WO1999021227A1

WO1999021227A1 - Connector assembly for accommodating bga-style components

Info

Publication number: WO1999021227A1
Application number: PCT/US1998/021904
Authority: WO
Inventors: Ryu Maeda
Original assignee: Molex Incorporated
Priority date: 1997-10-17
Filing date: 1998-10-16
Publication date: 1999-04-29
Also published as: TW415709U; JP4085186B2; JPH11121659A

Abstract

An improved connector assembly particularly useful for testing semiconductors of BGA structure has a base (1) with a plurality of holes formed in the base. The holes are surrounded by conductive material (5) so that they are conductive through the base. A flexible film (2) is disposed on the base and has a plurality of conductive metal bumps (11) formed on it and aligned with the base holes. A series of metal balls (6) are positioned beneath the base and are aligned with holes to form a short conductive path between the conductive bumps and the balls to reduce the latent inductance of the connector assembly.

Description

CONNECTOR ASSEMBLY FOR ACCOMMODATING BGA-STYLE COMPONENTS

Background of the Invention

The present invention relates generally to connector assemblies for components having a ball-grid array ("BGA") such as a BGA semiconductors, and more particularly, to a BGA connector that is appropriate for use with test sockets for semiconductor packages and devices- Conventional semiconductors or integrated circuits ("IC") are commonly formed as chips, that are referred to in the art as "packages". Conventional packages may have their leads formed on two sides, such as in DIPs or on four sides, such as in QFPs or TCPs. The number of leads connecting to such semiconductors and Ics have been increasing and accordingly, the distance, or pitch, between the leads has been reduced. The reduction of spacing between the leads increases the difficulty with which the closely spaced leads are soldered to a printed circuit board. In the case of the four-sided QFPs and TCPs mentioned above, the leads cannot be easily soldered to a circuit board because of the close lead-to-lead distance.

In order to meet this situation, a lattice-array or grid-array of electrically conductive raised lands are formed on the bottom surface of the semiconductor package in place of the conventional leads on the four sides of the package. These lands typically have balls of soldering material or metal physically connected to them and are referred to in the art as BGA. BGA sockets are known in semiconductor arts. The two- dimensional arrangement of the conductive metal balls or bumps on the bottom surface of the semiconductor package permits the lead-to-lead spacing to be increased up to three times as much as in the conventional two-sided or four-sided arrangement. This facilitates the soldering of the leads of the packages to circuit boards while reducing any connection errors. Despite these known BGA arrangements, there are not known less expensive BGA sockets for use in effecting burn-in tests for semiconductor packages, either with or without the metal balls or bumps. Some burn-in sockets appropriate for use with BGA semiconductor packages use a lattice arrangement of stamped contacts embedded in the insulating housing. In these structures, the stamped contacts are arranged upright on the socket surface in order to abut the conductive metal balls or bumps on the semiconductor package. These contacts must be long enough to be resilient, having lengths of 5mm or longer.

Testing sockets are commonly used for many burn-in tests. The long length of these contacts may detrimentally affect the large number of tests such that the lengths of the contacts may demonstrate a significant amount of inductance appearing on each contact. Thus, a need exists for a testing socket that accommodates BGA-type semiconductor packages wherein the length of the testing socket contacts is substantially reduced.

The aforementioned contacts are typically produced by stamping them out of sheet metal and it is difficult to reduce the spring constant of the stamped contacts from a structural perspective. The contacts must be placed in good, conductive contact with their counterpart balls or bumps on the semiconductor package. As the spring constant of the stamped contact reminds large, the load per contact is inevitable increased. The metal balls of multi-pole semiconductor packages used in microprocessor units cannot be placed into good contact with testing sockets without heavily loading them and the testing contacts. This is undesirable from the angle of required amount of labor and from the angle of stress applied on the semiconductor packages being tested.

Still a further disadvantage arises from the heavy ball to contact interface at the increased temperatures, such as 125°F encountered during testing will cause adverse chemical reactions between the contact and the metal ball, thus contaminating selected contact points with resultant alloys to lower the reliability with which a required electrical contact can be made between the socket contacts and the metal balls, thereby shortening the life of the testing sockets. The contact-to-contact interval in these conventional testing sockets cannot be reduced below a spacing of 1.5mm, and therefore, these testing sockets cannot meet semiconductor packages utilizing a BGA structure in which their leads are arranged at a shorter spacing. BGA structures may also be used with electronic components other than semiconductors and testing sockets.

