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INTERCONNECTED MULTIPLE CIRCUIT
BACKGROUND OF THE INVENTION
1. Field or the Invention
The present invention relates to multiple circuit modules which are used in electronic devices such as highspeed digital computers of the type produced by Cray Research, the assignee hereof. Specifically, the present invention relates to an improved multiple circuit module which requires less force to assemble and reduces cross-talk between circuit paths.
2. Description of the Prior Art Circuit boards are utilized in many types of electronic
equipment and it is often necessary, particularly in complex equipment, to interconnect the circuit boards into a module, and to interconnect modules into multiple circuit modules. For example, high-speed electronic digital computers of the type produced by Cray Research 20 utilize circuit modules consisting of four circuit boards mounted in close proximity on opposite sides of two cooling plates. Such circuit modules are arranged in banks and it is, therefore, desirable to interconnect adjacent circuit boards within a module in a manner which permits convenient disconnection for service and reconnection after service, and which also permits reversed stacking for testing.
One previously known example of an interconnected multiple circuit module is disclosed in U.S. Pat. No. 4,514,784 to Williams et al. In this apparatus, conductive pins were used to transmit signals from one circuit module to another. Electrical connection between the pins was accomplished by connector blocks positioned between the modules having bores defined therein for receiving the pins. This type of module connection was a great improvement over previous designs because it minimized twisting and misalignment of the connector elements, while facilitating connection over the shortest circuit paths.
However, as the architecture of high-speed electronic digital computers evolves, greater switching speed and circuit density are required. As circuit density increases, a greater number of connections are necessary between modules, thereby increasing the total force needed to connect the modules. In addition, as circuit density is increased, it becomes increasingly likely that induction caused by the transmission of a signal through a first circuit path will possibly affect the operation of an adjacent path. This phenomenon is known as cross-talk, and is a major impediment to improved circuit density in high-speed digital computers.
It is clear that there has existed a long and unfilled need in the prior art for an improved interconnected multiple circuit module which reduces the aggregate force necessary for assembly and disassembly, and which reduces inductive interference between adjacent circuit paths.
board having a plurality of pin receiving recesses defined therein; a plurality of cold plates positioned between the circuit boards in each of the facing pairs, respectively, for conducting waste heat away from the circuit boards, each cold plate having an open space defined therein for allowing electronic communication between the circuit boards; a plurality of pin headers positioned within the open spaces, respectively, each having a plurality of through-holes defined therein; at least one connector block interposed between two of the pin headers, the connector block having a plurality of connector through-holes defined therein; a plurality of electrically conductive signal pins for conducting electrical signals from one of the circuit boards to another of the circuit boards, the signal pins being selectively insertable in the pin receiving recesses, the through-bores and the connector bores, depending on the desired path of the signals; and shielding structure for shielding a selected number of signal pins against induction from other signal pins, whereby electric cross-talk between circuits is reduced.
These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side cutaway view, taken partially in cross-section, of a circuit module constructed according to a first embodiment of the present invention;
FIG. 2 is a top plan view of a connector block according to the embodiment of FIG. 1 or FIG. 7, with parts broken away for clarity;
FIG. 3 is a cross-sectional view taken along lines 3—3 in FIG. 2;
FIG. 4 is an isolated view of the metallic shielding element in the embodiment of FIG. 2;
FIG. 5 is a top view of the connector block in the embodiment of FIG. 1 or FIG. 7, with parts broken away for clarity;
FIG. 6 is a cross-sectional view taken along lines 6—6 in FIG. 5;
FIG. 7 is a side cutaway view of a circuit module constructed according to a second embodiment of the instant invention, taken partially in cross-section;
FIG. 8 is a top schematic view illustrating one species of shielding which may be used in a pin header or connector block according to either embodiment of the present invention;
FIG. 9 is an isolated perspective view of a first species of connector pin according to the embodiment of FIG. 7;
FIG. 10 is an isolated perspective view of a second species of connector pin according to the embodiment of FIG. 7;
FIG. 11 is an isolated perspective view of a third species of connector pin according to the embodiment of FIG. 7;
FIG. 12, is a top schematic view of an alternate species of shielding which may be used in either embodiment of the present invention;
FIG. 13 is a side view of the shielding arrangement illustrated in FIG. 12, with parts broken away for clarity; and
FIG. 14 is an alternate bottom view of the arrangement illustrated in FIGS. 12 and 13, with parts broken away for clarity.
