# Patent

## Title
Fine pitch electrical interconnect assembly

## Abstract

An electrical interconnect assembly for electrically interconnecting terminals on a first circuit member with terminals on a second circuit member. The electrical interconnect assembly includes a housing having a plurality of through openings extending between a first surface and a second surface. A plurality of electrical contact member are positioned in a plurality of the through openings. The contact members have at least one engagement feature forming a snap-fit relationship with the housing. A stabilizing structure on the housing limits deflection of the contact members in at least one direction.

## Background
The present application claims the benefit of U.S. Provisional Patent application Ser. No. 60/487,630, entitled Snap-in Retention Contact System, filed Jul. 16, 2003, and a continuation-in-part of PCT/US2004/022886 entitled Electrical Interconnect Assembly with Interlocking Contact System, filed Jul. 15, 2004.


FIELD OF THE INVENTION
The present invention is directed to an electrical interconnect assembly with an interlocking contact system for electrically connecting a first circuit members to one or more second circuit members.
BACKGROUND OF THE INVENTION
The current trend in connector design for those connectors utilized in the computer field is to provide both high density and high reliability connectors between various circuit devices. High reliability for such connections is essential due to potential system failure caused by improper connections of devices. Further, to assure effective repair, upgrade, testing and/or replacement of various components, such as connectors, cards, chips, boards, and modules, it is highly desirable that such connections be separable and reconnectable in the final product.
Pin-type connectors soldered into plated through holes or vias are among the most commonly used in the industry today. Pins on the connector body are inserted through plated holes or vias on a printed circuit board and soldered in place using a conventional mechanism. Another connector or a packaged semiconductor device is then inserted and retained by the connector body by mechanical interference or friction. The tin lead alloy solder and associated chemicals used throughout the process of soldering these connectors to the printed circuit board have come under increased scrutiny due to their environmental impact. The plastic housings of these connectors undergo a significant amount of thermal activity during the soldering process, which stresses the component and threatens reliability.
The soldered contacts on the connector body are typically the mechanical support for the device being interfaced by the connector and are subject to fatigue, stress deformation, solder bridging, and co-planarity errors, potentially causing premature failure or loss of continuity. In particular, as the mating connector or semiconductor device is inserted and removed from the connector attached to the printed circuit board, the elastic limit on the contacts soldered to the circuit board may be exceeded causing a loss of continuity. These connectors are typically not reliable for more than a few insertions and removals of devices. These devices also have a relatively long electrical length that can degrade system performance, especially for high frequency or low power components. The pitch or separation between adjacent device leads that can be produced using these connectors is also limited due to the risk of shorting.
Another electrical interconnection method is known as wire bonding, which involves the mechanical or thermal compression of a soft metal wire, such as gold, from one circuit to another. Such bonding, however, does not lend itself readily to high-density connections because of possible wire breakage and accompanying mechanical difficulties in wire handling.
An alternate electrical interconnection technique involves placement of solder balls or the like between respective circuit elements. The solder is reflowed to form the electrical interconnection. While this technique has proven successful in providing high-density interconnections for various structures, this technique does not allow facile separation and subsequent reconnection of the circuit members.
An elastomer having a plurality of conductive paths has also been used as an interconnection device. The conductive elements embedded in the elastomeric sheet provide an electrical connection between two opposing terminals brought into contact with the elastomeric sheet. The elastomeric material that supports the conductive elements compresses during usage to allow some movement of the conductive elements. Such elastomeric connectors require a relatively high force per contact to achieve adequate electrical connection, exacerbating non-planarity between mating surfaces. Location of the conductive elements is generally not controllable. Elastomeric connectors may also exhibit a relatively high electrical resistance through the interconnection between the associated circuit elements. The interconnection with the circuit elements can be sensitive to dust, debris, oxidation, temperature fluctuations, vibration, and other environmental elements that may adversely affect the connection.
BRIEF SUMMARY OF THE INVENTION
The present invention is directed to an electrical interconnect assembly for electrically interconnecting terminals on a first circuit member with terminals on a second circuit member. The electrical interconnect assembly includes a housing comprising a plurality of layers forming a plurality of non-moldable through openings that extend between a first surface and a second surface of the housing. A plurality of contact members are positioned in a plurality of the through openings. A sealing layer substantially seals the through openings between the contact members and the housing along at least one of the first surface and the second surface.
The contact members can form an interlocking, snap fit or press fit relationship with the housing. The contact members preferably can move relative to the housing through at least two degrees of freedom. In one embodiment, an alignment layer on the housing limits deflection of the contact members in at least two directions. At least one layer in the housing comprises a circuit layer. The plurality of through openings are preferably arranged in a two-dimensional array.
In one embodiment, the housing comprises at least a first discrete portion biased away from a second discrete portion, so that distal ends of the contact members are generally flush with, or below, one of the surfaces of the housing. In another embodiment, at least one secondary contact member is mechanically coupled with at least one of the contact members.
In one embodiment, the contact members comprise a pair of serpentine beams forming at least two loops. The contact members optionally comprise a pair of overlapping tips. The overlapping tips prevent the distal ends from separating, especially during compression. In another embodiment, the contact members comprise a pair of beams that form a snap-fit relationship with the non-moldable through openings. In one embodiment, a portion of the contact members extend beyond the first or second surface. The contact members can optionally be coupled to at least one layer of the housing using one or more of a compressive force, solder, a wedge bond, a conductive adhesive, an ultrasonic bond, a wire bond, and a mechanical coupling between the contact members and the first circuit member.



BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 is a schematic side sectional view of an electrical interconnect assembly with a contact system in accordance with the present invention.
FIG. 2 is a more detailed schematic side sectional view of a portion of the contact system of FIG. 1.
FIG. 3 is a schematic side sectional view of the interlocking operation to couple the contact member of FIG. 2 to the housing.
FIG. 4 is a schematic side sectional view of the operation of the contact member of FIG. 2 in both the engaged and disengaged positions.
FIG. 5 is a schematic side sectional view of the lateral movement within the housing of the contact member of FIG. 2.
FIG. 6 is a schematic side sectional view of the electrical interconnect assembly of FIG. 1 electrically coupled to a pair of circuit members.
FIG. 7 is a schematic top view of a portion of a housing of a contact system showing the drilling patterns in accordance with the present invention.
FIG. 8 is schematic top view of a portion of an alternate housing of the contact system showing a drilling pattern and elongated contact members in accordance with the present invention.
FIG. 9 is a schematic side view of an interconnect assembly with a interlocking portion formed from two discrete housing portions in accordance with the present invention.
FIG. 10 is a schematic side view of an alternate interconnect assembly with a interlocking portion formed from two discrete housing portions in accordance with the present invention.
FIG. 11 is a side sectional view of an alternate interconnect assembly with a two beam contact member in accordance with the present invention.
FIG. 12 is a side sectional view of another alternate interconnect assembly with a two beam contact member in accordance with the present invention.
FIG. 13 is a side sectional view illustrating removal of a circuit member from the interconnect assembly of FIG. 12.
FIG. 14 is a side sectional view of an alternate interconnect assembly that permits extensive axial displacement of a contact member in accordance with the present invention.
FIG. 15 is a side sectional view of an alternate interconnect assembly in accordance with the present invention.
FIGS. 16A-16C illustrate one method of constructing the interconnect assembly of FIG. 15.
FIG. 17A illustrates an alternate interconnect assembly with an additional circuitry plane in accordance with the present invention.
FIG. 17B illustrates the contact coupling layer of FIG. 17A.
FIGS. 17C-17D illustrate operation of the interconnect assembly of FIG. 17A.
FIG. 18 illustrates an alternate interconnect assembly with a sealing layer in accordance with the present invention.
FIG. 19 is a top view of a interconnect assembly in accordance with the present invention.
FIG. 20 is a side sectional view of an alternate interconnect assembly in accordance with the present invention.
FIG. 21 is a side sectional view of an alternate interconnect assembly in accordance with the present invention.
FIG. 22 is a side sectional view of an alternate interconnect assembly in accordance with the present invention.
FIGS. 23-27 are side sectional views of alternate connector members in accordance with the present invention.
FIG. 28 is a side sectional view of an alternate interconnect assembly in accordance with the present invention.
FIG. 29 is a side sectional view of an interconnect assembly in accordance with the present invention.
FIG. 30 is a side sectional view of an interconnect assembly with a two-part housing in accordance with the present invention.
FIG. 31 is a side sectional view of an interconnect assembly in accordance with the present invention.
FIG. 32 is a side sectional view of an interconnect assembly with a two-part housing in accordance with the present invention.
FIG. 33 is a side sectional view of an interconnect assembly with a two-part housing in accordance with the present invention.
FIG. 34 is a side sectional view of an interconnect assembly in accordance with the present invention.
FIG. 35 is a side sectional view of an interconnect assembly in accordance with the present invention.
FIG. 36 is a side sectional view of an interconnect assembly with a two-part contact member in accordance with the present invention.
FIGS. 37A-37C illustrate a contact member suitable for use with an LGA device in accordance with the present invention.
FIGS. 38A-38C illustrate an alternate contact member suitable for use with an LGA device in accordance with the present invention.
FIGS. 39A-39C illustrate an alternate contact member suitable for use with an LGA device in accordance with the present invention.
FIGS. 40A-40C illustrate a contact member suitable for use with an BGA device in accordance with the present invention.
FIGS. 41A-41C illustrate an alternate contact member suitable for use with an BGA device in accordance with the present invention.



