CN211406442U

CN211406442U - Electrical contact and connector

Info

Publication number: CN211406442U
Application number: CN202020163690.3U
Authority: CN
Inventors: 吴向葵; 刘绍明
Original assignee: Bece Pte Ltd
Current assignee: Bece Pte Ltd
Priority date: 2020-01-30
Filing date: 2020-02-12
Publication date: 2020-09-01
Anticipated expiration: 2030-02-12
Also published as: CN113207217A

Abstract

Electrical contacts and connectors for testing semiconductor devices such as integrated circuit packages, particularly high integration IC packages, the electrical contacts comprising a plurality of interwoven and mutually supporting wires including at least one electrical lead for providing a first electrical contact and a second electrical contact; wherein the at least one electrical lead has a multilayer structure. The connector includes the electrical contacts and a carrier having a plurality of through-holes; wherein at least one of the electrical contacts is disposed in at least one of the vias.

Description

Electrical contact and connector

Technical Field

The present application relates to electrical contacts, also referred to as resilient electrical contacts, for Integrated Circuit (IC) packages, in particular for ultra-high integration IC packages. In addition, the present application relates to connectors employing the electrical contacts.

Background

Currently, highly integrated IC packages are electrically connected to a substrate, such as a Printed Circuit Board (PCB), by a Land Grid Array (LGA), a land grid array (PGA), or a Ball Grid Array (BGA) that is soldered directly to the bottom of the package. Although the direct welding method described above has a low manufacturing cost, it has several significant drawbacks in detecting and correcting possible welding failures. Furthermore, direct soldering permanently fixes the IC package to the substrate and is therefore not suitable for testing of the IC package.

Disclosure of Invention

To address the above-mentioned problems, the present application discloses an electrical contact that does not need to be permanently secured between an IC package and a substrate. Thus, the electrical contacts may be used both as a product socket to permanently connect the IC package to the substrate and as a test socket to temporarily connect the IC package to the substrate. Conventional electrical contacts require the use of a dielectric mandrel to provide electrical energy storage; in contrast, the electrical contacts of the present application may have only electrical leads. In other words, the wires have on the one hand a good electrical conductivity and on the other hand sufficient elasticity so that the electrical contacts will spring back to their original state after removal from the substrate and the IC package. In addition, the electrical contacts are durable and can be tested over 50 million life cycles.

In a first aspect, the present application discloses an electrical contact. The electrical contact includes a plurality of wires that are interlaced (alternating, intertwined, interwoven, braided) and that support each other. The interleaved and mutually supporting wire comprises one or more electrical leads for providing a first electrical contact and a second electrical contact; wherein the at least one electrical lead has a multilayer structure. By connecting a first external electrical device (e.g. an IC package) and a second external device (e.g. a substrate) with a first electrical contact and a second electrical contact, respectively, the first external device and the second external device are electrically connected to each other through the electrical contacts. In some embodiments, the electrical contact comprises six electrical wires interwoven together. In other embodiments, the electrical contact includes eight electrical wires interwoven together.

Optionally, the electrical lead comprises a sharp edge for scraping an electrical contact surface of an external electrical device. In particular, the scratching is on the nanometer scale (less than 1 micron). The scraping establishes a physical connection between the electrical contacts and the external electrical device by eliminating contamination or oxidation on the external electrical device contact surface. The electrical lead may have a first tip and a second tip, the first and second scratches being formed at the first and second external electrical devices, respectively, on a nanometer scale. In some embodiments, the first tip or the second tip has a single sharp end for forming the scrape. In other embodiments, the first tip or the second tip has two or more minute protrusions to form the scraping. At the same time, the electrical leads do not damage the external electronics, since the scratching is controlled at the nanoscale. In this way, the first and second external electrical devices can be reliably electrically connected by the electrical leads of the electrical contacts.

Optionally, the plurality of wires comprises three or more individual wires that are interlaced and supported on each other to form a unitary structure. The individual wires (including the electrical leads) are not supported by any other object and are independent of each other. In this way, the individual wires can be moved within a limited range while still maintaining the overall structure. In other words, the integral structure can be elastically deformed. In particular, the monolithic structure is elastically deformed non-uniformly along its axial direction. The elastic deformation of the first and second portions near the first and second tips of the electrical lead, respectively, is greater; while the intermediate portion between the first portion and the second portion is less elastically deformed.

The unitary structure comprises a tubular structure (e.g., a cylindrical wall or shape). The tubular structure includes one or more open ends having the sharp edges. The tubular structure has spring properties for reversibly storing and releasing mechanical energy. In other words, the tubular structure may be longitudinally compressed from an initial position under an axial load and then substantially rebound to the initial position after removal of the axial load. During the elastic deformation process, each individual wire will only exhibit bending characteristics consistent with the elastic limit of the "stress-strain" or "force-deformation" curve of the material from which it is constructed.

In some embodiments, the wires are formed into a helical configuration by interweaving with each adjacent individual wire in the tubular structure. The tubular structure may be characterized by a tubular diameter (diameter), pitch (pitch), or repeat distance (lead). The compressibility of the tubular structure in its cylindrical or longitudinal direction does not exceed 30%. In other words, the minimum compressed length under axial load needs to be at least 70% greater than the initial length without axial load, before the tubular structure can remain elastically deformed.

Every two of the individual wires are interlaced and supported by each other, forming a point of intersection (i.e. in intersecting contact with each other, but not connected) on the cylindrical wall of the tubular structure. As described above, the two independent wires are not coupled or bonded at their intersection points; thus, at the intersection point, one of the individual wires may move relative to another individual wire crossing it. Additionally, the tubular structure has one or more of the repeat distances. The repetition distance is defined as the distance between the first intersection point and the second intersection point in the axial plane of the same wire. I.e. the wires are wound around the tubular structure starting from a first intersection point in an axial plane and then ending at a second intersection point in the axial plane.

