, 184 of the die package substrate 74. Fig. 6B illustrates this arrangement, where two opposing faces of the die package substrate 74, such as the first die package face 178 and the third die package face 182 or the second die package face 180 and the fourth die package face 184, may each have three die package footprints 141 and the remaining two opposing faces of the die package substrate 74 have four die package footprints 141. This arrangement may eliminate dead space (dead space) at the corners of the die package substrate 74, such as shown in fig. 6A. More generally, it can be said that the die package footprint 140 on at least one of the first die package face 178, the second die package face 180, the third die package face 182, and the fourth die package face 184 of the die package substrate 74 can be different from the die package footprint 140 on the opposite or opposite side of the die package substrate 74. Each die package contact 210 may be arranged in a series of package rows 212, the series of package rows 212 oriented parallel to adjacent respective first, second, third, and fourth die package faces 178, 180, 182, 184 of the die package substrate 74. Along the respective package rows 212, the die package contacts 210 may be arranged in suitable layouts of differential signal pairs and ground contacts, such as a repeating layout selected from the group consisting of G-S-S, G-S and G-S. FIG. 6A shows an exemplary G-S-S layout, but other layouts may be used, as previously described.

Each die package footprint 141 may be configured to interface directly with a single flex circuit 20 or with multiple stacked flex circuits 20, such as a first flex circuit 20A and a second flex circuit 20B of the flex circuits 20 shown in fig. 5A and 5B. Alternatively, as discussed later, each die package footprint 141 may be configured to be received in or on first electrical connector 42, second electrical connector 60, connectivity module 71, third electrical connector 80, package connector 138, anisotropic conductive film 164, or some other electrical connector or electrical component. The first electrical connector 42 may be configured to directly receive the at least one flexible circuit 20. The second electrical connector 60 may be configured to carry the flexible circuit 20. The third electrical connector 80 may be configured to carry the flexible circuit 20 and the third electrical connector 80 may be configured to be received in a mating connector, such as a receptacle connector 82.

The flexible circuit 20 may have a first circuit end 134 and a second circuit end 136. The first circuit end 134 may be configured to interface directly or indirectly with the die footprint 141. The flexible circuit 20 may be flared (flare) such that a first flexible width d1 of the flexible circuit 20 at the first circuit end 134 is less than a second flexible width d2 at the second circuit end 136. The amount of d2/d1, which represents the width difference between the ends, may be greater than about 1.2, 1.5, 2, 2.5, or 3. The splaying (flaring) between the first circuit end 134 and the second circuit end 136 of the flexible circuit 20 may be such that the pitch between the flexible signal pads 30 and/or flexible ground pads 35 on the second circuit end is greater than the pitch between the flexible signal pads 30 and/or flexible ground pads 35 on the first circuit end 134. Having a larger pitch may help establish electrical connection with the second end 136 of the flexible circuit 20, as described in more detail below.

The die package substrate 74 may carry at least 1024 differential signal pairs on only the first major surface 200, only the second major surface 202, or both the first and second major surfaces 200, 202 of the die package substrate 74. The die package footprint 140 may be arranged such that at least 1024 differential signal pairs are set by only the first major surface 200, only the second major surface, or both the first and second major surfaces 200, 202 of the die package substrate 74. At least two of each of the first die package face 178, the second die package face 180, the third die package face 182, and the fourth die package face 184 may be configured to receive the respective flexible circuit 20 on the socket connector 76, the package connector 138, the anisotropic conductive film 164, the first electrical connector 42, the second electrical connector 60, the communication module 71, the third electrical connector 80 in combination with the socket connector 76, the package connector 138, the anisotropic conductive film 164, the direct crimp connector, or other suitable electrical connector or electrical component, either through a direct connection between the respective flexible signal pad 30 and/or the flexible ground pad 35 and the respective package pad 162, or indirectly through a BGA-to-LGA connector.

The IC die package 72 may include an IC die 70 and a die package substrate 74, and the die package substrate 74 may define a first die package face 178, a second die package face 180, a third die package face 182, and a fourth die package face 184. The length of each of the respective die package faces 178, 180, 182, 184 may be no more than about 105 millimeters or about 110 millimeters or about 115 millimeters or about 120 millimeters, such as about 70 millimeters, about 75 millimeters, about 80 millimeters, about 85 millimeters, about 90 millimeters, and the like. At least one hundred twenty-eight package dice 162 or at least two hundred fifty-six package dice 162 may be disposed on each of the first die package face 178, the second die package face 180, the third die package face 182, and the fourth die package face 184. Each of the encapsulation sheets 162 may be configured to be directly attached to the flexible circuit 20 or indirectly attached to the flexible circuit 20, respectively, as described above. The electrical communication system 220 may include the IC die packages 72 described herein and one or more flexible circuits 20 physically attached, electrically attached, or both physically and electrically attached to the respective package pieces 162.

The die package substrate 74 may include a first die package face 178, a second die package face 180, a third die package face 182, and a fourth die package face 184. Each of the respective die package faces 178, 180, 182, 184 may be at least 50 millimeters in length, but no more than about 75 millimeters, about 80 millimeters, about 85 millimeters, about 90 millimeters, about 95 millimeters, about 100 millimeters, about 105 millimeters, about 110 millimeters, or about 115 millimeters. At least one hundred twenty-eight package pieces 162 or at least two hundred fifty-six package pieces 162 may be provided on each of the respective first die package face 178, second die package face 180, third die package face 182, and fourth die package face 184. Each of the package tabs 164 may be configured to be directly attached to the flexible circuit 20 or indirectly attached to the flexible circuit 20.

The die package substrate 74 may include a first major surface 200 and an opposing second major surface 202. At least 1024 differential signal pair tiles may be carried by only the first major surface 200, only the second major surface 202, or carried by both the first and second major surfaces 200, 202. At least 1024 differential signal pair tiles may be disposed on each of the respective first, second, third, and fourth package faces 178, 180, 182, 184 with at least two hundred fifty-six differential signal pair tiles. The at least 1024 differential signal pair plates may be SMT plates or crimp plates.

Referring now to fig. 6C-6G, the electrical communication assembly 40 may include a second electrical connector 60, the second electrical connector 60 configured to be mounted to the first circuit end 134 of the flexible circuit 20. The second electrical connector 60 may have a plurality of second electrical contacts 62, the plurality of second electrical contacts 62 including second electrical ground contacts and second electrical signal contacts that may be arranged in a differential signal pair, and a second dielectric connector housing 64 that may support the second electrical contacts 62. The second electrical contacts 62 of the second electrical connector 60 may be disposed in electrical communication with the flexible signal conductors 26 of the flexible circuit 20 or in physical connection with the corresponding flexible signal sheets 30. For example, in some examples, the second electrical contact 62 may be soldered to the flex circuit 20. In particular, the second electrical contacts 62 may have respective second mounting ends 66, the second mounting ends 66 being configured to mount to the flexible circuit 30, such as to the respective flexible signal sheets 30, such that the second electrical contacts 62 are in electrical communication with the flexible signal conductors 26 of the flexible circuit 20. The second electrical contacts 62 may be mounted to the flexible signal sheets 30 of the flexible circuit 20 that are aligned with each other in the lateral direction a in a single row. Alternatively, the flexible signal sheet 30 may be alternatively positioned as desired. For example, the second electrical contacts 62 may define two or more rows of second mounting ends 66 displaced in the longitudinal direction L that are configured to be mounted to corresponding ones of the flexible signal sheets 30 of the flexible signal conductors 26 of the flexible circuit 20. Fig. 6B and 6C illustrate examples of electrical communication systems 40 having two rows.

The second electrical connector 60, and in particular the second electrical contact 62, may be provided to electrically communicate the flex circuit 20 with an IC die 70 of an IC die package 72, the IC die package 72 including a die package substrate 74 and the IC die 70 mounted on the die package substrate 74. The die package substrate 74 may be provided as a PCB. The communication assembly 40 may also include a heat sink 67 (fig. 6F), the heat sink 67 may be in thermal communication with the IC die 70 and configured to dissipate heat from the IC die 70 during operation. The second electrical connector 60 may define a second receptacle 76, and the second receptacle 76 may be sized to receive edges of the respective first, second, third, and/or fourth package faces 178, 180, 182, 184 of the die package substrate 74 such that the second mating ends 68 of the second electrical contacts 62 may mate with the die package substrate 74 to define a separable interface therebetween. For example, the first row of second electrical contacts 62 may interface with the first major surface 200 of the die package substrate 74. The second row of second electrical contacts 62 may also interface with the first major surface 200 of the die package substrate 74. Alternatively, the second row of second electrical contacts 62 may interface with a second major surface 202 of the die package substrate 74 opposite the first major surface 200 in the transverse direction T. The flexible circuit 20 may be oriented substantially parallel to the die package substrate 74.

In the example shown in fig. 6A to 6F, the flexible circuit 20 may be single-sided. In particular, the flexible signal sheet 30 may be disposed at the first flexible circuit surface 23A of the first circuit end 134 to interface with the die package substrate 74. The flexible signal sheet 30 may be disposed at the second flexible circuit surface 23B at the second circuit end 136 to interface with the module substrate 73. The second circuit end 134 of the flexible circuit 20 may interface with a first surface of the module substrate 73 opposite a second surface of the module substrate 73 to which the fourth electrical connector 75 is mounted. The first surface may be opposite the second surface. Alternatively, the flexible circuit 20 and the fourth electrical connector 75 may be mounted on the same surface of the module substrate 73.

The flex circuit 20 may be docked to the die package substrate 74 in any manner as desired. In one example, the communication assembly 40 may include a first compression clip (not shown) compressed between the die package substrate 74 and the heat sink 67. The first circuit end 134 of the flex circuit 20 may be positioned between the first pinch-off clamp and the die package substrate 74. The compressive force of the first compression clip may be applied to the flex circuit 20, thereby causing the flex circuit 20 to bear against the die package substrate 74 and establish an electrical connection between the flexible signal sheet 30 at the first circuit end 134 of the flex circuit 20 and the die package substrate 74. The compressive force of the first compression clip may further maintain the flexible signal sheet 30 of the flexible circuit 20 in contact against the die package substrate 74. In one example, the flexible signal sheet 30 at the first flex circuit surface 23A of the flex circuit 20 may be placed against the die package substrate 74, thereby interfacing the flex circuit 20 to the die package substrate 74. The flexible signal sheet 30 of the flexible circuit 20 may be placed directly against the corresponding package sheet 162 of the die package substrate 74, or may be placed against the corresponding first electrical contact 44, which in turn interfaces with the corresponding package sheet 162 of the die package substrate 74, or may interface with the die package substrate 74 according to any suitable alternative described herein.

