KR20030004399A - Elastomeric electrical connector - Google Patents

Abstract

The present invention provides an electrical connector used for connecting the first and second thereon elements to each other. The body of the connector is formed of an elastomer having a top surface and a bottom surface. Elastomeric bumps extend from the top and bottom surfaces, and holes extend through the bump pairs and the body. The bumps and holes are metallized. To install the connector, the connector is pressed and retained between the first and second elements. The compressive force of the connector causes the bump to press the metalized layer of the connector against the first and second elements.

Description

Elastomer Electrical Connectors {ELASTOMERIC ELECTRICAL CONNECTOR}

The wire bonding between the conductive pad of the silicon die and the metal lead ultimately soldered to the circuit board interconnects the silicon die or other electronic device to the circuit board. The metal lead provides an input / output connection between the silicon die and the circuit board. Since the current trend is to package more devices in a given area of the circuit board, eventually a higher lead count is required. The increase in package lead count was achieved by making the pitch of the leads smaller and by increasing the number of sides or surfaces from which the leads extend. However, this technique reaches its limit when it is no longer possible to stamp smaller metal lead frames. As a result, there is a need for more input / output connections and higher output densities (ie, heat) per die area, and a need for more advanced packaging techniques.

Examples of such interconnects currently in use include Ball Grid Arrays (BGAs), CIN and APSEs manufactured by Cinch Connectors, and wire-on wafers improved by form factors. on Wafer (WOW) technology, electronic connectors for electronic packaging and testing (US Pat. No. 4,932,883), and metallized particle interconnect processes used by Thomas and Betts.

The BGA is enhanced to package silicon die on circuit boards with more input / output connections than may have metal lead packaging, such as a Quad Flat Package. This packaging approach uses "hot" solder balls attached to the pads on the bottom side of the silicon die. By using the entire bottom face of the die rather than the periphery of the die, the number of contacts in contact with the circuit board is significantly increased compared to quad flat packs. This approach requires a substrate, such as FR4, or a plated ceramic through the hole between the top wire bond pad and the bump pad on the bottom. The bump pad on the bottom has a hot solder ball mounted thereon, after which the complete assembly is mounted to the circuit board. This packaging approach is relatively expensive ($ 0.015 to $ 0.05 per input / output connection) and does not provide for itself for wafer level testing where the die must also be packaged before combustion in testing. Typical 70 position packages cost $ 1.00 and $ 3.00.

The second interconnect method, CIN :: APSE, is mainly used to interconnect high end silicon devices to circuit boards. And a flat plastic frame having a grid pattern of holes with a pitch between 0.8 mm and 2 mm pressed into the gold plated “steel wool”. This assembly is pressed between two conductive pads providing electrical contacts therebetween. A typical restraint for such a connector is 2 ounces per contact, which can eventually be hundreds of pounds of overall restraint. The cost of a CIN :: APSE connector averages $ 0.04 per contact. Thus, the cost of a typical 70 position device is $ 2.80. This approach to electrical element packaging is relatively expensive and does not in itself provide for wafer level testing.

A third technology, wire on wafer (WOW), mounts a metal spring directly on a silicon die. This spring provides an electrical interconnect between the die and a mating surface, such as a circuit board. This has the advantage of being relatively low cost and capable of wafer level testing. Disadvantages include the memory manufacturer's need to install a large amount of equipment for manufacturing and spring mount on the die. The feasibility and cost effectiveness of this packaging approach has not yet been determined.

A fourth approach to silicon packaging is to use an elastomeric substrate that is selectively metallized on the surface. Through holes are used to electrically connect the bottom pad to the top pad. The pad metalized on the flat elastomer surface is offset from the plated through hole so that the electrical connector in the barrel of the plated through hole cannot be broken when the elastomer is pressurized. One example of this type of connector is disclosed in US Pat. No. 5,071,359 and US Pat. No. 5,245,751.

The present invention provides an electrical connector that solves the problems presented in the prior art and provides additional advantages over the prior art. This advantage can be evident by reading the specification associated with the study of the drawings.

The present invention relates to an electrical connector providing an electrical connection between two conductive elements. In particular, the present invention contemplates a connector that includes an array of electrical path sets in a silicon body that uses spring force to provide a good electrical connection between two conductive elements, such as a silicon die and a circuit board. do.

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

2 is a bottom perspective view of the electrical connector of FIG.

3 is a top perspective view of the electrical connector of FIG.