A need therefore exists for a connector assembly that can accommodate the close lead-to-lead spacing found in BGA- style semiconductors and other components.

Summary of the Invention

It is therefore a general object of the present invention to provide a BGA connector assembly that can accommodate BGA semiconductor packages of small spacing. Another object of the present invention is to provide a BGA connector assembly for use with a BGA-style socket that results in a light, but reliable, loading of the ball contacts of a BGA style semiconductor package, when the package is loaded into the testing socket.

A further object of the present invention is to provide a BGA socket that eliminates the contamination of the testing socket conductive contacts.

Still yet another object of the present invention is to provide a connector assembly that accommodates BGA semiconductor packages having leads arranged at reduced lead-to- lead intervals and in which the conductive paths between the BGA semiconductor leads and the connector assembly leads are reduced to eliminate potentially high latent inductance. To attain these and other objects, the present invention, in one principal aspect thereof, provides a connector assembly that may be used as a connector for components such as burn-in sockets that accommodate BGA-style semiconductor packages and having an overlying flexible film that is laminated to the socket. The film includes a plurality of contacts in the form of metal bumps and an underlying relatively rigid substrate with a plurality of holes formed therein and extending therethrough, to form conductive paths therethrough.

In another principal aspect of the present invention, the testing socket includes a rigid substrate having a plurality of electrically conductive through holes formed therein, the holes being filled with a resilient material. A flexible film is disposed on the substrate and has a plurality of metal bumps formed thereon in positions so as to abut counterpart metal balls formed on the BGA semiconductor package. A corresponding plurality of electrically conductive contact pads are disposed on the bottom surface of the flexible film so as to be put in contact with the metal bumps and which also cover the through holes. A corresponding plurality of metal balls are partly fitted in the conductive through holes and the upper conductive lands of each through hole are placed in contact with each of the conductive pads and the lower conductive lands of the through holes are placed in contact with each of the metal balls.

In another principal aspect of the present invention, the flexible film is an insulating film, preferably a polyimide film. The film has a plurality of metal bumps arranged thereon in alignment with counter metal balls of a BGA style semiconductor package. The conductive metal bumps may be formed such as by electrolytic plating or non-electrolytic plating. Preferably, the metal bumps are plated with a noble metal such as for example, gold, platinum, palladium, ruthenium, rhodium or the like. Every such metal bump is put in a selected through hole formed in the flexible film and a circular, electrically conductive pad is laid under each of the through holes so as to be in conductive contact with the metal bump therein. The through holes that are formed in the rigid substrate are themselves made conductive by plating or applying a conductive material, such as silver paste inside of them, often called in the art as "silver through holes". The electrically conductive pad that lies under the flexible film will be repeatedly loaded and therefor it is preferred that it be made of a material or membrane of good flexible resistance, such as a beryllium-copper alloy. The surface of the conductive pad is preferably plated with gold or tin and is dimensioned to be large enough to cover or somewhat larger to extend over the conductive lands on the top of the through holes. In a still further principal aspect of the present invention, each of the metal bump and conductive pad combinations is provided independently to confront each metal ball in a BGA semiconductor package.

In yet another principal aspect of the present invention, the rigid substrate of the connector assembly may be formed from a sheet of insulative material, such as glass, epoxy, ceramic or the like and may have a thickness varying from 0.1 to 1 mm thick, with a preferred thickness being about 0.3 to 0.5 mm. The substrate has a series of holes formed in it that confront the metal bumps of the semiconductor and conductive pads formed on the flexible film. In one embodiment of the invention, the holes may be filled with a resilient material such as a silicone elastomer or other flexible material that is subsequently heated and cured. The resilient filler desirably projects above the upper parts of the holes, preferably about 0.3 mm higher. Upper and lower conductive lands which are annular, or ring-like in nature, and which are about 0.2 to about 0.3 mm larger than the diameters of the holes, with the lands being about 0.1 to about 0.24 mm wide. In order to effect the necessary electrical connection between the upper conductive land and the overlying conductive pad, one of the land and pad may be plated with gold, while the other is plated with tin and the two members are subsequently subjected to thermal compression to form a gold-tin eutectic metal bond therebetween. Alternatively, the required connection may be made by plating both the land and the pad with gold and subsequently subjecting the two to supersonic or ultrasonic wave bonding. Still further, the gold plated land and pad may be connected by an anisotropic conductive membrane.

