Electrical connector assembly having hybrid conductive polymer contacts

An electrical connector assembly includes a carrier having an upper surface and a lower surface. The carrier includes a plurality of contact openings therethrough. The electrical connector assembly includes contacts coupled to the carrier and passing through the corresponding contact openings. Each contact has a conductive polymer column extending between an upper mating interface and a lower mating interface. The conductive polymer column includes an inner core manufactured from a first material and an outer shell manufactured from a second material. The second material has a higher electrical conductivity than the first material. The first material has a lower compression set than the second material.

BACKGROUND OF THE INVENTION

The subject matter herein relates generally to electrical connector assemblies.

The ongoing trend toward smaller, lighter, and higher performance electrical components and higher density electrical circuits has led to the development of surface mount technology in the design of printed circuit boards and electronic packages. Surface mountable packaging allows for a separable connection of an electronic package, such as an integrated circuit or a computer processor, to pads on the surface of the circuit board rather than by contacts or pins soldered in plated holes going through the circuit board. Surface mount technology may allow for an increased component density on a circuit board, thereby saving space on the circuit board.

One form of surface mount technology includes socket connectors. A socket connector may include a substrate holding an array of contacts. Some known socket connectors have an array of conductive polymer columns that are compressible to provide an interposer between the host circuit board and the electronic package. However, known socket connectors have a low deflection and working range. Conductive polymers may exhibit stress relaxation over time as the loading material disrupts and adversely affects the crosslinking of the polymer material. The material of the conductive polymer may experience permanent set or creep over time causing the socket connector to have a potentially limited working lifespan and the inability to be reused.

A need remains for an electrical connector assembly having improved contacts with an extended working lifespan.

BRIEF DESCRIPTION OF THE INVENTION

In an embodiment, an electrical connector assembly is provided. The electrical connector assembly includes a carrier having an upper surface and a lower surface. The lower surface is configured to face a host circuit board. The upper surface is configured to face a component circuit board of an electrical component. The carrier includes a plurality of contact openings therethrough. The electrical connector assembly includes contacts coupled to the carrier and passing through the corresponding contact openings. Each contact has a conductive polymer column extending between an upper mating interface and a lower mating interface, the conductive polymer column being compressible between the upper mating interface and the lower mating interface. The conductive polymer column includes an inner core and an outer shell. The inner core is manufactured from a first material. The outer shell is manufactured from a second material. The second material has a higher electrical conductivity than the first material. The first material has a lower compression set than the second material.

In another embodiment, an electrical connector assembly is provided. The electrical connector assembly includes a carrier having an upper surface and a lower surface. The lower surface is configured to face a host circuit board. The upper surface is configured to face a component circuit board of an electrical component. The carrier includes a plurality of contact openings therethrough. The electrical connector assembly includes contacts coupled to the carrier and passing through the corresponding contact openings. Each contact has a conductive polymer column extending between an upper mating interface and a lower mating interface the conductive polymer column is compressible between the upper mating interface and the lower mating interface. The conductive polymer column includes an inner core and an outer shell. The inner core is secured to the carrier by a first molding. The outer shell is secured to the carrier by a second molding over the first molding.

In a further embodiment, an electrical system is provided. The electrical system includes a host circuit board. The system includes an electrical component having a component circuit board. The system includes an electrical connector assembly electrically connected between the host circuit board and the component circuit board. The electrical connector assembly includes a support frame having a frame opening. The frame opening receives the component circuit board. The support frame positions the component circuit board within the frame opening. The electrical connector assembly includes a carrier coupled to the support frame. The carrier has an upper surface and a lower surface. The lower surface faces the host circuit board. The upper surface faces the component circuit board. The carrier includes a plurality of contact openings therethrough. The electrical connector assembly includes contacts coupled to the carrier and passing through the corresponding contact openings. Each contact has a conductive polymer column extending between an upper mating interface and a lower mating interface. The upper mating interface is electrically coupled to the component circuit board. The lower mating interface is electrically coupled to the host circuit board. The conductive polymer column is compressible between the upper mating interface and the lower mating interface. The conductive polymer column includes an inner core and an outer shell. The inner core is manufactured from a first material. The outer shell is manufactured from a second material. The second material has a higher electrical conductivity than the first material. The first material has a lower compression set than the second material.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1is an exploded view of an electrical connector assembly100in accordance with an exemplary embodiment for an electrical system102.FIG. 2is a side view of the electrical connector assembly100of the electrical system102in accordance with an exemplary embodiment. The electrical system102includes a host circuit board104and a component circuit board106(shown in phantom) of an electrical component108. The electrical connector assembly100is used to electrically connect the component circuit board106with the host circuit board104. In various embodiments, the electrical component108is an electronic package, such as an ASIC. For example, the electrical component108may include a chip110mounted to the component circuit board106.