DETAILED DESCRIPTION OF THE INVENTION
The present invention is directed to a technique for creating an insulator housing in low, medium, or high volume by laminating layers of precisely patterned materials. The patterned layers can be constructed from the same or multiple material types. The layers are optionally selectively laminated to relieve stress caused by thermal expansion differentials.
The present construction method permits internal features that would normally be impossible to mold or machine. For large pin count devices, the laminating process produces an inherently flat part without requiring molds. Stiffening layers made of materials such as BeCu, Cu, ceramic, or polymer filled ceramic can be added to provide additional strength and to provide thermal stability during solder reflow.
The multi-layered housing can also include circuitry layers. Power, grounding and/or decoupling capacitance can be added between layers or between pins, and unique features such as embedded IC devices or RF antennae can optionally be incorporated. In some cases, layers can be used to assist with device insertion or removal, such as with ZIF or stripper plate actuation mechanisms. Consequently, the present interconnect assembly can be enhanced in ways not possible using conventional molding or machining techniques.
The present interconnect assembly permits the creation of high aspect ratio through holes and slots with internal cavities having non-moldable features, to allow for contact flexure clearance, on fine contact to contact spacing (pitch). The present interconnect assembly accommodates pin counts of 1000-2500 I/O range at 1.0 mm pitch, and more preferably a pitch of about 0.8 millimeter, and most preferably a pitch of about 0.5 millimeter. Such fine pitch interconnect assemblies are especially useful for communications, wireless, and memory devices.
The present interconnect assembly provides the ability to press-fit the contacts into lower layers to position, point and retain the contact and seal the interface to prevent solder or flux wicking during reflow. A post insertion solder mask (as done on printed circuit boards and IC packages) can also be added to improve solder deposit formation and wick prevention.
The present lamination process permits stiffening layers, spacer, circuitry, and/or protective layers to be added to the interconnect assembly. The lamination system also permits the creation of high aspect ratio contacts, in which almost 80-90% of the physical height of the contacts can be vertically compressed, even in quad contact beam systems. The present low cost, high signal performance interconnect assemblies, which have low profiles and can be soldered to the system PC board, are particularly useful for desktop and mobile PC applications.
Use of the present interconnect assembly permits manufactures to install expensive IC devices during system build, providing the opportunity to later customize the system without stocking substitute circuit boards. The use of the present interconnect assembly allows new IC devices to replace initial release IC devices in the field (or at OEM) without the need for disassembling the system or reworking the circuit board. Trends towards lead-free electronics also increases the attractiveness of the present interconnect assembly. The IC supplier can leave the solder balls off their package or device to reduce the lead content.
FIG. 1 illustrates an interconnect assembly 20 in accordance with the present invention. The interconnect assembly 20 includes a contact system 22 and a housing 24 having electrical insulating properties. The housing 24 includes a plurality of through openings 26. Contact members 28A, 28B, 28C and 28D (referred to collectively as “28”) are located in at least some of the through openings 26 and are coupled to the housing 24. In the illustrated embodiment, the interconnect assembly 20 is electrically coupled to circuit member 40. As used herein, the term “circuit members” refers to, for example, a packaged integrated circuit device, an unpackaged integrated circuit device, a printed circuit board, a flexible circuit, a bare-die device, an organic or inorganic substrate, a rigid circuit, or any other device capable of carrying electrical current.
The housing 24 may be constructed of a dielectric material, such as plastic. Suitable plastics include phenolics, polyesters, and Ryton® available from Phillips Petroleum Company. Alternatively, the housing 24 may be constructed from metal, such as aluminum, with a non-conductive surface, such as an anodized surface. For some applications, the metal housing may provide additional shielding of the contact members. In an alternate embodiment, the housing is grounded to the electrical system, thus providing a controlled impedance environment. Some of the contact members can be grounded by permitting them to contact an uncoated surface of the metal housing. As used herein, an “electrically insulative connector housing” or a “module housing” refers to a housing that is either non-conductive or substantially coated with a non-conductive material to prevent unwanted conductivity between the contact members and the housing, as discussed above.
The housings of the present invention can be constructed from a plurality of discrete layers. The layers can be etched or ablated and stacked without the need for expensive mold tooling. The layers can create housing features that have a much larger aspect ratio that possible with molding or machining. The layers also permit the creation of internal features, undercuts, or cavities that are difficult or typically not possible to make using conventional molding or machining techniques, referred to herein as a “non-moldable feature.” The present housings also permit stiffening layers, such as metal, ceramic, or alternate filled resins, to be added to maintain flatness where a molded or machined part might warp.
The housings of the present invention can optionally include circuitry, power, and/or ground planes to selectively connect or insulate contact members within a given field. The layers can be selectively bonded or non-bonded to provide contiguous material or releasable layers. As used herein, “bond” or “bonding” refers to, for example, adhesive bonding, solvent bonding, ultrasonic welding, thermal bonding, or any other techniques suitable for attaching adjacent layers of the housing. Multiple layers of differing contact members can be implemented to interact with each other, while being permanently engaged or separable. The layers can be structured in such a way as to rigidly retain the contact members or to allow the contacts to float or move along the X, Y, and/or Z axes of the contact members. The layers can be constructed in such a way that the base of the contact members are either in a sealed condition as a result of the insertion process to prevent solder or flux wicking during reflow, or the interface can be sealed post assembly.
FIG. 2 illustrates more detail of one of the contact members 28 interlocked to the housing 24. The contact member 28 has a first interface portion 30 and a second interface portion 36. The first interface portion 30 is positioned to electrically couple with terminal 32 on first circuit member 34 and the second interface portion 36 is positioned to electrically couple with terminal 38 on the second circuit member 40, when the first and second circuit members 34, 40 are biased toward the housing 24. Any method of securing can be used, including bolting, clamping and gluing.
The contact member 28 includes a interlocking feature 42 and a transition portion 44 connected to the interlocking feature 42. In the illustrated embodiment, the interlocking feature 42 is greater in size than the transition portion 44 in at least one direction. The through opening 26 in the housing 24 includes at least one interlocking feature 46 of sufficient size to accommodate the interlocking feature 42 on the contact member 28. In the illustrated embodiment, the interlocking feature 42 is a ball-shaped structure and the interlocking feature 46 is a socket. As used herein, “interlocking” and “interlocked” refer to a mechanical coupling where one part is trapped or captured by another part in such a way as to permit at least a portion of one of the parts to move relative to the other part through at least one degree of freedom, such as for example by hooking, snap-fit, non-binding interference fit, dovetailing. An “interlocking feature” refers to a structure for interlocking.
The housing 24 includes an opening 48 large enough to accommodate the transition portion 44 but smaller than the interlocking feature 42 in at least one direction so that the contact member 28 does not fall out of the housing 24. The interlocking feature 42 thus can be secured to the interlocking feature 46 with the transition positioned 44 extending through the opening 48.
