CN116095943A

CN116095943A - Multilayer impedance HDI circuit board

Info

Publication number: CN116095943A
Application number: CN202211629318.7A
Authority: CN
Inventors: 张志强; 余康玲; 王东府
Original assignee: Shenzhen Jinshengda Electronics & Technology Co ltd
Current assignee: Shenzhen Jinshengda Electronics & Technology Co ltd
Priority date: 2022-12-19
Filing date: 2022-12-19
Publication date: 2023-05-09
Anticipated expiration: 2042-12-19
Also published as: CN116095943B

Abstract

The invention discloses a multilayer impedance HDI circuit board, which comprises: the circuit board that pressfitting formed, the circuit board includes: the dielectric layers and the line layers are arranged and pressed from bottom to top according to a certain sequence, thickness and combination composition; the circuit board is provided with a via hole, the via hole is used for connecting each wire layer, the circuit board is provided with an attaching area, a shielding bracket is fixedly arranged on the attaching area, an antenna is arranged in the shielding bracket, and high-frequency signal wiring areas of the antenna are respectively arranged on two surface wire layers; and an isolation bonding pad is arranged on the bonding pad of the circuit board in a surrounding manner. The impedance mutation amplitude of the circuit board is effectively reduced, the efficiency of the circuit board under high-frequency and high-speed signals is improved, and the efficiency of the antenna is ensured.

Description

Multilayer impedance HDI circuit board

Technical Field

The invention relates to the technical field of PCB circuit boards, in particular to a multilayer impedance HDI circuit board.

Background

The multilayer impedance circuit board mainly refers to a high-density circuit board formed by laminating three or more layers of copper layers. In addition to the copper layers on the two sides, more copper layers are provided between the insulating material/medium. With the development of 5G communication, the multilayer impedance circuit board can reduce the requirements on wires and shorten the distance between signal wires, so that the characteristics of reducing EMI and meeting high-frequency and high-speed signal communication are fully exerted.

In order to reduce the volume and increase the integration level, the antenna is arranged on the circuit board, and the number of copper layers is increased to be more than three for arranging the radio frequency chip, the main power circuit and more components. The interference of the power supply circuit and the logic signal circuit to the antenna will also rise, the interference of the circuit board with fewer logic signal circuits and main power supply circuit is larger, and the problem of reducing abrupt impedance needs to be relieved when high-speed and high-frequency electric signals are propagated. As the number of copper layers increases, the number of levels of the overall circuit board increases, and the level structure thereof needs to be adjusted to reduce the impedance discontinuity and minimize the effect on the antenna performance. Furthermore, the arrangement of the antennas of the circuit board with a plurality of stages is also required to be more flexible, so that the antennas can be replaced in the surface layer wire layer, namely, the antennas with different efficiency ranges corresponding to a board body are realized.

Furthermore, the embedded antenna base that sets up of plate body, though can obtain higher firmness and wholeness, under long-term use, expend with heat and contract with cold can lead to the peripheral fracture of embedded groove, influences the use of circuit board, and this condition is comparatively obvious in thicker plate body, and thinner plate body heat dispersion and toughness can be made very strong, so not appear often. Therefore, the antenna arrangement mode of the rear circuit board with a plurality of layers also needs to be correspondingly adjusted.

Therefore, a multilayer impedance HDI circuit board capable of alleviating the impedance jump and reducing the influence of logic signal circuit on the antenna performance is needed.

Disclosure of Invention

The present invention provides a multilayer impedance HDI circuit board that solves one or more of the problems of the prior art. The invention adopts the technical proposal for solving the problems that: a multi-layer impedance HDI circuit board, comprising: the circuit board, the circuit board top-down is provided with: the circuit board is provided with a via hole, the via hole penetrates through the upper end surface and the lower end surface of the circuit board, and the circuit board is provided with a second via hole;

the first wire layer and the fourth wire layer are laminated plates formed by calendaring copper and are connected through taking fluorinated ethylene propylene copolymer as bonding sheets, and the second wire layer and the third wire layer are copper-clad laminated plates;

