FLEXIBLE BUSSING SYSTEM FOR DISTRIBUTING POWER

Abstract: A bussing bar system (10) for panels (11) such as a printed circuit board employs bus means (16) comprised of at least one ribbon of flexible, relatively thin, substantially flat, conductive material, such as copper. The ribbon of bus means (16) is bent as desired to be received within a plurality of taps, including at least one vertical tap (13), mounted on the panel at selected respective locations. The taps may also include at least one horizontal tap (14), in which case the ribbon is twisted to right angles thereto to be received in the horizontal tap. One or more standoffs (15) may be employed to maintain mechanical rigidity and to maintain the ribbon in a vertical orientation off of panel (11). The amount of copper (or other material) employed is held to a minimum to meet the circular mil area (or "CMA") requirements. Design flexibility is assured for accommodating a variety of configurations, thereby effecting a considerable savings in development, tooling and production costs.

Description: The present invention relates to a bussing system for distributing power to printed circuit boards, backplanes or the like and, more particularly, to a flexible bussing system adapted to bring in power from an electrical supply source and distribute the power to one or more adjacent printed circuit boards. Electronic equipment, and more particularly computers, have a backplane constituting a "mother" board for bringing in electrical power and distributing the power to a plurality of stacked printed circuit boards constituting "daughter" boards having the logic circuitry thereon. In the prior art, the backplane bussing arrangements rely upon copper bus bars deposited thereon. These bus bars have a fixed cross section and are sized to carry the maximum electrical current present anywhere in the bar. These bars are rigid and therefore require fixed straight paths, and the bars are bolted to the printed circuit ("PC") board in order to facilitate the entry of current into the PC board. An example of the prior art is illustrated in U.S. Patent No. 4,241,381 issued to Cobaugh et al., and assigned to us. In this '381 patent, the PC board is first defined, and then the designer decides where the current should be fed into the PC board. Thereafter, a coordinated grid constituting a rigid structure is laid down (by photo-etching or other depositing means) to overlay each hole in the PC board with a given tolerance therein. The grid must be sized for the total current going into the PC board (for the required circular mil area or ("CMA") and thus the same ("massive") amount of copper is used everywhere. After soldering, holes are drilled into the rigid grid structure to coincide with the plurality of holes in the PC board, thus requiring that the respective holes be located at relatively "tight" tolerances during the manufacturing operations. Bolts are run through the aligned holes, and the bolts are tightened to the desired torque. The bolted connections often become loose after the equipment has been operated out in the field, owing to a number of environmental factors, and internal losses due to increased resistance are encountered in the system. With these systems, changes in the electrical resistance (even in the micro-ohm range) can equate into significant losses and result in erratic operation of the logic circuitry in the equipment. Accordingly, periodic re-tightening or re-torquing of the bolts is required, and this is an annoying service problem. Accordingly, it is an object of the present invention to alleviate the disadvantages and deficiencies of the prior art by providing a bussing system for distributing power to PC boards, wherein the system is sufficiently flexible to accommodate a variety of desired configurations. It is another object of the present invention to provide a bussing system having inherent flexibility so that the power may be distributed where it is desired, thereby facilitating the building of prototypes, substantially reducing the cost of development and tooling, and saving considerable time and material. In accordance with one aspect of the present invention, there is provided a system for distributing power from a power supply to at least one circuit panel, the panel having a selected major surface, the system being characterised in that: a plurality of taps are secured to said selected panel surface at respective selected locations, each of the taps having respective electrical contact means therein; an input connection means comprises a first input connection member mounted on said selected panel surface and a second input connection member secured to an electrical cable connectable to a power supply, said first and second input connection members being adapted to be matably engageable; and bus means distributes power from the input connection means to said plurality of taps; said bus means is flexible and comprises at least one ribbon of flexible conductive material and extends along said selected panel surface from said input connection means to said plurality of taps at said respective selected locations; said first member of said input connection means is adapted to receive and hold a selected portion of said bus means; said input connection means includes means for electrically connecting said cable to said bus means upon mating of said first and second input connection members; and each tap includes bus receiving aperture means extending from one side to another thereof in a direction substantially