4 is a cross-sectional view of the electrical connector taken along line 3-3 of FIG.

Fig. 5 is a partial sectional view of an electrical connector embodying the features of the second embodiment of the present invention.

Fig. 6 is a partial sectional view of an electrical connector embodying the features of the third embodiment of the present invention.

Fig. 7 is a partial sectional view of an electrical connector embodying the features of the fourth embodiment of the present invention.

Figure 8 is a bottom perspective view of an electrical connector embodying the features of the fifth embodiment of the present invention.

Fig. 9 is a bottom plan view of an electrical connector embodying features of the sixth embodiment of the present invention.

It is an object of the present invention to provide an electrical connector which eliminates the need for wire bonded metal leads.

It is an object of the present invention to provide an electrical connector that provides more input / output connections per area of a circuit board than is possible with some prior art packaging techniques.

It is another object of the present invention to provide an electrical connector that can be electrically connected between a connector and a conductive pad in a circuit board, silicon die or other electronic device.

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

It is a particular object of the present invention to provide an electrical connector capable of wafer level testing.

Briefly, in connection with the above, the present invention eliminates the need for metal lead frames, provides many input / output connections per area on circuit boards, and provides good electrical connections between connected devices to Provided are electrical connectors that can be wafer level tested for overall alignment and can be manufactured cost effectively. Through holes and bumps are metalized to provide an electrical path between connected devices such as silicon dies and circuit boards. Raised bumps are provided on the top and bottom yarns of the elastomeric base and can be electrically connected between the conductive pads of the electrical device and the plated holes through the use of compressive forces. Embossed bumps provide spring force to create good electrical contact and compliance between connected devices.

Examples of areas of use include display interconnects used in liquid crystal displays (LCDs) as surface mount connector mounting examples, and interconnects of various silicon devices.

The structure and manner of construction and operation of the present invention can be well understood by referring to the following description, which is described in connection with the accompanying drawings, in which the same elements are identified by the same reference numerals together with the objects and advantages thereof.

The present invention may be applied to other forms of embodiments, and the present disclosure, which is considered as an illustration of the principles of the present invention, is illustrated in the drawings and described in detail herein, which limit the present invention to those illustrated and described. no.

A first embodiment of the present invention is shown in Figs. 1-4, a second embodiment of the present invention is shown in Fig. 5, a third embodiment of the present invention is shown in Fig. 6, and a fourth embodiment of the present invention. An embodiment 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.

A first embodiment of the connector 10 shown in Figs. 1 to 4 will be described. As shown in FIG. 1, electrical connector 10 provides a connection between two devices, such as silicon die 12 and circuit board 16. Although the connections of the silicon die 12 and the circuit board 16 have been described, it should be appreciated that the electrical connector 10 of the present invention can be used to connect various electrical devices. The silicon die 12 includes metal contact pads (not shown) spaced from each other and aligned in rows and columns. The silicon die 12 is housed in the cover 14. Four mounting posts 22 (three are shown) are provided in the cover 14 for the reasons described herein. The circuit board 16 includes contact pads 20 spaced from each other and aligned in rows and columns. In addition, the circuit board 16 includes four mounting holes 26 penetrating itself.

As shown in Figures 2 and 3, electrical connector 10 includes a body 30 formed of an elastomeric material that is optionally plated or metalized as described herein. The main body 30 has a bottom surface (30a in FIG. 2) and an upper surface (30b in FIG. 3). As shown in the figure, it is to be understood that the body 30 is a rectangle 30 and that the body 30 can take other forms.

An array of elastomer bumps 32 extends from the bottom surface 30a of the body 30, and an array of elastomer bumps 34 extends from the top surface 30b of the body 30. The diameter of bump 32 is larger than the diameter of bump 34. The bumps 32, 34 are annular in shape, and the surfaces of the bumps 32, 34 have a diameter of the respective bumps 32, 34 near the respective surfaces 30a, 30b of the main body 30. It inclines so that it may become larger than the diameter of bump 32,34 in the outermost surface. The bumps 32 are spaced apart from each other and aligned in rows and columns on the surface 30a of the body 30 in a manner similar to the contact pads 20 of the circuit board 16. The bumps 34 are spaced from each other and aligned in rows and columns on the surface 30b of the body 30 in a manner similar to the contact pads (not shown) on the silicon die 12. Each bump 32 is vertically aligned with each bump 34 to produce a pair of bumps. The bumps 32, 34 are preferably raised above the surfaces 30a, 30b of the body 30 and formed to act like spring washers such as, for example, Bellville spring washers.