The flexible circuit 20 may be similarly docked to the module substrate 73. In particular, the connectivity module 71 may include a housing seat 91 supported by the module substrate 73 or relative to the module substrate 73. The corresponding second clamping clips 77 may be compressed between the housing base 91 and the module substrate 73. The second circuit end 202 of the flexible circuit 20 may be positioned between the second clamp 77 and the module substrate 73 such that the clamping force of the second clamp 77 is applied to the flexible circuit 20 to urge the flexible circuit 20 against the module substrate 73 to establish an electrical connection between the flexible signal sheet 30 at the second circuit end 136 of the flexible circuit 20 and the module substrate 73. The force generated by the second clamping clip 77 may further maintain the compression of the flexible signal sheet 30 of the flexible circuit 20 against the module substrate 73. In one example, the flexible signal sheet 30 at the second flexible circuit surface 23B of the flexible circuit 20 may be placed against the module substrate 73, thereby interfacing the flexible circuit 20 to the module substrate 73. The flexible signal sheet 30 of the flexible circuit 20 may be placed directly against the package sheet 162 of the module substrate 73, or may be placed against the corresponding first electrical contact 42 or second electrical contact 62 or socket contact 94, which in turn may be docked or mounted to the corresponding package sheet 162 of the die package substrate 74, or the flexible signal sheet 30 of the flexible circuit 20 may be docked to the module substrate 73 according to any suitable alternative described herein.

As shown in fig. 6C, the package pieces 162 of the die package substrate 74 may be arranged in one or more rows 61, including two rows 61, three rows 61, four rows 61, or more rows 61 as desired. The rows 61 may be oriented substantially parallel to each other. Thus, the flexible signal sheets 30 of the flexible circuit 20 may be similarly arranged in more than one row to be in electrical communication with the corresponding row 61 of package sheets 162 of the die package substrate 74. The rows of flexible signal sheets 30 (see fig. 2A) may be oriented parallel to each other and displaced in association with the interfacing flexible circuit 20 along the longitudinal direction L. The ground contact pads 35 may be disposed between and aligned with adjacent flexible signal pads 30 or corresponding pairs of flexible signal pads 30 along each row as desired.

Referring now to fig. 7A-7E, the electrical communication assembly 40 may include a third electrical connector 80, which may be referred to as a first plug connector, and an edge card-type receptacle connector 82 configured to mate with the third electrical connector 80. The third electrical connector 80, in turn, may be placed in physical communication, electrical communication, or both physical and electrical communication with a corresponding electrical component, such as the flex circuit 20, thereby placing the flex circuit 20 in electrical communication with the receptacle connector 82. The receptacle connector 82 may be mounted directly or indirectly to an electrical component such as the second substrate 81 or PCB such that the second substrate 81 is in electrical communication with the flexible circuit 20 through the receptacle connector 82 and the electrical connector 80.

For example, the third electrical connector 80 may include a dielectric third connector housing 89 and a plurality of third electrical contacts 84 supported by the third connector housing 89. The third electrical contact 84 may be contoured in the manner described above. Alternatively, the third electrical contact 84 may be stamped and rolled and may be positioned edge-to-edge, e.g., edge-facing the contact. The third electrical contact 84 may include a third signal contact 86 and a third ground contact 88 in the manner described above.

The third electrical connector 80 may be configured to mate with the receptacle connector 82 along the longitudinal direction L. The third electrical connector 80 may be sized to receive the flexible circuit 20 such that the third electrical connector 80 is in electrical communication with the flexible circuit 20. In particular, the third electrical contacts 84 may be arranged in a first row 92A and a second row 92B, each of the first row 92A and the second row 92B extending along opposite faces of the third connector housing 89 opposite each other along the transverse direction T. Each of the first and second rows 92A, 92B may be oriented in a lateral direction a. The third electrical contacts 84 may each have a third mounting end 85, the third mounting ends 85 each being disposed at opposite faces of the receptacle connector 82 with respect to the transverse direction T. The first row 92A of third electrical contacts 84 may be in electrical communication with the respective flexible signal pad 30 and the respective flexible ground pad 35 of the flexible circuit 20 as described above, and the second row 92B of third electrical contacts 84 may be in electrical communication with the respective flexible signal pad 30 and the respective flexible ground pad 35, respectively, as described above. The flexible signal pad 30 and the flexible ground pad 35 may be positioned on a first flexible circuit surface 23A of the flexible circuit 20 and a second flexible circuit surface 23B of the flexible circuit 20, respectively.

In one example, the third electrical connector 80 may be mounted to the flexible circuit 20 such that the interface between the third mounting ends 85 of the third electrical contacts 84 is permanently secured to the corresponding flexible signal sheets 30 of the flexible circuit 20. Thus, the interface between the third electrical connector 80 and the flexible circuit 20 is not separable. In other examples, the third electrical connector 80 may interface with the flexible circuit 20, thereby setting a separable interface between the third electrical connector 80 and the flexible circuit 20. As described above, the first contact rows of the first plurality of flexible signal conductors 26 and their corresponding flexible signal pads 30 and flexible ground pads 35 of the flexible circuit 20 may be offset in the transverse direction T relative to the immediately adjacent second contact rows of the second plurality of flexible signal conductors 26 and their corresponding flexible signal pads 30 and flexible ground pads 35 of the flexible circuit 20. Accordingly, all differential signal pairs in the first row 92A of the third electrical contacts 84 may be offset in the transverse direction T relative to all differential signal pairs of the second row 92B of the third electrical contacts 84. In other words, at least one signal conductor of the differential signal pair in the first contact bank may face toward the ground conductor in the second contact bank, and vice versa.

The third electrical contacts 84 may each extend along opposite faces of the third connector housing 89 opposite each other in the transverse direction T to define third mating ends 87, the third mating ends 87 each being positioned opposite the third mounting ends 85, respectively, and each being configured to mate with the receptacle connector 82. In one example, the third mating end 87 and the third mounting end 85 of the immediately adjacent third electrical contact 84 may be spaced apart (jog) from each other in the lateral direction a. The third electrical contacts 84 of each of the first and second rows 92A, 92B may be spaced apart from each other in the lateral direction a by a center-to-center contact pitch. The contact pitch may be about 0.5 millimeters or any suitable alternative contact pitch as desired.

With continued reference to fig. 7A-7E, the receptacle connector 82 may have or define a receptacle housing 90, such as a card edge housing, the receptacle housing 90 defining a receptacle 92 and electrical receptacle contacts 94, such as edge card receptacle contacts, the electrical receptacle contacts 94 being arranged in first and second receptacle rows 96A, 96B disposed at opposite faces of a slot in the receptacle 92. The first socket row 96A and the second socket row 96B of the socket contacts 94, such as edge card socket contacts, may be opposite each other along the transverse direction T. In one example, the receptacle housing 90 has a maximum width in the transverse direction T, which may be in the range of about 1 millimeter to about 4 millimeters. For example, the width may be about 2 millimeters. Adjacent socket contacts 94 may be spaced apart from one another along a center-to-center contact pitch of, for example, about 1.2 millimeters, about 0.3 millimeters to about 2 millimeters.

The receptacle contacts 94 may each define a respective receptacle mating end 98 and a receptacle mounting end 100 positioned opposite the receptacle mating end 98 in the longitudinal direction L. The receptacle mating end 98 may be configured to mate with the third mating end 87 of the third electrical contact 84 of the third electrical connector 80 to set a separable interface therebetween. In particular, the receptacle housing 90 may receive the plug end of the third connector housing 89 in the receptacle 92, thereby mating the receptacle connector 82 with the third electrical connector 80. In one example, the entire width of the third connector housing 89 in the transverse direction T may be sized to be inserted into the receptacle housing 90 to mate the third electrical connector 80 with the receptacle connector 82. In one example, the respective socket mating end 98 of the socket contact 94 may be configured to wipe a distance along the third mating end 87, which may be less than about 2 millimeters when the socket mating end 98 and the third mating end 87 are mated to each other. In one example, the swab distance may be about 0.5 millimeters. In one example, the mating surfaces of the third mating end 87 and the receptacle mating end 98 may not be polished along their respective swabbing surfaces. The swabbing surface that is not polished may include smaller irregularities (irregulation) that help break through any oxide or organic film that may be present on the swabbing surface, thereby reducing contact resistance. In one example, the third connector housing 89 may define a third housing portion 83 coplanar with at least one of the third electrical contacts 84 in a plane including the longitudinal direction L and the lateral direction a, and the third housing portion 83 may be configured to abut the receptacle housing 90 in the receptacle 92 when the third electrical connector 80 is fully mated with the receptacle connector 82. The receptacle mounting ends 100 may each be configured to mount to an electrical component such as the substrate 81 or a PCB. Accordingly, the second substrate 81 may be in electrical communication with the flexible circuit 20. The second substrate 81 may be oriented substantially orthogonal to the flexible circuit 20. The immediately adjacent signal contacts of the differential signal pairs of the receptacle contacts 94 of the receptacle connector 82 may be spaced apart from each other at each of the receptacle mating end 98 and the receptacle mounting end 100. Moving the corresponding receptacle contacts 94 away (joging) may increase the mechanical tolerances allowed during mating while helping to maintain a relatively uniform impedance through the electrical communication assembly 40.

The receptacle contacts 94 may each be loaded into the receptacle housing 90 in any manner as desired. For example, the receptacle housing 90 may define a plurality of receptacle housing slots 102, with each of the plurality of receptacle housing slots 102 opening to at least one exterior surface of the receptacle housing 90. At least one of the outer surfaces may be set by opposing outer surfaces opposing each other in the transverse direction T. The receptacle contacts 94 may each be loaded into the receptacle housing slots 102 along an attachment direction in a plane perpendicular to the longitudinal direction L. In one example, the attachment direction may be oriented along the transverse direction T. If desired, the receptacle contacts 94 may be insert molded into a retention housing that prevents removal of the receptacle contacts 94 from the receptacle housing slots 102 in a removal direction that is substantially opposite the attachment direction. In another example, the receptacle contacts 94 may be insert molded into the receptacle housing 90.

In one example, the third electrical contact 84 or the receptacle contact 94 of one of the third electrical connector 80 and the receptacle connector 82 may be made differently than the third electrical contact 84 or the receptacle contact 94 of the other of the third electrical connector 80 and the receptacle connector 82. For example, the third electrical contact 84 or the receptacle contact 94 of one of the third electrical connector 80 and the receptacle connector 82 may be contoured, and the third electrical contact 84 or the receptacle contact 94 of the other of the third electrical connector 80 and the receptacle connector 82 may each be stamped and rolled. In one example, the receptacle contacts 94 of the receptacle connector 82 may each be contoured and the third electrical contacts 84 of the third electrical connector 80 may each be stamped and rolled. In one example, none of the third electrical contacts 84 or the receptacle contacts 94 of the third electrical connector 80 or the receptacle connector 82 circumscribe (circumscribing) a corresponding mating contact of the other of the third electrical connector 80 and the receptacle connector 82, respectively. In other words, a connection cannot be established with a socket-type electrical connection through a pin.