parallel to said selected panel surface, said aperture means receiving said bus means continuously therethrough to define a bus portion contained therewithin to which said electrical contact means of said taps are electrically connected, whereby said flexible bus means extends from said input connection means to all said plurality of taps along said panel surface and is bendable as desired such that said tap locations need not be aligned with each other. In accordance with another aspect of the invention, there is provided a system for distributing power from a power supply to at least one circuit panel, the panel having a selected major surface, the system being characterised in that: a plurality of taps are secured to said selected panel surface at respective selected locations, each of the taps having respective electrical contact means therein; an input connection means comprises a first input connection member mounted on said selected panel surface and a second input connection member secured to an electrical cable connectable to a power supply, said first and second input connection members being adapted to be matably engageable; and bus means distributes power from the input connection means to said plurality of taps; said bus means is flexible and comprises a plurality of ribbons of flexible conductive material and extends along said selected panel surface from said input connection means to said plurality of taps at said respective selected locations, said ribbons being superimposed upon one another at least at the input connection means on the panel, thereby forming a stack of ribbons, at least one of the ribbons being separable from the stack of ribbons, and bendable as desired for reception in at least one tap so as to make electrical connection with the respective electrical contact means therein, and others of said plurality of ribbon being bendable as desired for reception in other of said plurality of taps; said first input connection member of said input means is adapted to receive and hold a selected portion of said bus means; said input connection means includes means for electrically connecting said cable to said bus means upon mating of said first and second input connection members; and each tap includes bus receiving aperture means extending from one side to another thereof in a direction substant ally parallel to said selected panel surface, said aperture means receiving at least one ribbon of said bus means continuously therethrough to define a bus portion contained therewithin to which said electrical contact means of said taps are electrically connected, whereby said flexible bus means extends from said input connection means to all said plurality of taps along said panel surface and is bendable as desired such that said tap locations need not be aligned with each other. A bus bar means including at least one ribbon of flexible conductive material is connected to the input connection means. The or each ribbon is bent as desired and is received within the respective taps so as to make electrical connection with the respective electrical contact means therein, thereby accommodating current carrying capacity at any given location on the board without requiring additional conductive material beyond that which is necessary to carry the desired current, and thereby facilitating a substantially improved degree of flexibility for accommodating the distribution of the electrical power to the adjacent printed circuit boards. Preferably, the means for making electrical connections from the contact means in the respective taps to respective portions of the adjacent printed circuit boards includes plug-in terminals, thereby eliminating the traditional bolt-type of electrical connections, and thereby further eliminating the necessity for re-torquing the bolted connections at repeated intervals in servicing the equipment. In a preferred embodiment, a plurality of ribbons is employed, and the ribbons are superimposed upon one another in side-by-side relationship at least at the input connection means on the board, thereby forming a stack of ribbons. At least one of the ribbons is separated from the stack of ribbons, as desired, and is bent for reception in the respective taps. The bus bar ribbons are relatively thin and substantially flat, and may be bent into substantially mutually perpendicular planes. The conductive material of the ribbons comprises copper or copper alloy, which may be used unplated or plated with tin or silver as desired. In an alternate embodiment, respective insulation means separates the ribbons within the stack of ribbons, whereby a plurality of different voltages may be brought into the input connection means and flexibly distributed. The plurality of taps for the system may include all vertical taps wherein the bent ribbon is maintained in a vertical orientation, all horizontal taps wherein the bent ribbon is maintained in a horizontal position, or a combination of vertical and horizontal taps. The ribbon, being flexible, may be twisted substantially at right angles thereto for changing from one orientation to the other. Preferably, at least one standoff is provided between the input connection means and the taps, and at least one of the ribbons is run through the standoff, the standoff being adapted to provide mechanical stability for the distributed bus bar system and to hold the ribbon in either a vertical or horizontal orientation off the board. Reference will now be made to the accompanying drawings, in which: FIGURE 1 is a perspective of a PC