Each of the individual wires intersects with another wire to form at least one of the intersection points. The distance between two immediately adjacent intersections in the axial or cylindrical direction of the tubular structure is called the pitch. In some embodiments, the spacing is substantially the same. In some embodiments, when the tubular structure has eight interlaced and mutually supporting wires, the repeat distance (lead) has four of said pitches in the axial plane. Thus, the repeat distance (lead) of the wire is equal to the span of four pitches (pitch) in the axial plane. The tubular structure may be measured by the repeat distance or the pitch. Alternatively, the tubular structure may be formed to have compact and self-supporting properties when its initial length in the uncompressed state is in the range of 50 to 100 mils (mil). The tubular structure has a flexible design in terms of tubular diameter, repeat distance and wire diameter of the wire. In some embodiments, the wire diameter is about 1.2 mils; and when the repeat distance is set at 25 mils, 26 mils, and 30 mils, the tubular diameters are selected to be 5 mils, 6 mils, and 8 mils, respectively. In other embodiments, the wire diameter is about 0.85 mils; and when the repeat distance is set to be around 15 mils, the tubular diameter is selected to be around 3 mils.

In the absence of external forces (i.e. in the initial position or under the influence of gravity alone), two or more of the intersecting wires form a substantially right angle between them. The angle formed by the two wires at the point of intersection may vary slightly as the two wires may move about the point of intersection. The angle has a variation within 10 degrees, i.e. from 80 to 100 degrees. The right angle may assist the tubular structure to rebound to an initial position (i.e., initial position) after the axial load is removed.

The electrical leads are the most critical factor for the electrical contacts to electrically connect the first external device and the second external device. Accordingly, the electrical lead is required to have various properties, such as high electrical conductivity (or low electrical resistance), high durability under repeated flexing, ability to transmit high frequency signals, ability to withstand gradually increased operating temperatures, chemical stability (e.g., not prone to oxidation in the surrounding environment), and high mechanical strength. Optionally, the electrical lead comprises a multilayer structure having different materials. Due to the unique multilayer structure, the electrical conductor has a sufficiently large elastic range. In addition to the unique multilayer structure, the electrical lead may be subjected to an annealing process to expand its elastic range.

Alternatively, the multilayer structure may include an inner layer of a resilient or flexible material; and a covering layer for covering the inner layer to prevent at least one of the electrical leads from being corroded (e.g., oxidized) or to enhance the electrical conductivity thereof. When the covering layer is formed by plating, the covering layer is also referred to as plating. In addition, the inner layer also provides mechanical strength for maintaining the integrity of the wire. In some embodiments, the inner layer comprises a steel material, such as stainless steel (e.g., stainless steel 302, 304, or 316), spring steel, memory steel, and other similar shape memory alloys (e.g., nickel titanium (also known as nitinol)). In other embodiments, the inner layer includes a very low resistivity metal (e.g., copper) for enhancing the electrical conductivity of the electrical leads.

Optionally, the cover layer further comprises: a nickel (Ni) layer (e.g., a nickel plating layer) plated on the inner layer for covering the inner layer; and a gold layer (e.g., gold plating) plated on the nickel layer for encapsulating the nickel layer. The nickel and gold layers also serve to further enhance the electrical conductivity of the electrical contact because the electrical resistivity of nickel and gold is about 6.99x10, respectively, at room temperature (i.e., 20 deg.C)^-8Ohm-meters (Ω. m) (i.e. a conductivity of about 1430 ten thousand Siemens/meter) and 2.44x10^-8In some embodiments, a palladium (Pd) layer (e.g., a palladium plating layer) is first formed on the nickel layer prior to forming the gold layer, in other words, the palladium layer is located between the nickel layer and the gold layer, since the conductivity of palladium at room temperature (i.e., 20 ℃) is about 1.06x10^-8Ohm-m (i.e., conductivity of about 943 ten thousand decimeters per meter), the palladium is therefore presentThe layer further reduces resistivity; and also provides additional mechanical strength (e.g., stiffness) to the cover layer. In particular, the gold layers each have a thickness greater than 1.0 micrometer (μm); and the nickel layer and the palladium layer are each less than 1.0 micrometer (mum) thick.

Optionally, the cover layer further comprises a copper layer (e.g. a copper plating layer) formed on the inner layer for covering the inner layer, especially when the inner layer is made of a non-copper alloy. Since stainless steel has 6.90x10 at room temperature (i.e., 20 ℃)^-7A relatively high resistivity in ohm-meters (Ω -m) (i.e., a conductivity of about 140 ten thousand siemens/m), and the copper layer may therefore be used to enhance the conductivity of the electrical contact. The resistivity of copper at room temperature (i.e., 20 ℃) was 1.68x10^-8Ohm-meters (Ω · m) (i.e. a conductivity of about 6000 million siemens/m). Optionally, high performance copper or high strength copper (e.g., C17510 copper alloy) is used to enhance electrical conductivity. Similarly, the thickness of the copper layer may be greater than 2.0 micrometers (μm).

Optionally, the multilayer structure further comprises an outer layer for encapsulating the inner layer and/or the cover layer to prevent corrosion of the inner layer and/or the cover layer. In some embodiments, the outer layer comprises a self-assembled molecule (SAM) layer. The self-assembled molecular layer includes a plurality of multifunctional molecules having an immobilization group for attachment to the cover layer and a plurality of functional groups opposite to the immobilization group, the multifunctional molecules may enhance corrosion resistance and wear resistance. The self-assembled molecular layer can provide additional conductivity to the electrical leads if electrons can be transferred between the multifunctional molecules; thus, a conductive path is formed between adjacent electrical leads that are in direct contact. If electrons are not transferable between the multifunctional molecules, such a conductive path is not formed, and the adjacent electrical leads are insulated from each other. In some embodiments, the self-assembled molecular layer is formed over the capping layer, such that the self-assembled molecular layer prevents oxidation of the capping layer; thus. The gold layer may have a relatively thin thickness to save costs. In some embodiments, the self-assembled molecular layer is formed directly on the inner layer to prevent oxidation of the inner layer. Optionally, the self-assembled molecular layer is less than 0.5 micrometers (μm). Alternatively, the outer layer comprises a parylene coating having excellent non-porous and uniform barrier properties to various chemicals, such as organic solvents, inorganic agents, acids, oxygen, corrosive liquids and gases, and moisture. In addition, the parylene coating also has excellent electrical insulation and a lower dielectric constant.