As shown in fig. 7C, when the receptacle connector 82 is mated with the third electrical connector 80, the cross-section of the electrical communication assembly 40 may include, in order from left to right, the first receptacle contact 94 of the receptacle connector 82, the first third electrical contact 84 of the third electrical connector 80, the third connector housing 89 may be provided as part of a plug, the second third electrical contact 84 of the third electrical connector 80, and the second electrical contact 94 of the receptacle connector 82.

Referring now also to fig. 8A-8E, the receptacle connector 82 is configured to mate with the third electrical connector 80 described above, the third electrical connector 80 may also be referred to as a first plug connector or a first electrical edge card plug connector. The receptacle connector 82 may also be configured to mate with a second header connector 110, such as an electrical edge card header connector. Accordingly, the receptacle connector 82 may be configured to selectively mate with the third electrical connector 80 alone, the third electrical connector 80 may be in electrical communication with the flexible circuit 20, the second plug connector 110, or both, and the second plug connector 110 may be mounted to the second substrate 81, e.g., a PCB, and thus in electrical communication with the second substrate 81. In other words, the receptacle connector 82 may mate with the first or third electrical connector 80 or the second plug connector 110.

The description of the third electrical connector 80 may apply to the second plug connector 110, except that the second plug connector 110 may include at least one ground common strip 128a, 128b, and the second plug connector 110 may be configured to be mounted to the second substrate 114 as opposed to the flexible circuit 20, as will now be described. The second plug connector 110 may be configured to be received in the receptacle 92 of the receptacle connector 82. The second plug connector 110 may include a second plug connector housing 116, and the second plug connector housing 116 may be configured to be inserted into the receptacle housing 90 along the longitudinal direction L to mate the receptacle connector 82 with the second plug connector 110. In some examples, the entire width of the second plug connector housing 116 in the transverse direction T may be sized to be inserted into the receptacle housing 90. The second plug connector 110 may include one or more electrical plug contacts 118 arranged in first and second plug rows 120A, 120B, each of which may extend along opposing faces of the second plug connector housing 116 that oppose each other along the transverse direction T. Each of the first plug row 120A and the second plug row 120B of the electrical plug contacts 118 may include electrical signal contacts and/or electrical ground contacts, respectively, in the manner described above. Thus, each of the first header row 120A and the second header row 120B may each include a differential signal contact pair separated by at least one ground contact, which may be set by a single ground contact or a pair of ground contacts. The header contacts 118 of each of the first header row 120A and the second header row 120B may be spaced apart from each other along a center-to-center contact pitch in the range of about 0.3 millimeters to about 1.5 millimeters, such as along a contact pitch of about 1.2 millimeters, along the lateral direction a.

In one example, the receptacle mating end 98 of the receptacle contact 94 may be configured to wipe a wipe distance along the respective plug mating end 122 when the receptacle mating end 98 and the respective plug mating end 122 of the plug contact 118 are mated with each other, which may be less than about 2 millimeters. In one example, the swab distance may be about 0.5 millimeters. In one example, the mating surfaces of the receptacle mating end 98 and the corresponding plug mating end 122 may not be polished along their respective swabbing surfaces. In one example, the second plug connector housing 116 may define a second plug housing portion 117, the second plug housing portion 117 may be coplanar with the at least one plug contact 118 in a plane including the longitudinal direction L and the lateral direction a, and the second plug housing portion 117 may be configured to abut the receptacle housing 90 within the receptacle 92 when the receptacle connector 82 is fully mated with the second plug connector 110.

The plug contacts 118 may each define a respective plug mounting end 124 such that the plug mounting end 124 of each of the first and second plug rows 120A, 120B may be mounted to a respective electrical component, such as the second substrate 114, which may be configured as a PCB. When the second plug connector 110 is mounted to the second substrate 114 and the receptacle connector 82 is mounted to the substrate 81, the substrate 81 and the second substrate 114 may be spaced apart from each other to set a stacking height in the longitudinal direction L in a range of about 2 mm to about 4 mm. In one example, the stack height may be about 3 millimeters.

In one example, the receptacle contact 94 or the plug contact 118 of one of the receptacle connector 82 and the second plug connector 110 is made differently than the third electrical contact 84 or the plug contact 118 of the other of the receptacle connector 82 and the second plug connector 110. For example, the respective receptacle contact 94 or header contact 118 of the receptacle connector 82 or second header connector 110 may be contoured, while the other of the receptacle connector 82 or second header connector 110 may have a stamped and rolled receptacle contact 94 or header contact 118. In one example, the receptacle contacts 94 of the receptacle connector 82 may be contoured and the header contacts 118 of the header connector 110 may be stamped and rolled. In one example, either the receptacle contact 94 or the plug contact 118 does not circumscribe the corresponding mating contact of the other. In other words, the receptacle contacts 94 and the header contacts 110 may define the shape of the respective pins in the non-socket.

As shown in fig. 8C, when the receptacle connector 82 is mated with the second plug connector 110, the cross-section of the electrical communication assembly 40 includes, in order from left to right, the first receptacle connector 94 of the receptacle connector 82, the first plug contact 118 of the second plug connector 110, the plug housing portion 117 of the second plug connector housing 116, the second plug contact 118 of the second plug connector 110, and the second receptacle contact 94 of the receptacle connector 82.

The second plug connector 110 may also include first and second conductive ground common strips 128a, 128B, the first and second conductive ground common strips 128a, 128B electrically communicating at least some, or even all, of the plug contacts 118 of the first and second plug rows 120A, 120B, respectively, with one another. In particular, each of the first and second common ground strips 128a, 128B may extend in a longitudinal or mating direction from at least some, and even all, of the ground contacts of a respective one of the first and second plug rows 120A, 120B of plug contacts 118, respectively, to a location spaced from the mating ends of the signal or differential signal plug contacts 118 of the first and second rows 120A, 120B. In one example, the first and second ground common bars 128a, 128b may each define respective, opposing first and second main bar surfaces 130a, 130b that may each flare inwardly (fire) or converge toward each other as the first and second main bar surfaces 130a, 130b extend in the mating direction. For example, the first and second ground common bars 128a and 128b may each define opposing, corresponding first and second main bar surfaces 130a and 130b, respectively, which may each gradually widen toward each other as the first and second main bar surfaces 130a and 130b extend in the mating direction. In one example, the first and second major strip surfaces 130a, 130b may each linearly taper toward each other.

It should be appreciated that any electrical contact or conductor of the electrical communication assembly 40 may be made of any suitable electrically conductive material, such as metal. Any of the electrical connectors described herein may include magnetically attractable material and/or electrically conductive dissipative material, as desired. The introduction of an absorptive or dissipative material may help reduce cavity resonance in the electrical communication assembly 40. The introduction of conductive dissipative material can help reduce resonance that may be present in the assembly. Any electrically insulating element of the electrical communication assembly 40 may be made of any suitable dielectric material, such as plastic, glass, ceramic, or any suitable non-conductive dissipative material. In another example, it should be appreciated that any suitable component or components of the electrical communication assembly 40 may be constructed as described in PCT publication No. WO2020014597, which is incorporated herein by reference in its entirety.

It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. For example, while the electrical connectors described herein are shown as interfacing with or mounted to the flexible circuit 20 described above with reference to one of fig. 1A-1F and 2A-2F, it should be understood that the electrical connectors may alternatively interface with or be mounted to the flexible circuit 20 described above with respect to other figures herein. In particular, the flex circuit need not be a three-layer flex circuit, but may have two, five, or any number of conductive layers. The present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.

Referring now to fig. 9, a high density interconnect 132 is shown. In one or more embodiments, the flexible circuit 20 may fan out or spread out (flare out), widen or fan out from the first circuit end 134 to the second circuit end 136. Thus, the interconnect density may fan out or splay from the die package substrate 74 to the second circuit end 136. For example, the interconnect density may be fanout from a pitch of about 300 microns (about 0.3 millimeters) to a pitch of about 600 microns (about 0.6 millimeters). One advantage is that the die package substrate 74 may be a square of 50 mm to 110 mm or 115 mm or 120 mm, with a square of 70 mm to 90 mm being the most popular side length at present. The cables 79, such as twinax cables, have a tight cable conductor pitch, but the extruded insulation, shielding, outer jacket, and possibly drain wires that encase the first and second cable conductors thicken or widen each twinax cable to directly or indirectly interface 1024 differential encapsulation pieces 162 on the first major surface 200, the second major surface 202, or both, of the die package substrate 74.

The flexible circuit 20, either attached directly to the die package substrate 74 or attached to the die package substrate 74 through a connector attached directly to the die package substrate 142, can help solve density issues that coaxial and biaxial cables cannot provide. The flexible circuit 20 may be denser at the first circuit end 134 or the second circuit end 136 for connection with the high-density package piece 162. On the other respective end of flex circuit 20, flexible signal conductors 26 may be spaced farther apart from each other, which results in a lower density of signal flexible contact pads to accommodate thicker or wider extruded coaxial cables, extruded waveguides, or extruded and clad dual-axis cables. In this particular example, the length of flex circuit 20 may be kept short enough to establish a physical connection with IC die 70, either directly or indirectly through one or more connectors. The flexible circuit 20 may have more unwanted dissipation characteristics than a corresponding coaxial, twinaxial, or radio frequency cable of the same length. Thus, the respective lengths, pitches, AWGs, etc. of both the flex circuit 20 and the associated flex circuit cables 79 may be shortened, lengthened, modified or altered until the desired density and signal integrity is maintained at the first circuit end 134 of the flex circuit 20, the second end 136 of the flex circuit 20, any flex circuit cables 79 attached to the first end of the flex circuit 20, and any flex circuit cables 79 attached to the second end of the panel connector 203, the backplane connector, the parallel plate connector, or other electrical component. The present disclosure is not limited to cable assemblies that include a hybrid of flexible circuit 20 and non-flexible circuit cable 79.

As shown substantially in fig. 10A, the high density interconnect 132 may substantially include one or more flexible circuits 20, such as the flexible circuits 20 described above. Each of the one or more flexible circuits 20 may include at least two layers, at least three layers, at least four layers, at least five layers, only two layers, only three layers, only four layers, only five layers, only six layers, only seven layers, only eight layers, only nine layers, only ten layers, only eleven layers, only twelve layers, three or more layers, four or more layers, five or more layers, six or more layers. The minimum number of layers for the chosen application is preferred. In the three-layer flexible circuit 20 configured with the stripline transmission structure, the first and second layers may each be a ground layer, a ground plane, or a first conductive layer 22 and a second conductive layer 24. The third layer, positioned between the first and second layers, may be a signal layer comprising only signal traces or only flexible signal conductors 26 or a combination of signal traces and ground traces and possibly a second inter-dielectric layer 27. In a flex circuit 20 having more than three layers, the other individual conductive layers may be ground layers or signal layers as desired.