The through hole 36 formed by the wall extends through each pair of alignment bumps 32 and 34 and the body 30. Each through hole 36 is preferably located centrally in the bumps 32, 34. As best shown in FIG. 4, each through hole 36 has a diameter of each through hole 36 in each bump 32 and a respective through hole 36 in each bump 34. It is shaped or tapered to be larger than its diameter.

The mounting hole 24 extends through the body 30 from the bottom surface 30a to the top surface 30b. The mounting hole 24 is spaced apart from each corner of the body 30.

The bumps 32 and 34 are preferably formed integrally with the main body 30. The body 30 and bumps 32 and 34 are made of, for example, an elastomeric material such as silicone or a fluoroelastomer such as VITON®. The body 30, bumps 32 and 34, through holes 36 and mounting holes 24 may be molded using a process called fluid injection molding (LIM). By way of example, silicone and VITON® provide good characteristics of being moldable, they provide a high temperature low pressure set, good electrical properties, and are optionally metallizable. Suitable filters may be added to the material such that the thermal expansion properties (CTE) of the connector 10 approach metals such as copper. By way of example, the CTE for silicon is in the range of 150-300 ppm / ° C. but can be reduced to about 75 ppm / ° C. by adding a silicate filter. Copper has a CTE of about 17 ppm / ° C. Aluminum has a CTE of about 27 ppm / ° C. One example of a silicon material having a CTE of 20 ppm / ° C is GE MC550.

The surface of the through hole 36 and the bumps 32, 34 is metalized. As shown in FIG. 4, metallization is accomplished by depositing a metal layer 40 along the wall that forms the through holes 36 in the surfaces of the bumps 32, 34. Such metallization may be copper, nickel, gold, tin, aluminum, chromium, titanium or combinations of these metals or other suitable conductive metals. Copper and gold are preferred because of their ductility. The through holes 36 and bumps 32 and 34 may be metallized by using a direction vacuum deposition progress, such as sputtering, which is directed towards the surface where the metal is evaporated and metallized. Can be. This approach may be used for any of the seed layers that apply the full thickness of the metallized, or the base, or which is subsequently increased in thickness by various other plating methods. In addition, other techniques such as electroplating, non-electroplating and the like can be used to achieve metallization.

The through-holes 36 and bumps only need to be metalized, the through-holes 36 and coalesced bumps 32 and 34 needed to provide electrical connections between the silicon die 12 and the circuit board 16. 32 and 34 may optionally be metallized. A simple and cost effective way to selectively metallize the through holes 36 and bumps 32, 34 is to place a mask on the surface of the silicon array connector 10 before depositing a suitable metallization on the surface of the silicon. It is to let. Other methods for selectively metallizing the through holes 36 and bumps 32 and 34 may be used.

In use, the connector 10 is pressed between the silicon die 12 and the circuit board 16. The mounting post 22 of the cover 14 passes through the mounting hole 24 of the main body 30 of the connector 10. Then, it passes through the mounting hole 26 of the circuit board 16. The outline (not shown) at the ends of the four posts 22 is to fix the cover 14 and silicon die 12 to the connector 10 and the circuit board 16. The connection of the post 22 to the circuit board 16 applies a pressing force to the connector 10. When a pressing force is applied, the bumps 32 of the bottom surface 30a of the connector 10 are pressed against the contact pads 20 of the upper surface of the circuit board 16 and the upper surface 30b of the connector 10. Bumps 34 on the top are pressed against contact pads (not shown) on the bottom surface of silicon die 12. Typical contact force between bumps 32 and 34 and mating contact pads is about 5 to 50 grams per contact. This presses 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, a constant force is provided between the contact 20 and the bump 34 on the circuit board 16. Bumps 32 and 34 provide a constant force between connector 10 and die 12, and between connector 10 and circuit board 16, and the wiping action between these metalized surfaces is Ensure good electrical contact between them. Although only one clamping assembly is shown, various clamping assemblies may be used to mount the die 12 to the connector 10 and the circuit board 16.