the first dielectric layer is a combination layer of flat open-fiber glass woven cloth, improved resin and low-temperature co-fired ceramic particles, and a shielding layer is pressed on one surface of the first dielectric layer facing the second wire layer;

the second medium layer is a flat open fiber glass woven cloth and improved resin combination layer, the third medium layer is a combination layer of the flat open fiber glass woven cloth, improved resin and low-temperature co-fired ceramic particles, and the third medium layer is pressed with a shielding layer towards one surface of the third wire layer;

an attaching area is arranged on the upper end face or the lower end face of the circuit board, and an insulating layer is coated on the surface of the attaching area;

the shielding bracket is fixed on the attaching area through glue or screws, the projection area of the shielding bracket on the attaching area is smaller than or equal to the area of the attaching area, an antenna is fixedly installed on the shielding bracket and is electrically connected with the wiring on the circuit board through a wire slot, and the high-frequency signal wiring areas of the antenna are respectively arranged on the first wiring layer and the fourth wiring layer;

the first, second, third and fourth wire layers are electrically connected through the via holes, and the second wire layer or the third wire layer is electrically connected with the first wire layer and/or the fourth wire layer through the second via holes;

the end surfaces of the first wire layer and the fourth wire layer are respectively provided with a plurality of first bonding pads, and isolation bonding pads are arranged around the first bonding pads;

the second via hole is arranged on the first line layer and the fourth line layer, and the isolation pad is arranged around the pad;

the layout wiring on the circuit board integrally rotates, and the rotation angle is 0-30 degrees.

In some embodiments, the isolation pads are 40-50mil in size.

In some embodiments, the thicknesses of the first line layer, the first dielectric layer, the second line layer, the second dielectric layer, the third line layer, the third dielectric layer, and the fourth line layer are equal.

In some embodiments, the circuit board is provided with a concave hole, the concave hole is provided on the first line layer and/or the fourth line layer, and an impedance mutation component is installed in the concave hole, and the impedance mutation component includes: capacitance and inductance.

The bottom surface of the concave hole can be provided with a first via hole, the first via hole is connected with the second wire layer or the third wire layer, and the impedance mutation component is electrically connected with the second wire layer or the circuit on the third wire layer through the first via hole.

The beneficial value obtained by the invention is as follows: the invention is characterized in that the wire layer and the dielectric layer are arranged to be pressed into a circuit board, and the layout wire is integrally rotated by a proper angle, so that the dielectric constant is reduced by adopting flat open-fiber glass woven cloth as a dielectric layer material, the antenna efficiency is improved, the wire and the branch intersection point are connected more evenly by rotating the whole layout wire, and the intersection of the wire and the weaving layer is averaged, so that the glass fiber effect is reduced, the signal rate change is reduced, the antenna efficiency is improved, and the impedance mutation amplitude is reduced; the isolation bonding pad is arranged, and the design of the through hole is optimized, so that the impedance is controlled, and the amplitude of impedance mutation is reduced; the concave holes (ground holes) are arranged to mount components with easily abrupt changes in impedance of the capacitor and the inductor, and the amplitude of abrupt changes in impedance when a circuit passes through the components is optimized by the isolation reference of the concave holes; the circuit board can obtain a relatively smoother impedance mutation curve under high-frequency and high-speed signals, and the efficiency of the millimeter wave antenna is guaranteed not to be reduced.

Drawings

FIG. 1 is a schematic diagram of a wiring layer of the present invention;

FIG. 2 is a top view of the circuit board of the present invention;

fig. 3 is a cross-sectional view of a circuit board of the present invention;

fig. 4 is a partial enlarged view I of the circuit board of the present invention;

fig. 5 is a partial enlarged view II of the circuit board of the present invention;

fig. 6 is a partial enlarged view III of the circuit board of the present invention.

