JP2003533863A - Elastomer electrical connector - Google Patents

Abstract

(57) [Summary] An electrical connector is used to connect a first electrical element and a second electrical element. The body of the connector is made of an elastomer having a top and a bottom. Elastomer bumps extend from the top and bottom surfaces and holes extend through the pair of bumps and the body. The bumps and holes are metallized. To mount the connector, the connector is compressed and held between the first and second elements. Upon compression of the connector, the bumps press the metallized layer of the connector against the first and second elements.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to electrical connectors that provide electrical interconnection between two electrically conductive elements. More specifically, the present invention includes an array of electrical pathways provided within a silicone body, wherein the elastic force of the silicone body provides a force between two conductive elements, such as between a silicon die and a circuit board. The present invention relates to a connector for providing excellent electrical connection.

[0002]

[Prior art]

The connection of a silicon die or other electronic device to a circuit board has typically been made by wire bonding between conductive pads on the silicon die and metal leads that are ultimately soldered onto the circuit board. . Metal leads provide input / output connections between the silicon die and the circuit board. A recent trend is to mount more devices in a defined area on a circuit board, resulting in a greater number of leads required. Conventionally, the number of lead wires has been increased by reducing the pitch of the lead wires and increasing the number of side surfaces or surfaces from which the lead wires extend. However, this technique reaches its limits when it becomes impossible to stamp smaller metal leadframes. As a result, increasing the number of input / output connections per die area and power density (ie,
It is necessary to increase heat), and further, superior packaging technology is required.

Examples of such interconnects currently in use include ball grid arrays (BGA), in-board substrates described in JP-A-3-506094 and US Pat. No. 4,988,306. Real Connection Technology, Wire on Wafer (WOW) Technology Developed by Form Factor, Elastomer Connector for Electronic Packaging and Inspection (US Pat. No. 4,932,883), and Thom
The metallized particle interconnection method used by as and Betts is mentioned.

BGA is for mounting a silicon die on a circuit board with more input / output connections than was possible with packaging with metal leads such as flat packages. It has been developed. This mounting method utilizes a "high temperature" solder ball attached to a pad on the bottom side of the silicon die. By utilizing the entire bottom surface of the die rather than the perimeter of the die, the number of contacts to the circuit board can be significantly increased over flat packages. This method requires a substrate such as FR4 or ceramic with plated through holes between the wire bond pads on the top surface and the bump pads on the bottom surface. High temperature solder balls are attached to the bump pads on the bottom,
The completed assembly is then attached to the circuit board. This mounting method is relatively expensive ($ 0.01- $ 0.05 per input / output connection), and the die must be mounted before the burn-in test, making it ideal for wafer level testing. Not suitable. The price for a typical 70-position package is 1.
It is between $ 00 and $ 3.00.

The second interconnect method, solid-in-board technology, is primarily used to connect high performance silicon devices to circuit boards. A flat plastic frame with holes formed in a grid pattern with a pitch of 0.8 mm to 2 mm is used, and gold-plated "steel wool" is pressed into the holes. The assembly is compressed between two conductive pads to provide electrical contact between them. The typical pressing force of this connector is 2 ounces per contact and the total pressing force can be hundreds of pounds. The price of connectors using solid-in-board technology is $ 0.04 per contact on average. Therefore, a typical 70-position device costs $ 2.80. This electrical component mounting method is relatively expensive and is not suitable for testing at the wafer level.

A third technique, wire-on-wafer (WOW), relies on mounting metal springs directly on the silicon die. These springs provide electrical interconnection between the die and a mating surface such as a circuit board. The advantages include relatively low cost and wafer level testing. The downside is
Memory manufacturers must introduce a large amount of equipment to manufacture and mount springs on the die. The feasibility and cost effectiveness of this mounting method have not yet been determined.

A fourth silicon packaging method relies on the use of elastomeric substrates with selectively metallized surfaces. Through holes are used to electrically connect the bottom pad to the top pad. The metallized pads on the flat elastomer surface are offset from the plated through holes so that when the elastomer is compressed it does not break the electrical connector within the plated through hole barrel. Examples of this type of connector are US Pat. No. 5,071,359 and US Pat.
245,751.