Three or more flexible signal pads 30 and/or flexible ground pads 35 may be positioned on any of the following: only on the first flex circuit face 23A of the first circuit end 134 of the corresponding flex circuit 20; only on the second flex circuit face 23B of the first circuit end 134 of the corresponding flex circuit 20; only on the first flex circuit face 23A of the second circuit end 134 of the corresponding flex circuit 20; only on the second flex circuit face 23B of the second circuit end 134 of the corresponding flex surface; only on the first flexible surface face 23A and the second flexible surface face 23B of the first circuit end 134 of the respective flexible circuit 20; only on the first flexible surface face 23A and the second flexible surface face 23B of the second circuit end 136 of the respective flexible circuit 20; only on the first flex circuit face 23A of both the first circuit end 134 and the second circuit end 136 of the respective flex circuit 20; only on the second flex circuit face 23B of both the first circuit end 134 and the second circuit end 136 of the respective flex circuit 20; only on the first flexible circuit face 23A and the second flexible circuit face 23B of the first circuit end 134 of the respective flexible circuit 20, and on one or both of the first flexible surface face 23A and the second flexible surface face 23B of the second circuit end; and only on the first flex circuit face 23A and the second flex circuit face 23B at the second circuit end 136 of the respective flex circuit 20, and on one or both of the first flex surface face 23A and the second flex surface face 23B at the first circuit end 134 of the respective flex circuit 20.

Two of the three or more flexible signal sheets 30 may be differential signal sheets. Each respective differential signal pad may be surrounded by a counter pad 32, the counter pad 32 being disposed in the respective first conductive layer 22 and second conductive layer 24 of the flex circuit 20 to isolate the differential signal pad from the respective first conductive layer 22 and second conductive layer 24 and may be electrically, physically, or both connected to a respective signal trace or flex signal conductor 26 in the second inner dielectric layer 28 of the flex circuit 20. For example, the flexible signal sheet 30 may be electrically connected to the corresponding signal trace by a conductive filled via. The flexible signal sheet 30 pitch at the first circuit end 134 may be about 0.3 millimeters. In a differential pair arrangement, the differential pair pitch may be about 0.9 millimeters. These flexible signal sheets 30 and differential pair pitches may produce at least sixty-four to at least two hundred fifty-six differential signal pairs at the first circuit end 134 of each respective flexible circuit 20. The flexible signal sheet 30 adjacent the first circuit end 134 may be positioned only on the first flexible circuit face 23A, the second flexible circuit face 23B, or both, of the respective flexible circuit 20.

Three or more flexible signal sheets 30 may be positioned on the first flexible circuit face 23A, the second flexible circuit face 23B, or both, of the second circuit end 136 of the respective flexible circuit 20. Two of the three or more signal flex pads 30A may be differential signal pads. Each respective differential signal pair may be surrounded by a counter plate 32, the counter plate 32 being disposed in the ground plane or first conductive layer 22 of the respective flex circuit 20 and/or in the ground plane or second conductive layer 24 of the flex circuit 20. Each flexible signal sheet 30 that forms a differential signal pair may be electrically, physically, or both electrically and physically connected to a corresponding signal trace or flexible signal conductor 26 in a third or first inter-dielectric layer 27 of the flexible circuit 20. For example, the flexible signal pads 30 may be conductively filled via holes that are electrically connected to corresponding signal traces or flexible signal conductors 26. The flexible signal sheet 30 pitch at the second circuit end 136 or at the first circuit end 134 may be about 0.6 millimeters. In a differential pair arrangement, the differential pair pitch may be about 1.7 millimeters to 2 millimeters, which allows space for one or more ground contacts between each differential signal pair or differential pair package plate 162. These flexible signal sheets 30 and differential pair pitches may produce at least sixty-four to at least two hundred fifty-six differential signal pairs on each at the second circuit end 136 of each respective flexible circuit 20. The electrical contact pads 30a adjacent the second circuit end 136 may be positioned on only the first flex circuit face 23A of the respective flex circuit 20 or only the second flex circuit face 23B of the respective flex circuit 20, or on both sides, or on two different, spaced apart layers of the flex circuit 20 or on the first flex circuit face 23A and the second flex circuit face 23B.

Each of the three or more flexible signal sheets 30 positioned adjacent the first circuit end 134 of the respective flexible circuit 20 may be carried by the third signal layer or the first inner dielectric layer 27 of the respective flexible circuit 20, with the respective conductive trace and the respective via, e.g., filled with a conductive via, physically connected, electrically connected, or both physically and electrically connected to a respective one of the three or more electrical contact sheets 30 positioned adjacent the second circuit end 136 of the respective flexible circuit 20.

As shown in fig. 10B, for example, the flexible signal pad 30 and the flexible ground pad 35 near the second circuit end 136 of the flexible circuit 20 may be arranged in a repeating G-S-G arrangement, a repeating G-S arrangement, a repeating G-S arrangement, or any combination thereof.

As shown in fig. 10C, the high-density interconnects 132 may also include electrical package connectors 138, the electrical package connectors 138 being configured to electrically connect, physically connect, or both physically and electrically connect to corresponding die package footprints 140 of the die package substrate 74. The die package substrate 74 may have a plurality of die package footprints 140, such as one die package footprint 140 positioned along each edge or die package face 178, 180, 182, 184 of the die package substrate 74, as shown in fig. 6A. The package connector 138 may be made of a non-conductive material and/or a magnetically attractive material. The package connector 138 may set at least one, at least two, at least three, or at least four of the first mating surface 144, the second mating surface 146, the third mating surface 148, and the fourth mating surface 150. The first and second abutment surfaces 144, 146 may be stepped such that the second abutment surface 146 is spaced farther from the first major surface 200, such as the first major surface 200 or the second major surface 202, than the first abutment surface 144. The third abutment surface 148 may be stepped relative to both the first and second abutment surfaces 144, 146 such that the third abutment surface 148 is spaced further from the first major surface 200 than either of the first and second abutment surfaces 144, 146. The fourth abutment surface 150 can be stepped relative to the first, second and third abutment surfaces 144, 146, 148 such that the fourth abutment surface 150 is spaced further from the first major surface 200 than any of the first, second and third abutment surfaces 144, 146, 148. The package connector 138 may also be an LGA-LGA (land grid array) connector, a BGA-LGA connector, a crimp cable connector, or any other connector described herein that may be mounted to the first major surface 200, and/or the second major surface 202, wherein the LGA-LGA connector is, for example, a ZRAY brand connector commercially available from the shentai company of new albany, indiana.

Having multiple docking levels at different heights above the first major surface 200 is not mandatory, but may allow for higher density interconnects than a single docking level. This may allow IC die package 72 to have more high speed input/output channels, such as 512 differential signal pair channels or 1024 differential signal pair channels. The use of flexible circuit 20 may also provide advantages over packaging density. The flexible nature of the flexible circuits 20 may enable the spacing between the flexible circuits 20 to be changed from a first circuit end 134 of the flexible circuits 20 to a second circuit end 136 of the flexible circuits 20. This may allow more room for the flexible connector housing 168 and the flexible electrical connector 172 (both discussed below) at the second circuit end 136 of the flexible circuit 20. The ability of the flex circuit 20 to have a single-sided flex signal pad 30 and a flexible ground pad 35 at the first circuit end 134 of the flex circuit 20 and a double-sided connection of the flex signal pad 30 and the flexible ground pad 35 at the second circuit end 136 of the flex circuit 20 may allow for a pitch between adjacent contacts at the second circuit end 136 that is twice the pitch between adjacent contacts on the first circuit end 134 without any fanning out of the flex signal conductors 26. Fanning out of the signal traces may further increase the contact spacing. Increasing the contact spacing between adjacent flexible electrical connectors 172 may allow separable interconnections at the second circuit end 136 to be established more reliably with reduced mechanical tolerances.

Each of the first, second, third, and fourth mating surfaces 144, 146, 148, 150 may carry at least one, at least two, at least three, or three or more substantially parallel linear arrays or rows, respectively, of electrical package connector conductors 154. Each package connector conductor 154 may extend from a first package connector end 156 to an opposing second package connector end 158. The respective first package conductor ends 156 of each respective package connector conductor 154 may be electrically attached, physically attached, or both physically and electrically attached to the respective package tabs 162 of the die package footprint 140. The encapsulation sheets 162 may be arranged in a plurality of rows on each side of the die package substrate surface 152. The rows may be grouped such that each group of rows is aligned directly beneath a respective one of the first, second, third, and fourth mating surfaces 144, 146, 148, 150. As shown, each first package conductor end 156 may be electrically and physically attached to an intermediate anisotropic conductive film 164, as shown, to a corresponding package tab 162, or to an electrical connector that is physically attached to the package tab 162. There are various types of intermediate anisotropic conductive films 164. Some types of intermediate anisotropic conductive films provide a separable interface between the die package substrate 74 and the package connector conductors 154 of the package connector 138. Examples of intermediate anisotropic conductive films that provide separable interfaces include, but are not limited to: PARIPOSER brand anisotropic elastic fabric commercially available from pareconazole technologies (PARICON TECHNOLOGIES) of tangton, ma, and nanowires commercially available from norveder co (Nanowired GmbH) of ganassheim, germany. Alternatively, each first package conductor end 156 may be attached to a package piece 162 or trace on die package substrate 74 by a reflow process such as a C4 process or by a permanent intermediate anisotropic conductive film 164 such as, but not limited to, an aniolm brand anisotropic conductive film commercially available from the company s of electrical materials (united states) of san jose, california.

Flexible signal sheet30 may each be positioned at the first circuit end 134 of a respective flexible circuit 20, may be electrically attached, physically attached, or both electrically and physically attached to a second conductive film, such as the intermediate anisotropic conductor film 164A. Alternatively, the flexible signal sheet 30 may be directly physically connected to a corresponding second package conductor end 170 of a corresponding package connector conductor 154. In other words, the respective flexible signal sheets 30 positioned on the first side S1 or on the first flexible circuit surface 23A of the respective flexible circuit 20 may be electrically, physically, or both electrically and physically connected to the respective package connector conductors 154 or the intermediate anisotropic conductive film 164A. As shown, each second package conductor end 170 may be electrically and physically attached to the intermediate anisotropic conductive film 164A, such as is commercially available from parecon technologies, of tangon, maAn anisotropic elastic fabric.

Referring again to fig. 10A, the first flexible circuit 20 may be electrically attached, physically attached, or both physically and electrically attached to a respective second package conductor end 170 positioned adjacent the first mating surface 144. The second flex circuit 20 may be electrically attached, physically attached, or both physically and electrically attached to a respective second package conductor end 170 of a respective package connector conductor 154 that may be positioned adjacent to the second mating surface 146. The third flex circuit 20 may be electrically attached, physically attached, or both physically and electrically attached to a respective second package conductor end 170 of the respective package connector conductor 154 that may be positioned adjacent the third mating surface 148. The fourth flex circuit 20 may be electrically attached, physically attached, or both physically and electrically attached to a respective second package conductor end 170 of a respective package connector conductor 154 that may be positioned adjacent to the fourth mating surface 150. As shown, but not limited to, each respective flexible circuit 20 may be electrically attached or connected only to the respective first, second, third, and fourth mating surfaces 144, 146, 148, 150 by a respective intermediate anisotropic conductive film 164A.

Stiffener 166 may be added adjacent second circuit end 136 of the corresponding flex circuit 20 to increase the mechanical stability and durability of flex circuit 20. Stiffener 166 may engage holes in flex circuit 20 to help position flex circuit 20 so that flex circuit 20 may be properly aligned with respect to one or more flex connector housings 168. The respective flexible connector housing 168 may be mechanically attached to the respective stiffener 166 to form a flexible electrical connector 172 at least one, at least two, at least three, at least four, or at least four or more second circuit ends 136 of the flexible circuit 20. Each respective flexible connector housing 168 may support, clamp, squeeze, or otherwise retain the second circuit end 136 within the confines of the respective flexible connector housing 168, as well as being tightened (tab) and rigid. For example, each respective flexible connector housing 168 may clamp an opposite edge of each respective second circuit end 136.

In combination, at least one optional stiffener 166, at least one corresponding flexible connector housing 168, and at least one second circuit end 136 may define a flexible electrical connector 172 as shown in fig. 11. With continued reference to fig. 11, two or more flexible circuits 20 may be carried by a single flexible connector housing 168 or two flexible connector housings 168, and a single flexible electrical connector 172 may be formed. Each of the flexible electrical connectors 172 may each define a separable flexible electrical connector mating interface. Each flexible electrical connector 172 may be configured to dock and undock with any one or more of a dual-axis cable 79 or coaxial cable 79 or dielectric waveguide or cable connector 174 or an optical I/O module that may carry a light engine 176. Each cable connector 174 may carry one or more of the following: differential signal pair conductors that are physically attached, electrically attached, or both physically and electrically attached to respective cable signal conductors of cable 79, ground shields or drain wires that are physically attached, or both physically and electrically attached to respective cable 79, and/or dielectric waveguides.

Fig. 12 shows a schematic top view of cable connector subassembly 208 according to an embodiment of the present invention. The cable connector subassembly 208 may include a flexible circuit 20, the flexible circuit 20 having a first circuit end 134 and a second circuit end 136 opposite along the longitudinal direction L. The flexible circuit 20 may have a first conductive layer 22, a second conductive layer 24, flexible signal conductors 26, flexible signal pads 30, and flexible ground pads 35, as previously described, but not shown in fig. 12. Physically attached, electrically attached, or both physically and electrically attached to the second circuit end of the flexible circuit 20 may be a plurality of cables 79. The electrical cable may be a twinaxial cable having two cable signal conductors surrounded by a ground shield or drain wire; however, the cable 79 may be a coaxial cable having a single cable conductor surrounded by a ground shield. Each cable signal conductor of the twinax cable or coax cable may be formed from a wire having a gauge of between 30 and 40 (about 0.25 mm to 0.08 mm wire diameter), such as 32AWG, 34AWG, 36AWG, or 38AWG. All of the cables 79 may be attached to a single first flex circuit surface 23A of the flex circuit 20. Alternatively, some of the cables 79 may be attached to the first flexible circuit surface 23A and the second flexible circuit surface 23B, the second flexible circuit surface 23B being opposite to the first flexible circuit surface 23A in a transverse direction perpendicular to the longitudinal direction and the lateral direction. The cable signal conductors and ground members may be physically attached, electrically attached, or both physically and electrically attached to the respective flexible signal conductors 26, first and/or second conductive layers, flexible signal sheets 30, and/or flexible ground sheets 35 by solder, conductive adhesive, or some other adhesive material. The electrical connection between the flexible circuit 20 and each of the plurality of cables 79 may be a permanent interconnection by, for example, solder. For example, the cable signal conductors of the cable 79 may be soldered to the corresponding flexible signal pads 30 of the flexible circuit 20. Alternatively, as shown in fig. 11, the cable signal conductors and ground members may not be physically attached to the flex circuit, but may be in electrical communication with the respective flex signal contact pads 30 and flex ground pads 35 through intervening structures, couplers, or connectors. For example, the respective flexible signal sheets 30 may physically contact the fourth mating end of the respective electrical conductors of the mating cable connector 174 or the PCB or flex circuit carrying the light engine 176. The fourth mounting end of the corresponding electrical conductor of the mating cable connector 174 may be configured to attach to the corresponding cable signal conductor or the corresponding cable ground shield (either directly or through a common ground core) or the corresponding ground drain wire.

A first circuit end 134 or one end of flex circuit 20 that is disposed closer to IC die 70 or IC die package 72 than an opposite end of flex circuit 20 may be smaller than a second circuit end 136 in lateral direction a, as shown in fig. 12; however, this is not necessary. Thus, the flexible circuit 20 may be stretched (flare) between the first circuit end 134 and the second circuit end 136, but does not have to be stretched or widened. As described above, the splaying of the flex circuit 20 may be beneficial in some circumstances because it allows a first pitch between adjacent traces on the second circuit face 136, the flex signal pads 30, or the flex ground pads 35 to be greater than a second pitch on the first circuit face 134.

The signal transmission characteristics of the cable assembly having both the flexible circuit 20 and the cable 79 may be superior to those of the flexible circuit 20 itself. That is, over the same distance, the cable 79 may have a lower insertion loss than the flex circuit 20, a lower return loss than the flex circuit 20, and less crosstalk than the flex circuit 20. In some applications, such as those described below with reference to fig. 13B, it may be beneficial to use a shorter length of flexible circuit 20 and a longer length of cable 79. For example, the ratio of L2 to L1 may be greater than 1, 2, 5 or 10. The cable assembly may have any suitable end-to-end length, such as between about 7.6 centimeters and 1 meter, between about 7.6 centimeters and 2 meters, between about 7.6 centimeters and 3 meters, between about 7.6 centimeters and 4 meters, between about 7.9 centimeters and 14 centimeters, between about 10 centimeters and 14 centimeters, greater than 7.6 centimeters and less than or equal to 1 meter, at least 1 meter but less than or equal to about 2 meters, at least 2 meters but less than or equal to about 3 meters, at least 1 meter but less than or equal to 5 meters, and at least 3 meters but less than or equal to 10 meters.

As previously described, the first width d1 of the flexible circuit 20 at the first circuit end 134 in the lateral direction a may be less than the second width d2 at the second circuit end 136. Since the number of flexible signal pads 30 on both ends and the number of flexible ground pads 35 may be equal, this means that the pitch between the flexible signal pads 30 and the flexible ground pads 35 may be greater on the second circuit end 136. Having a larger pitch on the second circuit end 136 facilitates connection to the cable 79, and depending on the AWG, the cladding thickness of the shield, and the dielectric material thickness, the cable 79 may have a minimum pitch in the range of about 1.2 millimeters to 1.8 millimeters.

Fig. 13A shows a schematic top view of cable connector assembly 209 according to an embodiment of the present invention. The cable connector assembly 209 may include the cable connector sub-assembly 208 shown in fig. 12, wherein the first electrical connector 201 is attached to the first circuit end 134 of the flexible circuit 20 and the second electrical connector 203 is attached to the second cable end of the cable 79. In some embodiments, the height of the first electrical connector 201 may be less than 3 millimeters or 5 millimeters, such that the first electrical connector 201 may be easily received in the space between the heat sink 67 and the die package substrate 74 (see fig. 6F). Although fig. 13A shows each of the plurality of cables entering a single second electrical connector 203, the invention is not so limited. In alternative embodiments. Each cable 79 may have a separate and distinct second electrical connector 203. Alternatively, the cables 79 may be divided into a plurality of cable groups such that each cable in a cable group is attached to a common second electrical connector 203 and the cables in the other cable groups are attached to different second electrical connectors. The first electrical connector 201 and the second electrical connector 203 may be any of the electrical connectors described above.

Fig. 13B shows a schematic side view of an electrical communication system 220 including the cable connector assembly 209 of fig. 13A. The electrical communication system may include an IC die 70, with the IC die 70 mounted to a die package substrate 74 to form an IC die package 72, as previously described. IC die package 72 may be electrically and mechanically connected to host substrate 204 by solder balls (as shown in fig. 13B) or by connectors. Low speed (< 1 GHz) signals, control signals, and power signals may pass into and out of the IC package through these connections. At least one cable connector assembly 209 may be in electrical communication with IC die package 72. Cable connector assembly 209 may enable high-speed signal transmission between IC die package 72 and a second electrical connector 203 mounted to panel 206. The second electrical connector 203 may be mounted directly to the panel or indirectly to the panel 206 through a cage (not shown in fig. 13B). The length along the cable connector assembly 209 between the first electrical connector 201 and the second electrical connector 203 may be greater than or equal to about 5 centimeters and less than or equal to about 50 centimeters. This length range provides substantially sufficient length to route high speed signals between the IC die package 72 and the panel 206 in rack-mounted applications.

Fig. 13B shows two cable connector assemblies 209A and 209B in electrical communication with IC die package 72; however, more than two cable connector assemblies 209, such as three, four, five, or more cable connector assemblies 209, may be in electrical communication with the IC die package 72. In alternative embodiments, a single cable connector assembly 209 may route high-speed signals to the IC die package 72 and from the IC die package 72 to the panel connector 203 positioned adjacent to the panel 206. As described above, the panel connector 203 may be an I/O connector such as a card slot quad small form factor pluggable (QSFP) connector, an eight channel small form factor pluggable (OSFP) connector, a quad small form factor pluggable dual density (QSFP-DD) connector, a backplane connector, a non-slot connector such as a ACCELRATE brand connector commercially available from applicant, and an open pin field connector without a dedicated ground shield (open pin field connectors).

The cable connector 209 may include any one or more of the following: the flex circuit 20 itself, the combination of the flex circuit 20 and the cable 79, the flex circuit 79 attached to any of the electrical connectors described herein.

For example, the cable assembly may include a flexible circuit 20, the flexible circuit 20 including a first circuit end 134 and a second circuit end 136. The first circuit end 134 may include a first plurality of flexible signal sheets 30A and the second circuit end 136 may include a second plurality of flexible signal sheets 30B, wherein the first plurality of flexible signal sheets 30A are at a first pitch, the second plurality of flexible signal sheets 30B are at a second pitch, and the second pitch is greater in value than the first pitch, and a plurality of cables positioned adjacent to the second end of the flexible circuit. At least one flexible electrical connector 172 may be positioned adjacent the second circuit end 136. The at least one flexible electrical connector 172 may be configured to mate with a cable connector 174. The cable connector 174 may carry a plurality of cables 79. The plurality of cables 79 may each be physically attached to the flexible circuit 20. The plurality of cables 79 may be coaxial cables having coaxial cable conductors and coaxial cable shields. The plurality of cables 79 may be twinaxial cables having a pair of cable conductors and a twinaxial cable shield.