Optionally, the multilayer structure further comprises an insulating layer which completely or partially surrounds, encloses, encapsulates, covers the cover layer. The cover layer is exposed from within the insulating layer at first and second ends of the electrical contact. The insulating layer may prevent electrical interference between adjacent electrical contacts to enhance signal transmission. The insulation layer may be made of any insulating material, including but not limited to fiberglass, mineral wool, cellulose, natural fibers, synthetic polymers (e.g., polystyrene, polyisocyanurate, and polyurethane), or synthetic foams (e.g., urea-formaldehyde foam, cement foam), and phenolic foam).

Optionally, the wire further comprises one or more support wires for supporting other wires (e.g., electrical wires). The support wire is also wound in a similar manner (e.g., a helical path) and interleaved with the other wires (e.g., electrical wires) to form the unitary structure.

In a second aspect, the present application discloses a connector. The connector comprises a plurality of the electrical contacts; and a carrier (also referred to as a housing) containing a plurality of through holes. The carrier is disposed between a first external electronic device (e.g., an IC package) and a second external electronic device (e.g., a substrate). The plurality of electrical contacts are respectively placed in the plurality of through holes for electrically connecting the first external electrical device and the second external electrical device. First and/or second ends of the plurality of electrical contacts are exposed from the through-holes. In other words, the electrical contact has an initial length at an initial position; and the via has a via depth. The initial length must be greater than the via depth. The diameter of the through hole (through hole diameter) is slightly larger than the diameter of the electrical contact for guiding the electrical contact into the through hole.

Optionally, the through holes are arranged in an array corresponding to an external electrical device. The connector may also include a plurality of fasteners for securing, attaching or fastening the housing to the external electrical device. For example, the connector includes a first fastener for securing the housing to the first external electrical device after the electrical contacts are precisely aligned with the first external electrical device. Similarly, the connector further includes a second fastener for securing the housing to the second external electrical device after the electrical contacts are precisely aligned with the second external electrical device. Thus, an efficient path for the transfer of electrical signals from the first external electrical device to the second external electrical device is established through the connector.

Optionally, the carrier or housing comprises a top layer, a bottom layer and an intermediate layer sandwiched between the top and bottom layers. The carrier may be used as an interposer (interposer) for receiving and providing mechanical support for the electrical contacts. Optionally, the top layer is made of an insulating material (e.g. polyimide). Optionally, the bottom layer is also made of an insulating material (e.g., polyimide). Optionally, the intermediate layer is made of a thermally conductive material (e.g., copper). Thus, the intermediate layer may act as a heat sink for dissipating heat generated by the electrical contacts. The carrier may further comprise a top intermediate layer between the top layer and the intermediate layer for bonding the top layer and the intermediate layer; and a bottom intermediate layer between the bottom layer and the intermediate layer for joining the bottom layer and the intermediate layer. Additionally, the top interlayer may also include a top adhesion layer (e.g., pure silicone); the bottom intermediate layer may also include a bottom adhesive layer (e.g., pure silicone). Under heat and pressure, the neat silicone combines the top, middle and bottom layers into a single structure.

In a third aspect, the present application discloses a method of manufacturing (i.e., a method of manufacturing) the electrical contact described above. The manufacturing method comprises the following steps: a step of providing a plurality of wires comprising one or more electrically conductive wires; a step of interlacing, alternating, winding, braiding a plurality of said threads to form a unitary structure; a step of separating (e.g. cutting) the monolithic structure into a plurality of substantially identical or similar electrical contacts; and a step of coating the electrical contacts to form a multilayer structure. The at least one electrical lead has a first electrical contact and an opposing second electrical contact. In other words, the electrical leads have first and second electrical contacts around their first and second ends, respectively. Optionally, the thread is interwoven using a braiding machine. In some embodiments, the wire is configured into a helical configuration for forming the unitary structure. The interleaving step may be performed vertically or horizontally.

Optionally, the method of manufacturing the electrical contact comprises the steps of: a step of providing a plurality of wires comprising one or more electrical leads; a plating step for forming a multilayer structure of the electrical lead; a step of interlacing, alternating, winding, braiding to form said integral structure; a step of separating (e.g. cutting) said unitary structure for forming a plurality of substantially identical or similar said electrical contacts.

Optionally, the method for manufacturing the electrical contact further comprises the following steps: after the interleaving step (e.g., annealing process), the monolithic structure is first heated, during which the internal stresses of the electrical leads are eliminated; the monolithic structure is then cooled to room temperature. Optionally, the heating step is performed by a thermal radiation process. Heat is transferred from the thermal radiation source to the monolithic structure until the monolithic structure is heated to 200 to 500 degrees celsius for about 5 minutes. During thermal radiation heating, the monolithic structure is not in direct physical contact with a thermal radiation source, such that the monolithic structure may be configured to be substantially uniformly heated. In addition, the heat radiation process is performed in an inert atmosphere (e.g., a chamber filled with nitrogen gas).