The host circuit board104includes an upper surface112and a lower surface114. The electrical connector assembly100is mounted to the upper surface112of the host circuit board104. In an exemplary embodiment, a backer plate116is provided at the lower surface114to stiffen the host circuit board104. The electrical connector assembly100may be coupled to the backer plate116through the host circuit board104, such as using fasteners118.

In an exemplary embodiment, a thermal plate120(FIG. 1) is thermally coupled to the electrical component108to dissipate heat from the electrical component108. For example, the plate120may be used to dissipate heat from the chip110. The thermal plate120may be a heatsink or a cold plate in various embodiments. Other types of thermal plates may be used in alternative embodiments. The plate120may be coupled to the electrical connector assembly100and/or the host circuit board104and/or the backer plate116in various embodiments.

In an exemplary embodiment, the electrical connector assembly100includes a compressible interface for receiving the electrical component108. The electrical connector assembly100is electrically connected to the chip110through the component circuit board106. In an exemplary embodiment, the thermal plate120is coupled to the top of the chip110to dissipate heat from the chip110. The backer plate116may be used to secure the thermal plate120and/or the electrical component108and/or the electrical connector assembly100to the host circuit board104.

In an exemplary embodiment, the electrical connector assembly100includes an interposer150that holds a plurality of contacts200. In an exemplary embodiment, the contacts200are conductive polymer contacts. The contacts200may be metallized particle interconnects. The contacts200are configured to be electrically connected to the host circuit board104and are configured to be electrically connected to the component circuit board106to transmit data signals therebetween. The contacts are held in a contact array. In an exemplary embodiment, the array of contacts is configured to be coupled to the component circuit board106at a separable interface and configured to be coupled to the host circuit board104at a separable interface. For example, the contacts200may form a land grid array (LGA) interface with the component circuit board106and may form an LGA interface with the host circuit board104.

In various embodiments, the electrical connector assembly100includes a support frame152holding the interposer150and configured to hold the electrical component108. The support frame152may be a socket frame forming a socket that receives the electrical component108. The interposer150includes a carrier154holding the contacts200. The carrier154is coupled to the support frame152. For example, the support frame152may include a socket opening156that receives the electrical component108. The carrier154is held in the socket opening156for interfacing with the electrical component108, such as the component circuit board106. The support frame152is used to position the component circuit board106relative to the interposer150and the contacts200. The support frame152may be secured to the host circuit board104and/or the backer plate116using fasteners118. The thermal plate120may be coupled to the support frame152. Optionally, the support frame152may position the thermal plate120relative to the electrical component108, such as to limit compression of the thermal plate120against the electrical component108. In alternative embodiments, the interposer150may be provided without the support frame152.

FIG. 3is a cross-sectional view of a portion of the electrical connector assembly100in accordance with an exemplary embodiment showing one of the contacts200coupled to the carrier154.FIG. 4is a top view of a portion of the electrical connector assembly100in accordance with an exemplary embodiment showing the carrier154.

The interposer150includes the carrier154holding the contacts200. The carrier154may be a plate or film that supports the contacts200. The carrier154is manufactured from a dielectric material to electrically isolate the contacts200. For example, the carrier154may be a polyimide film. The carrier154includes an upper surface160and a lower surface162. The carrier154includes a plurality of contact openings164extending between the upper surface160and the lower surface162. The contact openings164receive the contacts200. In various embodiments, the contacts200are molded in situ on the carrier154. For example, the material of the contacts200passes through the contact openings164during the molding process to form the contact200above the upper surface160and below the lower surface162. In various embodiments, the contacts200may be formed by transfer molding, compression molding, injection molding, dispensing, printing, and the like. In an exemplary embodiment, multiple contact openings164are provided. For example, the contact openings164include primary contact openings166and secondary contact openings168. The primary contact openings166receive a first portion of the contact200and the secondary contact openings168receive a second portion of the contact200. In the illustrated embodiment, the mounting location for each contact200has a single primary contact opening166and a plurality of secondary contact openings168surrounding the primary contact opening166.

In an exemplary embodiment, each contact200includes a conductive polymer column202extending between an upper mating interface204at the top of the contact200and a lower mating interface206at the bottom of the contact200. The conductive polymer column202is compressible between the upper mating interface204and the lower mating interface206. The upper and lower mating interfaces204,206form separable mating interfaces. The upper and lower mating interfaces204,206may form upper and lower LGAs. The conductive polymer column202may include a metallized particle interconnect in various embodiments along at least a portion of the conductive polymer column202. The conductive polymer column202may include conductive caps at the upper and lower mating interfaces204,206.