board incorporating the bussing system embodying the present invention, the broken lines showing (in exploded relationship) a cable connection from the electrical power source to the input connection means on the PC board; and the view showing, first, a plurality of vertical taps, horizontal taps and standoffs, respectively, constituting the major modules of the system; and, second, further showing standard ribbons constituting relatively thin, substantially flat, flexible bus means running between the respective taps and standoffs on the top of the PC board. FIGURE 2 is a schematic illustration of a top plan view of a portion of the board of Figure 1, showing (in block diagram form) the input connection means, vertical tap, standoff, bend to a second vertical tap, and a twist at right angles to a horizontal tap. FIGURE 3 is a perspective view corresponding substantially to Figure 1, but showing portions of the input connection means, vertical taps, horizontal taps, and standoffs, respectively, in exploded relationship thereto. FIGURE 4 is a bottom plan view of the PC board of Figures 1 and 3, the electronic components and soldered interconnections being omitted for ease of illustration. FIGURE 5 is an exploded perspective of the input connection means, the cable connector leading to the power source (not shown), and the ribbons of flexible bus means of Figures 1 and 3, but drawn to an enlarged scale. FIGURE 6 is a section view, taken along the lines 6-6 of Figure 1 and drawn to an enlarged scale, and showing a cable connector within the receptacle of the input connection means on the PC board. FIGURE 7 is a stepped section view, taken along the lines 7-7 of Figure 6. FIGURE 8 is a section view, taken along the lines 8-8 of Figure 1 and drawn to an enlarged scale, and showing one of the vertical standoffs with its clamp secured thereto, the clamp having a wedge received in a complementary tapered seat in the standoff and lodged against the ribbon therein, thereby maintaining the ribbon a given distance above the top surface of the PC board, and thereby maintaining the rigidity and structural integrity of the flexible bussing system of the present invention. FIGURE 9 is a further section view, corresponding substantially to that of Figure 8, but showing the resilient fingers on the standoff being squeezed together so that the respective hook portions on the resilient fingers clear the respective openings in the top portion of the clamp such that, thereafter, the clamp may be lifted off of the standoff to release the wedge from its bearing engagement against the side of the ribbon. FIGURE 9A is a further section view, corresponding substantially to a portion of Figure 9, but showing an alternate embodiment of the standoff, wherein a plurality of ribbons is clamped therein (rather than a single ribbon as in Figure 9). FIGURE 10 is a perspective view of a standoff, showing the use of a tool to squeeze the resilient fingers together. FIGURE 11 is an section perspective view (drawn to an enlarged scale) of the vertical standoff, ribbon and clamp. FIGURE 11A is an exploded perspective view (drawn to an enlarged scale) of a horizontal standoff, ribbon and clamp. FIGURE 12 is a section view of one of the vertical taps, taken across the lines 12-12 of Figure 1 and drawn to an enlarged scale. FIGURE 13 is a perspective view of the vertical tap, showing a pair of ribbons therein, and further showing the cover for the vertical tap in exploded relationship thereto. FIGURE 13A is a perspective view of the pair of ribbons within the vertical tap, the cover being secured thereto. FIGURE 14 is a section view of the horizontal tap, taken across the lines 14-14 of Figure 1 and drawn to an enlarged scale. FIGURE 15 is an exploded perspective view of the horizontal tap, showing the contact, ribbon and cover. FIGURE 16 is a perspective view of the PC board, corresponding substantially to Figure 1, but showing the taps and standoffs constituting the modules mounted in the board but with the respective covers and clamps removed therefrom. FIGURE 17 corresponds to Figure 16, but shows the flexible ribbons constituting the respective bus means being received within the modules on the board. FIGURE 18 corresponds to a portion of Figure 17, but illustrates a right-angle twisting of the ribbon into a horizontal tap on the board. FIGURE 19 corresponds to Figure 17, but further illustrates how the ribbon may be bent on an acute (or oblique) angle, but still in its vertical orientation, thereby further illustrating the inherent flexibility and advantages of the system of the present invention. FIGURE 20 is a schematic view of three flexible ribbons in side-by-side stacked relationship, illustrating the variable circular mil area ("CMA") feature of the present invention. FIGURE 21 corresponds to a top plan view of the stacked ribbon of Figures 1-19, but further illustrates a modification thereto, wherein insulation is disposed between the respective ribbons, such that different input voltages and currents may be brought into the PC board through a single bussing system and distributed throughout the board. FIGURE 22 is a section view, taken across the lines 22-22 of Figure 21 and drawn to an enlarged scale, and showing the insulation between respective ribbons. FIGURE 23 is a top plan view of a first alternative embodiment of a vertical tap having a first alternative embodiment of the electrical contact means engaging one ribbon and pass through slots for other ribbons, the view being taken looking down on Figure 