CIRCUIT BOARD CONNECTIONS

Abstract: A circuit board comprises a carrier board which functions as a base structure to which is attached rigidly at least one electronics components card to form a wafer assembly where edge connectors to the components card are free for access, said card being attached to the carrier board by at least two rigid mechanical connectors for example glued plastic fasteners/screws or bolts, nuts and spacer means to maintain the carrier board and card at a selected separation.

Description: TITLE: CIRCUIT BOARD CONNECTIONS FIELD OF THE INVENTION: This invention relates to circuit board connections and methods of connecting circuit boards to provide circuit boards of a desirable format and to provide such boards with a rigid structure. BACKGROUND OF THE INVENTION: Circuit boards or cards provide the essential circuitry for many electronic products, including micro computers. Thus, the boards may bear printed circuits connecting microprocessors, transistors etc. These boards are often arranged in stacks which may be electrically connected. It may be necessary to disconnect a board and replace it if some component on the board proves faulty. Personal computer cards are of great interest to designers of equipment for technical, industrial or professional applications because of the broad range of cards available, the great variety of software and , typically, the availability of more than one source of supply. The electronic equipment on such cards is generally very good, it is only the mechanical side which causes problems. A particular problem which has developed over the years relates to variations in dimensions, for example, of personal computer cards from different sources, with respect to carrier boards so that the cards cannot be mounted in well-defined positions on the boards. This can, for example, result in mechanical instability if the computer cards cannot be attached rigidly to any brackets provided. Another serious problem which has developed relates to the lack of mechanical stability of stacks of certain circuit boards, particularly personal computers and microcomputers. For example, a personal computer card bearing printed circuits and electronic components may be "attached" to a carrier board. The "attachments" may comprise, for example, a single, vertically-oriented bracket mounted at one edge of the computer card and the electrical connections either between individual boards or to individual boards from external power sources or peripheral items of equipment. Neither, type of "attachment" is satisfactory. Thus, the computer card may shift up and down around the point or points of attachment. Furthermore, the electrical connectors are not designed to provided stability to the structure. Another problem which occurs relates to loose cables in compartments holding circuit boards. If the circuit boards are misaligned or relatively free to move within the compartment, this looseness in itself increases the difficulty of maintenance. Even "maintenance"causes problems where the "repairer" makes wrong connections. It is another object of this invention to eliminate the need to connect or disconnect individual cables when inserting or removing a circuit board. A considerable number of inventions relating to plug-in modules have been published in the patent literature. Many of these inventions incorporate rail guidance systems. The present invention is not related to such plug-in modules. In Australian patent no. 609017 (36746/39) Teknekron Infoswitch Corporation a plug-in card module is described. A printed circuit board forming part of the module is provided with elongate rail means to receive an electronic circuit board "slidably supported in each pair of elongate guide rails". The present invention is not concerned with such a plug-in card module or with such slidable support means for electrical circuit boards, This invention has three principal objects, firstly, to provide a carrier for circuit boards of differing dimensions so that a circuit board in one format may be converted to a different format and, accordingly, be usable in a modular form. SUBSTITUTE SHEET secondly, to improve the mechanical stability of stacks of circuit boards and thirdly, to make maintenance of circuit boards easier and less prone to errors. In this specification the word "format" is used to refer to the size and shape of a particular circuit board and also to refer to the placement of connectors in standardised positions. Furthermore, in this specification the term "wafer assembly 7 ' refers to structures in which some of the original connectors to electronic components cards are free for access, for example, the edge connectors on such cards. BRIEF SUMMARY OF THE INVENTION: This invention, therefore, provides a circuit board which comprises a carrier board, which functions as a base structure, to which is attached rigidly at least one electronic components card to form a wafer assembly, each card being attached to the carrier board by at least two rigid, mechanical connectors as defined herein. This invention further provides an array or stack of such circuit boards which comprises a plurality of circuit boards attachable movably or irremovably with respect one to another. This invention further provides a method of attaching rigidly at least one electronics components card to a carrier board to form a circuit board, the carrier board and electronics components card(s) forming a wafer assembly, which comprises the steps of: (a) aligning the card with designated regions of the carrier board; and (b) attaching the card to the carrier board using at least two rigid, mechanical connectors, as defined herein; SUBSTITUTE SHEET whereby the circuit board takes up a selected, standardised format and unwanted movements of portions of the circuit board with respect to each other are minimised. BRIEF DESCRIPTION OF THE DRAWINGS: Embodiments of the invention are illustrated in the accompanying drawings in which:- Figure 1A is a plan view, Figure IB is an exploded perspective view of one example of a circuit board according to the invention and Figure 1C is a detail of a component shown in Figure 1A and IB; and Figure 2A is a perspective view of a single circuit board according to the invention with an attached front panel and Figure 2B is a perspective view of a stacked set of the circuit boards of Figure 2A. DETAILED DESCRIPTION OF THE INVENTION: This invention has particular reference to personal computer cards, more particularly computer cards made to comply with IBM PC physical format. It is desirable to have carrier boards of a standard size which are sufficiently extensive in area to accommodate electronic components cards of various sizes. Thus the standard-sized carrier boards may be arranged in stacks housed in standard-sized racks. The "rigid, mechanical connectors" are , for example, fasteners of a suitable inert plastics material which may be glued to the carrier boards and cards to maintain them at a selected separation. Alternatively the connectors may comprise screws or nuts, bolts and spacer means, the spacer means being adapted to maintain the carrier boards and cards at a selected separation. The essential criterion is that the connection between the carrier boards and cards must be such that the components SUBSTITUTE SHEET are substantially rigidly connected given normal usage over the life-span of an item of equipment comprising the carrier board/card components. If the card is generally rectangular in shape, as is usually the case, it is convenient to position the connectors at each corner of the rectangle. Alternatively or in addition it may be desirable for greater rigidity to position one or more connectors at a point or points along each side of the rectangle. Turning to the construction of an array or stack of a plurality of circuit boards, it is convenient to slot the edges of such circuit boards into an arrangement of elongated apertures, positioned to receive the edges, in a suitable rack, for example, to comply with existing international standards. The circuit boards themselves can, of course, be arranged horizontally or vertically. With respect to the method according to the invention, a card may be aligned with designated regions of the carrier board by use of a jig or template. Thus, where a number of cards and carrier boards are to be assembled to form a circuit board, the operation may be automated by any suitable means. Turning to the drawings, in Figure 1A and IB a circuit board 1 comprises two principal components, a carrier board 2 which is attached , to form a wafer assembly, to a computer (electronic components) card 3 by means of a rigid, mechanical connector 4. This connector 4 takes the form of a bolt 4A provided with a washer 4B and nut 4C and is located adjacent one corner of card 3. Separator pads 5 are located at various points along sides of the card 3 by means of slot 6 along one end face of each pad; see detail in Figure 1C. At the right hand side of card 3 is located a perpendicular bracket 7, which may be part of the original card but with this arrangement is not necessary; see Figure 2A. Numeral 3 refers to edge connectors. SUBSTITUT! SHEET 93/20673 Turning now to Figure 2A and 2B, each circuit board 1 is provided in use with a lateral fascia plate 9 for use in constructing a stack of circuit boards. Each fascia plate is provided with vertically oriented (as viewed in use ) handles 10. Adjacent that corner of the end provided with attachment 4 is an electronic circuit connector 11. With particular reference to Figure 2B, a back plane 12 is provided to electrically • connect the circuit boards by means of sockets 13 interconnecting the original connectors on cards 3. SUBSTITUTE SHEET

