Abstract:
An electronic system which requires high current provides a connector assembly which enables power supplies to be plugged into the same etched backplane as the logic printed circuit boards. The connector assembly handles high current, typically 150 amps at 5V DC. A female connector includes sets of fingers which flex at the base of the fingers to provide a low resistance contact.

Description:
This application is a continuation of application Ser. No. 20,154, filed Feb. 26, 1987, now abandoned, which is a continuation of application Ser. No. 750,431, filed July 1, 1985, now U.S. Pat. No. 4,685,032. 
    
    
     RELATED APPLICATION 
     The following U.S. patent application filed on an even date with the instant application and assigned to the same assignee as the instant application is related to the instant application and is incorporated herein by reference. 
     &#34;Integrated Backplane&#34; by John W. Blomstedt, Paul S. Yoshida, Wesley F. Irving and Vladimir Roudenko, having U.S. Ser. No. 750,441 and filed on July 1, 1985. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to the field of packaging electronic assemblies, and more specifically to the design of a connector for providing the ability to plug power supplies into the same logic backplane into which are plugged logic printed circuit board assemblies. 
     2. Description of the Prior Art 
     Electronic systems generally, and data processing systems in particular, require large amounts of logic voltage, typically 5V DC to power the system. These systems had a number of logic printed circuit boards which plugged into connectors mounted on an etched backplane. Voltage and ground were distributed by their respective etches. 
     The power supplies were bulky and were usually mounted in a separate area since they generated considerable heat. This heat was directed away from the printed circuit boards to avoid circuit malfunctions. 
     Heavy single conductor cable, typically 2 or 4 AWG or copper bars, are bolted to the backplane and the power supply to provide power. This cabling requirement presents a number of problems including requiring special conduits in the cabinet, providing additional cost, and having an increased voltage drop across both end connections. At times the bolted connections may loosen thereby generating subtle logic problems which are intermittent and therefore difficult to find. These prior cabled mechanical arrangements also make it difficult to service power problems. 
     OBJECTS OF THE INVENTION 
     Accordingly, it is a primary object of the invention to provide an improved power system. 
     It is an object of the invention to provide an improved power system which is less costly to design into the system. 
     It is another object of the invention to provide an improved power system by eliminating the requirement for power cables. 
     It is yet another object of the invention to provide a power system having means for readily plugging the power supply into the logic backplane. 
     SUMMARY OF THE INVENTION 
     An electronic system is packaged by using an integrated multilayer etched backplane into which are plugged logic printed circuit boards and power supplies. A connector assembly made up of a female connector and a blade provide the voltage and ground paths between the power supplies and the logic printed circuit boards. The connector assembly is designed typically to carry up to 150 amps at 5V DC. 
     The female connector includes a number of pairs of fingers, typically five. A means is provided at the base of the fingers to provide a smaller cross-sectional area to allow the fingers to flex when the blade is inserted between the fingers. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features which are characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to organization and operation may best be understood by reference to the following description in conjunction with the drawings in which: 
     FIG. 1 is a breakout assembly view of the packaging of a typical electronic system; 
     FIG. 2 is a view of the back of the system; 
     FIG. 2A shows the detail of connecting the backplane to the bus bars; 
     FIGS. 3 through 6 show the various views of the female connector; and 
     FIG. 7 is a view of the elements of the power supply voltage and ground connectors. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows the use of a female connector 12 of electronic system 1. A number of power supplies 6 supply power to a number of printed circuit boards 4. Ground is provided by power supplies 6, blade 30, one of the connectors 12, a bus bar 14, a bushing 25 of FIG. 2A, an etch 5, an etched backplane 3 of integrated backplane assembly 2, a connector 8, an edge connector 9, and printed circuit boards 4. 
     Similarly, voltage is applied to printed circuit boards 4 via power supplies 6, connector 12, bus bar 16, bushing 25, etch 7, etched backplane 3, connector 8, edge connector 9, and printed circuit boards 4. 
