WO2001013422A1

WO2001013422A1 - Apparatus and method for protecting electronic assembly contacts

Info

Publication number: WO2001013422A1
Application number: PCT/US2000/022145
Authority: WO
Inventors: Thomas H. Ii Dozier; Douglas S. Ondricek
Original assignee: Formfactor, Inc.
Priority date: 1999-08-13
Filing date: 2000-08-10
Publication date: 2001-02-22
Also published as: AU6768500A; TW503498B

Abstract

A method and apparatus for protection of the interconnection elements of a substrate. In one embodiment, the present invention comprises a substrate having interconnection elements extending therefrom and a contact protector coupled to the substrate, wherein a spring mechanism separates the substrate and the contact protector. The contact protector supports and positions an electronic assembly having electrical contacts and has a plurality of slots allowing the interconnection elements to move freely therethrough. The electronic assembly is depressed such that the interconnection elements of the substrate extend through the slots in the contact protector to form an electrical connection with the electronic assembly. When released, the contact protector is raised such that the interconnection elements are protected and no electrical connection exists between the electronic assembly and the substrate.

Description

APPARATUS AND METHOD FOR PROTECTING ELECTRONIC ASSEMBLY CONTACTS

FIELD OF THE INVENTION

The present invention relates generally to electronic assemblies and protection thereof. More particularly, the present invention relates to a method and apparatus for protection of the electrical contacts of an electronic assembly when the electrical contacts are not in use.

BACKGROUND OF THE INVENTION

Electronic components, particularly microelectronic components such as semiconductor devices (chips), often have a plurality of terminals (also referred to as bond pads, electrodes, or conductive areas). In order to assemble such devices into a useful system (or subsystem), a number of individual devices must be electrically interconnected with one another, typically through the intermediary of a substrate, such as a printed circuit (or wiring) board (PCB, PWB).

Semiconductor devices are typically disposed within a semiconductor package having a plurality of external connection points in the form of pins, pads, leads, solder balls, and the like. Many types of semiconductor packages are known, and techniques for connecting the semiconductor device within the package include bond wires, tape-automated bonding (TAB), and the like. In some cases, a semiconductor device is provided with raised bump contacts and is connected by flip-chip techniques onto another electronic component. Generally, such interconnections between electronic components, (e.g., between a semiconductor package and a substrate), can be classified into the two broad categories of "relatively permanent" and "readily demountable".

An example of a "relatively permanent" connection is a solder joint. Once two components are soldered to one another, a process of unsoldering must be used to separate the components. The unsoldering process can damage either the substrate or the semiconductor device. Moreover, in order to unsolder a component from a substrate, it is generally necessary to entirely remove the substrate from the system in which it is located. A wire bond is another example of a "relatively permanent" connection.

An example of a "readily demountable" connection includes pins of one electronic component being received by socket elements of another electronic component. The socket elements exert a contact force (i.e., pressure) on the pins in an amount sufficient to ensure a reliable electrical connection therebetween. Interconnection elements intended to make pressure contact with an electronic component are referred to herein as "springs" or "spring elements". One very promising technology for providing spring elements involves securing small, resilient members onto a suitable substrate and using these members to effect contact between an active device and other circuitry. Methods are known for making such resilient interconnection elements used for microelectronics and for fabricating spring contact elements directly on semiconductor devices. A particularly useful resilient interconnection element comprises a free standing spring contact element secured at one end to an electronic device and having a free end standing away from the electronic device so as to readily contact a second electronic device. See, for example, United States Patent 5,476,211, entitled "Method for Manufacturing Electrical Contacts Using a Sacrificial Member", issued December 19, 1995, and assigned to the assignee of the present invention. A discussion of another resilient interconnection element, referred to as a MicroSpring™ contact, is found in United States Patent 5,829,128, issued November 3, 1998, entitled, "Method of Mounting Resilient Contact Structures to Semiconductor Devices" and assigned to the assignee of the present invention. A discussion of using and testing semiconductors with MicroSpring™ contacts is disclosed in United States Patent Application, Serial No. 09/205, 502, filed December 4, 1998, entitled, "Socket for Mating with Electronic Component, Particularly Semiconductor Device with Spring Packaging, for Fixturing, Testing, Burning-In or Operating Such a Component", and assigned to the assignee of the present invention.

One type of semiconductor package is typified by United States Patent. 4,700,276, entitled "Ultra High Density Pad Array Chip Carrier", issued October 13, 1987. As generally disclosed therein, a ceramic substrate is provided with a plurality of through holes plugged with solder on its bottom surface. These solder plugs (206) are arranged in an array pattern, and form external surface mount interconnection points for the final chip carrier arrangement. The solder plugs are generally hemispherical and permit the substrate to sit high above the board to which the carrier is mounted. Semiconductor packages having an array of solder balls as their interconnection points on an external surface thereof are referred to herein as Ball Grid Array (BGA) type packages. Another type of semiconductor package is the Land Grid Array (LGA), which is provided with a plurality (e.g., an array) of terminals (contact pads or "lands") on a surface thereof. Generally, resilient interconnection elements such as those described above are used to make electrical connections to the lands of an LGA type package.