As can be seen in Figure 4, the through hole 36 can take on an appearance. The purpose of forming the outline of the through hole 36 is two purposes. First, the contour of the through hole 36 minimizes the stress between the metal layer 40 and the elastomer body 30 due to the compressive force applied when installing the silicon die 12 and cover 14 to the circuit board 16. By using a through-hole with a straight wall, it is possible to increase the tendency for the compressive force to "buckle" along the surface of the through-hole of the metal while potentially creating an open circuit between the bump 32 and the bump 34. Can be. Secondly, the contour of the through hole 36 is such that the contour causes the surface of the through hole to be plated in a "line-of-sight" to the means used to metallize the through hole. The process of metallizing is simplified.

As shown in Figures 5-7, the elastomeric bumps 32, 34 and through holes 36 of the connector 10 may be of various shapes. These bumps 62, 64, 72, 74, 82, 84 and through holes 60, 70, 80 are replaced by the bumps 32, 34 and through holes 36 shown in the first embodiment. You have to understand.

Figure 5 shows through holes 60 and corresponding spring bumps 62, 64 associated with the characteristics of the second embodiment of the present invention. The through hole 60 has a uniform diameter from the bottom surface 30a of the main body 30 of the connector 10 to the top surface 30b of the main body 30. The elastomeric bumps 62, 64 are cylindrical and have flat contact surfaces 62a, 64a.

Figure 6 shows through holes 70 and corresponding spring bumps 72, 74 associated with the features of the third embodiment of the present invention. The through hole 70 is an hourglass having a diameter smaller than the diameter at the bottom surface 30a and the top surface 30b at its center. The elastomeric bumps 72, 74 have a cylindrical and flat contact surface 72a, 74a.

Figure 7 shows through holes 80 and corresponding elastomeric bumps 82, 84 associated with the features of the fourth embodiment of the present invention. The through hole 80 is an hourglass having a diameter smaller than the diameter at the bottom surface 30a and the top surface 30b at its center. The bumps 82 and 84 are generally circular in shape, but the contact surface 82a of the bump 82 is rippled, and the contact surface 84a of the bump 84 is flat. The corrugated surface 82a allows contact at several points between the connector 10 and the circuit board 16 while reducing electrical resistance between the contact surface 82a and the contact 20 on the circuit board 16. It can be seen that the corrugated surface 82a can take various shapes. By way of example, surface 82a includes a plurality of peaks spaced from each other. In addition to including a plurality of peaks, the surface 82a may be inclined as described for the first embodiment of the present invention. In addition, the waveform surface shown in FIG. 7 is not limited to the embodiment of FIG. 7, but may be used in certain embodiments described or contemplated herein, wherein the waveform surface is located on either or both sides of the connector. It can be between the bumps.

As described above, the through holes 36 and bumps 32 and 34 can be selectively metallized by using a masking process. Alternatively, as shown in FIG. 8, at least one surface 30a, 30b of the body 30 including the bumps 32, 34 and the through hole 36 is formed at least one entire surface of the connector 10. Metallized to provide a metallized layer 90 over it. Suitable materials include copper, nickel, gold, tin, aluminum, titanium, chromium or combinations of these materials or other suitable conductive metals. Path 92 is then etched, such as by laser scribing through metallized face 90 to expose the elastomeric surface of body 30 along laser scribed path 92. . By providing a laser scribe path 92 around each through hole 36 and pairs of bumps 32 and 34 incorporated therein, each through hole 36 and each pair of bumps 32 and 34 are left to rest. It is electrically insulated from the through hole 36 and the bump pairs 32, 34. It should be noted that each through hole can be electrically insulated from the remaining through holes without providing a laser scribe path around each pair of bumps. Insulation can also be achieved when the path is located through a portion of the bumps 32, 34. Further, by selectively selecting a path, one can selectively insulate a predetermined through hole from another through hole, and at the same time, electrically connect the other through hole.

In another embodiment, as shown in Figure 9, after the entire surface is metallized, the pattern 96 extends between the selected through holes 32, 34 to the elastomeric surfaces 30a, 30b of the connector 10. Is generated in the ized. As a result, the pattern 96 insulates the selected through holes 36 from each other. By not creating a pattern between the predetermined through holes, these selected through holes are electrically connected to each other. The pattern can be produced by conventional methods such as, for example, laser scribing or photolithography.

The connector 10 of the present invention allows a user to directly interconnect the silicon die 12 to the circuit board 16. The post 22 of the plastic cover 14 clamps the die 12 between the cover 14 and the circuit board 16. The compressive force due to this clamping operation results in good electrical contact between the metallized bumps 32 and 34 on the connector 10 and the contacts of the silicon die 12 and the circuit board 16. The manufacturing cost of the silicon array connector can be significantly lower than the prior art methods. In addition, most die manufacturers do not need to install additional equipment to manufacture the connector 10 of the present invention, thereby cost-effectively approaching the electrical packaging of the silicon die 12 on the circuit board 16.

