System level test socket

[0002] The present invention relates to a system level test socket for a semiconductor package having a non-pin grid array footprint. The present invention has particular applicability in testing a semiconductor package having either a land grid array footprint or a ball grid array footprint.

[0003] Bum-in boards are used to test semiconductor packages, such as integrated circuit (IC) chips, to ensure that the semiconductor packages are operating in a proper manner. Typically, the semiconductor package to be tested is inserted into a socket mounted on a burn-in board. For example, an IC chip is inserted into an IC socket on a bum-in board. The bum-in board is then placed in a testing chamber and power, ground and test signals are coupled to the bum-in board. The semiconductor packages in the IC chip are then tested for a period of time under stress conditions to ensure that the semiconductor packages are performing according to set standards or specifications.

[0004] As long as the semiconductor package has a pin grid array footprint, the semiconductor package can be placed directly into a pin grid array socket on the circuit board. However, semiconductor packages having non-pin grid array footprints, such as land grid array or ball grid array footprints are becoming more commonly employed. Problems arise when these non-pin grid array semiconductor packages need to be tested. In order to test such semiconductor packages, the footprint of the semiconductor package needs to be adapted for connection to the pin grid array socket. Therefore, a device such as an interposer, is used to convert the semiconductor package footprints. For example, a semiconductor package having a ball grid array footprint is inserted into an interposer having a pin grid array and the interposer is inserted into a pin grid array socket on a circuit board. However, using an interposer or other converting device creates a high profile with long electrical connections. Moreover, requiring an additional device unnecessarily increases the chance of a defective component and as a result, can damage the semiconductor package.

[0005] Therefore, there is a need for a system level test socket capable of receiving a semiconductor package having either a land grid array footprint or a ball grid array footprint, without requiring an additional component to convert the footprint.

[0006] There also exists a need for a simplified methodology for testing a semiconductor package having either a land grid array footprint or a ball grid array footprint, using a system level test socket on a circuit board, where the semiconductor package and socket have a low profile and short electrical paths between the semiconductor package and the circuit board.

[0007] These and other needs are met by embodiments of the present invention which provide method ad apparatus for testing a semiconductor package having either a land grid array footprint or a ball grid array footprint, without requiring an additional component to convert the footprint.

[0008] The test socket and method of using the socket of the present invention connect a semiconductor package having a non-pin grid array to a circuit board. The test socket includes a plurality of solder pads, wherein the solder pads are positioned to be aligned with corresponding leads from the non-pin grid array of a semiconductor package and a plurality of corresponding internal leads for connecting the plurality of solder pads to a plurality of leads on the bottom surface of the test socket. The test socket allows for the testing of semiconductor packages having non-pin grid array without having to use an interposer to convert the non-pin grid array. Also, the test socket allows for a lower profile since the interposer is not needed.

[0009] The testing system of the present invention includes a test socket for connecting a semiconductor package having a non-pin grid array to a circuit board. The test socket includes a plurality of solder pads, wherein the solder pads are positioned to be aligned with corresponding leads from the non-pin grid array of a semiconductor package and a plurality of corresponding internal leads for connecting the plurality of solder pads to a plurality of leads on the bottom surface of the test socket. The testing system includes one or more test sockets on a circuit board with a fastener for pressing a semiconductor package against a test socket. The testing system allows for a plurality of semiconductor packages having a non-pin grid array to be inserted into the test sockets on a circuit board and tested at the same time.

[0010] Additional advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description, wherein only the preferred embodiment of the present invention is shown and described, simply by way of illustration of the best mode contemplated for carrying out the present invention. As will be realized, the present invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

[0011] Reference is made to the attached drawings, wherein elements having the same reference numeral designations represent like elements throughout, and wherein:

[0012] FIG. 1ais a front view of an exemplary semiconductor package having a land grid array footprint.

[0013] FIG. 1bis a front view of an exemplary semiconductor package having a ball grid array footprint.

[0014] FIG. 2 is top view of an exemplary system level test socket in accordance with an embodiment of the present invention.

[0015] FIG. 3ais a front view of an exemplary system level test socket having a pin grid array in accordance with an embodiment of the present invention.

[0016] FIG. 3bis a front view of an exemplary system level test socket having a ball grid array in accordance with an embodiment of the present invention.

[0017] FIG. 3cis a front view of an exemplary system level test socket having a land grid array in accordance with an embodiment of the present invention.

[0018] FIG. 4 is a front view of an exemplary testing system with an exemplary system level test socket in accordance with an embodiment of the present invention.

[0019] FIG. 5 is a flow diagram of the steps for using an exemplary system level test socket in accordance with an embodiment of the present invention.

[0020] Current system level test sockets are incapable of receiving a semiconductor package having either a land grid array footprint or a ball grid array footprint. Conventional test sockets for semiconductor packages require a component to convert the footprint of semiconductor package having a non-pin grid array footprint to a pin grid array footprint. Moreover, the component for converting the footprint increases the profile of the test package semiconductor package and as a result, increases the length of the electrical connection between the semiconductor package and the test socket. The present invention addresses and solves these and other problems stemming from conventional test sockets requiring a component to convert the footprint of a semiconductor package having a non-pin grid array footprint.

[0021] According to the methodology of the present invention, a system level test socket is able to provide electrical connections between a semiconductor package having a non-pin grid array footprint and the circuit board. Moreover, the system level test socket provides a low profile, thereby providing shorter electrical connections between the semiconductor package and the circuit board.