United States Patent 5,772,451, issued June 30, 1998, entitled "Sockets for Electronic

Components and Method of Connecting to Electronic Components", and assigned to the assignee of the present invention, describes a technique whereby an electronic component such as a BGA or an LGA type semiconductor package can readily be demounted, without unsoldering, from a PCB. Note also however, that in addition to the PGA and LGA packages, a semiconductor device with springs (e.g., a die) may also be useful to achieve a readily demountable connection. The ability to remove a BGA and/or an LGA package from a pressure connection with an interconnection substrate having contact elements would be useful in the context of replacing or upgrading the given semiconductor device. A very useful object is achieved simply by making reversible connections to a given semiconductor device. Semiconductor devices having reversible connections are also useful for mounting, temporarily or permanently, to an interconnection substrate of a system to burn-in the given semiconductor device or to ascertain whether or not the given semiconductor device measures up to its specifications. As a general proposition, this can be accomplished by making pressure connections between the package and the interconnection substrate via the contact elements. As discussed above, the pressure connections may be achieved between the BGA and/or LGA packages through use of a contact element such as a socket with springs. For example, a substrate with sockets having MicroSpring™ contacts may be used wherein the contacts provide the pressure connection between the substrate and BGA balls or LGA pads (See e.g., U.S. Patent 5,772,451). Note also that although spring contact elements are the preferred contact elements, the readily demountable pressure connection may also be achieved through use of ball contacts, elastomeric contacts, etc (For a discussion of such other contact elements, see for example, United States Patent No. 5,109,596, entitled "Adapter Arrangement for Electrically Connecting Flat Wire Carriers," issued May 5, 1992).

The contact elements of an electronic assembly, although relatively strong, are still subject to permanent deformation if displaced too far. Thus, a method and apparatus that would provide protection of the spring contacts is desired. Such an apparatus would protect the electrical contacts of the electronic assembly from being knocked about and becoming misaligned, damaged, permanently deformed or broken. It would be advantageous if such an apparatus also would prevent the unwanted accumulation of dust or other particles on the electrical contacts. A method and apparatus that could also positionally align the contact elements while compressing the contact elements to achieve an electrical interconnection is further desirable. A method and apparatus that would allow the contact elements to retreat back into the protected environment after the need for the electrical interconnection was complete would also be beneficial. Such a method and apparatus would increase the life of the contact elements, and hence also increase the life of the electronic assembly the contact elements extend from.

SUMMARY OF THE INVENTION A method and apparatus for protection of the electrical contacts of an electronic assembly is described. In one embodiment, the apparatus of the present invention comprises a substrate having a plurality of spring contacts extending therefrom and a contact protector coupled to the substrate. The contact protector is spring loaded to a raised, resting position which covers or protects the springs in their resting position, but the springs can be compressed as the contact protector is moved to reveal the springs. The contact protector provides a frame that supports and positions an electronic assembly having a plurality of electrical contacts (e.g., an integrated circuit package) that can mate with the spring contacts on the substrate. The contact protector has a plurality of slots which allow the spring contacts extending from the substrate to move with some freedom in selected dimensions. A latching mechanism is coupled to the substrate. When closed, the latching mechanism depresses the electronic assembly such that the spring contacts of the substrate extend through the slots of the contact protector and form an electrical interconnection with the electrical contacts on the electronic assembly. When the latching mechanism is released, the contact protector is raised to its resting position by spring pressure acting against the contact protector. As before, in the resting position, the spring contacts do not extend past the contact protector, no electrical connection exists between the electronic assembly and the substrate, and the spring contacts are protected from inadvertent mishandling, deformation, and/or contamination.

In one embodiment of the invention, a freestanding, elongate resilient contact element extends upwardly and laterally through an opening in the contact protector. This contact element resembles a cantilever beam which when depressed moves down; often (in certain embodiments of the contact element) the geometry and shape of this contact element causes this contact element to also have a lateral dimension (e.g. perpendicular to the up/down movement) change within the opening as the contact element is depressed (compressed). In this embodiment, the opening is large enough to allow for the contact element to have its lateral dimension changed as the contact element is depressed.

The contact protector provides an added benefit of limiting the amount of compression of the spring contacts, thus generally preventing permanent deformation or other damage from overcompression of the spring contacts. In a preferred embodiment, the dimensions of the contact protector are selected to provide optimal compression of the spring contacts when in contact with the electronic assembly.