FIG. 3 is a composite drawing showing both before and after the contact member 28 is installed in the housing 24. The portions 50, 52 on either side of the opening 48 and/or the interlocking feature 42 are sufficiently flexible to permit the interlocking feature 42 to snap-fit into the corresponding interlocking feature 46. As used herein, “snap fit” refers to interlocking by substantially elastic deformation of a contact member and/or a housing.
FIG. 4 illustrates the operation of the contact member 28 in the housing 24. The housing 24 includes a top surface 60 and a bottom surface 62. The top surface 60 is adapted to be biased toward the first circuit member 34 and the bottom surface 62 is adapted to be biased toward the second circuit member 40 (see e.g., FIG. 2). The first interface portion 30 of the contact member 28 is biased by elastomeric member 64 to protrude above the top surface 60 (position A) when the first circuit member 34 is not secured to the housing 24. The first interface portion 30 is displaced toward the top surface 62 (position B) when the first circuit member 34 is biased toward the housing 24. The location of the second interface portion 36 is biased against the second circuit member 40 when both the first and second circuit members 34, 40 are biased toward the housing 24.
In the embodiment shown in FIG. 4, the biasing of the first interface portion 30 is provided, at least in part, by a elastomeric member 64 located under the first interface portion 30. The elastomeric member 64 can be in any form suitable to provide the necessary biasing force, including spherical, cylindrical and rectangular. It can be secured in a variety of ways, including being glued to the housing 24 and/or the contact member 28, press-fitted into a cavity defined on either the housing of the contact member, or simply trapped in a space defined between the housing and the contact member. As the first circuit member 34 is biased toward the housing 24, the elastomeric member 64 is compressed, and the moment arm created by the forces at the tip portion 66 by the elastomeric member 64 and at the first interface portion 30 results in a force biasing the second interface portion 36 toward the second circuit member 40 secured to the bottom surface 62 of the housing 24.
It should be noted that the designations of “top” and “bottom” in this context is purely for the convenience of distinguishing different parts of the contact system and the environment in which it is used. These and other directional designations are not intended to restrict the scope of the invention to require the housing to be oriented in any particular direction.
The present contact system 22 can also include features that provide stress relief to the contact member. For example, in one embodiment, best shown in FIG. 4, the second interface portion 36 has an arcuate bottom surface to allow the contact member 28 to roll when the first contact portion is pushed down by the first circuit member 34. The contact member 28 and the housing 24 can also be sufficiently compliant to provide stress relief.
The contact members 28 are preferably constructed of copper or similar metallic materials such as phosphor bronze or beryllium-copper. The contact members are preferably plated with a corrosion resistant metallic material such as nickel, gold, silver, palladium, or multiple layers thereof. In some embodiments the contact members are encapsulated except the interface portions. The encapsulating material is typically silicone based with a Shore A durometer of about 20 to about 40. Examples of suitable encapsulating materials include Sylgard® available from Dow Corning Silicone of Midland, Mich. and Master Sil 713 available from Master Bond Silicone of Hackensack, N.J.
FIG. 5 illustrates lateral movement or shifting of the contact member 28 within the housing 24. The amount of shift, d, is preferably smaller than the difference between the width of the interlocking feature 42 and the that of the opening 48 so that the contact member 28 does not fall out of the interlocking feature 46.
FIG. 6 illustrates the present interconnect assembly 20 in operation. The interconnect assembly 20 is preferably compressed between the first and second circuit members 34, 40. Optional alignment member 70 forms a device site 71 that aligns the terminals 32 on the first circuit device 34 with the first interface portions 30 of the contact members 28 (see FIG. 2). The alignment member 70 can optionally include secondary elastomeric members 72 that provide an additional biasing force on contact members 28A and 28D. The interconnect assembly 20 of FIG. 6 can optionally be designed to receive multiple circuit members 34, such as the replaceable chip modules disclosed in U.S. Pat. Nos. 5,913,687; 6,178,629; and 6,247,938, all of which are incorporated by reference.
In the illustrated embodiment, the first circuit member 34 is an LGA device and the second circuit member 40 is a PCB. The housing 24 is optionally secured to the PCB 40, with the second interface portions 36 of each contact member 28 positioned over a conductive pad 38 on the PCB 40. As the LGA device 34 is pressed against the contact system 22, the first interface portions 30 are pressed down against the primary elastomers 64. The arcuate second interface portions 36 the contact members 24 roll and slide somewhat over the respective conductive pads 38 on the PCB 40 and are biased against the conductive pads 38, ensuring reliable electrical contact. The interlocking features 42 tend to move upwards, but are restrained by a downward force from either housing 24 cover or a secondary elastomer 72.
In the embodiment of FIGS. 7 and 8, the contact members 80 are elongated in shape and the housing 82 includes elongated cavities 84 that accommodate the respective contact members 80 and prevent them from sideward rotation or shift. The elongated cavities or slots 84 can be made by a variety of methods, including mechanical or laser drilling, etching, molding, and the like.
FIG. 9 illustrates an interconnect assembly 100 with a two-part housing 102 in accordance with the present invention. The housing 102 includes a top portion 104 and a bottom portion 106. The interlocking portion 108 preferably extends across the interface 110 between the top and bottom portions 104, 106. By translating the upper portion 104 in the direction 112 relative to the bottom portion 106, the interlocking portion 108 traps the interlocking feature 114 on the contact member 116. The interlocking feature 114 is preferably retains the contact member 116 in the housing 102, but does not limit or restrict movement of the contact member 116 through the range of motion necessary to couple with the first and second circuit members 118, 120. Elastomeric member 122 biases the contact member 116 against the circuit members 118, 120.
FIG. 10 illustrates an alternate interconnect assembly 130 with a two-part housing 132 in accordance with the present invention. The top portion 134 and the bottom portion 136 form a interlocking portion 138 that traps the interlocking feature 140 on the connector member 142. A secondary elastomeric member 144 is optionally located adjacent to the interlocking portion 138. The elastomeric members 144, 146 bias the contact member 142 against the circuit members 148, 150.
FIG. 11 is a side sectional view of an alternate interconnect assembly 200 in accordance with the present invention. In the embodiment of FIG. 11, housing 202 includes a contact coupling layer 204, an alignment layer 206, and a stabilizing layer 208. In one embodiment, the layers 204, 206, 208 are laminated using a variety of techniques, such as thermal or ultrasonic bonding, adhesives, and the like. The contact coupling layer 204 includes a pair of through openings 210, separated by a center member 212. The contact alignment layer 206 also includes a pair of through openings 214 generally aligned with the through openings 210. The through openings 214 are separated by center member 216. The stabilizing layer 208 in the embodiment of FIG. 11 includes a single through opening 218 generally aligned with the through openings 214.
The contact system 220 of the present invention includes a plurality of contact members 222 coupled with the housing 202 in a snap fit relationship. In the embodiment of FIG. 11, contact member 222 has a generally U-shaped configuration with a pair of beams 224A, 224B (referred to collectively as “224”) joined at a center portion 226. The beams 224 include a pair of opposing protrusions 228A, 228B (referred to collectively as “228”), located near the center portion 226 that form an enlarged opening 227. Gap 230 between the protrusions 228 is smaller than the enlarged opening 227, but preferably smaller than the width of center member 212.