24. FIGURE 24 is a perspective section view of the vertical tap of Figure 23, taken along the lines 24-24 of Figure 23. FIGURE 25 is a top plan view of a second alternative embodiment of a vertical tap having a second alternative embodiment of the electrical contact means engaging two ribbons and a pass-through slot for another ribbon, the view being taken looking down on Figure 26. FIGURE 26 is a perspective section view of the vertical tap of Figure 25, taken along the lines 26-26 of Figure 25. With reference to Figures 1-4, there is illustrated the bussing system 10 embodying the present invention. The system 10 is embodied on circuit panel 11 having a selected major surface, the panel being adapted for distributing electrical power from a source to a plurality of adjacent circuit panels, such as PC boards or the like which may be used, for example, in a computer. These adjacent panels form no part of the present invention, hence have been omitted for ease of illustration. Accordingly, the bussing system 10 generally comprises an input connection means having a first input connection member 12 mounted on the selected panel surface and a second input connection member 22 secured to electrical cable 23, one or more vertical taps 13, and/or one or more horizontal taps 14, one or more standoffs 15, and a bus means comprising a flexible ribbon (or ribbons) 16. Taps 13 and 14 and standoffs 15 comprise the major modules of the system 10, and the modules are molded from a suitable dielectric material. Preferably, bus means or ribbons 16 are arranged in side-by-side relationship (at least at the first input connection member 12 of the input connection means) to form a stack of ribbons. For illustration purposes, two of the ribbons 16A and 16B are shown; however, it will be appreciated that just one ribbon may be employed (or any number of ribbons may be employed in side-by-side relationship) consonant with the teachings of the present invention. With this in mind, Figures 1 and 2 illustrate, first, how ribbons 16 may be "routed" between the modules on the board 11. For example, a ribbon 16B may be bent away from the stack (or "peeled off") to form a right-angle bend, as at 17, for directing ribbon 16B to a vertical tap 13. Second, Figures 1 and 2 illustrate how a ribbon (either 16A or 16B) may be twisted, as at 18, substantially at right angles from its vertical orientation so that the ribbon is disposed in a horizontal plane (substantially parallel to the panel 11) and received in a respective horizontal tap 14. The ribbons 16, which comprise the flexible bus means of the present invention, are relatively thin and relatively flat and are made of copper or copper alloy which may be used unplated or plated with tin or silver, as desired. In a practical embodiment, the ribbons 16 are 0.0508 cm (0.020 inches) thick and 1.524 cm (0.600 inches) wide. With reference to Figures 5-7, first input connection member 12 of the input connection means generally comprises two standoff portions spaced apart from one another and connected by a housing constituting a receptacle 21 therebetween. Receptacle 21 is secured to panel 11 by, for example, one or more screws 31, as shown in Figure 6. Other hardware means as known in the art may also be used to mount the standoff modules to the panel. Each of the standoff portions is substantially identical to a standoff 15 (hereinafter to be described in detail) and the two standoff portions and receptacle 21 therebetween are preferably integrally molded together as a unitary assembly. A selected portion 216 of ribbon stack 16 is received in bus receiving aperture means 75, which extends continuously through first input connection member 12. Bus means or ribbon stack 16 is gripped between the two standoff portions of the unitary assembly and is disposed within receptacle 21 therein. In the embodiment shown herein, receptacle 21 is adapted to receive a complementary second input connection member 22, which carries an electrical cable 23 leading to the power source (not shown herein). It is to be understood that power may be supplied to the input connection means by "blind mating" it directly to a power supply through a drawer connector or the like. Conventionally, power is brought to a mother board in a vertical orientation. Respective bifurcated side portions 24 of second input connection member 22 are adapted to be received in respective slots 25 in receptacle 21 as second input connection member 22 is received therein, and these respective bifurcated side portions 24 are sufficiently flexible to be cammed outwardly as latching portion 26 of side portions 24 rides up over an outwardly inclined ledge 27 formed integrally with receptacle 21. Thereafter, respective ledges 27 are received in respective slotted openings 28 in the bifurcated side portions 24 and are "snapped" therein with a detent-type of action, thereby removably retaining second input connection member 22 in receptacle 21 of first input connection member 12. The second input connection member 22 carries resiliently biased respective contacts 29 which grip ribbons 16 therebetween, as shown more clearly in Figure 6, and effect electrical connection from cable 23 to ribbons 16. With respect to Figures 8-11, vertical standoff 15 comprises housing 30 secured to panel 11 by means of screw 31 or other mechanical means known in the art. The housing has bus receiving aperture means comprising a tapered slot 32 formed therein. Standoff 15 further comprises clamp 33 having depending tapered wedge 34 adapted to be