Alternatively, the heating step may be performed by an induction heating process, due to the ferromagnetic nature of the monolithic structure. The induction heater generates eddy currents that generate heat within the electrical leads of the monolithic structure. The induction heating process has at least several advantages. First, the induction heating process can be performed very rapidly. Secondly, the induction heating process does not involve any foreign matter, and thus can be performed in a general environment. Third, the induction heating process may be directed or focused on the monolithic structure, and thus the monolithic structure may be heated very uniformly. In addition, the induction heating process may of course also be carried out in an inert environment.

Alternatively, the electrical lead may be prepared by: providing an inner layer as a wire core; a step of forming at least one covering layer (e.g., plating layer) for encapsulating the inner layer; the cover layer is formed by the steps of: a step of plating a copper layer on the inner layer to seal the inner layer; a step of plating a nickel layer on the copper layer to cover the copper layer; and a step of plating a gold layer on the nickel layer to cover the nickel layer. Optionally, the method of making the electrical contact may further comprise the step of forming a palladium layer between the nickel layer and the gold layer.

Optionally, the method of manufacturing the electrical contact may further comprise: a step of forming an outer layer on the cover layer for encapsulating the cover layer. Optionally, the outer layer comprises a self-assembled molecular (SAM) layer. The self-assembled molecule (SAM) layer is formed, for example, by soaking the electrical leads in a precursor solution of the multifunctional molecule (precursor solution). The multifunctional molecules will spontaneously be immobilized on the cover layer and regularly arranged in a certain configuration. Optionally, the cover layer comprises a parylene coating. Such as a parylene coating (i.e., a parylene layer) formed by a parylene deposition process. The parylene deposition process requires three stages to complete. In the first stage (i.e., the vaporization stage), the parylene dimer is added in powder form to a vaporizer, and then heated to 150 ℃ to change it to a vapor state. In the second stage, i.e., the pyrolysis stage, the parylene dimer vapor is transferred to a pyrolysis furnace and then heated to 690 ℃ at a pressure of 0.5 Torr (about 67 pascals) to form the parylene monomer. In the third stage (i.e., the deposition stage), the electrical leads are first placed into the coating chamber before the parylene monomer is introduced into the coating chamber. A portion of the parylene monomer forms a polymer of parylene and is simultaneously deposited and secured to an outer surface of the electrical lead. Optionally, the parylene deposition process may further include a fourth stage: excess parylene monomer is drained from the coating chamber to an external liquid cold trap.

Alternatively, the method of manufacturing the electrical contact may further comprise: a step of forming an insulating layer on the cover layer and/or the outer layer. Optionally, the insulating layer is formed by winding an insulating sheet on the cover layer and/or the outer layer.

In a fourth aspect, the present application discloses a method (i.e., a method of use) of using the electrical contact described above. The using method comprises the following steps: a step of providing one or more of said electrical contacts; a step of arranging the electrical contacts on or in a second external electrical device; and a step of arranging a first external electronic device on the electrical contacts. The electrical contacts are slightly compressed between the first and second external electrical devices by a compressed length of no more than 30%. In particular, the electrical contact is very robust, which can be almost completely restored to an uncompressed state after removal of the first and second external electrical devices. Thus, the electrical contacts may be used as a product socket or a test socket.

The electrical contact has a first end and a second end opposite thereto in direct contact with the first and second external electrical devices, respectively. At least one of the first and second ends is configured to scrape surfaces of the first and second external electrical devices, respectively, on a nanometer scale to form reliable electrical contacts.

Optionally, the method of using the electrical contact may further comprise: a step of providing a carrier (or housing) having one or more through holes; a step of placing the carrier on a second external electrical device; and inserting the electrical contact into the through hole.

Optionally, the method of using the electrical contact may further comprise: a step of fixing the carrier to the first and/or second external electrical device. Before the securing step is performed, precisely aligning the electrical contacts with the first and/or second external electrical devices.

Optionally, the method of using the electrical contact may further comprise: a step of providing electrical contact pads between said electrical contacts and the first external electrical device and/or the second electrical apparatus. The electrical contact pads (e.g., solder pads or copper posts) may further provide a good and reliable electrical connection between the electrical contacts and the first and/or second external electronic devices.

In a fifth aspect, the present application discloses a method of manufacturing a carrier for the electrical contact (i.e., a method of manufacturing a carrier). The method for manufacturing the carrier comprises the following steps: a step of providing a top layer, a middle layer and a bottom layer; and a step of aligning the top, middle and bottom layers to a stack; a step of assembling the top, bottom and intermediate layers into the carrier, the carrier forming a single integral structure; and a step of forming a plurality of through holes on the top layer, the intermediate layer, and the bottom layer.

Optionally, the method for manufacturing the carrier may further include: a step of providing the top intermediate layer and the bottom intermediate layer; a step of stacking the top intermediate layer between the top and intermediate layers; a step of stacking the bottom intermediate layer between the intermediate layer and the bottom layer; and assembling the top and bottom middle layers with the top, middle and bottom layers.

Alternatively, the method of manufacturing the carrier includes: a step of providing a top layer having a plurality of first vias; a step of providing an intermediate layer having a plurality of second through holes; a step of providing a bottom layer having a plurality of third through holes; a step of aligning the top layer, the middle layer and the bottom layer by aligning the first through hole, the second through hole and the third through hole; a step of assembling the top layer, the middle layer and the bottom layer into a single structure.

Optionally, the method for manufacturing the carrier further comprises: a step of providing a top intermediate layer having a fourth via hole. A step of providing a bottom intermediate layer having a fifth via hole; a step of aligning the top intermediate layer with the top layer and the intermediate layer by aligning the fourth via with the first via and the second via; a step of aligning the bottom intermediate layer with the intermediate layer and the bottom layer by aligning the fifth via with the second via and the third via; a step of assembling the top middle layer and the bottom middle layer with the top layer, the middle layer and the bottom layer.