[ reference numerals ]

1 Circuit Board

2 adhesion area

21 shielding bracket

3 & lt3 & gtwiring region

4.Via

41 first isolation pad

5. First bonding pad

6. Concave holes

7 impedance mutation component

8 first via

9 second via

91 second isolation pad

10 first line layer

20 first dielectric layer

30 second wire layer

40 second dielectric layer

50 third layer

60 third dielectric layer

70 fourth wire layer

101. Example Wiring one

102 example routing two

201- & gt braided wire

301. Branch intersection points.

Detailed Description

In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention briefly described above will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The invention may be embodied in many other forms than described herein without departing from the spirit or scope of the invention as defined in the following claims.

In particular, it should be noted that, in order to facilitate the display of the hierarchical structure of the circuit board, the scale of the drawing is exaggerated, and the arrangement positions of the via holes and the components are appropriately adjusted for the convenience of the display.

As shown in fig. 2-6, the present invention discloses a multi-layer impedance HDI circuit board, which includes: the circuit board 1, circuit board 1 top-down is provided with: the circuit board 1 is provided with a via hole 4, the via hole 4 penetrates through the upper end face and the lower end face of the circuit board 1, and the circuit board 1 is provided with a second via hole 9;

the first wire layer 10 and the fourth wire layer 70 are laminated plates composed of rolled copper and are connected by using fluorinated ethylene propylene copolymer as an adhesive sheet, and the second wire layer 30 and the third wire layer 50 are copper-clad laminated plates;

the first dielectric layer 20 is a combination layer of flat open-fiber glass woven cloth, improved resin and low-temperature co-fired ceramic particles, and the surface of the first dielectric layer 20 facing the second wire layer 30 is pressed with a shielding layer;

the second dielectric layer 40 is a flat open-fiber glass woven fabric and an improved resin composite layer, the third dielectric layer 60 is a composite layer of a flat open-fiber glass woven fabric, an improved resin and low-temperature co-fired ceramic particles, and the third dielectric layer 60 is a shielding layer pressed towards one surface of the third wire layer 50;

an attaching area 2 is arranged on the upper end face or the lower end face of the circuit board 1, and an insulating layer is coated on the surface of the attaching area 2;

the shielding bracket 21 is shown in fig. 2 and 3, the shielding bracket 21 is fixed on the attaching area 2 through glue or screws, the projection area of the shielding bracket 21 on the attaching area 2 is smaller than or equal to the area of the attaching area 2, an antenna is fixedly installed on the shielding bracket 21, the antenna is electrically connected with the wiring on the circuit board 1 through a wire slot, and the high-frequency signal wiring areas of the antenna are respectively arranged on the first wire layer 10 and the fourth wire layer 70;

as shown in fig. 3, 5 and 6, the first, second, third and fourth wire layers are electrically connected through the via hole 4, and the second wire layer 30 or the third wire layer 50 is electrically connected to the first wire layer 10 and/or the fourth wire layer 70 through the second via hole 9;

as shown in fig. 2, the end surfaces of the first wire layer 10 and the fourth wire layer 70 are respectively provided with a plurality of first bonding pads 5, the first bonding pads 5 are surrounded by isolation bonding pads, and the size of the isolation bonding pads is 40-50mil;

as shown in fig. 5 and 6, the pads of the first wire layer 10 and the fourth wire layer 70 are surrounded by the second via hole 9, that is, the second isolation pad 91 in the drawing, and similarly, the isolation pad may be surrounded by the via hole 4 on the pads of the first wire layer and the fourth wire layer;

referring to fig. 2, the layout trace on the circuit board 1 is integrally rotated by 0-30 degrees, and fig. 2 illustrates an example of 6 degrees.

Specifically, as shown in fig. 1, mutually perpendicular knitting wires 201 forming a flat open-fiber glass knitting cloth are arranged in a wire layer, a branch intersection point 301 is formed at the intersection of the knitting wires 201, an example first wire trace 101 is an existing common layout wire trace, an example second wire trace 102 is a wire trace obtained after the whole layout wire trace is rotated, and from the figure, the intersection of the example second wire trace 102 and the knitting wires 201 is relatively to the example first wire trace 101, so that the intersection is more even, and the more even intersection can effectively reduce the change of signal rate and improve the antenna efficiency. Such as: the intersection of example trace one 101 with the braid is from dense to sparse, as viewed from left to right, while the intersection of example trace two 102 is relatively even. The rotation angle can be adjusted according to actual conditions.