DETAILED DESCRIPTION OF THE
Referring now to the drawings, wherein like reference numerals designate corresponding elements throughout the views, and particularly referring to FIGS. 1-6, there is shown an improved interconnected multiple circuit module 10 according to a first preferred embodiment of the invention. As is best illustrated in FIG. 1, circuit module 10 includes a plurality of planar circuit boards 12a through 12d, generally referred to as 12, which are arranged to extend in a parallel, spaced relationship. In order to maintain the circuit boards 12 at a proper operating temperature, pairs of circuit boards 12a, 12b and 12c, 12d are disposed about cold plates 14a and 14b respectively, generally referred to as 14. Cold plates 14 conduct excess heat energy away from the circuit boards as described in U.S. Pat. No. 4,628,407 and is described in co-pending patent application Ser. No. 07/284,992, entitled "Cold Plate With Interboard Connector Apertures for Circuit Board Assemblies", filed on the same date as the present patent application and assigned to the assignee of the present patent application. The two pairs of circuit boards 12 disposed about two cooling plates 14 form a single module. Each pair of circuit boards 12 is secured to cold plate 14 by a spacer/connector assembly 16 which includes a pair of spacers 18 disposed between the circuit boards 12 and cold plate 14, a threaded stud 20 and a pair of fastening nuts 22, as is shown in FIG. 1.
In order to permit communication between circuitry on the various circuit boards 12, a number of open spaces are defined by surfaces 24 on each of the cold plates 14, as is shown in FIG. 1. Each of the spaces defined by surfaces 24 extend through the entire width of the corresponding cold plate 14 and has a pin header block 26 secured by means of a bolt 32 which extends through a mounting hole 31 in a tab portion of the pin header block 26, and into cold plate 14 so that tab 30 is pulled tightly against cold plate 14. Each of the pin header blocks 26 is provided with an array of throughbores or holes 36 defined therein which may be coincident with pin receiving recesses or bores defined in the attached circuit boards 12. The pin header blocks 26 may be manufactured with a pre-defined array of holes such that all the holes may not be used in a particular application. The pin header blocks 26 may also contain various types of shielding (as described in more detail 55 below) to minimize cross-talk between adjacent pins.
In order to provide electronic signal, voltage and ground communication between the various circuit boards 12, a plurality of conductive pin members 38 extend through the recesses provided in circuit boards 12 and through the bores 36 and pin headers 26. Pins 38 may be electrically connected to circuitry on each of the various circuit boards 12 by soldering, or such connection may be effected by plating the surfaces defining the pin receiving recesses or holes on circuit boards 12. In the preferred embodiment, pins 38 are soldered to one of the circuit boards 12 of the half module to hold them in place during assembly and disassembly.
A complete circuit module is formed from four circuit boards and two cold plates, two circuit boards sandwiching each cold plate. A half circuit module is formed of a single pair of circuit boards 12, a single cold plate 14 and a pin header block 26. In order to interconnect two half modules, pins 38 may be provided with first and second end portions 40, 42, respectively, the second end 42 of which extend outwardly beyond the surfaces of circuit boards 12b and 12c. As shown in FIG. 1, a connector block 28 is freely disposed between a pair of such half modules and has an array of connector through-holes 46 defined therein for receiving end portions 42 of the connector pins 38. For example, as is shown in FIG. 1, connector hole 46 receives the second end portion 42 of pin 38 from the upper half module and a corresponding pin end portion from the lower half module so as to electrically connect the two pins 38 by means of a dual entry contact or other suitable means (not shown in FIG. 1, but described in more detail below in conjunction with FIG. 3). The two half modules are secured together by suitable means and spaced apart by means of spacer 34 controlling the amount of space and gaps between the upper and lower half modules.
The connector blocks 28 may be manufactured with a pre-defined array of holes such that all the holes may not be used in a particular placement on the circuit module. The connector blocks 28 may also contain various types of shielding (as described in more detail below) to minimize cross-talk between adjacent pins.
Referring to FIGS. 2-4, a preferred construction of connector block 28 will now be described. As shown in FIGS. 2 and 3, connector holes 46 may be either of a signal pin opening type 48 or a constant potential opening type 50, which is used to supply a ground or DC voltage connection between the various circuit boards. As best shown in FIG. 3, each of the signal pin openings 48 are formed by a pair of conical recesses 58 connected to cylindrical bores 59 which, in turn, open out into a cavity defined in the connector block 28 by a surface 52. A contact element 56 is disposed within the cavity defined by surface 52, and is formed of a resilient, electrically conductive material. Contact element 56 includes an inner surface having contact points 60 which are adapted to contact the outer surfaces of pins 38 when the pins are inserted into signal pin opening 48. Thus, electric signals may be transmitted from one pin 38 to another pin 38 when each pin is inserted into one end of the same signal pin opening 48.
Constant potential pin openings 50 are preferably defined as a cylindrical bore in connector block 28 by a surface 54. A constant potential contact element 64 which is preferably made of an electrically conductive resilient material is disposed within the board defined by surface 54 and includes a pair of inner contact points 62 which are adapted to contact outer surfaces of any ground or voltage connection pins 38 inserted therein. Thus, ground and voltage connection may be achieved between the various circuit boards 12.
The ground and voltage connections between circuit boards in a module are typically made between edge connectors and backplanes to supply voltages and ground current return paths for the operating logical circuits located on circuit boards 12. Electrical signals propagating between circuit boards 12a-12d require that a signal path be established from one board to another and a voltage or ground current return path also exists for the requisite current to flow. Traditionally,