[0008]

[Problems to be Solved by the Invention]

The present invention provides an electrical connector that overcomes the problems of the prior art and provides additional advantages not found in the prior art. Such advantages will become apparent upon examining the drawings and reading the specification.

A general object of the present invention is to provide an electrical connector that eliminates the use of metal leads for wire bonding.

It is an object of the present invention to provide an electrical connector that can increase the number of input / output connections per area on a circuit board compared to conventional packaging techniques.

A further object of the present invention is to provide an electrical connector that enables electrical contact between the connector and a conductive pad on a circuit board, silicon die, or other electronic device. Is.

[0012] Another object of the present invention is to provide an electrical connector that can be manufactured cost effectively.

A particular object of the present invention is to provide an electrical connector that can be tested at the wafer level.

[0014]

[Means for Solving the Problems]

In view of the above problems, the present invention can eliminate the need for metal leadframes, increase the number of input / output connections per area on a circuit board, and provide excellent electrical connections between the devices to be connected. Discloses an electrical connector that enables wafer level testing of an entire array of completed integrated chips and is cost effective to manufacture. The electrical connector includes an elastomeric base formed with a through hole and a raised elastomeric bump. The through holes and bumps are metallized to provide electrical paths between devices to be connected such as silicon dies and circuit boards. Raised bumps are provided on the top and bottom surfaces of the elastomeric base and allow the use of compressive forces to make electrical contact between the conductive pads on the electrical device and the plated holes. The raised bumps provide elastic forces that create good electrical contact and compliance between interconnected devices.

Examples of ranges of use include mounting surface mount connectors, connecting display devices such as those used in liquid crystal displays (LCDs), and connecting various silicon devices.

[0016]

DETAILED DESCRIPTION OF THE INVENTION

While the invention may be embodied in various forms, specific embodiments are shown in the drawings and are described in detail in the specification. However, this disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to that described in the specification and illustrated in the drawings.

The first embodiment of the present invention is shown in FIGS. 1 to 4, the second embodiment of the present invention is shown in FIG. 5, and the third embodiment of the present invention is shown in FIG. A fourth embodiment of the present invention is shown in FIG. 7, a fifth embodiment of the present invention is shown in FIG. 8, and a sixth embodiment of the present invention is shown in FIG.

Attention is drawn to the connector 10 of the first embodiment shown in FIGS. As shown in FIG. 1, electrical connector 10 provides a connection between two devices, such as between silicon die 12 and circuit board 16. Although the connection of the silicon die 12 and the circuit board 16 is described, it should be understood that the electrical connector 10 of the present invention can be used to connect a variety of electrical devices. Silicon die 12 includes metal contact pads (not shown) spaced from each other and aligned along rows and columns. Silicon die 1
2 is accommodated in the cover 14. Four mounting posts 22 (three of which are shown) are provided on the cover 14 for reasons described below. The circuit board 16 includes contact pads 20 spaced apart from one another and aligned along rows and columns. The circuit board 16 also includes four mounting holes 26 penetrating therethrough.

As shown in FIGS. 2 and 3, electrical connector 10 includes a body 30 formed of an elastomer that is selectively plated or metallized, as described below. The body 30 has a bottom surface 30a (FIG. 2) and a top surface 30b (FIG. 3). As shown in these figures, the body 30 is rectangular, but it should be understood that the body 30 can have other shapes.