In a sixth aspect, the present application discloses a method of using the electrical contact arrangement (i.e. a method of using the electrical contact arrangement). The method of using the electrical contact device comprises: a step of providing a first external electrical device and a second external electrical device; a step of connecting the electrical contact arrangement to the second external electrical device; and a step of connecting the first external electronic device to the electrical contact arrangement.

Optionally, the method of using the electrical contact device may further comprise the steps of: a step of aligning the electrical contact device with a top contact pad of a second external electrical device; and the step of aligning the electrical contact arrangement with a bottom contact pad of a first external electrical device.

Alternatively, the electrical contact device may be prepared by: a step of providing a carrier having a plurality of through holes; a step of providing a plurality of electrical contacts; a step of assembling the electrical contacts with the carrier; and a step of transferring said electrical contact arrangement to a second external electrical apparatus. The assembling includes inserting the electrical contacts into their respective through holes. The insertion step may be performed by any known method. Optionally, the electrical contact device may also be prepared by: a step of providing a carrier having a plurality of through holes; a step of providing a plurality of electrical contacts; a step of placing the carrier onto a second external electronic device; and assembling the electrical contacts with the carrier.

Drawings

The following drawings (figures) represent embodiments and serve to explain the principles of the disclosed embodiments. It should be understood, however, that the drawings are given for illustrative purposes only and are not limiting on the relevant features.

FIG. 1 shows a perspective view of an electrical contact in an initial state;

FIG. 2 shows a side view of the electrical contact in the initial state;

FIG. 3 shows a top view of the electrical contact in the initial state;

FIG. 4 shows an enlarged perspective view of the top end of the electrical contact;

FIG. 5 shows a side view of a solder ball mounted at the top end of the electrical contact;

FIG. 6 shows a side view of the electrical contact in an initial state (FIG. 6(a)) and in a compressed state (FIG. 6 (b));

FIG. 7 shows a top view of another electrical contact having two types of electrical leads;

FIG. 8 shows a cross-sectional view of a first embodiment of the electrical lead;

figure 9 shows a cross-sectional view of a second embodiment of the electrical lead;

figure 10 shows a cross-sectional view of a third embodiment of the electrical lead;

figure 11 shows a cross-sectional view of a fourth embodiment of the electrical lead;

fig. 12 shows an exploded perspective view of the first connector;

FIG. 13 shows a cross-sectional view of the first connector;

FIG. 14 shows an exploded perspective view of the second connector;

FIG. 15 shows a cross-sectional view of the second connector;

FIG. 16 shows a process flow diagram for the electrical contacts;

fig. 17 shows a process flow diagram for forming the plating of the electrical contact.

The numbers in the figures are as follows:

100. an electrical contact; 102. a first electrically conductive line; 103. a second electrically conductive line; 104. a third electrically conductive line; 105. a fourth electrically conductive line; 106. a fifth electrically conductive line; 107. a sixth electrically conductive line; 108. a second gas-electric wire; 109. an eighth electrically conductive line; 110. the whole structure; 112. a point of intersection; 114. pitch; 116. an initial diameter; 118. an initial length; 120. a repeat distance; 122. a top end; 126. an IC device; 128. a Printed Circuit Board (PCB); 130. an inner layer; 132. plating; 134. copper plating; 136. A nickel plating layer; 138. a palladium plating layer; 140. gold plating; 142. a self-assembled molecular (SAM) layer; 143. a parylene coating; 144. an initial state; 146. a compressed state; 147. compressing the length; 148. a solder ball; 152. a first top sharpened tip; 153. a second top sharpened tip; 154. a third top sharpened tip; 155. a fourth top sharp tip; 156. a fifth top sharpened tip; 157. a sixth top sharpened tip; 158. a seventh top sharpened tip; 159. an eighth top sharpened tip; 160. a first embodiment of an electrical lead; 170. a second embodiment of an electrical lead; 180. a third embodiment of an electrical lead; 190. a fourth embodiment of an electrical lead;

200. a resilient electrical contact; 202. a first electrically conductive line; 203. a second electrically conductive line; 204. a third electrically conductive line; 205. a fourth electrically conductive line; 206. a fifth electrically conductive line; 207. a sixth electrically conductive line; 208. a seventh electrically conductive line; 209. an eighth electrically conductive line; 210. The whole structure;

300. a first electrical contact system; 302. a carrier; 304. a through hole; 314. a top layer; 316. an intermediate layer; 318. a bottom layer; 320. a first through hole; 322. a second through hole; 324. a third through hole; 326. a printed circuit board recess; 328. a first hole; 330. a second hole; 332. a third hole; 334. a top layer groove; 350. a second electrical contact system; 352. a carrier (housing); 354. a through hole; 364. a top layer; 366. an intermediate layer; 368. a bottom layer; 370. a first through hole; 372. a second through hole; 374. a third through hole; 378. a first hole; 380. a second hole; 382. a third hole;

400. a process flow diagram for electrical contact 100; 410. a first step; 420. a second step; 430. a third step; 440. a fourth step; 450. a fifth step;

500. a processing flow chart of the plating layer; 510. a first step; 520. a second step; 530. a third step; 540. a fourth step; 550. and a fifth step.

Detailed Description

Fig. 1-6 illustrate an electrical contact 100 having a single type of electrical conductor, referred to as a first type of electrical conductor. Fig. 1 shows a perspective view of the electrical contact 100 in an initial state. The electrical contact 100 includes eight interwoven or braided and unsupported

electrical conductors

102 and 109, namely a first electrical conductor 102, a second electrical conductor 103, a third electrical conductor 104, a fourth electrical conductor 105, a fifth electrical conductor 106, a sixth electrical conductor 107, a seventh electrical conductor 108, and an eighth electrical conductor 109. The eight

electrical leads

102 and 109 are interleaved with one another in a helical configuration to form a unitary structure 110 of tubular configuration. In particular, the unitary structure 110 does not require a central support structure on which the

electrical leads

102 and 109 are wound, nor does it require a support structure on which the

electrical leads

102 and 109 are placed on the outside or inside thereof. The electrical leads 102 and 109 belong to a first type of electrical leads, which are substantially identical in material, dimensions and other respects.