received in the tapered slot 32. The wedge 34 is lodged against the side of selected portion 516 of the ribbon (or ribbons) 16 within slot 32 so as to securely retain ribbons 16 therein. Clamp 33 has a top portion 35 provided with a pair of spaced-apart openings 36 formed therein. Housing 30 has a pair of complementary spaced-apart resiliently-biased fingers 37 integrally molded therewith. Fingers 37 are adapted to be received in respective pairs of openings 36 in top portion 35 of clamp 33. Each of the fingers 37 has an outwardly-extending hook portion 38 adapted to be lodged over top portion 35 of clamp 33, thereby retaining clamp 33 on housing 30. The resiliently-biased fingers 37 may be squeezed together by a pliers 39 or suitable tool (as shown more clearly in Figure 10) so as to clear hooks 38 through respective openings 36 in top portion 35 of clamp 33, thereby allowing clamp 33 to be removed from housing 30. Thereafter, ribbon 16 may be lifted out of slot 32 in housing 30 of vertical standoff 15. With reference to Figure 9A, an alternate embodiment of vertical standoff, denoted by 15', is illustrated. Standoff 15' has an identical housing 30 (as standoff 15 of Figures 8-11) but is provided with an alternate clamp 33' having a thinner tapered wedge 34'. This alternate standoff 15' is adapted for retaining a plurality of ribbons 16. However, the components and operation of the standoff 15' of Figure 9A (including its openings 36, resilient fingers 37, and hooks 38) are identical to that of standoff 15 of Figure 9, thereby resulting in a standardization of molded parts for manufacturing economy. In a practical commercial embodiment of the standoffs, one, two, or three ribbons 16 (stacked side-by-side) may be employed, in which case only the wedge portion 34 of the clamp 33 is different. However, it may be appreciated that the standoffs could be made to accommodate more than three ribbons 16, if desired, consonant with the teachings of the present invention. Figure 11A is a section view of a horizontal standoff 115. Standoff 115 is comprised of housing 130 and clamp 134. In the assembled standoff, selected portion 616 of ribbon 16 is received in and passes through bus receiving aperture means 77 which comprises a space between the top surface 230 of housing 130 and bottom surface 234 of clamp 134. Since ribbon 16 is inserted horizontally into standoff 115, housing 130 does not require a vertical slot as does vertical standoff 15. There is no corresponding wedge required on clamp 134. In other respects, however, housing 130 is essentially identical to vertical standoff housing 30. Clamp 134 attaches to housing 130 using the same components and operation of openings 36, resilient fingers 37 and hooks 38. The thickness of clamp 134 may be varied to provide sufficient space 77 between the lower surface of clamp 134 and upper surface of housing 130 to accommodate a plurality of ribbons 16, thereby resulting in a standardization of molded parts for manufacturing economy. With reference to Figures 12, 13 and 13A, vertical tap 13 includes an insulated or dielectric base 40. A contact 41 is carried by the base 40, and contact 41 has respective portions extending above and below the base. The portion of the contact 41 extending above the base 40 is slotted to form respective pairs of resiliently-biased contact members 42 disposed in a parallel stacked relationship with each other and defining therebetween a contact plane comprising a bus receiving aperture means or slot 43 for receiving at least one of the ribbons 16 such that selected portion 316 of ribbon 16 makes an electrical connection with the contact 41 in the vertical tap 13. The respective portions 44 of contacts 41 extending below base 40 is preferably formed as a compliant pin, such as the one disclosed in U.S. Patent 4,186,192 wherein a section of the pin is sheared or split to form a pair of offset legs which fit into and grip the walls of through holes 19 in the panel or printed circuit board without damaging the plated surface of the holes of the printed circuit board. The legs of the compliant pin described therein move inwardly as the pin is inserted, thereby producing an opposing force between the legs and the plated through hole, thus anchoring the component on the board and providing electrical connection to the undersurface of the board. It is to be understood that other means and other contacts, such as those having solder posts, may also be used to mechanically anchor and electrically connect components to the board. Each of the vertical taps 13 includes a cover 45 adapted to be received on its base 40 to enclose the contact 41 and the ribbon 16 therein. The cover 45 is also integrally molded of a suitable dielectric material and, preferably, is substantially prismatic and is provided with aligned slots 46 to accommodate the passage of the ribbon 16 through the vertical tap 13. The cover 45 includes a pair of parallel side walls 47. The side walls 47 have respective inwardly-protruding longitudinal ribs 48 formed thereon, one of which is shown more clearly in Figure 13; and the base 40 has a pair of complementary longitudinal relieved portions 49, one on each side thereof, such that the cover 45 may be received over the base 40 and snapped in place. With reference to Figures 14 and 15, horizontal tap 14 includes a cover 50 and further includes at least one contact 51 having a portion 51a thereof bent substantially at right angles thereto so as to be substantially parallel to panel 11 when horizontal tap 14 is mounted