The array of elastomeric bumps 32 extends from the bottom surface 30 a of the body 30, and the array of elastomeric bumps 34 extends from the top surface 30 b of the body 30. The diameter of the bump 32 is larger than the diameter of the bump 34. The bumps 32, 34 are formed in an annular shape so that the diameters of the bumps 32, 34 near the surfaces 30a, 30b of the main body 30 are larger than the diameters of the bumps 32, 34 on the outermost surfaces. Each bump 32
, 34 has a sloped surface. The bumps 32 are spaced apart from one another on the surface 30a of the body 30 and aligned in rows and columns in a manner similar to the contact pads 20 on the circuit board 16. The bumps 34 are spaced apart from one another on the surface 30b of the body 30 and aligned in rows and columns in a manner similar to contact pads (not shown) on the silicon die 12. Each of the bumps 32 is vertically aligned with each of the bumps 34, forming a pair of bumps. The bumps 32 and 34 are on the surface 3 of the main body 30.
Raised from 0a and 30b, for example, Belleville spring washer
It is preferable to have a shape that operates like a spring washer such as a washer.

A through hole 36 defined by a wall extends through each pair of aligned bumps 32, 34 and through the body 30. Each through hole 36 is
It is preferably centered within the bumps 32, 34. As best shown in FIG. 4, each through hole 36 is contoured or tapered so that the diameter of each through hole 36 in each bump 32 is equal to the diameter of each through hole in each bump 34. Larger than 36 diameters.

A mounting hole 24 extends through the body 30 from the bottom surface 30a to the top surface 30b. The mounting holes 24 are separated from the corners of the main body 30.

The bumps 32, 34 are preferably formed integrally with the body 30. The body 30 and the bumps 32, 34 are made of, for example, an elastomeric material such as silicone or, for example, fluororubber. The body 30, the bumps 32 and 34, the through holes 36, and the mounting holes 24 can be molded using a method called liquid injection molding (LIM). For example, silicones and fluororubbers have desirable properties. That is, they are moldable, provide high temperature properties, low compressive strain properties, good electrical properties, and are selectively metallizable. Thermal expansion characteristics (CTE) of connector 10
Appropriate fillers can be added to these materials to approximate the thermal expansion properties of metals such as copper. For example, the CTE of silicones is in the range of 150-300 ppm / ° C, but can be reduced to about 75 ppm / ° C by adding silicic acid filler. The CTE of copper is about 17 ppm / ° C. The CTE of aluminum is about 27 ppm / ° C. An example of a silicone material having a CTE of 20 ppm / ° C is G
E MC550.

The surfaces of the through holes 36 and the bumps 32, 34 are metallized. As shown in FIG. 4, metallization is accomplished by depositing a metal layer 40 along the surfaces of the bumps 32, 34 and the walls forming the through holes 36. This metallization consists of copper, nickel, gold, tin, aluminum, chromium, titanium and combinations of these metals,
Alternatively, it can be any other suitable conductive metal. Copper and gold are preferable because they have excellent ductility. Through holes 36 and bumps 32, 34 can be metallized, for example, by using an anisotropic vacuum deposition method such as sputtering in which the metal is evaporated and directed at the surface to be metallized. This method can be used to make a layer of a given thickness entirely by metallization, or to make a base or seed layer. In the latter case, the layer thickness can be increased by various other plating methods. Further, the metallization can be performed by using other techniques such as electroplating and electroless plating.

Since it is only necessary to metallize these through holes 36 and the associated bumps 32, 34, which are needed to provide the electrical connection between the silicon die 12 and the circuit board 16, the through holes 36 and The bumps 32, 34 may be selectively metallized. A simple and cost effective method of selectively metallizing the through holes 36 and bumps 32, 34 is to provide a surface of the silicone array connector 10 prior to depositing a suitable metallization layer on the surface of the silicone array connector 10. Is to put a mask on. Other methods may be utilized to selectively metallize the through holes 36 and the bumps 32,34.