To assemble the present interconnect assembly 200, distal ends 232A, 232B (referred to collectively as “232”) of the beams 224 are inserted through the through openings 210. When the protrusions 228A, 228B meet the center member 212, the contact member 222 and/or the center member 212 deform substantially elastically to create a snap fit coupling. Once assembled the protrusions 228 retain the contact member 222 to the center member 212. The protrusions 228 are preferably positioned against or adjacent to the center member 216 on the contact alignment layer 206, thereby minimizing rotation of the contact member 222 relative to the housing 202. The center member 216 also maintains a gap between the first interface portions 234. In one embodiment, a sealing material is deposited in the openings 210 between the contact members 216 and the contact coupling layer 204 to prevent debris or solder from migrating into the housing 202.
The sizes and shape of the enlarged opening 227 and the center member 212 can be adjusted so as to permit the contact member 222 some movement relative to the housing 202. Movement of the contact member 222 along longitudinal axis 250 and rotation generally around the center member 212 are of particular interest in obtaining consistent and reliable electrical coupling with the circuit members 240, 242.
The contact member 222 includes first interface portions 234 near the distal ends 232 and second interface portion 236 near the center portion 226. The first and second interface portions 234, 236 can be electrically coupled to first and second circuit members 240, 242 using solder, a compressive force, or a combination thereof. The configuration of the first interface portions 234 of the contact member 222 are particularly well suited for engaged with solder balls 244 on the first circuit member 240. The contact member 222 can be configured to electrically couple with a wide variety of circuit members 240, including for example a flexible circuit, a ribbon connector, a cable, a printed circuit board, a ball grid array (BGA), a land grid array (LGA), a plastic leaded chip carrier (PLCC), a pin grid array (PGA), a small outline integrated circuit (SOIC), a dual in-line package (DIP), a quad flat package (QFP), a leadless chip carrier (LCC), a chip scale package (CSP), or packaged or unpackaged integrated circuits.
As the first circuit member 240 is brought into compressive relationship with the housing 202, distal ends 232 of the contact member 222 are displaced in a direction 246 towards side walls 248 of the stabilizing layer 208. The sidewalls 248 limit the displacement of the distal ends 232.
FIG. 12 is a side sectional view of an alternate interconnect assembly 300 in accordance with the present invention. A plurality of contact members 302A, 302B, 302C, 302D, 302E (referred to collectively as “302”) are positioned in through openings 326 in the housing 304, generally as discussed in connection with FIG. 11. In the embodiment of FIG. 12, circuit layer 306 and optional stiffening layer 308 are positioned between the contact coupling layer 310 and the contact alignment layer 312. The circuit layer 306 can be a power plane, a ground plane, or any other circuit structure. In the illustrated embodiment, the through openings 326 are non-moldable and are typically created by forming the housing 304 from multiple laminated layers.
The contact members 302 are coupled to the contact coupling layer 310 as discussed in connection with FIG. 11. The first interface portions 318 of the contact members 302 are preferably configured to form a snap-fit engagement with solder ball 320 on the first circuit member 322. In some embodiments, the snap fit relationship between the solder ball 320 and the first interface portions 318 may be sufficient to retain the first circuit member 322 to the interconnect assembly 300.
The embodiment of FIG. 12 includes an extraction layer 314 attached to top surface 316 of the contact alignment layer 312. The extraction layer 314 is preferably releasably attached to the surface 316, such as by a low-tack pressure sensitive adhesive. In the preferred embodiment, the extraction layer 314 is constructed from a flexible sheet material that can be peeled off of the top surface 316 of the contact alignment layer 312. As illustrated in FIG. 13, as the extraction layer 314 is peeled in the direction 324, the first circuit member 322 is safely disengaged from the first interface portions 318 of the contact members 302.
FIG. 14 illustrates an alternate interconnect assembly 400 in accordance with the present invention. Contact members 402 are configured generally as illustrated in FIG. 11. The opposing protrusions 404A, 404B apply a compressive force 406 on the center member 408. In the embodiment illustrated FIG. 14, however, the center member 408 does not constraint movement of the contract member 402 along axis 410. Rather, the contact member 402 can slide along the axis 410 in order to achieve the optimum position for coupling the first circuit member 412 to the second circuit member 414.
In the illustrated embodiment, the first circuit member 412 is an LGA device with a plurality of terminals 416. Intermediate contacts set 418 provides an interface between the terminal 416 and the first interface portions 420 of the contact member 402. The intermediate contact set 418 includes a carrier 422 with a plurality of conductive members 424. In the illustrated embodiment, the lower portion of the conductive members 424 simulate a BGA device adapted to couple with the first interface portions 420. The upper portion of the conductive member 424 is adapted to couple with the contact pad 416 on the first circuit member 412. The carrier 422 can be flexible or rigid. In the preferred embodiment, the carrier 422 is a flexible circuit member with circuit traces that carry power, signals, and/or provides a ground plane for the first and second circuit members 412, 414.
FIG. 15 is a cross sectional view of an alternate interconnect assembly 500 in accordance with the present invention. Contact member 502 includes an enlarged second interface portion 504, with a narrow engagement region 506 located between the second interface portion 504 and the beams 508. In the illustrated embodiment, the first circuit member 510 is a BGA device with a solder ball 512 compressive coupled with the beams 508.
The length of the engagement region 506 relative to the thickness of the contact coupling layer 514 permits the contact member 502 to float within the housing 520 along the axis 516. Sidewalls 522 of the stabilizing layer 524 and the sidewalls 526 of the contact alignment layer 528 limit lateral displacement of the beams 508.
FIGS. 16A through 16C illustrate one method for constructing the connection 500 of FIG. 15. As illustrated in FIG. 16A, the contact coupling layer 514 includes a series of through openings 530 surrounded by a plurality of adjacent slits 532. The second interface portions 504 of the contact members 502 are inserted into the through openings 530. The contact coupling layer 514 deforms elastically, due in part to the slits 532, to permit the second interface portion 504 to pass through the through opening 530. The elastic deformation of the contact coupling layer 514 creates a snap-fit relationship with the contact members 502. Depending upon the configuration of the slits 532, the contact member 502 may have some rotational freedom 513 (see FIG. 15) around the engagement region 506. Consequently, the connector 500 can be designed with contact members 502 having one or two degrees of freedom.
FIG. 16B illustrates installation of a contact alignment layer 528. The contact alignment layer 528 is typically a separate and discreet structure that is bonded to the contact coupling layer 514.
FIG. 16C illustrates installation of the stabilizing layer 524. In the illustrated embodiment, the stabilizing layer 524 includes a plurality of through openings 536 adapted to receive the solder balls 512 on a BGA device 510. The through openings 536 can optionally include a pair of opposing recesses 538 into which the beams 508 of the contact member 502 can deflect. The recesses 538 also limits rotation of the contact member 502 in the direction 540 within the housing 520.