The electrical connection between the lower conductive land and the metal ball of the testing socket may be made by soldering or gold-tin eutectic metal bonding. The metal ball is preferably made highly conductive by gold plating a steel or copper ball. The ball may have a diameter of about 0.3 to 2 mm. The resilient filler used will not have its resiliency affected by the metal ball and the ease of soldering may be lower for smaller sized metal balls.

The electrically conductive pad that is formed underneath the flexible film will be subjected to repeated loading and will also be bent repeatedly toward the underlying rigid substrate. The conductive pad has an open-loop slit of a somewhat C-shaped configuration that allows its inner circle to be readily displaced toward the through hole when loaded to avoid permanent deformation of the flexible film.

The BGA sockets of the present invention may be used as a burn-in socket or packaging socket when a cover member is provided to push the semi-conductor package against the flexible film of the socket. The socket may be fixed to a printed circuit board or burn-in board by soldering the metal balls with the socket to the printed circuit or burn-in board. The socket may be reused by unsoldering and removing the metal balls of the BGA socket from the circuit or burn-in board each time after conducting a burn-in test. The structure of the present invention permits the bump-to-ball conductive path to be reduced to a possible minimum. The required electrical connection may be made abutting each metal ball of a BGA semiconductor package onto an opposing metal bump to thereby permit the loading to be significantly reduced as compared with a conventional test socket structure. By utilizing a direct pushing contact design between the metal balls of BGA semiconductor package against the metal pumps of the socket, it permits the socket to accommodate semiconductor packages whose leads are arranged at very small intervals.

These and other objects, features and advantages of the present invention will be clearly understood through a consideration of the following detailed description.

Brief Description Of The Drawings

In the course of the following detailed description reference will be made to the attached drawing wherein like reference numerals identify like parts and wherein:

FIG. 1 is an enlarged elevational detail view, partly in section of a BGA semiconductor package and a BGA connector assembly constructed in accordance with the principles of the present invention and illustrated in the context of a testing socket ;

FIG. 2 is the same view as FIG. 1, but illustrating how contact is effected between the BGA semiconductor package and the connector assembly and how the substrate is connected to a circuit board associated with the socket;

FIG. 3 is a plan view of the surface of the film at the location of a BGA contact illustrating the metal bump and associated conductive pad; and,

FIG. 4 is an enlarged view of the underside surface of the conductive pad.

Description of Preferred Embodiments

Referring now to FIG. 1, a BGA socket connector assembly constructed in accordance with the principles of the present invention is indicated generally at 100 and can be seen to include a rigid substrate 1, having a plurality of conductive through holes 102 formed therein in a preselected pattern corresponding to the pattern of conductive balls 15 formed on a BGA style semiconductor package 16. A flexible film 2 overlies the substrate 1 and has a corresponding plurality of metal bumps 11 formed thereon, each metal bump 11 being positioned in alignment with a through hole 102 and a BGA ball 15.

As mentioned above, the present invention finds its greatest utility in providing connections for semiconductors, or other electronic components , having a BGA-type structure or as shown in FIG. 1, where the semiconductor body, or package 16, has a plurality of conductive raised portions 106 formed in a pattern on a lower surface 104 thereof. The raised portions 106 are illustrated in FIGS. 1 & 2 as raised hemispherical balls 15. However, it will be understood that the configuration of the raised portions 106 may differ from that shown. The substrate 1 is preferably formed from an insulative material such as glass, fiberglass, epoxy, ceramic or the like. The thickness of the substrate may vary from about 0.1 to about 1 mm thick, with a preferred thickness being about 0.3 to about 0.5 mm. In one example of the invention, an epoxy plate approximately 27 by 27 mm, and 0.8 mm thick was used and provided effective results. A flexible film 2 comprising a square polyimide film of approximately the same dimensions, 27 x 27 mm was provided and included a conductive layer 108 formed from a copper-beryllium alloy. The film is laid on the top surface 103 of the substrate 1.

A plurality of openings are formed in the substrate 1 in the form of holes 102 that extend through the substrate and in a 15 by 15 array so that 275 of such holes are formed in the substrate 1. These through holes 102 were arranged in a preselected pattern where they were spaced both longitudinally and laterally at intervals about 1.5 mm.