In an exemplary embodiment, the conductive polymer column202of each contact200includes an upper portion210above the upper surface160of the carrier154and a lower portion212below the lower surface162of the carrier154. The carrier154extends into the contact200to support the contact200. The upper portion210extends between the upper surface160and the upper mating interface204. The lower portion212extends between the lower surface162and the lower mating interface206. In an exemplary embodiment, the conductive polymer columns202are frustoconical shaped. For example, the upper portion210is frustoconical shaped and the lower portion212is frustoconical shaped. For example, an upper portion wall220is tapered between the upper surface160and the upper mating interface204and a lower portion wall222is tapered between the lower surface162and the lower mating interface206. The upper portion210has a first upper diameter at the upper surface160and a second upper diameter at the upper mating interface204less than the first upper diameter. The lower portion212has a first lower diameter at the lower surface162and a second lower diameter at the lower mating interface206less than the first lower diameter.

In an exemplary embodiment, the conductive polymer column202includes an inner core230and an outer shell232. The inner core230extends through the carrier154, such as through an inner opening. The portion of the inner core230extending through the carrier154may be narrowed to fit through the inner opening. The outer shell232extends through the carrier154, such as through outer openings. The portions of the outer shell232extending through the carrier154may be narrowed to fit through the outer openings. The outer shell232fully or partially surrounds the inner core230. In an exemplary embodiment, the inner core230and the outer shell232are manufactured from different materials. For example, the inner core230is manufactured from a first material, such as a non-conductive polymer material, and the outer shell232is manufactured from a second material, such as a conductive polymer material. The second material has a higher electrical conductivity than the first material. For example, the outer shell232is manufactured from a polymer material having conductive particles, such as silver particles, embedded in the polymer base material. The outer shell232may be internally conductive through the second material of the outer shell232. The outer shell232may additionally or alternatively be plated or coated to be electrically conductive along the exterior surface. The outer shell232forms an electrically conductive path between the upper mating interface204and the lower mating interface206.

In an exemplary embodiment, the first material of the inner core230has a lower compression set than the second material. The compression set is the amount of permanent deformation remaining after removal of force. The lower compression set of the second material means less permanent deformation of the second material. In other words, the second material has a greater ability to return to shape when the force is removed. In various embodiments, the inner core230is manufactured from a non-conductive polymer material, such as a silicone rubber material, such as a heat cured rubber. The inner core230is compressible with the outer shell232and presses outward against the outer shell232when released to return the outer shell232to the normal, uncompressed position. The elastic nature of the first material of the inner core230reduces permanent set or creep of the conductive polymer column202(for example, permanent set or creep of the material of the outer shell232. The inner core230increases the elasticity of the conductive polymer column202.

In an exemplary embodiment, the inner core230is formed in place on the carrier154and the outer shell232is formed in place on the carrier154over the inner core230. The outer shell232may have a uniform thickness covering the inner core230. The outer shell232may completely surround and enclose the inner core230. For example, the outer shell232may cover the sides, the top and the bottom of the inner core230such that no portion of the inner core230is exposed. In other various embodiments, the outer shell232partially covers the inner core230, such as leaving a portion of the inner core230exposed at an exterior of the contact200. In an exemplary embodiment, the inner core230is secured to the carrier154by a first molding using a first mold and the outer shell232is secured to the carrier154by a second molding over the first molding using a second mold. When molding the inner core230, the first material flows through the primary contact opening166to secure the inner core230to the carrier154. The inner core230extends above the upper surface160and extends below the lower surface162. When molding the outer shell232, the second material flows through the secondary contact openings168to secure the outer shell232to the carrier154. The upper and lower portions of the outer shell232are electrically connected to each other through the carrier154. The secondary contact openings168surround the central primary contact opening166. The outer shell232extends above the upper surface160and extends below the lower surface162.

FIG. 5is a cross-sectional view of a portion of the electrical connector assembly100in accordance with an exemplary embodiment showing an array of the contacts200coupled to the carrier154.FIG. 6is a top view of a portion of the electrical connector assembly100in accordance with an exemplary embodiment showing a portion of the carrier154. In an exemplary embodiment, the inner cores230may be formed at the same time using a common mold. The outer shells232may then be formed over the inner cores230using a common mold. When molding the inner cores230, the first material flows through the primary contact openings166. When molding the outer shells232, the second material flows through the secondary contact openings168.