The spring mechanism biasing the contact protector away from the substrate may take several forms.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further described by way of example with reference to the accompanying drawings, wherein:

Figure 1 A is a side cross-sectional view of one embodiment of the present invention illustrating the apparatus of the present invention in the raised position, wherein the spring contacts on a contact array are protected.

Figure IB is an exploded cross-sectional view of Figure 1A.

Figure 2 A is a side cross-sectional view of the apparatus illustrated in Figure 1A, wherein the contact protector is depressed such that the spring contacts on the contact array extend through slots in the base of the contact protector and form an electrical interconnection with the electrical contacts on a chip package.

Figure 2B is an exploded cross-sectional view of Figure 2A.

Figure 3A is a side cross-sectional view of the contact array illustrated in Figure 1 A.

Figure 3B is a bottom view of the substrate of the contact array of Figure 3A. Figure 3C is a side cross-sectional view of the contact array 3A and 3B in contact with a chip package.

Figure 4A is a top view of the contact protector illustrated in Figures 1 A and 2 A.

Figure 4B is a side cross-sectional view of Figure 4A.

Figure 5 is a side cross-sectional view of the apparatus of Figure 2A wherein a mechanism is depressing a chip package, which then depresses the contact protector.

Figure 6 provides a top view of the apparatus illustrated in Figure 5.

Figure 7A is an exploded side cross-sectional view of the contact array and contact protector in the raised position, wherein the spring contacts of a contact array are protected. Figure 7B is an exploded side cross-sectional view of the contact aπay and contact protector in the lowered position, wherein the spring contacts of a contact array are compressed.

Figure 8A is a perspective view of the top side of a second embodiment of the apparatus of the present invention.

Figure 8B is a perspective view of the bottom side of a second embodiment of the apparatus of the present invention.

Figure 9A is a side cross-sectional view of the apparatus illustrated in Figures 8A and 8B wherein the contact protector is in a raised position and is supported by a leaf spring. Figure 9B is a side cross-sectional view of the apparatus illustrated in Figures 8 A and

8B wherein the contact protector is in the depressed position such that the spring contacts are compressed and extending through the contact protector.

Figure 10 is a top view of the apparatus illustrated in Figures 8 A and 9 A. Figure 11A is a perspective view of the contact protector illustrated in Figures 8-10 with a latch mechanism mounted thereto.

Figure 1 IB is a partial cross-sectional view of the assembly shown in Figure 11 A. Figure 12 is a block diagram illustrating the basic steps of protecting the electrical contact of a first electronic assembly when the electrical contacts are not being used to establish an electrical interconnection with a second electronic assembly.

DETAILED DESCRIPTION OF THE INVENTION

A method and apparatus for protection of the electrical contacts of an electronic assembly is described. In the following detailed description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. However, it will be obvious to one skilled in the art that the present invention may be practiced without these specific details. In general, well-known devices, methods, procedures, and individual components have not been described in detail so as to not unnecessarily obscure aspects of the present invention. For illustrative purposes only, the present invention is discussed with use of electronic assemblies having spring interconnection elements such as MicroSpring™ contacts. Note, however, that other types of interconnection elements may also be used.

The method and apparatus of the present invention provide for protection of the electrical contacts (contact elements) of an electronic assembly when no electrical interconnection is desired. The present invention provides positional alignment of the contact elements during compression of the contact elements when achieving an electrical interconnection and also provides a travel stop to limit compression of the contact elements. After the need for an electrical connection is met, the present invention provides a protective environment for the electrical contacts. Thus, the present invention increases the life of the electrical contacts by protecting against damage from over-compression, movement in undesired directions, and/or contamination.

Figure 1 A is a side cross-sectional view of one embodiment of the present invention. Figure IB is an exploded cross-sectional view of Figure 1A. Figures 1A and IB illustrate the apparatus 10 of the present invention in the raised (i.e., up, protected, first, initial, etc.) position, wherein the spring interconnection elements 12 of contact array 14 are protected within protective environment 13 defined by contact protector 16. Note that although in this embodiment the interconnection elements 12 are spring contacts, other interconnection elements such as balls, elastomeric contacts, etc. may also be used.

Figure 2A is a side cross-sectional view of the apparatus 10 illustrated in Figures 1A and IB. Figure 2B is an exploded cross-sectional view of Figure 2A. Figures 2A and 2B illustrate the contact protector 16 depressed such that the spring interconnection elements 12 extend through openings (i.e., slots, channels, etc.) in the contact protector 16. (See Figure 4A for a top view of the contact protector 16 and its openings 34.) In general use, as described below, an electrical interconnection with an electronic assembly, such as a chip package (not shown, but positioned within opening 33 of contact protector 16 shown in the side cross-sectional view of the contact protector 16 illustrated in Figure 4B) will compress the spring interconnection elements 12. The openings 34 (see Figure 4A) of contact protector 16 allow the spring interconnection elements 12 to move freely in the desired directions. In this manner, the spring interconnection elements 12 may achieve the electrical interconnection through compression, but their motion in other directions is limited. The limitation of motion prevents the spring interconnection elements 12 from being knocked about and misaligned. Note that the contact protector 16 also provides a travel stop to prevent the over-compression of the spring interconnection elements 12. Over-compression of the spring interconnection elements 12 may result in the spring interconnection elements 12 becoming permanently deformed. Thus, the contact protector 16 prevents damaging permanent deformation of the spring interconnection elements 12.