While the array and bumps 36 and 34 of the bumps 32 and 34 are shown and described, the bumps and through holes do not need to be aligned in columns and rows, and may preferably be placed in a predetermined arrangement. This merely aligns the bumps 32 of the surface 30a with the selected contact pads 20 of the circuit board 16 and the bumps 34 of the surface 30b with the selected contact pads 20 of the silicon die 12. It is only necessary to align and to align the bump pairs with each other. In addition, although the connector 10 has been described as including several through holes 36 and bumps 32 and 34 pairs, this is given to certain applications, where only one through hole and bump pair provides the necessary electrical connection. It is necessary to

While the preferred embodiments of the invention have been illustrated and described, it will be apparent to those skilled in the art that various changes in the invention may be made without departing from the spirit and scope of the appended claims.

Claims (22)

A connector for electrically connecting the electrical contact of the first element to the electrical contact of the second element, An elastomer body having a first surface and a second surface, An elastomeric bump extending from said first surface, An elastomer bump extending from the second surface, A hole formed by the wall and extending through the bump and the body, And a metal coating the bump and the wall forming the hole. The connector of claim 1, wherein the elastomer body and the elastomer bump are integrally formed. The connector according to claim 1, wherein the elastomer body, the elastomer bumps and the holes are integrally formed. The connector of claim 1, wherein the elastomer body and the bump have a coefficient of thermal expansion of about 75 ppm / ° C. or less. The connector of claim 1 wherein the bumps of the first surface are aligned perpendicular to the bumps of the second surface. The connector of claim 1 wherein the bump comprises a surface and the surface of the at least one bump is corrugated. A connector according to claim 1, wherein the wall forming the hole is tapered. The connector according to claim 1, wherein each bump has a predetermined diameter, and the diameter of the bump of the first surface is smaller than the diameter of the bump of the second surface. The connector of claim 1, wherein the coating is formed from one of a group of copper, nickel, gold, tin, aluminum, titanium, and chromium or a combination of copper, nickel, gold, tin, aluminum, titanium, and chromium. . The method of claim 1, A plurality of additional elastomeric bumps extending from the first surface, A plurality of additional elastomeric bumps extending from the second surface, Each one of the elastomeric bumps extending from the first surface aligned with each one of the elastomeric bumps extending from the second surface to form a plurality of bump pairs, A plurality of additional holes formed by the walls, each extending through the bump pair and the body, And a metal coating a wall forming the plurality of bumps and the plurality of holes. The connector of claim 10, wherein the elastomer body and the bump have a coefficient of thermal expansion of about 75 ppm / ° C. or less. The connector of claim 1, wherein at least one of the first and second surfaces is metallized. The connector of claim 10, wherein at least one of the plurality of holes is electrically insulated from another of the plurality of holes. 11. The connector of claim 10, wherein the bumps forming the pair of bumps are vertically aligned. 11. The connector of claim 10, wherein each bump comprises a surface, and at least one of the surfaces is corrugated. A connector according to claim 10, wherein each wall forming each hole extending through the bump pair and the body is tapered. 11. The connector of claim 10, wherein each bump has a predetermined diameter and the diameter of the bumps of the first surface is smaller than the diameter of the bumps of the second surface. The connector of claim 10, wherein the coating is formed from one of a group of copper, nickel, gold, tin, aluminum, titanium, or chromium or a combination of copper, nickel, gold, tin, aluminum, titanium, and chromium. A first elastomer comprising a plurality of elastomeric first bumps extending from a first surface, a plurality of elastomeric second bumps extending from a second surface, and holes extending through the pair of bumps with the body to form a plurality of holes And forming an elastomeric body having a second surface; Metallizing the bump pairs and holes; Wherein each one of said first and second bumps is aligned to form a pair of bumps, each of said holes formed by a wall. 20. The method of claim 19, wherein the metallization is formed by directional vacuum deposition. 20. The method of claim 19, wherein at least one of the first and second sides of the body is metallized. 22. The method of claim 21, wherein the path is etched around at least one of the plurality of holes to electrically insulate at least one of the plurality of holes from the other of the plurality of holes.