FIGS. 17A-17D illustrate various aspects of an alternate interconnect assembly 800 in accordance with the present invention. Contact members 804 are slidingly engaged with center members 812 on contact coupling layer 806. In one embodiment, the contact member 804 form a friction fit with the center member 812. In another embodiment, dielectric layers 816, 818 are positioned above and below the center member 812 to trap or retain the contact members 804 on the interconnect assembly 800. The contact members 804 are optionally crimped to the contact coupling layer 806. Alternatively, the contact members 804 are attached to the center member 812 using a variety of techniques, such as thermal or ultrasonic bonding, adhesives, mechanical attachment, and the like.
Upper and lower dielectric layers 816, 818 prevent shorting and rollover of the contact members 804 during compression. An additional circuitry plane 820 and dielectric covering layer 822 can optionally be added to the present interconnect assembly 800. In one embodiment, the contact coupling layer 806 includes a flexible circuit member. In the embodiment of FIGS. 17A-17D, the flexible circuit member is singulated prior to attachment to contact coupling layer 806.
As illustrated in FIG. 17B, the contact coupling layer 806 includes pairs of adjacent slots 808, 810. The center portion 812 of the contact coupling layer 806 between the slots 808, 810 acts as a torsion bar. A contact members 804 are inserted though the slots 808 and positioned on the center portion 812. Alternatively, the compliant members 804 can be coupled to the contact coupling layer 806 through single slot 814.
As best illustrated in FIGS. 17C and 17D, the center portion 812 twists and/or deforms to permit the contact members 804 to compensate for non-planarity in the first and second circuit members 824, 826 (see FIG. 17A). Distal ends 828, 830 of the contact members 804 also flex when compressed by the first and second circuit members 824, 826. The amount of displacement and the resistance to displacement can be adjusted by changing the size and shape of the center portion 812 on the carrier 806, the size and shape of the distal ends 828, 830 (see FIG. 17A) of the contact members 804, and/or by constructing the carrier 806 from a more rigid or less rigid material that resists displacement of the compliant members 804.
FIG. 18 illustrates an interconnect assembly 840 that is a variation of the interconnect assembly 800 of FIGS. 17A-17D. The interconnect assembly 840 includes a plurality of discrete contact members 842 coupled to the contact coupling layer 844 as discussed above. Distal end 846 is positioned to electrically couple with terminal 848 on first circuit member 850. Solder ball 852 replaces the distal end 830 in FIG. 17A. The solder ball 852 is positioned to electrically couple with terminal 854 on second circuit member 856.
In one embodiment, dielectric layer 856 and/or the dielectric layer 858 preferably form a seal between the contact members 842 and the contact coupling layers 844. The dielectric layers 856, 858 are optionally a sealing material that flows around the contact members 842 to seal any gaps. The sealing material is preferably a flowable polymeric material that cures to form a non-brittle seal. A solder mask material can optionally be used as the sealing material. In one embodiment, distal ends 860 and/or the 846 are planarized to remove any accumulated sealing material 856, 858. The sealing material prevents solder from wicking past the contact coupling layer 844. In one embodiment, the sealing material 856, 858 helps to retain the contact member 842 coupled to the contact coupling layer 844.
FIG. 19 is a top view of an interconnect assembly 900 in accordance with the present invention. Any of the contact member configurations disclosed herein can be used with the interconnect assembly 900. Housing 902 includes an array of holes 904 through which distal ends of the contact members are coupled with circuit members. Additional circuit planes are preferably ported from the side of the interconnect assembly 900, preferably by flexible circuit members 906, 908.
FIG. 20 is a side sectional view of an alternate interconnect assembly 1000 in accordance with the present invention. Housing 1002 includes a contact coupling layer 1004 and a stabilizing layer 1006. The contact coupling layer 1004 includes through openings 1008 adapted to couple with contact members 1010.
Contact members 1010 include three beams 1012a, 1012b, 1012c (referred to collectively as “1012”) adapted to electrically couple with solder ball 1014 (see e.g., FIG. 11), such as found on a BGA device, or conductive member 1016 on intermediate contact set 1018 (see e.g., FIG. 14). The left most contact member 1010 is oriented 90° relative to the contact members so as to better illustrate the configuration of the beams 1012.
The proximal ends 1020 of the contact members 1010 include a narrow region 1022 that forms a snap fit relationship with the openings 1008 in the contact coupling layer 1004. The contact member 1010 can move along axis 1024 in order to achieve the optimum position for coupling the solder ball 1014 or the intermediate contact set 1018 on the first circuit member (not shown) and the second circuit member 1028. The beams 1012 flex in the directions 1028, limited by sidewalls 1032, to form an optimum electrical interface with the solder ball 1014 or conductive member 1016.
A sealing layer 1030, such as a solder mask film, or flowable sealing material, is optionally applied to the exposed surface of the contact coupling layer 1004. The sealing layer 1030 preferably seals the opening 1008 around the contact members 1010.
FIG. 21 is a side sectional view of illustrates an alternate interconnect assembly 1050 in accordance with the present invention. Housing 1052 includes a contact coupling layer 1054, an alignment layer 1056, and a stabilizing layer 1058. The contact coupling layer 1054 includes through openings 1060 that form snap fit relationships with narrow regions 1062 on the contact members 1064.
Contact members 1064 include two beams 1066a, 1066b (referred to collectively as “1066”) adapted to electrically couple with BGA device or conductive members on intermediate contact set (see e.g., FIG. 14). The left most contact member 1064 is oriented 90° relative to the other contact member so as to better illustrate the configuration of the beams 1066.
The contact member 1064 can move along axis 1068 in order to achieve the optimum positioning relative to the circuit members 1070, 1072. The beams 1066 flex in the directions 1074, limited by sidewalls 1076, to form an optimum electrical interface with solder balls 1078.
FIG. 22 is a side sectional view of illustrates an alternate interconnect assembly 1100 substantially as shown in FIG. 21, except that the contact members 1064 are interlocked with the housing 1102. Sealing layer 1104 is optionally applied to the surface 1106 of the housing 1102. The sealing layer 1104 can assist in retaining the contact members 1064 in the housing 1102 and/or prevent solder from wicking along the contact members 1064. In one embodiment, the sealing layer 1104 is a solder mask film applied to the housing 1102 before the contact members 1064 are inserted.
FIG. 23 illustrates an alternate connector member 1150 in accordance with the present invention. Snap-fit feature 1152 interlocks with housing 1154. Distal end 1156 flexes in direction 1158, limited by sidewall 1160 on spacer 1164. Alignment feature 1162 engages with the housing 1154 to keep the contact member 1150 oriented relative to the circuit members (not shown).
FIG. 24 illustrates alternate connector member 1170 interlocked with a contact coupling layer 1172. FIG. 25 illustrates connector member 1174 interlocked with contact coupling layer 1176. FIG. 26 illustrates connector member 1178 interlocked with contact coupling layer 1180. FIG. 27 illustrates connector member 1182 interlocked with contact coupling layer 1184. The connector members of FIGS. 23-27 can be used in a variety of the embodiments disclosed herein.
FIG. 28 illustrates an alternate interconnect assembly 1200 that is a variation of the interconnect assemblies of FIGS. 17A and 18. The interconnect assembly 1200 includes a contact coupling layer 1202 with a plurality of discrete contact members 1204, 1206 coupled thereto. Bend 1208 and solder ball 1210 help retain the contact member 1204 to the contact coupling layer 1202. The bend 1208 permits distal end 1212 to flex when coupled with the first circuit member 1214.
Contact member 1204 includes first and second bends 1216, 1218. The bend 1218 can form an angle of 0° to about 90° to lock the contact member 1206 in place, to reduce the over height of the interconnect assembly 1200 and to increase the pull-out strength or solder joint reliability. By forming the bend 1218 at an angle less than 90°, the proximal end 1220 can flex when compressively coupled with the second circuit member 1222.