In use, the connector 10 is compressed between the silicon die 12 and the circuit board 16. The mounting post 22 of the cover 14 penetrates the mounting hole 24 on the body 30 of the connector 10 and the mounting hole 26 of the circuit board 16. The shape (not shown) at the ends of the four posts 22 fixes the cover 14 and the silicon die 12 to the connector 10 and the circuit board 16. By coupling the post 22 to the circuit board 16, a compressive force is applied to the connector 10. When a compressive force is applied, the bumps 32 on the bottom surface 30a of the connector 10 are pressed against the contact pads 20 on the top surface of the circuit board 16, and the bumps 34 on the top surface 30b of the connector 10 are sized to the
2 is pressed against a contact pad (not shown) on the bottom surface. A typical contact force between the bumps 32, 34 and the mating contact pad is about 5-50 grams per contact. This compresses the bumps 32, 34 and provides a constant force between the mating contacts (not shown) of the silicon die 12 and the bumps 32. In addition, the contacts 20 on the circuit board 16
A constant force is also provided between the bump and the bump. The bumps 32, 34 provide a constant force between the connector 10 and the die 12 and between the connector 10 and the circuit board 16, but also cause a wiping action between these metallized surfaces, Ensure good electrical contact between these surfaces. Although only one type of clamp assembly has been shown and described, various clamp assemblies can be used to attach the silicon die 12 to the connector 10 and the circuit board 16.

As can be seen in FIG. 4, the through hole 36 is contoured. The purpose of outlining the through hole 36 is twofold. First, the contouring of the through holes 36 minimizes the stress between the metallization layer 40 and the elastomer body 30 that results from the compressive forces applied when attaching the silicon die and cover 14 to the circuit board 16. . If a through hole with a straight wall is used, the metal along the surface of the through hole will be more likely to "buckle" during compression, potentially opening the circuit between bump 32 and bump 34. is there. Second, the contouring of the through holes 36 simplifies the method of metallizing the through holes 36.
Because the contours make the surface of the through-hole to be plated visible in the "line-of-sight" with respect to the means used to metallize the through-hole, i.e. from the side of the connector 10. This is because it makes it possible to place it in a position.

As shown in FIGS. 5-7, the elastomeric bumps 32, 34 and the through holes 36 of the connector 10 can have various shapes. These bumps 62, 64
, 72, 74, 82, 84 and the through holes 60, 70, 80 should be understood as alternatives to the bumps 32, 34 and the through holes 36 shown in the first embodiment.

FIG. 5 shows through holes 60 and corresponding elastic bumps 62, 64 incorporating features of the second embodiment of the present invention. The diameter of the through hole 60 is the connector 10
It is unchanged from the bottom surface 30a of the body 30 to the top surface 30b of the body 30. The elastomeric bumps 62, 64 have cylindrical, flat contact surfaces 62a, 64a.

FIG. 6 shows a through hole 70 and corresponding elastomeric bumps 72, 74 incorporating features of the third embodiment of the present invention. The through hole 70 has a constricted shape, and the diameter at the center thereof is smaller than the diameters at the bottom surface 30a and the top surface 30b. The elastomeric bumps 72, 74 are cylindrical shaped flat contact surfaces 72a,
74a.

FIG. 7 illustrates a through hole 80 and corresponding elastomeric bumps 82, 84 incorporating features of the fourth embodiment of the present invention. The through hole 80 has a constricted shape, and the diameter at the center thereof is smaller than the diameters at the bottom surface 30a and the top surface 30b. The bumps 82, 84 are substantially cylindrical, but the contact surface 82a of the bump 82 is wavy and the contact surface 84a of the bump 84 is flat. The corrugated surface 82a allows for several contact points between the connector 10 and the circuit board 16 and reduces the electrical resistance between the contact surface 82a and the contacts 20 on the circuit board 16. It should be appreciated that the wavy surface 82a can take a variety of shapes. For example, surface 8
2a can include any number of peaks spaced apart from each other. In addition to providing multiple peaks, the surface 82a can be sloped as described with respect to the first embodiment of the invention. Further, the corrugated surface shown in FIG. 7 is not limited to the embodiment of FIG. 7 and may be used in any of the embodiments described or contemplated herein, and the corrugated surface is a connector. The bumps may be provided on only one side or on both sides.