The apparatus 10 illustrated in Figures 1A and 2A comprises a contact array 14 coupled to a contact protector 16 by a plurality of shoulder screws 18. Spring mechanisms (e.g., coil springs) 20 encircle the shoulder screws 18 and act against the contact protector 16 to force the contact protector 16 against heads 17 of the shoulder screws 18 and support the contact protector 16 in this raised position. The spring coefficient of the coil springs 20 is high enough that a casual touch of the contact protector 16 will not be sufficient to depress the contact protector 16, but rather an intentional application of force will be required. The spring coefficient may be selected by one skilled in the art depending on the desired application. If the spring coefficient is too low (i.e., too weak), contact protector 16 will be able to be moved too easily. If the spring coefficient is too high (i.e., too strong), the apparatus 10 of the present invention will require an unnecessarily heavy clamping mechanism (as described below in more detail). In one embodiment of the present invention, a force of approximately 0.5-2.0 lbs. is required to expose the spring interconnection elements 12.

A side cross-sectional view of the contact array 14 is illustrated in Figure 3 A. The contact array 14 is comprised of a substrate 26 having solder balls 22 electrically connected to respective spring interconnection elements (spring contacts) 12 by respective electrically conductive vias 24. The balls 22 are used to electrically couple the spring contacts 12 to contacts on a printed circuit board which is positioned under the balls 22 (such as contacts 81 A on the printed circuit board 81 shown in Figures 9 A and 9B). This printed circuit board may be a test or burn-in circuit board which provides signals to and from the integrated circuit (e.g. a chip package 15) which is electrically connected to the spring contacts 12. Alternatively, this printed circuit board may be an electrical interconnection substrate used in a completed, fully assembled product which is ready for use (e.g. in a final consumer product). Note that the substrate 26 may comprise molded plastic that has been metallized, flex film, ceramic, a printed circuit board (PCB), or an insulator that can be metallized. Certain possible materials of substrate 26 are discussed in detail in United States Patent 5,772,451, entitled "Sockets for Electronic Components and Methods of Connecting to Electronic Components", issued June 30, 1998, assigned to the assignee of the present invention, and incorporated herein by reference (referred to as the '451 patent). In this preferred embodiment, the spring interconnection elements 12 are cantilevered resilient contact structures mounted to terminals 28 on the substrate 26. Additional details on the various shapes and composites of the spring interconnection elements 12 will not be discussed herein, but may be found in detail in the above referenced U.S. Patent '451. Figure 3B is a bottom view of the substrate 26 of the contact array 14. Shoulder screws 18 (see Figures 1A and 2A) pass through holes 29 and assist in correctly aligning the contact protector 16 with the spring contacts 12 of the contact array 14. Figure 3C is a side cross- sectional view of the contact array 14 in electrical contact with a chip package 15. The chip package 15 may be a bare semiconductor integrated circuit with contact pads which face the interconnections and which electrically connect with them or the chip package 15 may be a packaged semiconductor integrated circuit which includes the integrated circuit and some packaging or housing for securing or encapsulating the integrated circuit.