The bends 1208, 1216, 1218 can be used alone or in combination with a snap fit coupling with the contact coupling layer 1206. In one embodiment, sealing material 1224 is applied to one or both sides of the contact coupling layer 1202 to prevent solder, such as solder ball 1210, from wicking along the contact members 1204, 1206.
FIG. 29 illustrates an interconnect assembly 1300 in accordance with the present invention. In the embodiment of FIG. 29, housing 1302 includes a sealing layer 1304, an optional leveling layer 1306, contact coupling layer 1308, a spacer or stiffening layer 1310, and an alignment or protective layer 1312. In the illustrated embodiment, one or more of the layers 1302, 1304, 1306, 1308, 1310 and 1312 are laminated using a variety of techniques, such as thermal or ultrasonic bonding, adhesives, and the like.
The sealing layer 1304 is optionally a solder mask film or a solder mask liquid that is at least partially cured before insertion of contact members 1316. Alternatively, the sealing layer can be a flowable/curable polymeric material.
The contact coupling layer 1308 includes at least one openings 1314 adapted to receive the contact members 1316. The contact members 1316 typically form a press-fit, snap-fit or interengaged relationship with the contact coupling layer 1308. Alternatively, the contact members 1316 are coupled to the housing 1302 using one or more of a compressive force, solder, a wedge bond, a conductive adhesive, an ultrasonic or thermal bond, or a wire bond. The contact members 1316 preferably forms a sealing relationship with the sealing layer 1304 to prevent the solder 1324 from wicking along the contact members 1316 during bonding with the second circuit member 1330.
In the illustrated embodiment, the alignment layer 1312 and the sealing layer 1304 extend over the stiffening layer 1310 to form a non-moldable cavity 1318. The cavity 1318 provides a region for the contact member 1316 to expand without limiting flexure of beams 1326A, 1326B. The beams 1326A, 1326B of the contact members 1316 flex outward toward the surfaces 1328 during compression. The alignment layer 1312 positions distal ends 1320 of the contact member 1316 in the desired location to electrically couple with the first circuit member 1322.
To assemble the present interconnect assembly 1300, distal ends 1320 of the contact members 1316 are inserted through the openings 1314 until engagement with the contact coupling layer 1308 is achieved. The contact members 1316 are electrically coupled to first and second circuit members 1322, 1330 using solder, a compressive force, or a combination thereof. The configuration of the distal ends 1320 are particularly well suited for engagement with an LGA device, such as the first circuit member 1322. The contact member 1316 can be configured to electrically couple with a wide variety of circuit members 1322, 1330, including for example a flexible circuit, a ribbon connector, a cable, a printed circuit board, a ball grid array (BGA), a land grid array (LGA), a plastic leaded chip carrier (PLCC), a pin grid array (PGA), a small outline integrated circuit (SOIC), a dual in-line package (DIP), a quad flat package (QFP), a leadless chip carrier (LCC), a chip scale package (CSP), or packaged or unpackaged integrated circuits.
FIG. 30 is an interconnect assembly 1348 that is a variation of FIG. 29. In the embodiment of FIG. 30, the alignment layer 1312 is replaced by a stripper plate 1350. The stripper plate 1350 is biased away from the stiffening layer 1310, such as by springs 1311, so that the distal ends 1320 of the contact members 1316 are generally protected prior to use. The distal ends 1320 are preferably flush with, or below, the surface 1354 of the stripper plate 1350. The size of gap 1352 depends on the size of the contact members 1316. When a compressive force is applied between the first and second circuit members 1322, 1330, the stripper plate 1350 is displaced toward the stiffening layer 1310 to expose the distal ends 1320 of the contact members 1316. Alternatively, the stripper plate 1350 is displaced toward the stiffening layer 1310 to expose the distal ends 1320. The stripper plate 1350 can be displaced prior to, during, or after the second circuit member 1330 is positioned for engagement with the contact members 1316.
FIG. 31 illustrates an interconnect assembly 1368 that is a variation of FIG. 29. In the embodiment of FIG. 31, the contact members 1370 include a pair of beams 1372, 1374 forming loops 1376, 1378, 1380. The loop 1376 forms a press-fit relationship with the contact coupling layer 1308. The loops 1378 and 1380 expand within the cavity 1318, as discussed above.
FIG. 32 illustrates an interconnect assembly 1400 in accordance with the present invention. In the embodiment of FIG. 32, housing 1402 includes a sealing layer 1404, a contact coupling layer 1406, and a stripper plate 1408, such as discussed in connection with FIG. 30. The contact members 1410 include a pair of beams 1412, 1414 forming loops 1416, 1418, 1420. The loop 1420 forms a press-fit relationship with the contact coupling layer 1406. The sealing layer 1404 minimizes or eliminates the migration of solder 1426 into cavity 1422. The loops 1418 and 1420 expand within the cavity 1422 as the stripper plate 1408 is advanced toward the contact coupling layer 1406.
FIG. 33 illustrates an interconnect assembly 1428 that is a variation of FIG. 32. Contact coupling layer 1430 includes recesses 1432 formed to receive contact members 1434. The contact members 1434 preferably include tabs 1436 formed to create a seal with the recesses 1432. A sealing layer can optionally be used to decrease the risk of solder 1438 wicking along the contact members 1434.
FIG. 34 illustrates an interconnect assembly 1450 in which a portion of contact members 1452 extend beyond surface 1454 of housing 1456. In the illustrated embodiment, the contact members 1452 form a loop 1458 that extends below the surface 1454 of the contact coupling layer 1460. Solder 1462 flows into the loop 1458 during reflow to form a stronger joint. Sealing material 1464 is optionally deposited at the interface between the contact members 1452 and the contact coupling layer 1460 to prevent solder wicking. The embodiment of FIG. 34 can optionally be a split constructed, such as illustrated in FIGS. 30,32 and 33.
FIG. 35 illustrates an interconnect assembly 1480 in which beams 1482, 1484 of contact members 1486 bow outward. The resiliency of the beams 1482, 1484 retains the contact members 1486 in non-moldable cavities 1488. In one embodiment, the contact members 1486 form a snap-fit relationship with the cavities 1488.
FIG. 36 illustrates an interconnect assembly 1500 with a secondary contact members 1502 that form a snap-fit interface with distal ends 1504, 1506 of contact members 1508. The secondary contact member 1502 and the contact member 1508 work together during actuation. When the first circuit member 1510 is pressed against the interconnect assembly 1500, the secondary contact member 1502 induces a bow in the beams 1512, 1514 of the contact member 1508.
FIG. 37A-37C illustrate a dual loop contact member 1600 with reversed, overlapping tips 1602, 1604. The overlapping tips 1602, 1604 are more resistant to damage from handling than single tip configurations. The tips 1602, 1604 overlap so that upon compression, beams 1606, 1608 bow outward in the direction 1610, but the tips 1602, 1604 remain in close proximity. In the preferred embodiment, the tips 1602, 1604 remain engaged during compression. The contact member 1600 can be constructed from a variety of conductive material, such as for example 0.002 inch thick, BeCu A390. FIG. 38A-38C illustrate an alternate dual loop contact member 1620 with modified overlapping tips 1622, 1624. FIGS. 39A-39C illustrate an another dual loop contact member 1630 with reversed overlapping tips 1632, 1634. The contact members 1600, 1620, 1630 are particularly well suited for use with an LGA device and can be used in a variety of the interconnect assemblies disclosed herein.
FIG. 40A-40C illustrate a dual loop contact member 1650 with reversed, overlapping tips 1652, 1654 particularly well suited for use with BGA devices. Again, upon compression, beams 1656, 1658 bow outward in the direction 1660, but the tips 1652, 1654 remain in close proximity. FIGS. 41A-41C illustrate an alternate dual loop contact member 1670 with modified overlapping tips 1672, 1674.
The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. For example, the contact members and housings disclosed herein can be combined in a variety of ways. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention.