on panel 11. The portion 51a of the contact 50 is formed with a plurality of resiliently-biased contact members 52 having bus receiving aperture means or slot 76 defined therebetween, which receives therein a selected portion 416 of ribbon 16 (similar to the contact members 42 of vertical tap 13, but arranged in a horizontal rather than a vertical plane). Horizontal tap 14 further includes a plurality of posts 53 which are anchored in respective through holes 19 in board 11. These posts 53 are suitably connected to a high-density ("HDI") connector 90 carried by an adjacent PC panel or board. The HDI connector, being conventional, has been illustrated only partially in Figures 1 and 14. A retention locking spring 54 locks the posts 53 to the contact 51. The modules of the present invention are integrally molded from a suitable dielectric material, and the various contacts are stamped and formed from a suitable metal. With reference to Figures 16-19, the inherent utility, features, and advantages of the bussing system of the present invention will become more readily apparent. In Figure 16, the major modules of the system --including the first input connection member 12, vertical taps 13, horizontal taps 14, and standoffs 15 -- have been arranged on board 11 at locations convenient for interconnection to existing PC boards or the like. This arrangement provides the engineer or designer (or even the installer) a much desired flexibility in tailoring the panel 11 (or backplane) to a wide variety of configurations and existing installations, thereby substantially reducing the time factors involved, and thereby effecting a substantial reduction in development and tooling costs. In Figure 16, the respective covers for the major modules on the board have been removed. Thereafter, and as shown in Figure 17, a single ribbon 16 (provided on coil C) is routed between the major modules of the system 10 on the board 11. The ribbons 16 which are made of relatively soft, plated or unplated, copper or copper alloy (and are relatively thin and substantially flat) are fed from one module to another --in this case, from first input connection members 12 through a first vertical tap 13 and then through a standoff 15 -- thereby quickly and easily routing the ribbons 16 around the panel 11. As shown in Figure 18, the ribbon 16 has been twisted at right angles thereto for passing the ribbon 16 through a first horizontal tap 14. As the routing of the ribbon 16 has been effected (partially or completely), the covers may be installed on the modules, respectively. With reference to Figure 19, a pair of ribbons 16 is employed, being in side-by-side stacked relationship to one another, and constituting a first ribbon 16A and a second ribbon 16B. The ribbons 16A and 16B are clamped within the receptacle 21 of the first input connection member 12 (for electrical connection with the second input connector member 22) and the "first" part of the ribbons 16A and 16B extend from the receptacle 21 through a first vertical tap 13 and a first standoff 15. Ribbon 16A continues through a second standoff 15 and, thereafter, ribbon 16A is twisted at right angles thereto (as at 18) and is received within a first horizontal tap 14. Ribbon 16B is bent at right angles thereto (but still maintained in a vertical orientation) and is received within a second vertical tap 13 and into a second horizontal tap 14. The "rear" part of ribbons 16A and 16B pass out the opposite end of receptacle 21 and through a third standoff 15. Thereafter, ribbon 16B is bent away from ribbon 16A and passes into a pair of vertical taps 13a and 13b arranged in a stacked formation and comprising a third vertical tap and a fourth vertical tap. The ribbon 16B is bent at an acute (or oblique) angle, which further illustrates the total flexibility of the system of the present invention; that is, the flexible ribbons 16 of the distributed bus bar system of the present invention may be bent and/or twisted as desired for a particular set of conditions so that the designer is not constrained but, rather, has almost complete freedom to readily produce a board (or backplane) as may be needed. This is a substantial improvement heretofore not available in the prior art. Of still further significance, the flexible bus bar system of the present invention provides a variable "CMA" (circular mil area) feature, so that sufficient current-carrying capacity is available at any place on the board without requiring extra (or "massive") material beyond that which is necessary to carry the desired current, thereby resulting in a considerable savings in material costs. For example, and as illustrated schematically in Figure 20, a stack of three ribbons (16X, 16Y, and 16Z), each carrying ten (10) amps is employed. The input consisting of thirty (30) amps (in this example) is accommodated by all three ribbons (16X, 16Y, and 16Z) in region 55; twenty (20) amps is accommodated in region 56 (ribbons 16Y and 16Z); and ten (10) amps is accommodated in region 57 (ribbon 16Z) which has a still smaller CMA. With reference to Figures 21 and 22, an alternate embodiment is illustrated, wherein the flexible ribbons 16R, 16S and 16T have insulation 58 disposed therebetween. With this arrangement, the flexible bus bar of the present invention is adapted to distribute electric current around a printed circuit board, and the insulation on the bus bar allows multiple bus bars to be routed in close physical proximity while remaining electrically isolated. Adjacent insulated bus bars may carry identical