     Power control signals are transferred between the power supplies 6 via edge connectors 32, connectors 10, and etched backplane 3. Power control signals are transferred between the power supplies 6 via edge connectors 32, connectors 10, etched backplane 3, connectors 8, edge connectors 9, and printed circuit boards 4. 
     Included in electronic system 1 are a guide 18 fastened to etched backplane 3 and containing channels 20 for supporting printed circuit boards 4. Also, a cage 22 provides physical support for power supplies 6. 
     Connectors 12 are bolted to bus bars 14 and 16 by means of bolts 26. 
     Bus bars 14 and 16 are also fastened to printed circuit boards 4 via bolt 24 into a tapped hole in bushing 25, FIG. 2A. Bushing 25 is soldered to the power etches 5 and 7. 
     FIG. 2 is a back view of the electronic system 1 packaging showing the bus bars 14 and 16 coupled to backplane 3 of integrated backplane assembly 2. Bolts 26 fasten connectors 12 of FIG. 1 to bus bars 14 and 16. Also shown is the guide 18 and the cage 22. 
     FIG. 2A shows how the bus bars 14 and 16 are electrically coupled to the etch 5 or 7 by soldering and physically coupled to backplane 3 by the bushing 25 having a threaded hole for receiving screw 24. Note that bus bars 14 and 16 are fastened to the etches 5 and 7 in a number of locations thereby reducing the possibility of circuit ground loops. 
     FIGS. 3, 4, 5 and 6 show the top, bottom, side and front views, respectively, of connector 12. FIG. 6 shows the sets of fingers 41. Five sets of fingers 41 are shown but this invention is not limited to the five sets of fingers 41. 
     Referring to FIG. 5, connector 12 includes a hole 13 to establish a thin section 15 to act as a fulcrum about which each finger of the sets of fingers 41 will flex when blade 30 of FIG. 7 is inserted. 
     The distance between one row of fingers of each set of fingers 41 is related to the centerline of the hole by a dimension 11 and the distance between corresponding fingers of the set of fingers 41 is dimension 31 wherein dimension 31 is twice dimension 11. 
     FIG. 4 shows the tapped hole 33 at a predetermined depth sufficient to hold connector 12 securely to bus bar 14 or 16 by bolts 26, FIG. 2. 
     FIG. 7 shows power supply 6 having blade 30 mounted to an etched board 33 by means of a block 10 and a screw 13. 
     The material of connector 12 is typically a copper beryllium alloy plated with 0.0005 inches of silver. 
     The blade 30 material is typically silver-plated copper having a thickness of typical 0.093 inches. 
     The current carrying capability of connector 12 of 150 amps DC is determined by the minimum cross-sectional area 15, FIG. 5, of the set of fingers 41. Typically one finger of the set of fingers 41 would have a cross-sectional area 0.00816 square inches or 8160 square mils. Since 1 square mil equals 1.274 circular mils, the cross-sectional area is approximately 10,400 (8160×1.274) circular mils or 104,000 circular mils for 10 fingers. The current carrying capacity is 500 circular mils per ampere or 208 amps. This value is deroted to 150 amps for reliability reasons. 
     The contact area for carrying the 150 ampere current between the connector 12 and the blade 30 is typically 0.0527 square inches. This contact area occurs after insertion at the dimension 15 located at the tip of each finger. This is calculated by multiplying the width of each finger, typically 0.170 inches by 1/32 inches which approximates the distance perpendicular to the finger width and multiplying by 10, the number of fingers. 
     This contact area gives a resistance of 0.00000274 ohms or a voltage drop at 5V DC of approximately 400 microvolts. 
     Having shown and described a preferred embodiment of the invention, those skilled in the art will realize that many variations and modifications may be made to affect the described invention and still be within the scope of the claimed invention. Thus, many of the elements indicated above may be altered or replaced by different elements which will provide the same result and fall within the spirit of the claimed invention. It is the intention, therefore, to limit the invention only as indicated by the scope of the claims.