As mentioned above, the through holes 36 and the bumps 32, 34 can be selectively metallized by using a masking process. Alternatively, as shown in FIG. 8, at least one surface 3 of the body 30 including the bumps 32, 34 and the through holes 36.
0a, 30b may be metallized to provide a metallization layer 90 over at least one surface of connector 10. Suitable metals include copper, nickel, gold, tin, aluminum, titanium, chromium and combinations of these metals, or other suitable conductive metals. Thereafter, laser scribing or the like penetrates the metallized surface 90 to engrave a groove 92 by etching, thereby exposing the elastomeric surface of the body 30 along the groove 92 engraved by the laser. By providing a laser-engraved groove 92 around each through-hole 36 and its associated pair of bumps 32, 34, each through-hole 36 and each pair of bumps 32, 34 is made to remain in the remaining through-hole 36 and Insulated from the pair of bumps 32, 34. It should be understood that each through hole can be electrically isolated from the remaining through holes without providing a laser engraved path around each bump pair. Isolation can be achieved if the path is provided through a portion of the bumps 32,34. Furthermore,
By selectively choosing a path, one through hole can be selectively isolated from another through hole while at the same time electrically connecting another through hole.

In another form, as shown in FIG. 9, the entire surface is metallized and then within the metallization layer to reach the elastomeric surfaces 30 a and 30 b of the connector 10 between the selected through holes 36. A pattern 96 is created. This results in pattern 96
These selected through holes 36 are insulated from each other. No pattern is made between some of the through holes, and these selected through holes are electrically connected. The pattern can be created by any known method, such as laser scribing or photolithography.

The connector 10 of the present invention allows a user to connect the silicon die 12 directly onto the circuit board 16. The posts 22 on the plastic cover 14 clamp the silicon die 12 between the cover 14 and the circuit board 16. The compressive force resulting from this clamping action creates excellent electrical contact between the metallized bumps 32, 34 on the connector 10 and the contacts on the silicon die 12 and circuit board 16. The cost of manufacturing a silicone array connector is expected to be significantly lower than prior art methods. In addition, most die manufacturers will find the connector 10 of the present invention.
Silicon die 1 without the need to install any additional equipment to manufacture
2 is an effective method in terms of cost for electrically mounting 2 on the circuit board 16.

Although the arrangement of the bumps 32, 34 and the through holes 36 has been shown and described, the bumps and through holes need not be arranged along rows and columns, but can be arranged arbitrarily as required. All that is required is that the bumps 32 on the surface 30a are
In position with the selected contact pads 20 above, with bumps 34 on the surface 30b in position with selected contact pads on the silicon die 12, and in pairs of bumps with each other. Only. Further, while the connector 10 has been described as including some through holes 36 and some pairs of bumps 32, 34,
In particular applications, only a single through-hole and a single pair of bumps are required to provide the required electrical connection.

While the preferred embodiment of the invention has been illustrated and described, it will be appreciated by those skilled in the art that various modifications of the invention can be devised without departing from the spirit and scope of the appended claims. Deafness is foreseen.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an electrical connector incorporating features of the first embodiment of the present invention, a silicon die placed in a cover, and a circuit board to which the silicon die is connected by the electrical connector.

[Fig. 2] It is the perspective view seen from the lower side of the electric connector of FIG.

[Figure 3] It is the perspective view seen from the upper side of the electric connector of FIG.

[Figure 4] FIG. 3 is a sectional view of the electric connector taken along line 3-3 of FIG. 2.

[Figure 5] FIG. 6 is a partial cross-sectional view of an electrical connector incorporating features of the second embodiment of the present invention.

[Figure 6] FIG. 7 is a partial cross-sectional view of an electrical connector incorporating features of the third embodiment of the present invention.

[Figure 7] FIG. 9 is a partial cross-sectional view of an electrical connector incorporating features of the fourth embodiment of the present invention.

[Figure 8] It is the perspective view seen from the lower side of the electric connector incorporating the 5th embodiment of the present invention.

FIG. 9 is a bottom plan view of a connector incorporating features of the sixth embodiment of the present invention.