voltages or different voltages, depending upon the design of the board. The insulation 58 may be of any suitable type, preferably a strippable type so that connection can be made to the bus bar at numerous places along its length as the bus bar is routed around the printed circuit board. Figure 21 also illustrates vertical tap module 113 having housing 140 which includes a plurality of vertical taps 113A, 113B and 113C, one for each of bus bar ribbons 16R, 16S and 16T such that a plurality of bus bars can be terminated in a single housing member. The flexibility of ribbons 16R, 16S and 16T permit them to enter housing 140, be bent to enter respective taps 113A, 113B or 113C, and bent again to exit housing 140. With reference to Figures 23 and 24, an alternate vertical tap 59 is illustrated which is capable of terminating to a printed circuit board, preferably by means of compliant pins or solder tabs as previously described. Tap 59 has a molded dielectric housing 60 preferably having a flat top 61 for ease of inserting the tap into the board with conventional tooling. Housing 60 is slotted, as at 62, to receive one or more contacts 63. Contact 63 -- referred to in the art as a "tuning fork" contact -- is bifurcated to receive flexible bus bar ribbon 16 and has compliant pin portion 64 which extends through board 11 and is securely gripped therein. The amperage rating for the module can be varied by providing a plurality of contacts. Additional (parallel) slots 65, not having electrical contacts therein, may be formed in the plastic housing 60 to mechanically support additional bus bars 16 if desired. It is to be understood that tap 59 may be used with bare or insulated bus bars, and with bus bars having identical or multiple voltages. With reference to Figures 25 and 26, a further vertical tap module 66 is illustrated, wherein plastic housing 67 is slotted as at 68 to receive one or more dual contacts 69. These dual contacts 69 will allow current to be taken off of two bus bar ribbons 16. In this embodiment, both bus bar ribbons passing through contact 69 would carry the same voltage. Thus, if each bus bar 16 is rated (for example) at twenty (20) amps, then the module 66 could tap off up to forty (40) amps from the two bus bars 16. The number of contacts 69 on the module 66 may be increased, if required, to handle the current. An additional section can be added to the plastic housing 67 to provide a slot 70 to mechanically support a third bus bar. This third bus bar is not terminated in this housing 67, and thus no contacts are disposed in the slot 70.

Claims: A system (10) for distributing power from a power supply to at least one circuit panel, the panel having a selected major surface, the system being characterised in that: a plurality of taps (13,14) are secured to said selected panel surface at respective selected locations, each of the taps having respective electrical contact means therein; an input connection means comprises a first input connection member (12) mounted on said selected panel surface and a second input connection member (22) secured to an electrical cable (23) connectable to a power supply, said first and second input connection members (12), (22) being adapted to be matably engageable; and bus means (16) distributes power from the input connection means to said plurality of taps; said bus means (16) is flexible and comprises at least one ribbon of flexible conductive material and extends along said selected panel surface from said input connection means to said plurality of taps at said respective selected locations; said first member (12) of said input connection means is adapted to receive and hold a selected portion (216) of said bus means (16); said input connection means includes means for electrically connecting said cable to said bus means (16) upon mating of said first and second input connection members (12), (22); and each tap includes bus receiving aperture means extending from one side to another thereof in a direction substantially parallel to said selected panel surface, said aperture means receiving said bus means (16) continuously therethrough to define a bus portion contained therewithin to which said electrical contact means of said taps are electrically connected, whereby said flexible bus means (16) extends from said input connection means to all said plurality of taps along said panel surface and is bendable as desired such that said tap locations need not be aligned with each other. The system of claim 1, wherein said flexible bus means (16) is relatively thin and substantially flat, and may be bent into substantially mutually perpendicular planes. The system of claim 1 or 2, wherein said flexible bus means (16) comprises a plurality of ribbons, the ribbons being superimposed upon one another in side-by-side relationship at least at the input connection means on the panel, thereby forming a stack of ribbons,and wherein at least one of said plurality of ribbons is separable from the stack of ribbons, and is bendable as desired for reception in at least one of said plurality of respective taps, said others of said plurality of ribbons being bendable as desired for reception in others of said plurality of taps. A system (10) for distributing power from a power supply to at least one circuit panel, the panel having a selected major surface, the system being characterised in that: a plurality of taps are secured to said selected panel surface at respective selected locations, each of the taps having respective electrical contact means