Each such through hole 102 had a diameter of about 1.0 mm and upper and lower electrically conductive lands 3, 4 were formed on the respective upper and lower surfaces 103, 104 of the substrate 1 surrounding the holes 102. In this regard, the conductive lands 3, 4 are annular, or ring-like in nature with outer diameters that are equal to or slightly larger than the diameters of the holes 102, such as about 0.2 to about 0.3 mm larger than the diameters of the holes, with the lands being typically about 0.1 to about 0.24 mm wide. The diameters of the lands may range from about 1.0 mm to about 1.3 mm. The upper and lower lands 3, 4 are conductively joined together by an inner plating 5 that is disposed on the interior surface 106 of the through holes. (FIGS. 1 & 2.) The inner plating 5 and the upper and lower lands 3 , 4 may be plated with tin and also conductively connected, such as by the use of a gold-tin solder joint 7, to a conductive ball 6 that is partly received within the through hole 102. The ball 6 in the example referred to had a diameter of about 1.2 mm, slightly greater than that of the through hole 102 and the lower conductive land 4 and may be formed of a conductive material, such as a gold-plated copper. In an important aspect of the invention, portions of the conductive layer on the bottom of the flexible film 2 was removed such as by forming a slit 12 to define circular conductive pads 9 having diameters in the order of 1.3 mm so as to match and contact the upper lands 3. The through holes 102 may be partly filled, as in the embodiment shown, with a resilient filler material such as a silicone elastomer or other elastomeric material in order to provide a resilient body 8 that fills the through holes 102 and projects partly above the upper annular lands, on the order of a height of about 0.2 mm over that of the upper lands 3.

The flexible film 2 further includes a plurality of conductive raised contact portions, illustrated as bumps 11 that are disposed on the top of the film 2 and extending down through a hole 10 formed in the center of the film 2. These holes 10 are preferably located in the approximate center of the through holes 102 and the conductive pads 9 that overlie the through holes 102. The conductive contact bumps 11 may be easily formed on the upper surface of the film by electrolytic plating or other suitable means. They extend through the holes 10 to reach conductive layer 108 therebeneath. In the example referred to above, the contact bumps 11 were formed having about a 0.3 mm diameter and about a 0.4 mm height. Both the conductive layer 108 and the bumps 11 were plated with a highly conductive material, such as gold to achieve good conductivity. Referring now to FIGS. 3 and 4, each conductive pad 9 formed on the underside of the film 2 may have an open portion, such as a circular slit 12 (FIG. 4) formed therein where the conductive layer 108 has been removed, such as by laser etching. The slit 12 illustrated has a generally open ring or C-shaped configuration that defines an inner conductive area 9a spaced apart from and within an outer conductive area 9b. The two conductive areas 9a, 9b are connected by a bight portion 13 that is disposed between the free ends 109 of the slit 12. The slit 12 may have a width of about 0.02 mm and it preferably runs along the inner circumference of the upper land 3 of surrounding the through hole 102. This slit extends, in the embodiment illustrated, completely through the thickness of the film 2. With this structure, the inner conductive area 9a of the conductive pad 9 may be displaced from its completely flat orientation of FIG. 1 to the deflected orientation of FIG. 2. The bight portion 13 may be about 0.3 mm to form the desired electrical connection between the inner and outer conductive areas. The conductive layer 108 may be gold-tin soldered to the upper land of the substrate 1 and may, as explained above, provide a desired electrical connection therebetween by way of gold-tin eutectic bonding.

The conductive pads 9 of the flexible film 2 may be gold-tin soldered to the upper annular lands as shown along their common mating faces as at 112 in FIGS. 1 and 2 in order to provide reliable electrical connections via gold-tin eutectic metal bonding therebetween, In FIG. 2, the socket 100 is illustrated as being fixed to a semiconductor burn-in circuit board 14 by way of soldering the gold-plated copper balls to the electrically conductive contact pads 17 of the burn-in circuit board 14. A 225 pole BGA semiconductor package 16 having soldering balls 15 of about 1.0 mm in diameter as the semiconductor contacts was inserted into the socket 100 so that the solder balls 15 abuttingly contacted the metal bumps 11 of the flexible film 2 of the BGA socket 100. A total load of about 6 kilograms was applied to push the BGA semiconductor package 16 into the socket 100. Thus, the load experienced by each contact was about 27 grams. The semiconductor package 16 was subjected to a burn- in test at 135 °C for 5 minutes. This testing was repeated for 10,000 cycles and then the contact resistance and contact loads were measured. The contact resistance per pole (combined conductive path defined by the solder ball 15, metal bump 11, conductive lands 3, 4 & 5 and contact ball 6) was 12 + 4 milliohms, and the contact load per pole was about 25 + 12 grams .