Claims: The claims defining the invention are as follows: 1. A circuit board which comprises a carrier board, which functions as a base structure, to which is attached rigidly at least one electronic components card to form a wafer assembly, as defined herein, each card being attached to the carrier board by at least two rigid, mechanical connectors, as defined herein. 2. A circuit board as claimed in claim 1, wherein the carrier board is of a standard size which is sufficiently extensive in area to accommodate cards of various sizes. 3. A circuit board as claimed in claim 1 or claim 2, wherein each card is generally rectangular in shape and connectors are positioned at each corner of the rectangle. 4. A circuit board as claimed in any one of claims 1 to 3, wherein one of more connectors are positioned at a point or points along each side of each card. 5. An array or stack of circuit boards as claimed in any one of claims 1 to 4 which comprises a plurality of circuit boards attachable movably or irremovabl with respect one to another. 6. An array or stack of circuit boards as claimed in claim 5, wherein the edges o the circuit boards are slotted into an arrangement of elongated apertures, positione to receive the edges, in a suitable rack. 7. A method of attaching rigidly at least one electronics components card to carrier board to form a circuit board, which functions as a base structure, the carrie board and electronics components card(s) forming a wafer assembly, whic comprises the steps of : (a) aligning the card with designated regions of the carrier board; and (b) attaching the card to the carrier board using at least two rigid, mechanic connectors, as defined herein; SUBSTITUTE SHEET 93/20673 8 whereby the circuit board takes up a selected, standardised format and unwanted movements of portions of the circuit board with respect to each other are minimised. 8. A circuit board as claimed in claim 1, substantially as described with reference to the accompanying drawings. 9. An array or stack of circuit boards as claimed in claim 5, substantially as described with reference to the accompanying drawings. 10. A method as daimed in daim 7, substantially as described with reference to the accompanying drawings. SUBSTITUTE SHEET

Inventors: JANIAK ANDREW, JANIAK, ANDREW
Applicants: JANIAK ANDREW, JANIAK HOLDINGS PTY LTD, JANIAK HOLDINGS PTY. LTD.
Application year: 1993
Main classification: H05K1
IPC codes: G06F1, G06F13, H05K1, H05K3, H05K7