The flexible circuit 20 may have an end-to-end length that is shorter than an end-to-end length of one of the plurality of cables 79. For example, the end-to-end length of the flexible circuit 20 may be at least two times shorter than the end-to-end cable length of one of the plurality of cables 79, at least three times shorter than the end-to-end cable length of one of the plurality of cables 79, at least four times shorter than the end-to-end cable length of one of the plurality of cables 79, at least six times shorter than the end-to-end cable length of one of the plurality of cables 79, at least seven times shorter than the end-to-end cable length of one of the plurality of cables 79, at least eight times shorter than the end-to-end cable length of one of the plurality of cables 79, at least nine times shorter than the end-to-end cable length of one of the plurality of cables 79, or at least ten times shorter than the end-to-end cable length of one of the plurality of cables 79.

The first circuit end 134 of the flex circuit 20 may be configured to be physically attached, electrically attached, or both physically and electrically attached to the IC die 70 or the die package substrate 74. The first circuit end 134 of the flexible circuit 20 may be configured to be physically attached, electrically attached, or both physically and electrically attached to a corresponding package tab 162 on the first major surface 200.

The cable assembly may include a flexible circuit 20 attached to a dual-axis cable 79. The flexible circuit 20 may have a first circuit end 134 and a second circuit end 136, and the dual-axis cable 79 may be attached directly or indirectly to the second circuit end 136 through, for example, a flexible electrical connector 172 or a coupler or bridge. The first plurality of flexible signal sheets 30 may each be positioned at the first circuit end 134 on the first flexible circuit surface 23A. The first plurality of flexible signal sheets 30 may include a first differential flexible signal pair sheet 30A. The third plurality of flexible signal sheets 30 may each be positioned at the first circuit end 134 on the second flexible circuit surface 23B. The third plurality of flexible signal sheets 30 may include a third differential flexible signal pair sheet 30C. The flexible signal sheets 30 of the first differential flexible signal pair sheet 30A may be offset from the flexible signal sheets 30 of an adjacent opposing third differential flexible signal pair sheet 30C such that a line perpendicular to both the first flexible circuit surface 23A and the second flexible circuit surface 23B passes through one of the flexible signal sheets 30 of the first differential flexible signal pair sheet 30A but not through any of the flexible signal sheets 30 of the third differential flexible signal pair sheet 30C.

The second plurality of flexible signal pads 30 may each be positioned at the second circuit end 136 on the second flexible circuit surface 23B. The second plurality of flexible signal sheets 30 may include a second differential flexible signal pair sheet 30B. The fourth plurality of flexible signal pads 30 may each be positioned at the second circuit end 136 on the first flexible circuit surface 23A. The fourth plurality of flexible signal tiles 30 may include a fourth differential flexible signal pair tile 30D. The flexible signal sheets 30 of the second differential flexible signal pair sheet 30B may be offset from the adjacent opposing flexible signal sheets 30 of the fourth differential flexible signal pair sheet 30D such that a line perpendicular to both the first flexible circuit surface 23A and the second flexible circuit surface 23B passes through one of the flexible signal sheets 30 of the second differential flexible signal pair sheet 30B but not through any of the flexible signal sheets 30 of the fourth differential flexible signal pair sheet 30D.

The first or second or third electrical connector may be releasably or non-releasably attached to the first circuit end 134. A panel connector 203 or other electrical component may be attached to the second end of the dual-axis cable 79. As described above, the flexible circuit 20 may have an end-to-end length that is shorter than the end-to-end length of one of the two-axis cables 79. The end-to-end length of the flexible circuit 20 may be at least two times shorter than the end-to-end cable length of one of the twinax cables 79, at least three times shorter than the end-to-end cable length of one of the twinax cables 79, at least four times shorter than the end-to-end cable length of one of the twinax cables 79, at least six times shorter than the end-to-end cable length of one of the twinax cables 79, at least seven times shorter than the end-to-end cable length of one of the twinax cables 79, at least eight times shorter than the end-to-end cable length of one of the twinax cables 79, at least nine times shorter than the end-to-end cable length of one of the twinax cables 79, or at least ten times shorter than the end-to-end cable length of one of the twinax cables 79. The first differential flexible signal pair pad 30A and the flexible ground pad 35 may extend along a first common row. The third differential flexible signal pair pad 30C and the flexible ground pad 35 may extend along a second common row. The first common row and the second common row may be staggered or offset by less than one row pitch, or more than one row pitch. The second differential flexible signal pair pad 30B and the flexible ground pad 35 may extend along a third common row. The fourth differential flexible signal pair pad 30D and the flexible ground pad 35 may extend along a fourth common row. The third common row and the fourth common row may be staggered or offset by less than one row pitch, or more than one row pitch. For example, as shown in fig. 1E, the second differential signal pair chip 30B and the fourth differential signal pair chip 30D, which are sequentially adjacent to each other, are offset from each other by more than one row pitch in the direction a. The second differential signal pair pad 30B and the fourth differential signal pair pad 30D may each be positioned on opposite sides of the flexible circuit 20, but remain adjacent to each other in sequence along the direction a. In other words, there may be no signal pair slices between the second differential signal pair slice 30B and the fourth differential signal pair slice 30D or between the first differential signal pair slice 30A or the third differential signal pair slice 30C. In yet another aspect, there may be an offset between the differential signal pair slices in the immediately adjacent first and second common rows. There may be an offset between the differential signal pair slices in the immediately adjacent third and fourth common rows.

Fifth electrical connector 201 of cable connector assembly 209 may be any of the electrical connectors described herein, as well as a crimp connector or a crimp cable connector. The fifth electrical connector 201 may be in physical communication, electrical communication, or both physical and electrical communication with the die package substrate 74 or the IC die 70 discussed previously. The panel connector 203 may be mounted to a panel 206 such as a front panel. The faceplate 206 may be a standard 1RU (rack unit), or have a height of about 44.5 millimeters. In various embodiments, at least 500 or at least 1000 or at least 1026 or at least 1088 high-speed differential pair signals may be routed between the panel 206 and the IC die package. High speed may mean at least 28Gbps at an acceptable crosstalk level of, for example, 0% to 4% or-40 dB, at least 56Gbps at an acceptable crosstalk level of, for example, 0% to 4% or-40 dB, at least 112Gbps at an acceptable crosstalk level of, for example, 0% to 4% or-40 dB, and any one or more of at least 224Gbps, at least 56G NRZ, at least 112G PAM-4, at least 112G NRZ, and at least 224G PAM-4 at an acceptable crosstalk level of, for example, 0% to 4% or-40 dB. An exemplary number of high-speed differential pair signals may be 512, 1024, or 1152 on only one or both of the first or second major surfaces 200, 202 of the die package substrate 74. If each of the first die package face 178, the second die package face 180, the third die package face 182, and the fourth die package face has the same number of differential pair signal connections, the number of differential pair signal connections per die package face 178, 180, 182, 184 may be at least 128, 256, or 288. Multiple electrical communication systems 220 may be mounted in a single rack, which may be part of a larger installation, such as a server farm.

Finally, there are individual embodiments. A method of manufacturing a dense, high-speed transmission line may include the steps of providing a flexible circuit 20 having a first circuit end 134, wherein the first circuit end 134 is configured to be attached to a die package substrate 74 or a connector carried by the die package substrate 74, and attaching a cable 79, such as a coaxial cable or a twinaxial cable, to a second circuit end 136 of the flexible circuit 20. Another method of manufacturing a dense, high-speed transmission line includes the steps of using a flex circuit 20 having a first flex length, routing differential signals from an IC die package 72 or from a die package substrate 74 to an electrical connector, a connectivity module, or an electrical or optical component, and determining whether the first flex length of the flex circuit 20 has excessive parasitic loss that cannot be used in a predetermined application. If the parasitic losses are excessive, further steps may include shortening the first flex length of flex circuit 20 to a second flex length that is less than the first flex length, and adding a cable 79, such as a coaxial cable or a twinaxial cable, to flex circuit 20 such that the combined length of flex circuit 79 and cable 79 is at least as long as the first flex length, or shortening the distance between IC die package 72 or die package substrate 74 and an electrical connector, communication module or electrical or optical component.

The IC die package 72 with the die package substrate 74 or the die package substrate 74 without the IC die 70 may include a first die package face 178, a second die package face 180, a third die package face 182, and a fourth die package face 184, the flex circuit 20, and the first flex circuit 20A1. The flex circuit 20 may be directly attached or indirectly attached to the die package substrate 74 adjacent at least one of the first die package face 178, the second die package face 180, the third die package face 182, and the fourth die package face 184. The first flex circuit 20A1 may be directly attached or indirectly attached to the die package substrate 74 adjacent to another one of the first die package face 178, the second die package face 180, the third die package face 182, and the fourth die package face 184. The flex circuit 20 may be attached to three or four of the first die package face 178, the second die package face 180, the third die package face 182, and the fourth die package face 184 of the die package substrate 74.

The method of manufacturing a high-speed, high-density system may independently include any of the following steps: routing at least 512 or at least 1024 differential signal pairs from only one major surface of a die package substrate having die package faces each having a length of at least 50 millimeters but less than or equal to 120 millimeters; routing at least 512 or at least 1024 differential signal pairs from only one major surface of a die package substrate having die package faces each having a length of at least 50 millimeters but less than or equal to 110 millimeters; routing at least 512 or at least 1024 differential signal pairs from only one major surface of a die package substrate having die package faces each having a length of at least 50 millimeters but less than or equal to 100 millimeters; routing at least 512 or at least 1024 differential signal pairs from only one major surface of a die package substrate having die package faces each having a length of at least 50 millimeters but less than or equal to 95 millimeters; routing at least 512 or at least 1024 differential signal pairs from only one major surface of a die package substrate having die package faces each having a length of at least 50 millimeters but less than or equal to 90 millimeters; routing at least 512 or at least 1024 differential signal pairs from only one major surface of a die package substrate having die package faces each having a length of at least 70 millimeters but less than or equal to 110 millimeters; routing at least 512 or at least 1024 differential signal pairs from only one major surface of a die package substrate having die package faces each having a length of at least 70 millimeters but less than or equal to 100 millimeters; routing at least 512 or at least 1024 differential signal pairs from only one major surface of a die package substrate having die package faces each having a length of at least 70 millimeters but less than or equal to 90 millimeters; routing at least 512 or at least 1024 differential signal pairs from only one major surface of a die package substrate having die package faces each having a length of at least 75 millimeters but less than or equal to 110 millimeters; routing at least 512 or at least 1024 differential signal pairs from only one major surface of a die package substrate having die package faces each having a length of at least 75 millimeters but less than or equal to 100 millimeters; routing at least 512 or at least 1024 differential signal pairs from only one major surface of a die package substrate having die package faces each having a length of at least 75 millimeters but less than or equal to 95 millimeters; at least 512 or at least 1024 differential signal pairs are routed from only one major surface of a die package substrate having die package faces each having a length of at least 75 millimeters but less than or equal to 90 millimeters.