In particular, the shielding layers disposed on the first dielectric layer 20 and the third dielectric layer 60 are used for alleviating the EMI effect of the first and the fourth wire layers on the second and the third wire layers, and the second dielectric layer 40 between the second and the third wire layers may be also provided with a shielding layer according to the need, and the shielding layer is composed of a shielding net.

It should be noted that the working performance of the antenna is mainly affected by the dielectric constant of the material on the circuit board 1, and generally, the smaller the dielectric constant of the conductor away from the glass fiber, the better the working performance of the antenna, such as using the tu_872LK low dielectric constant (3.8) material of the stage , although the lower dielectric constant can be obtained, the cost is relatively higher, and then a part of the PCB is added with high frequency ceramic to obtain good high frequency and high speed characteristics, and the dielectric constant of the high frequency ceramic PCB is generally above 5.0. The millimeter wave has serious attenuation in atmospheric propagation due to the characteristics of the millimeter wave, namely the working range of the millimeter wave antenna is smaller, and the number of the antenna layout is more, so that the antenna can obtain good working efficiency and excellent high-frequency and high-speed characteristics in the smaller working range, and therefore, the antenna does not need very low dielectric constant, but the requirement of a circuit board on high frequency and high speed is high.

Therefore, the first and third dielectric layers are both doped with low-temperature co-fired ceramic to improve high-speed and high-frequency performance, and the second dielectric layer 40 is a middle isolation layer, which is relatively far away from the first and fourth wire layers with high-speed and high-frequency, so that the adhesion of the whole circuit board 1 is stronger, and the dielectric constant between the second and third wire layers with low-speed is lower, so that the second dielectric layer 40 is a flat open-fiber glass woven cloth and an improved resin combination layer.

Flat open glass woven cloth mainly refers to glass cloth employing such a weaving method, for example: 1078 type glass cloth PTFE polytetrafluoroethylene, 1080 type glass cloth ceramic filled non PTFE laminate. Compared with a standard braiding mode, the flat open-fiber braiding mode has smaller dielectric constant, can improve the efficiency of the antenna, and has lower cost compared with TU_872LK material; the dielectric constant of the flat open-fiber glass woven cloth is about 4.4, which is lower than that of the traditional standard woven cloth, and is higher than TU_872LK material, and is close to high-frequency ceramic and low-temperature co-fired ceramic particles (the dielectric constant is about 5.0, and the dielectric constant can be partially lower than 5.0).

It should be noted that the purpose of the isolation pads is to optimize the impedance at the bond so that the abrupt magnitude of the impedance is smaller. The first wire layer 10 and the fourth wire layer 70 are high-frequency and high-speed wire layers which are in contact with air and are made of rolled copper, and the smooth rolled copper can enable the wire to obtain lower impedance abrupt change characteristics and reduce loss under the skin effect; the second and third wire layers are middle low-speed wire layers, which can adopt a copper plating mode to obtain relatively low impedance abrupt change and control cost. In particular, the density of the flat open-fiber glass woven fabric in the first and third dielectric layers is higher than that of the second dielectric layer 40 (the higher the density is, the better the signal high-speed performance is in a certain range), so as to ensure the performance of the high-speed and high-frequency line layers and reduce the loss of the low-speed line layer.

It should be noted that, for the antenna-integrated circuit board, the attachment area 2 is provided to mount the shielding bracket 21, while a part of the circuit board space is wasted and the connection strength is also reduced, the efficiency of the antenna is not reduced, and the phenomenon of cracking of the embedded groove caused by expansion with heat and contraction with cold under long-term operation of the circuit board can be effectively overcome, and the situation is rapidly deteriorated after occurrence, so that the service life of the circuit board is greatly shortened. The mounting structure can effectively prolong the service life of the thick plate above the three layers of wire layers and is easy to replace antennas of different types. When the shield holder 21 is attached by using glue, it can be peeled off by a heat gun.