A top view of the contact protector 16 is illustrated in Figure 4 A, with a side cross- sectional view shown in Figure 4B. The contact protector 16 provides the housing or frame to hold or support the electronic assembly (e.g., chip package) with which the spring contacts 12 will eventually make an electrical connection. The chip package (not shown) is placed in the contact protector and resides in the opening 33 such that the chip package's electrical contacts are positioned over the openings 34 in the contact protector 16. The bumpers 32 are beveled to provide a lead-in for the placement of the chip package into the frame opening 33 provided by the sidewalls 36 of the contact protector 16. The bumpers 32 secure the chip package properly in position, yet leave a gap around much of the perimeter of the package. In one embodiment, the bumpers 32 position the chip package within a tolerance of ±1 mil (25 microns). This tolerance is merely exemplary, with the exact tolerance chosen a design choice. The contact protector 16 is comprised of a base 38 having a plurality of openings 34 extending therethrough and side walls 36 having a plurality of bumpers 32. Holes 30 provide means for aligning the contact protector 16 with the contact array 14 through use of shoulder screws 18 (see Figures 1A and 2 A) and will be placed directly over holes 29 of the contact array 14 (see Figure 3B) to allow screws 18 to pass therethrough (see Figures 1A and 2A). Proper alignment is important, ensuring that the spring interconnection elements 12 pass through the slots 34 and are able to connect with the electrical contacts of the chip package. Holes 30 also allow the contact protector 16 to slide up and down the shoulder screws 18 as required to allow the establishment of an electrical interconnection. When in the raised position, illustrated in Figures 1A and IB, the spring interconnection elements 12 are protected within region 13. When the contact protector 16 is depressed, as in Figures 2A and 2B, the coil springs 20 are compressed and the spring interconnection elements 12 establish an electrical connection with the electrical contacts of the chip package. The contact protector 16 is preferably a single piece fabricated using injection molding of a high temperature electronics plastic, such as liquid crystal polymer (LCP). In another embodiment, the contact protector 16 is manufactured in a machining process. The bumpers 32 may be a continuous piece of the sidewall 36 or may be a separate entity affixed to the inner side of the sidewall 36. The bumpers 32 are typically made out of the same material as the contact protector 16. Springs may be used to provide a centering effect, and such springs may be made of plastic. Note that any combination of solid bumpers and plastic springs may be used to bias the chip package to one side or the other. Note also that although two bumpers are shown on each side for a total of eight, the exact number of bumpers and their placement is a design choice.

In one embodiment, a mechanism 50 is typically used to depress the chip package 15 and contact protector 16 and to allow the spring interconnection elements 12 to extend through the openings 34 of the base 38 of the contact protector 16. One such mechanism is illustrated in Figure 5. Figure 5 is a side cross-sectional view of the apparatus 10 of Figures 1A and 2 A wherein a latch mechanism 50 is used to depress the chip package 15 and contact protector 16. Note that in this embodiment, the mechanism 50 acts directly on the chip package 15 to press the chip package 15 against the spring interconnection elements 12. The contact protector 16 moves to allow this interconnection. The mechanism 50 acts indirectly (through the package 15) on the contact protector 16. Other embodiments may comprise a mechanism acting directly on the contact protector 16 itself. The latch mechanism 50 is coupled to the substrate 26 of the contact array 14. A top brace 52 is rotatably coupled (e.g., hinged) to a support arm 54 to form the latch mechanism 50. When an electrical connection is desired, the top brace 52 is laid across the back of the chip package 15 housed in the contact protector 16 and may be locked around the opposite side of the apparatus 10. The top brace 52 may be bowed slightly downward, as shown in Figure 5, such that a pressure is only exerted against the back side of a chip package 15 housed within the frame of the contact protector 16. Figure 6 provides a top view of the apparatus illustrated in Figure 5, illustrating the overall shape of one embodiment of a latch mechanism.

Note that depending on the size of the substrate 26 of the contact array 14 and the amount of downward pressure exerted on the contact protector 16, a support plate may be added to the backside of the PCB to which the substrate 26 is coupled to, to prevent the substrate 26 from warping. If required, a support plate could be easily coupled to the backside of a PCB. Note also that any of a variety of latching mechanisms can be used. For example, a locking slot may be secured to extend beyond the substrate more or less perpendicular to the substrate 26. Top brace 52 may not, in this case, wrap around the substrate and may include a locking tab which engages with the locking slot.

Figures 7A and 7B are exploded cross-sectional views illustrating the position of the spring interconnection element 12 relative to the openings 34 in the base 38 of contact protector 16 in both the raised and depressed positions of the contact protector 16 respectively. Figure 7 A depicts the spring interconnection element 12 and opening 34 of contact protector 16 in the raised or protected position. In one embodiment, the height of the spring interconnection element 12 when at rest is 47 mils (1.2 millimeters) from the substrate surface (HI) and when compressed is 35 mils (0.9 mm) (H2). This allows an excess force to be applied at the top with a fixed amount of compression. Note that the thickness H2 of contact protector 16 limits the maximum compression of spring interconnection element 12. Thus, in this embodiment the space (S) between the lower side of the contactor protector 16 (in the raised position) and the substrate 26 is approximately 22 mils (0.56 mm) that is, 12 mils (0.3 mm) for compression with a ± 10 mils (0.25 mm) for tolerance.