therein; an input connection means comprises a first input connection member (12) mounted on said selected panel surface and a second input connection member (22) secured to an electrical cable (23) connectable to a power supply, said first and second input connection members (12), (22) being adapted to be matably engageable; and bus means (16) distributes power from the input connection means to said plurality of taps; said bus means is flexible and comprises a plurality of ribbons of flexible conductive material and extends along said selected panel surface from said input connection means to said plurality of taps at said respective selected locations, said ribbons being superimposed upon one another at least at the input connection means on the panel, thereby forming a stack of ribbons, at least one of the ribbons being separable from the stack of ribbons, and bendable as desired for reception in at least one tap so as to make electrical connection with the respective electrical contact means therein, and others of said plurality of ribbon being bendable as desired for reception in other of said plurality of taps; said first input connection member (12) of said input means is adapted to receive and hold a selected portion (216) of said bus means (16); said input connection means includes means for electrically connecting said cable (23) to said bus means (16) upon mating of said first and second input connection members (12), (22); and each tap includes bus receiving aperture means extending from one side to another thereof in a direction substantially parallel to said selected panel surface, said aperture means receiving at least one ribbon of said bus means (16) continuously therethrough to define a bus portion contained therewithin to which said electrical contact means of said taps are electrically connected, whereby said flexible bus means extends from said input connection means to all said plurality of taps along said panel surface and is bendable as desired such that said tap locations need not be aligned with each other. The system of claim 3 or 4, wherein the ribbons are relatively thin and substantially flat, and may be bent into substantially mutually perpendicular planes. The system of claim 3, 4 or 5, further including respective insulation means (58) separating the ribbons within the stack of ribbons, whereby a plurality of different voltages may be brought into the input connection means and distributed throughout the panel. The system of any preceding claim, wherein said bus receiving aperture means is a vertical slot (43) through said tap, said slot defining a vertical tap (13), the vertical tap (13) comprising an insulated base (40), wherein the electrical contact means comprises a contact (41) carried by the base (40), the portion of contact (41) extending above the base including respective pairs of resiliently biased contact members (42) disposed in a parallel stacked relationship with each other and defining therebetween a contact plane and a bus receiving aperture means (43) for receiving at least one ribbon, whereby the at least one ribbon makes an electrical connection with the contact in the vertical tap (13). The system of any preceding claim, wherein the taps include at least one horizontal tap (14), comprising at least one contact (51) having a portion (51a) thereof bent substantially at right angles thereto so as to be substantially parallel to the panel when the horizontal tap (14) is mounted on the panel, said portion (51a) having a plurality of resiliently biased contact member (52), which define a contact plane therebetween for receiving at least one ribbon therebetween, whereby the at least one ribbon makes an electrical connection with the contact (51) in the horizontal tap (14), and a cover (50) fitting over the contact (51), the cover including latch means for locking the ribbon and the contact together. The system of any preceding claim, further including at least one vertical standoff (15) between respective taps, the standoff (15) being adapted to hold at least one ribbon in a vertical attitude and at a distance off of the panel, thereby providing mechanical stability to the bus means (16), the vertical standoff (15) comprising a housing (30), means for securing the housing (30) of the standoff to the panel (11), the housing (30) having a tapered vertical slot (32) formed therein for receiving at least one ribbon therethrough, a clamp (33) having a depending wedge (34) adapted to be received in the slot (32) in the housing and to be lodged against at least one layer or ribbon, thereby retaining at least one layer in the slot, the clamp (33) further including means for latchably engaging said housing (30). The system of any preceding claim, further including at least one horizontal standoff (115) between respective taps, the standoff (115) being adapted to hold at least one ribbon in a horizontal attitude and at a distance off of the panel, thereby providing mechanical stability to the bus means (16), the standoff comprising a housing (130), means for securing the housing of the standoff to the panel, the housing having a clamp (134) adapted to engage the housing (130) and defining a slot (77) between the housing (130) and clamp (134) such that at least one layer or ribbon may be lodged therebetween, the clamp (134) further including means for latchably engaging said housing (130).

Inventors: HIMES, JOHN LEWIS, JR., WISE, JAMES HENRY
Applicants: AMP INCORPORATED
Application year: 1988
Main classification: H02G5
IPC codes: H01R12, H01R24, H02G5