[Procedure Amendment] Patent Cooperation Treaty Article 19 Amendment Translation Form

[Submission date] April 9, 2002 (2002.4.9)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Contents of correction]

[Claims]

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE, TR), OA (BF , BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, G M, KE, LS, MW, MZ, SD, SL, SZ, TZ , UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, B Z, CA, CH, CN, CR, CU, CZ, DE, DK , DM, DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, J P, KE, KG, KP, KR, KZ, LC, LK, LR , LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, R O, RU, SD, SE, SG, SI, SK, SL, TJ , TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW

Claims (22)

[Claims] 1. A connector for electrically connecting electrical contacts on a first element to electrical contacts on a second element, the elastomer body comprising a first surface and a second surface, said first surface An elastomeric bump extending from the second surface; an elastomeric bump extending from the second surface; a hole defined by a wall and extending through the bump and the body; A connector having a metal coating on the wall. 2. The connector according to claim 1, wherein the elastomer body and the elastomer bump are integrally formed. 3. The connector according to claim 1, wherein the elastomer body, the elastomer bump and the hole are integrally formed. 4. The thermal expansion coefficient of the elastomer body and the bump is about 75.
The connector according to claim 1, which has a ppm / ° C or less. 5. The connector of claim 1, wherein the bumps on the first surface are vertically aligned with the bumps on the second surface. 6. The connector of claim 1, wherein each of the bumps includes a surface, and the surface of at least one of the bumps is wavy. 7. The connector of claim 1, wherein the wall defining the hole is tapered. 8. The method of claim 1, wherein each of the bumps has a predetermined diameter, and the diameter of the bumps on the first surface is less than the diameter of the bumps on the second surface. connector. 9. The coating is formed from one of the group consisting of copper, nickel, gold, tin, aluminum, titanium and chromium, or a combination of copper, nickel, gold, tin, aluminum, titanium and chromium. The connector according to claim 1, wherein 10. A connector for electrically connecting an electrical contact on a first element to an electrical contact on a second element, comprising an elastomer body having a first surface and a second surface, said first body comprising: A plurality of elastomer bumps extending from the surface and a plurality of elastomer bumps extending from the second surface, each of the elastomer bumps extending from the first surface extending from the second surface. A plurality of holes aligned with each of the elastomeric bumps to form a plurality of bump pairs, each further defined by a wall, extending through the bump pair and the body; A metal coating on the wall defining the plurality of holes. 11. The thermal expansion coefficient of the elastomer body and the bump is about 7.
The connector according to claim 10, which has a concentration of 5 ppm / ° C or less. 12. The connector of claim 10, wherein at least one of the first and second surfaces is metallized. 13. The connector according to claim 10, wherein at least one hole of the plurality of holes is electrically insulated from other holes. 14. The connector of claim 10, wherein the bumps forming the pair of bumps are vertically aligned. 15. The connector of claim 10, wherein each of the bumps includes a surface and at least one of the surfaces is wavy. 16. The connector of claim 10, wherein the walls defining each of the pair of bumps and each of the holes extending through the body are each tapered. 17. Each of said bumps has a predetermined diameter, said diameter of said bumps on said first surface being less than said diameter of said bumps on said second surface.
The connector according to claim 10. 18. The coating is formed from one of the group consisting of copper, nickel, gold, tin, aluminum, titanium and chromium, or a combination of copper, nickel, gold, tin, aluminum, titanium and chromium. The connector according to claim 10, wherein 19. An elastomer body having a first surface from which a plurality of elastomer first bumps extend and a second surface from which a plurality of elastomer second bumps extend, wherein the first bump and the second bump. Each of which is aligned to form a pair of bumps and has a hole extending through each of the body and each of the pair of bumps to form an elastomeric body that defines a plurality of holes each defined by a wall. And a step of metallizing the bump pair and the hole. 20. The method of claim 19, wherein the metallization is formed by anisotropic vacuum deposition. 21. The method of claim 19, wherein at least one of the first and second surfaces of the body is metallized. 22. A path is etched around at least one hole of the plurality of holes to electrically isolate at least one hole of the plurality of holes from another hole. The method described in.