Figure 7B depicts the spring interconnection element 12 and opening 34 of contact protector 16 in the compressed position. The element 12 makes electrical contact with a corresponding contact pad 15 A on the chip package 15 as shown in Figure 7B. As it is compressed, the spring interconnection element 12 generally bends somewhat which may cause the spring interconnection element 12 to occur more space laterally (e.g. the element's lateral dimension increases from a first size in an uncompressed state to a second size, which is larger than the first size, in the compressed state). This can be seen by comparing the larger lateral dimension (L2) of element 12 in Figure 7B relative to the lateral dimension (LI) of the same element 12 shown in Figure 7 A. The spring interconnection element 12 typically bends (curves) along the opening (e.g., slots) rather than across it and the opening has a size which allows for the change in lateral size of the element 12 as it bends. The spring interconnection element may occupy more lateral space when compressed than when uncompressed, and the opening is designed to accommodate this change in the element's dimension. Figures 8A and 8B are perspective views illustrating a second embodiment of the apparatus of the present invention. Figure 8A is a perspective view of the top side of the apparatus 80 illustrating the frame 82 and the free floating contact protector 84 with slots 86 extending through the contact protector 84 as did slots 34 in the previous embodiment. Rather than using coil springs to provide the force to act against the contact protector, this second embodiment utilizes a leaf spring (see Figure 9A), acting, for example, between contact aπay 85A, which includes spring contact elements, and the contact protector 84. Figure 8B is a perspective view of the bottom side of the apparatus 80 illustrating the base of the contact array 85A comprising the solder balls 22 which are used to couple electrically the contact array 85A to, for example, a printed circuit board. The tabs 92 support the contact aπay 85A.

Figure 9A is a side cross-sectional view of the apparatus 80 illustrated in Figures 8A and 8B wherein the contact protector 84 is in the raised position and is supported therein by leaf spring 94. The frame 82 of the apparatus has an inner ledge 93 that resides against the leaf spring 94. Figure 9B is a side cross-sectional view of the apparatus 80 illustrated in Figure 9A wherein the contact protector 84 is in the depressed position such that the spring contacts 85 are compressed and extending through said contact protector 84. Note that in neither Figure 9A nor 9B is an electronic assembly shown with which contact aπay 85A will be making an electrical connection, neither is a mechanism for depressing the contact protector 84 against the leaf spring 94 shown. As in the previous embodiment, a mechanism such as a latch may be used to depress the contact protector 84 and allow the contact springs 85 to pass through the slots 86 (not shown) and extend therethrough.

Figure 10 is a top view of the apparatus 80. The bumpers 94 serve the same purpose as in the previous embodiments. The upper limit of motion for the contact protector 84 is determined by tabs 92. See Figures 8A and 8B. The lower limit of motion for the contact protector 84 is set when the contact protector 84 touches the substrate 90. As the electronic assembly is first set into the contact protector, and before compression or displacement of the contact protector, the bumpers 94 provide a secure fit to ensure that the electronic assembly remains in place. As described above, a locking tab engages a locking slot to secure the latch mechanism in place.

Figure 11 A provides a perspective view of the apparatus 80 of Figures 8 A and 9 A with a latch mechanism 99 rotatably coupled to a hinge 98 mounted on the frame 82. As with the latch mechanism described above (see latch 52 of Figures 5 and 6), the latch mechanism 99 is typically used to depress the chip package (not shown) and the contact protector 84 to allow the spring interconnection elements to extend through the slots 86 of the contact protector 84. Thus, when an electrical connection is desired, the latch mechanism 99 may be closed over the back of the chip package (not shown). Note that the latch mechanism 99 may be bowed slightly downward (as shown in Figure 1 IB) such that pressure is exerted against the back side of the chip package (not shown) housed within the frame 82 of the apparatus

80. The locking tab 99A engages locking slot 99B to secure the latch mechanism 99 in place.

Each of these embodiments serve the same basic function of protecting the electrical contacts (e.g., spring interconnection elements) of a first electronic assembly when the electrical contacts are not being used to establish an electrical interconnection with a second electronic assembly. Figure 12 is a block diagram illustrating the basic steps of protecting the electrical contacts of a first electronic assembly when the electrical contacts are not being used to establish an electrical interconnection with a second electronic assembly. First, a second electronic assembly is placed within a frame (step 100). Next, a mechanism coupled to the first electronic assembly is closed such that the second electronic assembly is depressed which subsequently depresses the contact protector (step 102). The electrical contacts of the first electronic assembly extend through the contact protector as it is depressed (step 104). Once the electrical contacts of the first electronic assembly extend through the contact protector, an electrical interconnection between the electrical contacts of the first electrical assembly and the second electrical assembly is established (step 106).