As can be seen from the above, the improved BGA sockets of the invention have a very short bump to ball conductive metal passage and thereby reduces the latent inductance to its most possible minimum. Burn-in tests utilizing such sockets can be effected at increased frequencies. The useful structure of the metal bumps abutting the leads of the semiconductor package has the effect of significantly reducing the contact load so that the attachment of the BGA semiconductor package to the BGA socket is facilitated and the stress on the semiconductor is significantly reduced. Therefore the metal bumps of the socket cannot be contaminated with soldering material of the semiconductor leads, thus preventing the shortening of the life of the BGA socket. The use on the metal bumps as the socket contacts therefore permits the socket to establish reliable contact with a BGA semiconductor package having leads at very small intervals.

While the preferred embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made therein without departing from the spirit of the invention, the scope of which is defined by the appended claims. For example, the configuration of the leads of the semiconductor and socket metal bumps need not be hemispherical, but may take other configurations .

Claims

What is Claimed:

1. A connector assembly for establishing an electrical connection between an electronic component of ball grid array (BGA) structure and a circuit member, the electronic component having a base portion with a plurality of raised, conductive leads formed thereon and extending out therefrom, said electronic component raised leads further being arranged thereon in a first preselected pattern, said connector assembly comprising: a substrate having a predetermined thickness extending between opposing first and second surfaces of said substrate, said substrate further including a plurality of openings disposed in said substrate, each of said substrate openings providing a passage extending through said substrate between said substrate first and second surfaces; said substrate openings being disposed on said substrate in a second preselected pattern that matches said first preselected pattern, whereby each of said substrate openings opposes a single raised lead of said electronic component when said electronic component is placed into contact with said substrate, each said substrate opening having an electrically conductive portion associated therewith defining a conductive path through said substrate between said substrate first and second surfaces; a plurality of conductive substrate contacts aligned with said substrate openings at said substrate second surface, whereby a single substrate contact conductively engages the conductive portion of a single substrate opening; a flexible interface disposed on said substrate between said substrate first surface that separates said substrate from said electronic component raised leads when said electronic component is placed into contact with said substrate, the interface including an insulative layer and a plurality of individual conductive pads arranged on said insulative layer in said second preselected pattern in opposition to said substrate openings such that a single conductive pad is associated with a single substrate opening, each conductive pad being dimensioned so that said conductive pad extends over said substrate opening; said interface further including a plurality of raised contacts disposed thereon so as to confront said electronic component leads when said electronic component is placed into contact with said substrate, the raised contacts communicating with said conductive pads and extending through said insulative layer, said raised contacts being arranged in said second preselected pattern such that a single raised contact is associated with a single substrate opening and confronts a single electronic component raised lead, whereby when said electronic component is placed in contact with said substrate, said electronic component leads abuttingly engage said raised contacts of said interface and said conductive pads abuttingly engage said substrate opening conductive portions to thereby establish conductive paths from said electronic component leads to said substrate contacts.

2. The connector assembly as set forth in claim 1, further including a resilient filler disposed in each of said substrate openings, the filler being interposed between said conductive pads and said substrate contacts to resiliently support said conductive pads when said electronic component is placed into contact with said substrate.

3. The connector assembly as set forth in claim 1, wherein said conductive portions of said substrate openings each include a pair of upper and lower conductive land portions respectively disposed on said substrate first and second surfaces and interconnected along interior surfaces of said substrate openings.

4. The connector assembly as set forth in claim 1, wherein said interface includes a flexible film and said conductive pads are formed from a conductive metal.

5. The connector assembly as set forth in claim 3, wherein said interface includes a flexible film.

6. The connector assembly as set forth in claim 1, wherein each of said conductive pads has a displacement slit formed therein, the displacement slit defining respective interior and exterior portions of said conductive pads, said displacement slits permitting said conductive pad interior portions to partially displace toward said substrate openings under urging of said electronic component leads when said electronic component is placed into contact with said substrate.

7. The connector assembly as set forth in claim 6, wherein said substrate openings are filled with a resilient filler, said resilient filler yieldingly supporting said conductive pads.

8. The connector assembly as set forth in claim 6, wherein said slit has a generally C-shaped configuration.

9. The connector assembly as set forth in claim 1, wherein said substrate contacts are joined to said circuit member proximate to lower ends of said substrate contacts.

10. The connector assembly as set forth in claim 3, wherein said substrate contacts include conductive balls, portions of said conductive balls fitting into said substrate openings at said substrate second surface, said conductive balls being joined to said substrate at said lower conductive land portions thereof.

11. The connector assembly as set forth in claim 3, wherein said substrate openings are plated with a conductive material along their interior surfaces.