Generally, the attachment area 2 is disposed at a corner of the circuit board 1 to bypass the projection of the chip logic signal circuit or be far away from the chip logic signal circuit, so as to reduce the influence of the high-speed and high-frequency logic signal circuit on the antenna.

Specifically, the thicknesses of the first line layer 10, the first dielectric layer 20, the second line layer 30, the second dielectric layer 40, the third line layer 50, the third dielectric layer 60, and the fourth line layer 70 are equal. The purpose is to make the mechanical properties of each layer of the board body tend to be uniform so as to improve the antenna efficiency, and the consumed cost is relatively low.

Specifically, as shown in fig. 2 to fig. 4, the circuit board 1 is provided with a concave hole 6/ground hole, the concave hole 6 is provided on the first wire layer 10 and/or the fourth wire layer 70, an impedance mutation component 7 is installed in the concave hole 6, and the impedance mutation component 7 includes: capacitance and inductance. The purpose is that: and (3) performing isolation reference on individual components (such as coupling capacitors) so as to ensure that impedance abrupt change is as small as possible, namely, the components are closer to a reference plane of a transmission line, and impedance change is smaller. Furthermore, a first via hole 8 may be disposed on the bottom surface of the concave hole 6, the first via hole 8 is connected to the second wire layer 30 or the third wire layer 50, and the resistance mutation component 7 is electrically connected to the second wire layer 30 or the third wire layer 50 through the first via hole 8.

It should be noted that, the wiring of the chip, the circuit, etc. and the components disposed on the circuit board 1 are conventional technologies (the layout position refers to the upper layer wiring area 3 in fig. 2), the layout and the connection modes thereof can be flexibly changed according to the requirements, and the result of the change can be directly expected, so that the description thereof will not be repeated here.

In summary, the present invention is to set the wire layer and the dielectric layer to be pressed into a circuit board, and to integrally rotate the layout wire by a proper angle, so as to reduce the dielectric constant by using the flat open-fiber glass woven cloth as the dielectric layer material, to improve the antenna efficiency, and to make the wire and the branch intersection point more even by rotating the whole layout wire, to average the intersection of the wire and the woven layer, to reduce the glass fiber effect, to reduce the signal rate variation, to further improve the antenna efficiency and to reduce the impedance mutation amplitude; the isolation bonding pad is arranged, and the design of the through hole is optimized, so that the impedance is controlled, and the amplitude of impedance mutation is reduced; the concave holes (ground holes) are arranged to mount components with easily abrupt changes in impedance of the capacitor and the inductor, and the amplitude of abrupt changes in impedance when a circuit passes through the components is optimized by the isolation reference of the concave holes; the circuit board can obtain a relatively smoother impedance mutation curve under high-frequency and high-speed signals, and the efficiency of the millimeter wave antenna is guaranteed not to be reduced.

In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Wherein the terms "first position" and "second position" are two different positions.

The foregoing examples are merely representative of one or more embodiments of the present invention and are described in more detail and are not to be construed as limiting the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of the invention should be assessed as that of the appended claims.

Claims

1. A multilayer impedance HDI circuit board comprising: the circuit board, the circuit board top-down is provided with: the circuit board is provided with a via hole, the via hole penetrates through the upper end surface and the lower end surface of the circuit board, and the circuit board is provided with a second via hole;

2. The multi-layer impedance HDI circuit board of claim 1 wherein said isolation pads are 40-50mil in size.

3. The multilayer impedance HDI circuit board of claim 1 wherein the first, second, third, fourth wire layers have equal thicknesses.

4. The multilayer impedance HDI circuit board of claim 1, wherein a recess is provided in the circuit board, the recess is provided in the first wire layer and/or the fourth wire layer, and an impedance mutation component is mounted in the recess, and the impedance mutation component includes: capacitance and inductance.

5. The multilayer impedance HDI circuit board of claim 4 wherein a bottom surface of the recess may be provided with a first via, the first via being connected to the second wire layer or the third wire layer, and the impedance mutation element being electrically connected to a wire on the second wire layer or the third wire layer through the first via.