It should be understood that the description and discussion of the embodiments illustrated in the figures are for illustrative purposes only and should not be construed as limiting the present disclosure. Those skilled in the art will appreciate that the present disclosure contemplates various embodiments. Additionally, it is to be understood that the concepts described above and the embodiments described above may be used alone or in combination with any of the other embodiments described above. It should also be understood that the various alternative embodiments described above with respect to one illustrated embodiment may be applied to all embodiments described herein unless otherwise indicated.

Claims

1. A flexible circuit, the flexible circuit comprising:

the first circuit end, the opposite second circuit end, the first flexible circuit surface and the opposite second flexible circuit surface;

a first conductive layer positioned adjacent to the first flex circuit face;

a second conductive layer opposite the first conductive layer and adjacent the second flexible circuit surface;

a plurality of flexible signal conductors disposed between the first conductive layer and the second conductive layer; and

a first plurality of flexible signal sheets positioned at the first circuit end and a second plurality of flexible signal sheets positioned at the second circuit end, wherein the first plurality of flexible signal sheets are all positioned on the first flexible circuit surface and the second plurality of flexible signal sheets are all positioned on the second flexible circuit surface.

2. The flexible circuit of claim 1, further comprising a third plurality of flexible signal sheets all positioned at the first circuit end and all positioned on the second flexible circuit surface.

3. The flexible circuit of claim 2, wherein the first plurality of flexible signal tiles comprises first differential flexible signal pair tiles, the third plurality of flexible signal tiles comprises third differential flexible signal pair tiles, and a first differential flexible signal pair tile of the first plurality of flexible signal pair tiles is offset from a third differential flexible signal pair tile of the third plurality of flexible signal tiles such that a line perpendicular to both the first flexible circuit surface and the second flexible circuit surface passes through one of the flexible signal tiles of one of the first flexible signal pair tiles but does not pass through any of the flexible signal tiles of the third differential flexible signal pair tile.

4. The flexible circuit of any of claims 1-2, wherein the first plurality of flexible signal tiles comprises differential flexible signal pair tiles spaced apart from one another such that at least two hundred fifty-six of the differential flexible signal pair tiles are received in an area of about 500 square millimeters.

5. The flexible circuit of any of claims 1-2, wherein the first plurality of flexible signal tiles comprises differential flexible signal pair tiles spaced apart from one another such that at least two hundred fifty-six of the differential flexible signal pair tiles are received in an area of about 550 square millimeters.

6. The flexible circuit of any of claims 1-2, wherein the first plurality of flexible signal tiles comprises differential flexible signal pair tiles spaced apart from one another such that at least two hundred fifty-six of the differential flexible signal pair tiles are received in an area of about 600 square millimeters.

7. The flexible circuit of any of claims 1-2, wherein the first plurality of flexible signal tiles comprises differential flexible signal pair tiles spaced apart from one another such that at least two hundred fifty-six of the differential flexible signal pair tiles are received in an area of about 650 square millimeters.

8. The flexible circuit of any of claims 1-2, wherein the first plurality of flexible signal tiles comprises differential flexible signal pair tiles spaced apart from one another such that at least two hundred fifty-six of the differential flexible signal pair tiles are received in an area of about 700 square millimeters.

9. The flexible circuit of any of claims 1-2, wherein the first plurality of flexible signal tiles comprises differential flexible signal pair tiles spaced apart from one another such that at least two hundred fifty-six of the differential flexible signal pair tiles are received in an area of about 750 square millimeters.

10. The flexible circuit of any of claims 1-2, wherein the first plurality of flexible signal tiles comprises differential flexible signal pair tiles spaced apart from one another such that at least two hundred fifty-six of the differential flexible signal pair tiles are received in an area of about 800 square millimeters.

11. The flexible circuit of any of claims 1-2, wherein the first plurality of flexible signal tiles define a row of at least sixty-four differential flexible signal pair tiles spaced apart from each other such that a row of at least sixty-four differential flexible signal pair tiles is received in a first die package face having a length greater than 50 millimeters but no more than about 75 millimeters.

12. The flexible circuit of any of claims 1-2, wherein the first plurality of flexible signal tiles define a row of at least sixty-four differential flexible signal pair tiles spaced apart from each other such that a row of at least sixty-four differential flexible signal pair tiles is received in a first die package face having a length greater than 55 millimeters but no more than about 80 millimeters.

13. The flexible circuit of any of claims 1-2, wherein the first plurality of flexible signal tiles define a row of at least sixty-four differential flexible signal pair tiles spaced apart from each other such that a row of at least sixty-four differential flexible signal pair tiles is received in a first die package face having a length greater than 60 millimeters but no more than about 85 millimeters.

14. The flexible circuit of any of claims 1-2, wherein the first plurality of flexible signal tiles define a row of at least sixty-four differential flexible signal pair tiles spaced apart from each other such that a row of at least sixty-four differential flexible signal pair tiles is received in a first die package face having a length greater than 65 millimeters but no more than about 90 millimeters.

15. The flexible circuit of any of claims 1-2, wherein the first plurality of flexible signal tiles define a row of at least sixty-four differential flexible signal pair tiles spaced apart from each other such that a row of at least sixty-four differential flexible signal pair tiles is received in a first die package face having a length greater than 70 millimeters but no more than about 95 millimeters.

16. The flexible circuit of any of claims 1-2, wherein the first plurality of flexible signal tiles define differential flexible signal pair tiles spaced apart from one another such that a row of at least sixty-four differential flexible signal pair tiles are received in a first die package face having a length greater than 75 millimeters but no more than about 100 millimeters.

17. A flexible circuit according to any one of claims 1 to 3, further comprising a fourth plurality of signal tiles, all positioned at the second circuit end and all positioned on the first flexible circuit surface.

18. The flexible circuit of claim 17, wherein the second plurality of flexible signal tiles comprises a second differential flexible signal pair tile, the fourth plurality of flexible signal tiles comprises a fourth differential flexible signal pair tile, and the second differential flexible signal pair tile is offset from the fourth differential flexible signal pair tile such that a line perpendicular to both the first and second flexible circuit tiles passes through one flexible signal tile of the second differential flexible signal pair tile, but does not pass through any of the flexible signal tiles of the fourth differential flexible signal pair tile.

19. The flexible circuit of any of claims 17 and 18, wherein a flexible electrical connector is attached to the second circuit end and is configured to receive a mating cable connector.

20. The flexible circuit of any one of claims 17 and 18, wherein respective coaxial cables and/or dual-axis cables are directly attached to the third differential flexible signal pair slice, the fourth differential flexible signal pair slice, or both.

21. The flexible circuit of any of the preceding claims, further comprising a flexible ground patch positioned at the first circuit end on the first flexible circuit surface.

22. The flexible circuit of any of the preceding claims, further comprising a flexible ground patch positioned at the second circuit end on the second flexible circuit surface.

23. The flexible circuit of any of claims 2-22, further comprising a flexible ground patch positioned at the first circuit end on the second flexible circuit surface.

24. The flexible circuit of any of claims 17-23, further comprising a flexible ground patch positioned at the second circuit end on the first flexible circuit surface.

25. A flexible circuit according to any preceding claim, wherein the flexible signal sheet is free of fusible elements both before and during use.

26. The flexible circuit of any of the preceding claims, wherein the flexible circuit is made of a liquid crystal polymer material.

27. A flexible circuit according to any of the preceding claims, wherein the flexible circuit is arranged to transmit data at frequencies up to 55GHz while producing worst case multiple active asynchronous crosstalk of no more than-60 dB.

28. A flexible circuit according to any of the preceding claims, wherein the flexible circuit is arranged to transmit data at frequencies up to 55GHz while producing worst case multi-active asynchronous near end crosstalk of no more than-65 dB.

29. The flexible circuit of any of the preceding claims, wherein the flexible circuit is configured to transmit data at frequencies up to 55GHz while producing worst case multiple active asynchronous far end crosstalk of no more than-68 dB.

30. A flexible circuit according to any of the preceding claims, wherein the flexible circuit is arranged to transmit data at frequencies up to 100GHz while producing worst case multiple active asynchronous crosstalk of no more than-50 dB.

31. A cable assembly, the cable assembly comprising:

a flexible circuit comprising a first circuit end and a second circuit end, the first circuit end comprising a first plurality of flexible signal tiles and the second circuit end comprising a second plurality of flexible signal tiles, wherein the first plurality of flexible signal tiles are at a first pitch, the second plurality of flexible signal tiles are at a second pitch, and the second pitch is numerically greater than the first pitch; and

A plurality of cables positioned adjacent to the second end of the flexible circuit.

32. The cable assembly of claim 31, further comprising at least one flexible electrical connector positioned adjacent the second circuit end, wherein the at least one flexible electrical connector is configured to interface with a cable connector, and the cable connector carries the plurality of cables.

33. The cable assembly of any one of claims 31 and 32, wherein the plurality of cables are each physically attached to the flexible circuit.

34. The cable assembly of any one of claims 31-33, wherein the plurality of cables are coaxial cables having coaxial cable conductors.

35. The cable assembly of claims 31-34, wherein the plurality of cables are twinaxial cables having a pair of cable conductors.

36. The cable assembly of any one of claims 31-35, wherein the flexible circuit has an end-to-end length that is shorter than an end-to-end length of one of the plurality of cables.

37. The cable assembly of any one of claims 31-35, wherein an end-to-end length of the flexible circuit is at least twice shorter than an end-to-end cable length of one of the plurality of cables.

38. The cable assembly of any one of claims 31-35, wherein an end-to-end length of the flexible circuit is at least three times shorter than an end-to-end cable length of one of the plurality of cables.

39. The cable assembly of any one of claims 31-35, wherein an end-to-end length of the flexible circuit is at least four times shorter than an end-to-end cable length of one of the plurality of cables.

40. The cable assembly of any one of claims 31-35, wherein an end-to-end length of the flexible circuit is at least five times shorter than an end-to-end cable length of one of the plurality of cables.

41. The cable assembly of any one of claims 31-35, wherein an end-to-end length of the flexible circuit is at least six times shorter than an end-to-end cable length of one of the plurality of cables.

42. The cable assembly of any one of claims 31-35, wherein an end-to-end length of the flexible circuit is at least seven times shorter than an end-to-end cable length of one of the plurality of cables.

43. The cable assembly of any one of claims 31-35, wherein an end-to-end length of the flexible circuit is at least eight times shorter than an end-to-end cable length of one of the plurality of cables.

44. The cable assembly of any one of claims 31-35, wherein an end-to-end length of the flexible circuit is at least nine times shorter than an end-to-end cable length of one of the plurality of cables.

45. The cable assembly of any one of claims 31-35, wherein an end-to-end length of the flexible circuit is at least ten times shorter than an end-to-end cable length of one of the plurality of cables.

46. The cable assembly of any one of claims 31-45, wherein the first circuit end of the flexible circuit is configured to be physically attached, electrically attached, or both physically and electrically attached to an IC die or die package substrate.

47. The cable assembly of any one of claims 31-46, wherein the first circuit end of the flexible circuit is configured to be physically attached, electrically attached, or both physically and electrically attached to a corresponding package piece on a die package surface.