## Claims

1. An electrical interconnect assembly for electrically interconnecting terminals on a first circuit member with terminals on a second circuit member, the electrical interconnect assembly comprising:
a housing comprising a plurality of layers forming a plurality of substantially non-moldable through openings that extend between a first surface and a second surface of the housing;
a plurality of contact members positioned in a plurality of the through openings; and
a sealing layer substantially sealing the through openings between the contact members and the housing along at least one of the first surface and the second surface.

2. The electrical interconnect assembly of claim 1 wherein the contact members form an interlocking relationship with the housing.

3. The electrical interconnect assembly of claim 1 wherein the contact members form a snap-fit relationship with the housing.

4. The electrical interconnect assembly of claim 1 wherein the contact members form a press fit relationship with the housing.

5. The electrical interconnect assembly of claim 1 wherein the sealing layer comprises a curable polymeric material.

6. The electrical interconnect assembly of claim 1 wherein an alignment layer on the housing limits deflection of the contact members in at least two directions.

7. The electrical interconnect assembly of claim 1 wherein distal ends of the contact members have shapes that corresponds to shapes of terminals on one of the circuit members.

8. The electrical interconnect assembly of claim 1 wherein at least one layer in the housing comprises a circuit layer.

9. The electrical interconnect assembly of claim 1 wherein the plurality of through openings are arranged in a two-dimensional array.

10. The electrical interconnect assembly of claim 1 wherein the housing comprises at least a first discrete portion biased away from a second discrete portion, so that distal ends of the contact members are generally flush with or below, one of the surfaces of the housing.

11. The electrical interconnect assembly of claim 1 comprising at least one secondary contact member mechanically coupled with at least one of the contact members.

12. The electrical interconnect assembly of claim 1 wherein the contact members comprise a pair of serpentine beams forming at least two loops.

13. The electrical interconnect assembly of claim 1 wherein the contact members comprise a pair of overlapping tips.

14. The electrical interconnect assembly of claim 1 wherein the contact members comprise a pair of overlapping tips that prevent the distal ends from separating.

15. The electrical interconnect assembly of claim 1 wherein the contact members comprise a pair of beams that form a snap-fit relationship with the substantially non-moldable through openings.

16. The electrical interconnect assembly of claim 1 wherein a portion of the contact members extend beyond the first or second surface.

17. The electrical interconnect assembly of claim 1 wherein the contact members are coupled to at least one layer of the housing using one or more of a compressive force, solder, a wedge bond, a conductive adhesive, an ultrasonic bond, a wire bond, and a mechanical coupling between the contact members and the first circuit member.

18. An electrical interconnect assembly for electrically interconnecting terminals on a first circuit member with terminals on a second circuit member, the electrical interconnect assembly comprising:
a housing comprising a plurality of layers forming a plurality of substantially non-moldable through openings that extend between a first surface and a second surface of the housing;
a plurality of contact members positioned in a plurality of the through openings;
a stabilizing layer on the housing that limits deflection of the contact members in at least one direction; and
a sealing layer substantially sealing the through openings between the contact members and the housing along at least one of the first surface and the second surface.