Fig. 2 shows a side view of the electrical contact 100 in the initial state. In the overall structure 110, each two of the eight

electrical leads

102 and 109 overlap to form an intersection 112. As such, the overall structure 110 includes a plurality of intersection points 112. Electrical leads 102 and 109 overlap at intersection point 112. At the intersection 112, there is no physical, chemical, or mechanical bond or interconnection. Thus, the

electrical leads

102 and 109 are free to move at the intersection point 112. The overall structure 110 has an initial length 118 when it is in its initial state. In contrast, it is more commonly used to characterize the overall structure 110 that the pitch 114, which is defined as the distance between two adjacent intersection points 112, is. Since the

electrical leads

102 and 109 can be moved at the intersection point 112, the pitch 114 can be adjusted within a small range without damaging the overall structure 110. In particular, when in the initial state, the angle formed by the two

electrical leads

102 and 109 at each intersection point 112 is substantially a right angle (90 degrees). The right angle helps the overall structure 110 to spring back from the compressed state to the initial state and form a stable structure in the initial state. In addition, the overall structure 110 has a particular parameter called the repeat distance 120. The repeat distance 120 is determined by measuring the distance between two adjacent intersection points 112 in the axial plane for a single electrical conductor 102-109. In the initial state, the repeat distance 120 is limited to less than 90 mils (mils) to keep the overall structure 110 more stable.

Fig. 3 shows a top view of the electrical contact 100 in the initial state. The monolithic structure 110 has an initial diameter 116 at its top end 122. It is also clearly shown in fig. 3 that there is no central support structure inside the overall structure 110 and that the eight

electrical conductors

102 and 109 are interwoven together. The unitary structure 110 also has a bottom end (not shown) opposite the top end 122. The bottom end has a similar structure to the top end 122. The top end 122 and the bottom end are to be electrically connected with an IC device 126 as a first external electrical apparatus and a Printed Circuit Board (PCB)128 as a second external electrical apparatus, respectively. The electrical contacts 100 have very high bulk conductivity (i.e., very low bulk resistivity) so that the IC device 126 and the printed circuit board 128 are effectively electrically connected through the electrical contacts 100. Optionally, the bulk conductivity is in a range of 10 to 30 milliohms (milliohms).

Fig. 4 shows an enlarged perspective view of the tip 122 of the electrical contact 100. Each of the eight

electrical leads

102 and 109 has a sharp top end at its top end 122. In detail, the first electrical lead 102 has a first top sharpened tip 152, the second electrical lead 103 has a second top sharpened edge 153, the third electrical lead 104 has a third top sharpened tip 154, the fourth electrical lead 105 has a fourth top sharpened tip 155, the fifth electrical lead 106 has a fifth top sharpened tip 156, the sixth electrical lead 107 has a sixth top sharpened tip 157, the seventh electrical lead 108 has a seventh top sharpened tip 158, and the eighth electrical lead 109 has an eighth top sharpened tip 159. Similarly, each of the eight

electrical leads

102 and 109 also has a bottom sharpened tip at its second end.

Fig. 5 shows a side view of a solder ball 148 mounted at the top end 122 of the electrical contact 100. Figure 5 clearly shows that the top

sharp tip

152 and 159 at the tip 122 creates multiple scratches on the solder balls 148 on a nanometer scale (less than 1 micron). The electrical leads 102 and 109 are slightly bent inside the solder balls 148 at the top ends 122 thereof so that the solder balls 148 are not severely damaged by the

electrical leads

102 and 109. In this manner, electrical contact 100 is in physical contact with solder ball 148 at tip 122. Thus, a reliable electrical connection is established between the electrical contact 100 and the solder ball 148 regardless of contamination of the exterior surface of the solder ball 148. As solder balls 148 are further attached to IC device 126, electrical contacts 100 also establish a reliable electrical connection with IC device 126. Similarly, the bottom end also has a sharp tip for forming scratches on a nanometer scale. Thus, a reliable electrical connection is established between the electrical contact 100 and the printed circuit board 128. As a whole, current is free to flow from IC device 126 to printed circuit board 128 through electrical contacts 100.

Fig. 6 shows a side view of electrical contact 100 in an initial state (fig. 6(a)) and in a compressed state (fig. 6 (b)). When an axial load or force is applied longitudinally, the monolithic structure 110 may deform axially from an initial state 144 to a compressed state 146. As shown in fig. 6(b), the deformation experienced by the electrical leads 102-109 during compression is substantially elastic, i.e., the electrical leads 102-109 will only exhibit bending characteristics that are fully consistent with the elastic limit portion of the "stress-strain" or "force-deformation" curve of the material from which they are formed. In other words, the

electrical leads

102 and 109 do not substantially plastically deform during compression. Generally, electrical contact 100 has a compressed length 147 in compressed state 146. The typical compression ratio of the overall structure 110 does not exceed 30%. In other words, the compressed length 147 is not less than 70% of the initial length 118.

Fig. 7 shows a top view of another electrical contact 200 having two types of electrical leads. Electrical contact 200 has a first electrical conductor 202, a second electrical conductor 203, a third electrical conductor 204, a fourth electrical conductor 205, a fifth electrical conductor 206, a sixth electrical conductor 207, a seventh electrical conductor 208, and an eighth electrical conductor 209. Electrical contact 200 has a similar structure to electrical contact 100, except that electrical contact 200 has two types of electrical leads. In detail, the

electrical conductors

203, 205, 206, 208 are of a first type; the

electrical conductors

202, 204, 207, 209 are of a second type. Electrical leads 202 and 209 are also wound and interwoven in a helical configuration to form a unitary structure 210. In particular, the first type of

electrical leads

203, 205, 206, 208 comprise stainless steel or memory steel to provide additional spring properties. For assisting the electrical contacts 200 to spring back to the initial position after the axial load is removed; while the second type of

electrical leads

202, 204, 207, 209 comprise copper or other high conductivity metal to provide sufficient electrical conductivity to the electrical contact 200.