48. A cable assembly including a flexible circuit attached to a twinax cable.

49. The cable assembly of claim 48, wherein the flexible circuit has a first circuit end and a second circuit end, and the dual-axis cable is attached directly to the second circuit end or indirectly to the second circuit end through a connector or coupler or bridge.

50. The cable assembly of any one of claims 48-49, further comprising a first plurality of flexible signal tiles each positioned at the first circuit end on the first flexible circuit face and including a first differential flexible signal pair tile, and a third plurality of flexible signal tiles each positioned at the first circuit end on the second flexible circuit face and including a third differential flexible signal pair tile, the first differential flexible signal pair tile being offset from the third differential flexible signal pair tile of the third plurality of flexible signal pair tiles such that a line perpendicular to both the first and second flexible circuit faces passes through one of the flexible signal tiles of the first differential flexible signal pair tile but not through any of the flexible signal tiles of the third differential flexible signal pair tile.

51. The cable assembly of any one of claims 49 and 50, further comprising a second plurality of flexible signal tiles each positioned at the second circuit end on the second flexible circuit face and comprising a second differential flexible signal pair tile, and a fourth plurality of flexible signal tiles each positioned at the second circuit end on the first flexible circuit face and comprising a fourth differential flexible signal pair tile, the second differential flexible signal pair tile being offset from the fourth differential flexible signal pair tile such that a line perpendicular to both the first and second flexible circuit faces passes through one of the flexible signal tiles of the second differential flexible signal pair tile but not through any of the flexible signal tiles of the fourth differential flexible signal pair tile.

52. The cable assembly of any one of claims 48-51, further comprising a first or second or third electrical connector releasably or non-releasably attached to the first flexible circuit end.

53. The cable assembly of any one of claims 48-52, further comprising a panel connector attached to a second end of one of the two-axis cables.

54. The cable assembly of any one of claims 48-53, wherein the flexible circuit has an end-to-end length that is shorter than one of the two-axis cables.

55. The cable assembly of any one of claims 48-53, wherein an end-to-end length of the flexible circuit is at least twice shorter than an end-to-end cable length of one of the twinax cables.

56. The cable assembly of any one of claims 48-53, wherein an end-to-end length of the flexible circuit is at least three times shorter than an end-to-end cable length of one of the twinax cables.

57. The cable assembly of any one of claims 48-53, wherein an end-to-end length of the flexible circuit is at least four times shorter than an end-to-end cable length of one of the twinax cables.

58. The cable assembly of any one of claims 48-53, wherein an end-to-end length of the flexible circuit is at least five times shorter than an end-to-end cable length of one of the twinax cables.

59. The cable assembly of any one of claims 48-53, wherein an end-to-end length of the flexible circuit is at least six times shorter than an end-to-end cable length of one of the twinax cables.

60. The cable assembly of any one of claims 48-53, wherein an end-to-end length of the flexible circuit is at least seven times shorter than an end-to-end cable length of one of the twinax cables.

61. The cable assembly of any one of claims 48-53, wherein an end-to-end length of the flexible circuit is at least eight times shorter than an end-to-end cable length of one of the twinax cables.

62. The cable assembly of any one of claims 48-53, wherein an end-to-end length of the flexible circuit is at least nine times shorter than an end-to-end cable length of one of the twinax cables.

63. The cable assembly of any one of claims 48-53, wherein an end-to-end length of the flexible circuit is at least ten times shorter than an end-to-end cable length of one of the twinax cables.

64. The cable assembly of any one of claims 51-63, wherein the first plurality of differential flexible signal pair patches are at a first flexible patch pitch and the third plurality of differential flexible signal pair patches are at a second flexible patch pitch that is greater in value than the first flexible patch pitch.

65. A die package, the die package comprising:

an IC die;

a die package substrate, the die package substrate having a first die package face, a second die package face, a third die package face, and a fourth die package face each not longer than 100 millimeters,

wherein at least 128 or at least 256 package pieces are provided on each of the first die package face, the second die package face, the third die package face, and the fourth die package face, each of the package pieces being configured to be directly attached to a flexible circuit or indirectly attached to a flexible circuit through a first electrical connector, a second electrical connector, or a third electrical connector or a package connector, respectively.

66. An electrical communication system, the electrical communication system comprising:

the die package of claim 65; and

one or more flexible circuits attached to respective ones of the package pieces.

67. A die package substrate, the die package substrate comprising:

a first die package face, a second die package face, a third die package face, and a fourth die package face, each of the die package faces being no longer than 85 millimeters,

wherein at least 128 or at least 256 package pieces are provided on each of the first die package face, the second die package face, the third die package face, and the fourth die package face, each of the package pieces being configured to be directly attached to a flexible circuit or indirectly attached to a flexible circuit through a first electrical connector, a second electrical connector, or a third electrical connector.

68. A die package substrate comprising a first major surface and an opposing second major surface, wherein at least 1024 differential signal pair slices are carried by either only the first major surface or only the second major surface.

69. The die package substrate of claim 68, wherein the at least 1024 differential signal pair patches are arranged with at least 256 differential signal pair patches on each of the respective first, second, third, and fourth package faces.

70. The die package substrate of any one of claims 68 and 99, wherein the at least 1024 differential signal pair dice are SMT dice.

71. The die package substrate of any one of claims 68 and 69, wherein the at least 1024 differential signal pair patches are crimp patches.

72. An electrical communication system, the electrical communication system comprising:

an IC die package defining a first major surface, a first die package face, a second die package face, a third die package face, and a fourth die package face;

a first electrical connector carried by the IC die package, the first electrical connector having first electrical contacts arranged in a first row and a second row; and

a flexible circuit including a first circuit end received between the first and second rows and an opposing second circuit end.

73. The electrical communication system of claim 72, further comprising a cable having respective first and second cable ends, the first cable end being removably or permanently attached to the second circuit end.

74. The electrical communication system of any one of claims 72 or 73, further comprising a panel connector, a communication module, a substrate, or an electrical component directly attached or indirectly attached to the second cable end.

75. The electrical communication system of any one of claims 72-74, wherein the first die package face has at least 256 differential signal package patches on the first major surface.

76. The electrical communication system of any one of claims 72-75, wherein the second die package face has at least 256 differential signal package patches on the first major surface.

77. The electrical communication system of any one of claims 72 to 76, wherein the third die package face has at least 256 differential signal package patches on the first major surface.

78. The electrical communication system of any one of claims 72-77, wherein the fourth die package face has at least 256 differential signal package tiles on the first major surface.

79. A flexible circuit, the flexible circuit comprising:

a first circuit terminal; and

a second circuit side of the first circuit side,

wherein the first circuit end has at least 256 differential flexible signal pair pads and is sized and shaped to be received on a first die package face, the first die package face being about 60 millimeters to about 100 millimeters.

80. The flexible circuit of claim 79, wherein the first die package face is about 70 millimeters to about 90 millimeters.

81. The flexible circuit of claim 79, wherein the first die package face is about 75 millimeters to about 85 millimeters.

82. The flexible circuit of any of claims 79-81, wherein the second circuit end is sized and shaped to receive at least 256 twinax cables, each of the at least 256 twinax cables being 32AWG to 40AWG.

83. The flexible circuit of any of claims 79-81, wherein the second circuit end is sized and shaped to receive at least 256 twinax cables, each of the at least 256 twinax cables being 32AWG to 36AWG.

84. The flexible circuit of any of claims 79-81, wherein the second circuit end is sized and shaped to receive at least 256 twinax cables, each of the at least 256 twinax cables being 33AWG to 35AWG.

85. The flexible circuit of any one of claims 79 to 81, wherein the second circuit end has a second width of between 95 millimeters and 120 millimeters.

86. The flexible circuit of any one of claims 79 to 85, wherein the flexible circuit further comprises a first flexible circuit face, an opposing second flexible circuit face, and a flexible signal sheet, wherein the flexible signal sheet is disposed on the first flexible circuit face adjacent the first circuit end as a first differential flexible signal pair sheet, and is disposed on the second flexible circuit face adjacent the first circuit end as a third differential flexible signal pair sheet, and the first differential flexible signal pair sheet is offset from the third differential flexible signal pair sheet.

87. The flexible circuit of claim 86, wherein the flexible signal pads are arranged as fourth differential flexible signal pair pads on the first flexible circuit face adjacent the second circuit end and as second differential flexible signal pair pads on the second flexible circuit face adjacent the second circuit end, and the second differential flexible signal pair pads are offset from the fourth differential flexible signal pair pads.

88. The flexible circuit of any one of claims 79 to 85, wherein flexible circuit further comprises a first flexible circuit face, an opposing second flexible circuit face, and a flexible signal sheet, wherein the flexible signal sheet is disposed on the first flexible circuit face adjacent the second circuit end as a fourth differential flexible signal pair sheet, and is disposed on the second flexible circuit face adjacent the second circuit end as a second differential flexible signal pair sheet, and the second differential flexible signal pair sheet is offset from the fourth differential flexible signal pair sheet.

89. A method of manufacturing a dense, high-speed transmission line, comprising the steps of:

providing a flexible circuit having a first circuit end configured to be attached to or carried by a die package substrate; and

A coaxial cable or a twinax cable is attached to the second circuit end of the flex circuit.

90. A method of manufacturing a dense, high-speed transmission line, comprising the steps of:

routing differential signals from the IC die package to the electrical component using a flex circuit having a first flex length;

determining whether the first flex length of the flex circuit has excessive parasitic loss that cannot be used for a predetermined application; and

any one of the following:

shortening the first flexible length of the flexible circuit to a second flexible length that is less than the first flexible length, and adding a coaxial cable to the flexible circuit such that a combined length of the flexible circuit and the coaxial cable is at least equal to the first flexible length; or alternatively

Shortening the distance between the IC die package and the electrical component.

91. An IC die package comprising a die package substrate comprising:

a first die package face, a second die package face, a third die package face, and a fourth die package face;

a flexible circuit and a first flexible circuit are provided,

wherein the flex circuit is directly attached or indirectly attached to the die package substrate adjacent to one of the first die package face, the second die package face, the third die package face, and the fourth die package face, and the first flex circuit is directly attached or indirectly attached to the die package substrate adjacent to at least another of the first die package face, the second die package face, the third die package face, and the fourth die package face.

92. A method comprising the step of routing at least 512 or at least 1024 differential signal pairs from only one major surface of a die package substrate, the major surface having die package faces each having a length of at least 50 millimeters but less than or equal to 120 millimeters.

93. A method comprising the step of routing at least 512 or at least 1024 differential signal pairs from only one major surface of a die package substrate, the major surface having die package faces each having a length of at least 50 millimeters but less than or equal to 110 millimeters.

94. A method comprising the step of routing at least 512 or at least 1024 differential signal pairs from only one major surface of a die package substrate, the major surface having die package faces each having a length of at least 75 millimeters but less than or equal to 110 millimeters.