12. A BGA connector assembly for establishing a connection between a semiconductor and a circuit member, the semiconductor having a ball grid array ("BGA") disposed on a contact surface thereof, the ball grid array including a plurality of raised contact members, said BGA connector assembly comprising: a connector body in the form of a planar substrate of relatively low thickness and having an insulative, flexible film disposed thereon in opposition to said semiconductor ball grid array, the insulative film having a plurality of raised contact members disposed thereon in opposition to said semiconductor raised contact members, said substrate having a plurality of through holes formed therein that define passages through said substrate, said through holes being disposed in a pattern such that a single semiconductor raised contact member opposes a single through hole and said insulative film raised contact members extend above said through holes; said substrate including individual first conductive land portions disposed on a first surface thereof so that a single first conductive land portion surrounds a single through hole, and said substrate further including individual second conductive land portions disposed on a second surface thereof so that a single second conductive land portion surrounds a single through hole on said substrate second surface, said substrate further including connective conductive portions extending through said through holes to interconnect said first and second conductive land portions together, said through holes being filled with a resilient filler; said insulative film including a conductive layer disposed thereon in opposition to said insulative film raised contact members, the conductive layer including a plurality of conductive pads aligned with said through holes, the conductive pads having distinct first and second portions, said conductive pad first portions overlying said substrate first conductive land portions surrounding said through holes and said conductive pad second portions being spaced apart from said first portions and overlying said resilient filler; and, said connector assembly further including a plurality of substrate contact members associated with said through holes in opposition to said resilient filler and said conductive pad second portions, said substrate contact members extending out from said substrate through holes to define a plurality of connector contacts for connecting to opposing contacts on the circuit member.

13. A BGA socket for effecting a connection with a semiconductor having a plurality of leads extending therefrom in the form of a ball grid array, the array including a plurality of conductive balls extending from a surface of said semiconductor, the socket comprising: a connection substrate having opposing first and second surfaces, the substrate having a plurality of through holes formed therein that extend through said substrate between said first and second surfaces thereof; the through holes having conductive portions associated therewith to define electrically conductive paths along said through holes between said substrate first and second surfaces, said through hole conductive portions including first and second conductive lands respectively disposed on said substrate first and second surfaces, said first and second lands being interconnected by conductive liners disposed on interior surfaces of said through holes; a flexible film disposed on said substrate first surface in opposition to said semiconductor ball grid array, the film including a plurality of conductive bump members disposed thereon in opposition to said semiconductor ball grid array, a single bump member opposing a single conductive ball of said ball grid array; a plurality of conductive pads disposed on said film in opposition to said substrate first surface and in alignment with said through holes, said conductive pads having configurations that approximate those of said through holes, and said conductive pads being slightly larger than said through holes so as to be in contact said first conductive land portions on said substrate first surface, said bump members of said film being in contact with said conductive pads; a plurality of conductive socket ball members partially fitted within said through holes at said substrate second surface, the socket ball members contacting said second conductive land portions of said through holes to thereby establish electrically conductive paths between said semiconductor balls and said socket ball members ; said through holes being filled with a resilient material that supports said conductive pads in positions above said through holes, said resilient material being deflectable under pressure of said semiconductor balls when said semiconductor is inserted into said socket.

14. The BGA socket as set out in claim 13, wherein said through holes are generally circular in configuration and said conductive pads are generally circular in configuration.

15. The BGA socket as set out in claim 13, wherein said film in formed from an insulative material and each of said conductive pads includes a channel formed therein defining interior and exterior portions of said conductive pads, the interior and exterior portions of said conductive pads being interconnected by a conductive bight portion, said channel permitting said conductive pad interior portion to deflect relative to said conductive pad exterior portion when said bump members are contacted by said semiconductor balls.

16. The BGA socket as set out in claim 15, wherein said channel has a generally C-shaped configuration with two free ends, the two free ends of said channel being separated by said conductive bight portion.

17. The BGA socket as set out in claim 15, wherein said conductive pad exterior portions and said first conductive land portions are in contact with each other by way of eutectic metal bonding.

18. The BGA socket as set out in claim 15, wherein said conductive pad exterior portions and said first conductive land portions are in contact with each other by way of an anisotropic conductive film.

19. The BGA socket as set out in claim 13, wherein said socket ball members are held in said through holes by solder joints between said socket ball members and said second conductive land portions.

20. The BGA socket as set out in claim 13, wherein said film is a flexible polyimide film and wherein said resilient material extends slightly above a level of said substrate first surface.