Figure 8 shows a cross-sectional view of a first embodiment 160 of the

electrical leads

102 and 109. FIG. 8(a) is a cross-sectional view taken along the longitudinal axis; and fig. 8(b) shows a cross-sectional view perpendicular to the longitudinal axis. Electrical leads 102 and 109 include an inner or core layer 130 and a plating or cladding layer 132. The plating 132 substantially completely encapsulates the inner layer 130 within the interior of the

electrical leads

102 and 109. Inner layer 130 has a diameter of 0.3 to 5 mils (mils). The plating layer 132 has a thickness of 0.1 to 0.5 mils (mils). The inner layer 130 is made of stainless steel having a cubic crystal structure. The change in cubic crystal structure (e.g., face-centered cubic) provides the stainless steel with sufficient ductility to allow the inner layer 130 to elastically bend when the

electrical leads

102 and 109 are wrapped or woven into the tubular monolithic structure 110.

The plating layers 132 further include, from the inside to the outside of the first electrically conductive wire 102: copper plating 134, nickel plating 136, palladium plating 138, and gold plating 140. The copper plating 134, nickel plating 136, palladium plating 138, and gold plating 140 have a first thickness greater than 2.0 microns (μm), a second thickness greater than 1.0 micron, a third thickness less than 1.0 micron, and a fourth thickness greater than 1.0 micron, respectively.

Figure 9 shows a cross-sectional view of a second embodiment 170 of the

electrical leads

102 and 109. FIG. 9(a) is a cross-sectional view taken along the longitudinal axis; and fig. 9(b) is a cross-sectional view perpendicular to the longitudinal axis. The second embodiment 170 has a similar structure to the first embodiment 160 except that the

electrical leads

102 and 109 further include a self-assembled molecular (SAM) layer 142 for preventing oxidation of the plating layer 132 and the inner layer 130. The thickness of the self-assembled molecular layer 142 is less than 0.5 micrometers (μm). Also, the inner layer 130 may be made of copper alloy instead of stainless steel.

FIG. 10 shows a cross-sectional view of a third embodiment 180 of the

electrical leads

102 and 109. FIG. 10(a) is a cross-sectional view taken along the longitudinal axis; and fig. 10(b) is a cross-sectional view perpendicular to the longitudinal axis. The third embodiment 180 has a similar structure to the second embodiment 170 except that

electrical lead

102 and 109 include a parylene coating 143 in place of the self-assembled molecular layer 142. The thickness of the parylene coating 143 is less than 0.5 micrometers (μm). Also, the inner layer 130 may be made of copper alloy instead of stainless steel.

FIG. 11 shows a cross-sectional view of a fourth embodiment 190 of the

electrical leads

102 and 109. FIG. 11(a) is a cross-sectional view taken along the longitudinal axis; and fig. 11(b) is a cross-sectional view perpendicular to the longitudinal axis. Similarly,

electrical leads

102 and 109 include an inner layer 130 and a plating layer 132. However, the plating layer 132 includes only a self-assembled molecular (SAM) layer 142 directly on the inner layer 130 for preventing oxidation of the inner layer 130. The layer of self-assembled molecules 142 also has a thickness of less than 0.5 micrometers (μm). In addition, the inner layer 130 is made of only a copper alloy.

Fig. 12 shows an exploded perspective view of the first connector 300. The first connector 300 includes a plurality of electrical contacts 100, 200 and a housing or carrier 302 defining a plurality of through-holes 304. A plurality of electrical contacts 100, 200 are each placed in their corresponding through-holes 304. The carrier 302 has a sandwich structure comprising a top layer 314, a bottom layer 318 and a middle layer 316 between the top layer 314 and the bottom layer 318. The top layer 314 and the bottom layer 318 are made of an insulating material, such as polyimide; while the intermediate layer 316 is made of copper or a copper alloy. Thus, the via 304 has a first via 320, a second via 322, and a third via 324 throughout the top layer 314, the middle layer 316, and the bottom layer 318, respectively. First through-hole 320, second through-hole 322, and third through-hole 324 are precisely aligned to form through-hole 304. The printed circuit board 128 also has a plurality of printed circuit board recesses 326 aligned with their respective through

holes

320 and 324 for guiding and receiving the electrical contacts 100, 200. In addition, first holes 328, second holes 330, and third holes 332 are distributed at peripheral locations of the top layer 314, the middle layer 316, and the bottom layer 318, respectively. The top layer 314, the middle layer 316, and the bottom layer 318 are also integrally joined into the carrier 302 using carrier fasteners (e.g., bolts or screws) by threading the carrier fasteners through the first holes 328, the second holes 330, and the third holes 332. In addition, the carrier 302 also includes a top fastener (e.g., top retaining ring) (not shown) and a bottom fastener (e.g., bottom retaining ring) (not shown) for securing the carrier 302 to the IC device 126 and the printed circuit board 128, respectively. Thus, the IC device 126 and the printed circuit board 128 may be precisely aligned with the electrical contacts 100, 200, respectively, in the carrier 302.

Fig. 13 shows a cross-sectional view of the first connector 300. Fig. 13 clearly shows that the electrical contacts 100, 200 are placed within their respective through holes 304. Via 304 has a via depth 310 that is substantially equal to the thickness of carrier 302; the via 304 also has a via diameter 312 of 0.1 to 0.8 millimeters (mm). The initial length 118 is significantly longer than the via depth such that the top end 122 and the bottom end are exposed from the via 304 for making physical contact with both the IC device 126 and the printed circuit board 128. Instead, the via diameter is slightly larger than the initial diameter 116 for guiding the electrical contacts 100, 200 into the via 304. Thus, once the electrical contacts 100, 200 are dropped into the through holes 304, the electrical contacts 100, 200 remain in a vertical standing position. At the same time, the through-holes 304 also limit lateral deformation of the electrical contacts 100, 200 when the electrical contacts 100, 200 are compressed. In addition, the IC device 126 of fig. 13 has an IC chip. Thus, the IC chip is connected to the electrical contacts 100, 200 through the solder balls 148. The top layer 314 also has a plurality of top layer indentations 334 for locating and receiving their respective solder balls 148.

Fig. 14 shows an exploded perspective view of the second connector 350. The second connector 350 has a similar structure to the first connector 300, including electrical contacts 100, 200 and a housing or carrier 352. The carrier 352 has a plurality of through holes 354 for receiving the electrical contacts 100, 200. The carrier 352 also has substantially the same sandwich structure as the carrier 302, including a top layer 364, a bottom layer 368, and an intermediate layer 366 between the top layer 364 and the bottom layer 368. The top layer 364 has a first through hole 370 and a first hole 378; the intermediate layer 366 has a second via 372 and a second hole 380; the bottom layer 368 has a third through hole 374 and a third hole 382. The first through hole 370, the second through hole 372, and the third through hole 374 are aligned to form the through hole 354. The first hole 378, the second hole 380, and the third hole 382 are also aligned so that the top layer 364, the middle layer 366, and the bottom layer 368 are integrally combined into the carrier 352 using carrier fasteners (e.g., bolts or screws).

Fig. 15 shows a cross-sectional view of the second connector 350. The second connector 350 has a similar structure to the first connector 300. However, the IC device 126 in fig. 15 includes an IC package with external contact pads. Thus, the IC package does not need to be directly connected to the electrical contacts 100, 200 using solder balls 148. Thus, the top layer 364 need not have a structure similar to the top layer groove 334 for the first connector 300.

Fig. 16 shows a process flow diagram 400 for electrical contact 100. Process flow diagram 400 includes the following steps: a first step 410 of providing eight

point wires

102 and 109; a second step 420 of interweaving or weaving the eight

electrical conductors

102 and 109 into the overall structure 110; a third step 430 of relieving the stress inside the monolithic structure 110 generated in the second step 420; a fourth step 440 of cutting the unitary structure 110 into a plurality of electrical contacts 100; and a fifth step 450 of plating the plating layer 132 over the electrical contact 100.

Fig. 17 shows a process flow diagram 500 for forming the plating 132 of the electrical contact. Process flow diagram 500 includes the following steps: a first step 510 of cleaning the inner layer 130; a second step 520 of manufacturing the nickel plating layer 136 for the encapsulation inner layer 130 through a nickel electrolytic plating process until the thickness of the nickel plating layer 136 is greater than 1.0 micrometer (μm); a third step 530 of fabricating the palladium plating 138 for encapsulating the nickel plating 136 by a palladium electrolytic plating process until the palladium plating 138 has a thickness of about 1.0 micrometer (μm); a fourth step 540 of fabricating the gold plating layer 140 for encapsulating the palladium plating layer 138 by a gold electrolytic plating process until the thickness of the gold plating layer 140 is greater than 1.0 micrometer (μm); and a fifth step 550 of drying the plating 132 of the electrical contact 100.

Throughout this application, the word "comprising" and variations thereof mean "open" or "inclusive" language including not only the stated elements, but also additional, non-explicitly stated elements, unless otherwise specified.

The term "about" as used herein in reference to constituent component concentrations generally means a deviation of no more than +/-5%, or even +/-4%, +/-3%, +/-2%, +/-1%, or +/-0.5% of the stated value.

In this disclosure, some embodiments may employ a range format. The description of ranges is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the disclosure. Accordingly, the recitation of a range encompasses all possible sub-ranges as well as individual values within the range. For example, a range of "1 through 6" should be interpreted to include both the sub-ranges 1 through 3, 1 through 4, 1 through 5, 2 through 4, 2 through 6, 3 through 6, etc., and also include individual values within the ranges, such as 1, 2, 3, 4, 5, and 6. This rule applies regardless of the range size.

It will be apparent to those skilled in the art having read the foregoing disclosure that various modifications and adaptations to the use can be made without departing from the spirit and scope of the use and these various modifications and adaptations are intended to be covered by the following claims.

Claims

1. An electrical contact comprising a plurality of interwoven and inter-supporting wires, the plurality of wires comprising at least one electrical conductor for providing a first electrical contact and a second electrical contact; wherein the at least one electrical lead has a multilayer structure.

2. The electrical contact of claim 1, wherein said at least one electrical lead includes a sharp edge for scraping an electrical contact surface of an external electrical device.

3. The electrical contact of claim 1, wherein the plurality of wires comprises at least three individual wires for forming a unitary structure.

4. The electrical contact of claim 3, wherein said unitary structure comprises a tubular structure.

5. The electrical contact of claim 4, wherein at least two wires of the plurality of wires form a substantially right angle in the absence of an external force.

6. The electrical contact of claim 1, wherein said multilayer structure comprises an inner layer having elasticity and a cover layer for encapsulating said inner layer to prevent corrosion or enhance electrical conductivity of at least one of said plurality of wires.

7. A connector comprising the electrical contact of any one of claims 1-6 and a carrier having a plurality of through-holes; wherein at least one of the electrical contacts is disposed in at least one of the vias.

8. The connector of claim 7, wherein the carrier includes a top layer, a bottom layer, and an intermediate layer between the top layer and the bottom layer.

9. The connector of claim 8, wherein the intermediate layer is made of a thermally conductive material.