Further depression applies force against the interconnection. This helps provide a dependable electrical connection. In one embodiment, where the interconnection element is resilient, the interconnection element deforms to a compressed position. When the need for an electrical connection between the first and second electrical assemblies is complete, the mechanism is released (step 108). As the mechanism is released, the electrical interconnection is broken since the electrical contacts of the first electrical assembly no longer extend through the contact protector (step 110) and the second electronic assembly and the contact protector returns to its original position (step 112). The above embodiments of the present invention have been discussed and illustrated with use of resilient contact structures as the interconnection elements. Note, however, that solder balls could also be used as the interconnection elements on the contact aπay. Further, LGA packages with lands, BGA packages with solder balls, or modified BGA packages having spring elements rather than solder balls may be used with the present invention. Embodiments of the invention have been discussed with an opening in the contact protector protecting one spring contact. Alternatively, each opening of the contact protector may contain more than one resilient contact structure. The method and apparatus described above provide the novel ability of being capable of protecting the electrical contacts of a first electronic assembly when the need for an electrical interconnection with the first electronic assembly does not exist, and yet still allowing the electrical interconnection between two electronic assemblies as needed. The method and apparatus described above also provide positional alignment of the contact elements of the chip package with the interconnection elements during an electrical interconnection. Thus, the present invention increases the life of the electrical contacts (or interconnection elements) of a chip package, by protecting them against damage from over- compression, movement in undesired directions, and/or contamination. Although the present invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character. It being understood that only prefeπed embodiments have been shown and described, and that all changes and modifications that come within the spirit invention are desired to be protected. Undoubtedly, many other variations on the examples set forth hereinabove will occur to one having ordinary skill in the art to which the present invention most nearly pertains, and such variations are intended to be within the scope of the invention, as disclosed herein.

Claims

CLAIMSWhat is claimed:

1. An apparatus comprising: a substrate having a plurality of interconnection elements extending therefrom; a contact protector having a plurality of openings; and, a mechanism coupled to said contact protector, said mechanism maintaining said contact protector in an oriented relationship to said substrate, said oriented relationship including a first position wherein said interconnection elements can make an electrical connection through said openings and a second position wherein said interconnection elements are protected.

2. The apparatus of claim 1 wherein said contact protector provides a frame for housing an electronic assembly having a plurality of electrical contacts.

3. The apparatus of claim 2 further comprising a latch mechanism coupled around said substrate, wherein when closed said latch mechanism depresses said electronic assembly such that said interconnection elements establish said electrical connection with said electrical contacts of said electronic assembly through said openings of said contact protector.

4. The apparatus of claim 3 wherein said contact protector limits the force on said interconnection elements.

5. The apparatus of claim 1 wherein when in said second position said contact protector is positioned such that said interconnection elements do not extend through said contact protector.

6. The apparatus of claim 1 wherein said contact protector is coupled to said substrate in positional alignment.

7. The apparatus of claim 6 wherein said mechanism further comprises a plurality of shoulder screws.

8. The apparatus of claim 7 further comprising a spring mechanism wherein said spring mechanism tends to move said contact protector to said second position.

9. The apparatus of claim 8 wherein said spring mechanism further comprises a plurality of coil springs located around said screws between said substrate and said contact protector.

10. The apparatus of claim 2 further comprising means for depressing said electronic assembly such that said interconnection elements establish said electrical connection with said electrical contacts of said electronic assembly through said opening of said contact protector.

11. The apparatus of claim 1 wherein said substrate is a printed circuit board.

12. The apparatus of claim 1 wherein said substrate is ceramic.

13. The apparatus of claim 1 wherein said interconnection elements are resilient contact structures.

14. The apparatus of claim 13 wherein said resilient contact structures are free-standing.

15. The apparatus of claim 13 wherein said resilient contact structures are composite interconnection elements.

16. The apparatus of claim 2 wherein said frame further comprises a bumper for positioning said electronic assembly in said frame.

17. The apparatus of claim 16 wherein said bumper comprises a plastic spring.

18. The apparatus of claim 1 wherein said contact protector is fabricated from liquid crystal polymer (LCP) through injection molding.

19. An apparatus for protecting electrical contacts of a first electrical assembly comprising: a first electrical assembly having a plurality of interconnection elements extending therefrom; a contact protector having a plurality of openings; and, a mechanism coupled to said contact protector, said mechanism maintaining said contact protector in an oriented relationship to said first electrical assembly, said oriented relationship including a first position wherein said interconnection elements can make an electrical connection through said openings and a second position wherein said interconnection elements are protected.

20. The apparatus of claim 19 wherein said contact protector provides a frame for housing a second electrical assembly having a plurality of electrical contacts.

21. The apparatus of claim 20 further comprising a latch mechanism coupled around said first electrical assembly, wherein when closed said latch mechanism depresses said second electrical assembly such that said interconnection elements establish said electrical connection with said second electrical assembly.

22. The apparatus of claim 21 wherein said contact protector limits the force on said interconnection elements.

23. The apparatus of claim 19 wherein when in said second position said contact protector is positioned such that said interconnection elements do not extend through said contact protector.

24. The apparatus of claim 19 wherein said contact protector is coupled to said first electrical assembly in positional alignment.

25. The apparatus of claim 24 further comprising a spring mechanism wherein said spring mechanism tends to move said contact protector to said second position.

26. The apparatus of claim 20 further comprising means for depressing said second electrical assembly such that said interconnection elements establish said electrical connection with said electrical contacts of said second electronic assembly through said openings of said contact protector.

27. The apparatus of claim 13 wherein said first electrical assembly comprises a printed circuit board.

28. The apparatus of claim 1 wherein said first electrical assembly comprises ceramic.

29. The apparatus of claim 19 wherein said interconnection elements are resilient contact structures.

30. The apparatus of claim 29 wherein said resilient contact structures are free-standing.

31. The apparatus of claim 29 wherein said resilient contact structures are composite interconnection elements.

32. The apparatus of claim 20 wherein said frame further comprises a bumper for positioning said second electronic assembly in said frame.

33. The apparatus of claim 32 wherein said bumper comprises a plastic spring.

34. The apparatus of claim 19 wherein said contact protector is fabricated from liquid crystal polymer (LCP) through injection molding.

35. An apparatus comprising : a frame having a first side and a second side, said frame having a plurality of tabs extending inward on said second side and a plurality of bumpers extending inwardly on said first side, said plurality of bumpers for securing a second electrical assembly; a first electrical assembly having a plurality of interconnection elements extending therefrom, said first electrical assembly supported within said frame by said tabs; and, a contact protector having a plurality of openings, said contact protector housed within said frame in an oriented relationship to said first electrical assembly, said oriented relationship including a first position wherein said interconnection elements can make an electrical connection through said openings and a second position wherein said interconnection elements are protected.

36. The apparatus of claim 35 further comprising a spring mechanism between said first electrical assembly and said contact protector, said spring mechanism acting against said contact protector and wherein said interconnection elements are, in said second position, not positioned to make said electrical connection.

37. The apparatus of claim 36 further comprising a latch mechanism coupled around said frame, wherein when closed said latch mechanism depresses said second electrical assembly such that said interconnection elements establish said electrical contacts of said second electrical assembly.

38. The apparatus of claim 37 wherein said contact protector limits the force on said interconnection elements.

39. The apparatus of claim 35 wherein when in said second position said contact protector is positioned such that said interconnection elements do not extend through said contact protector.

40. The apparatus of claim 35 wherein said first electrical assembly comprises a printed circuit board.

41. The apparatus of claim 40 wherein said first electrical assembly comprises ceramic.

42. The apparatus of claim 35 wherein said interconnection elements are resilient contact structures.

43. The apparatus of claim 42 wherein said resilient contact structures are free-standing.

44. The apparatus of claim 42 wherein said resilient contact structures are composite interconnection elements.

45. The apparatus of claim 35 wherein said bumpers are comprised of plastic springs.

46. The apparatus of claim 35 wherein said contact protector is fabricated from liquid crystal polymer (LCP) through injection molding.

47. The apparatus of claim 25 wherein said frame is fabricated from liquid crystal polymer (LCP) through injection molding.

48. A method of protecting electrical contacts of a first electronic assembly, comprising: placing a second electronic assembly within a frame of a contact protector, wherein said contact protector is coupled to said first electronic assembly; depressing said second electronic assembly; exposing said electrical contacts through said contact protector as said second electronic assembly is depressed; and, forming an electrical interconnection between said electrical contacts and said second electrical assembly.

49. The method of claim 48 wherein said step of depressing said second electronic assembly further comprises closing a latch mechanism coupled around said first electronic assembly such that said second electronic assembly is depressed.

50. The method of claim 49 further comprising the step of releasing said mechanism such that said second electronic assembly is not depressed and said electrical contacts no longer extend through said contact protector.

51. An apparatus comprising: a substrate having a plurality of compressible contact elements extending therefrom, said contact elements having a first state in which said contact elements are uncompressed and having a second state in which said contact elements are compressed; and, a contact protector coupled to said substrate and being moveable relative to said substrate.

52. The apparatus of claim 51 wherein said contact protector has a first position that shields said contact elements and a second position that allows said contact elements to compress and wherein said contact protector has a plurality of openings, each of said openings for protecting at least one of said contact elements.

53. The apparatus of claim 52 wherein said contact protector moves from said first position to said second position as said contact elements are compressed.

54. The apparatus of claim 53 wherein said second position of said contact protector limits the compression of said contact elements.

55. The apparatus of claim 54 wherein said contact elements are freestanding, elongate resilient contact structures.

56. The apparatus of claim 55 wherein said freestanding, elongate resilient contact structures have a shape which allows for bending as said freestanding, elongate resilient contact structures are compressed.

57. The apparatus of claim 55 wherein said freestanding, elongate resilient contact structures are composite interconnect elements which comprise a first conductive material and a second conductive material.

58. The apparatus of claim 55 wherein said freestanding, elongate resilient contact structures are for making electrical contact to a semiconductor integrated circuit.