[0022] Referring to FIGS. 1aand 1b, front views of semiconductor packages having a land grid array footprint and a ball grid array footprint, respectively, are illustrated. As shown, a semiconductor package 10 has a plurality of lands 12a-hon the bottom surface of the semiconductor package 10. Similarly, semiconductor package 14 has a plurality of solder balls 16a-h. The lands 12a-hand solder balls 16a-gprovide electrical signals to and from the semiconductor packages 10, 14, respectively.

[0023] Referring to FIG. 2, the top view of a system level test socket in accordance with an embodiment of the present invention is illustrated. As shown, the test socket 20 includes a socket body 22, solder pads 24, and guide pins 26a, 26b. The socket body 22 and guide pins 26a, 26bare preferably made of a metal material, such as stainless steel. The socket body 22 includes walls 28a-dwhich allow a semiconductor package to be inserted into the cavity created by the walls 28a-d. The solder pads 24 are positioned to align with the footprint of the semiconductor package that will be tested. Therefore, test sockets 20 are designed for semiconductor packages having standard footprints. In addition, a test socket 20 can be custom designed for semiconductor packages having non-standard footprints. The guide pins 26a, 26bare used to guide a hydraulic cylinder having guide slots which fit around the guide pins 26a, 26b. The hydraulic cylinder uses pressure to press a semiconductor package against the test socket 20. In alternate embodiments, the semiconductor package is pressed against the test socket 20 using a fastener, such as a clamp or screwed down fastener. By pressing the semiconductor package onto the test socket 20, the connections or leads on the bottom of the semiconductor package, such as solder balls or lands, are pressed against the solder pads 24 of the test socket 20, thereby ensuring electrical connectivity between them.

[0024] Referring to FIG. 3a, a front view of an exemplary system level test socket having a pin grid array in accordance with an embodiment of the present invention is illustrated. As shown, the test socket 20 includes internal leads 30a-hwhich provide electrical connections between the leads on the bottom of the non-pin grid array package and the leads on the bottom of the test socket 20. In FIG. 3a, the leads on the bottom of the test socket 20 are pins 32a-h. FIGS. 3band 3cillustrate solder balls 34a-hand lands 36a-hon the bottom of the test socket 20, respectively. In alternate embodiments, the leads on the bottom of the test socket 20 can be other leads as known in the art. The leads on the bottom of the test socket 20 are used to provide electrical connections between the test socket 20 and a circuit board.

[0025] Referring to FIG. 4, a front view of a testing system for testing a semiconductor package in a test socket in accordance with an embodiment of the present invention is illustrated. As shown, a test socket 20 having a semiconductor package 10 with a land grid array footprint is mounted on a circuit board 48. The test socket 20 can be mounted by either soldering it directly to the circuit board 48 or using other methods of attachments known in the art, such as pressure or an elastomer.

[0026] In the preferred embodiment, the circuit board 48 is a burn-in board. The circuit board 48 can be a motherboard or a fatherboard which plugs into a motherboard. Therefore, the test socket 20 of the present invention functions as a system test level socket for inserting a semiconductor package into the test socket 20 and to test the semiconductor package in an oven for a period of time under stress conditions such as heat and humidity.

[0027] As shown, a hydraulic cylinder 40 having guide slots 44a, 44bis used to press the semiconductor package 10 against the test socket 20. The hydraulic cylinder 40 causes the leads 12a-hon the bottom of the semiconductor package 10 to press against the solder pads 24a-hon the test socket 20, thereby ensuring electrical connectivity between the leads 12a-hon the bottom of the semiconductor package 10 and the solder pads 24a-hof the test socket 20. The amount of pressure applied is controlled by a controller 46 such that the package leads (pins, solder balls, lands, etc.) are not damaged. The guide pins 26a, 26b, are used to guide the hydraulic cylinder 40 onto the test socket 20 with the guide slots 44a, 44blining up with and sliding over the guide pins 26a, 26bon the test socket 20.

[0028] Referring to FIG. 5, a flow chart of the steps for using the test socket in accordance with an embodiment of the present invention is illustrated. As shown, the process starts with a semiconductor package being inserted into the test socket mounted on a bum-in board at step 50. The semiconductor package is pressed against the test socket ensuring electrical connectivity between the connections on the bottom of the semiconductor package and the solder pads in the test socket at step 52. In some embodiments, it is not necessary to press the semiconductor package against the test socket as long as there are adequate connections between the semiconductor package and test socket. The semiconductor package is electrically tested at step 54. The pressure is removed from the semiconductor package at step 56. The semiconductor package is removed from the test socket at step 58.

[0029] The present invention allows for the testing of semiconductor packages having non-pin grid array footprints without requiring an interposer to convert the footprint of the semiconductor package to a pin grid array footprint so it can be inserted into a pin grid array test socket. Therefore, the test socket of the present invention provides connections between the semiconductor package having a non-pin grid array footprint and the circuit board on which the test socket is mounted. In addition, the test socket includes guide pins to assist in guiding a hydraulic cylinder onto the test socket to compress the semiconductor package to the test socket.

[0030] Only the preferred embodiment of the present invention and but a few examples of its versatility are shown and described in the present disclosure. It is to be understood that the present invention is capable of use in various other combinations and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein.