AN IMPROVED POWER CONTACT FOR TESTING A POWER DELIVERY SYSTEM

Abstract: An improved test system comprises a printed circuit board and a test assembly wherein the printed circuit board has a plastic chassis encompassing one surface and a set of power pads mounted thereon. A first surface of the set of power pads may be coupled to conductors on the one surface of the printed circuit board and a second surface of the set of power pads is available for electrical coupling through an opening in the plastic chassis. The test assembly vertically pushes down on the printed circuit board until the second surface of the set of power pads contacts a power source, thus electrically coupling the printed circuit board to the power source.

Description: AN IMPROVED POWER CONTACT FOR TESTING A POWER DELIVERY SYSTEM FIELD OF THE INVENTION This invention relates to an improved power contact for testing a power delivery system. Specifically, the present invention discloses an improved contact for testing a power delivery system where only one dimensional pushing is required to establish the contact. BACKGROUND OF THE INVENTION In a typical computer system, a large printed circuit board known as a motherboard is provided. The motherboard contains a certain number of basic components including connectors for daughterboards which can be plugged in to provide different capabilities for the computer. The daughterboards may provide, for example, an interface to disk drives, CD- ROMs and modems. In order to test the printed circuit boards (both motherboards and daughterboards), current test assemblies push down on the board to establish contacts with power supplies. An example of a current test assembly is illustrated in Figure 1. The illustrated test assembly requires that pins be accessible at the bottom of the processor board to establish contact with a power supply for testing the pins. If alternative architectures are utilized where pins are not accessible at the bottom of the processor boards, current test assemblies must be significantly reworked in order to perform testing of the processor boards. SUMMARY OF THE INVENTION The present invention discloses an improved test system. The test system comprises a printed circuit board and a test assembly wherein the printed circuit board has a plastic chassis encompassing one surface and a set of power pads mounted thereon. A first surface of the set of power pads may be coupled to conductors on the one surface of the printed circuit board and a second surface of the set of power pads is available for electrical coupling through an opening in the plastic chassis. The test assembly vertically pushes down on the printed circuit board until the second surface of the set of power pads contacts a power source, thus electrically coupling the printed circuit board to the power source. Other features and advantages of the present invention will be apparent from the accompanying drawings and from the detailed description. BRIEF DESCRIPTION OF THE DRAWINGS The present invention is illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like reference numerals refer to similar elements and in which: Figure 1 illustrates an example of a current test assembly Figure 2A illustrates a schematic view of an improved power delivery system Figure 2B illustrates schematically the manner in which the pads of the multi-chip module extend into the dc to dc converter contact surfaces Figure 2C illustrates an alternate embodiment of the claimed invention Figure 3 illustrates changes that have to be made to the test assembly of Figure 1 to accommodate testing of the improved power delivery system Figure 4A illustrates a side view of a printed circuit board, together with a test assembly and a test socket Figure 4B illustrates a bottom view of a printed circuit board, including a plastic chassis that covers the bottom of the printed circuit board DETAILED DESCRIPTION OF THE INVENTION An improved contact for testing a power delivery system where only one dimensional pushing is required to establish the contact is disclosed. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent to one of ordinary skill in the art, however, that these specific details need not be used to practice the present invention. In other instances, well known structures, interfaces and processes have not been shown in detail in order not to unnecessarily obscure the present invention. Figure 2A is a schematic view of an improved power delivery system. The three basic elements are a motherboard 11, a power consuming module 13, and a DC to DC power converter 15. Figure 2B illustrates a side view of the arrangement according to one embodiment. Specifically, Figure 2B illustrates schematically (not to scale) the manner in which pads 33 and 35 of the multi-chip module extend into the DC to DC converter contact surfaces 39 and 41. Figure 2C illustrates an alternate embodiment of the claimed invention, with additional pads 50 and 55 extending into the DC to DC converter contact surfaces 60 and 63. Further details of this improved power delivery system can be found in co- pending patent application having Serial No. , filed (Atty docket no: 42390.P4488). According to these embodiments, pads 33, 35, 50 and 55 are not easily tested utilizing current test assemblies. Specifically, test assemblies that push down on a circuit board, such as the one illustrated in Figure 1, do not allow pads 33, 35, 50 and 55 to make contact with a test power supply. Instead, new assemblies must be designed that make side contacts with the pads to test the power contacts, while continuing to push down on the circuit board to continue testing of the signals on the pins as in the prior art board architectures. An example of the required new assembly is illustrated in Figure 3. This new assembly would require a reworking of all current test assemblies in order to use them to test the circuit boards having the improved architecture described above. This is clearly an expensive and time consuming solution. As such, an improved test contact is desirable, that allows for the use of currently available test assemblies to test circuit boards having a variety of architectures. Figures 4A-B illustrate an improved system for testing circuit boards having the improved architecture described above. Figure 4A shows a side view of a printed circuit board, together with a test assembly and a test socket. Figure 4B is a bottom view of a printed circuit board, including a plastic chassis that covers the bottom of the printed circuit board. According to this embodiment, portions of the plastic chassis covering the bottom surface of the printed circuit board are removed, thus creating an opening that enables the illustrated power pads to be accessible. The power pads electrically couple to the test socket's power contacts through the opening, thus allowing the power pad contacts to be tested. According to this embodiment, currently available test assemblies may continue to be utilized. Specifically, as illustrated in Figure 4, with the power pads placed at the bottom of the printed circuit boards, current test mechanisms or assemblies may continue pushing down on printed circuit boards in order to establish contacts with a power source. In contrast with the prior art method of establishing contacts with pins, however, according to the presently claimed invention, contacts are made with power pads instead. According to one embodiment, these power pads are designed to enable improved electrical characteristics, such as low inductance. Significantly improved (i.e., lower) inductance may be achieved by closely spacing power pads of opposite polarity. Although the improved test system is described above for use with circuit boards having the architecture described above, the improved test system requiring only one dimensional pushing may also be utilized with other circuit board architectures. Thus, an improved contact for testing a power delivery system where only one dimensional pushing is required to establish the contact is disclosed. The specific arrangements and methods described herein, are merely illustrative of the principles of the present invention. Numerous modifications in form and detail may be made by those of ordinary skill in the art without departing from the scope of the invention. Although this invention has been shown in relation to a particular preferred embodiment, it should not be considered so limited. Rather, the present invention is limited only by the scope of the appended claims.

Claims: CLAIMS What is claimed is: 1. An improved test system, comprising: a printed circuit board having a plastic chassis encompassing one surface, said printed circuit board having a set of power pads mounted thereon, a first surface of said set of power pads being coupled to conductors on said one surface of said printed circuit board, a second surface of said set of power pads being available for electrical coupling through an opening in said plastic chassis; a test assembly for vertically pushing down on said printed circuit board until said second surface of said set of power pads contacts a power source, thus electrically coupling said printed circuit board to said power source. 2. A printed circuit board having improved test contacts, said printed circuit board comprising; an upper surface; a lower surface; a plastic chassis encompassing said lower surface, said plastic chassis having at least one opening therethrough; a set of power pads mounted on said lower surface of said printed circuit board, said set of power pads being visible through said at least one opening in said plastic chassis , wherein said set of power pads are adapted to electrically couple to a power source for testing said printed circuit board. 3. An improved test system, comprising: a printed circuit board having improved test contacts, said printed circuit board including; an upper surface; a lower surface; a plastic chassis encompassing said lower surface, said plastic chassis having at least one opening therethrough; a set of power pads mounted on said lower surface of said printed circuit board, said set of power pads being visible through said at least one opening in said plastic chassis; a test assembly for vertically pushing down on said printed circuit board until said set of power pads are electrically coupled to a power source for testing said printed circuit board. 4. An improved method for testing a printed circuit board comprising the steps of: creating an opening in a plastic chassis encompassing one surface of the printed circuit board, said printed circuit board having a set of power pads mounted thereon, a first surface of said set of power pads being coupled to conductors on said one surface of said printed circuit board, a second surface of said set of power pads being available for electrical coupling through the opening in said plastic chassis; vertically pushing down on said printed circuit board until said second surface of said set of power pads contacts a power source to electrically couple said printed circuit board to said power source. 5. An improved method for testing a printed circuit board, the method comprising the steps of: creating an opening in a plastic chassis encompassing one surface of the printed circuit board, the printed circuit board also including an upper surface, a lower surface and a set of power pads mounted on said lower surface, said set of power pads being visible through said at least one opening in said plastic chassis; and vertically pushing down on said printed circuit board until said set of power pads are coupled to a power source for testing said printed circuit board.

Inventors: AYERS DAVID J, BROWNELL MICHAEL, AYERS, DAVID, J., BROWNELL, MICHAEL
Applicants: AYERS DAVID J, BROWNELL MICHAEL, INTEL CORP, AYERS, DAVID, J., BROWNELL, MICHAEL, INTEL CORPORATION
Application year: 1999
Main classification: G06F
IPC codes: G01R1, G01R31, G06F1, H01R12, H05K3