GB2189351A - Mounting circuit boards - Google Patents

Abstract

A printed circuit box magazine is a parallelepipedal box with an open front face and a back plane for connectors to be engaged by boards plugged in. The top and bottom members each consists of two plates made up of parallel zig-zag strips and assembled together in parallel so that a board plugged in is engaged by the apices 10 of the zig-zags at spaced points on both faces. In addition, the open-work nature of these plates is good for cooling. In an alternative version the strips are each straight with projecting fingers so that a band is engaged on one face by a strip and on the other face at spaced points by the fingers. The other sides of the box are also of open-work construction, to further improve cooling. <IMAGE>

Description

SPECIFICATION Electricailelectronic equipment practice This invention relates to electrical or electronic equipment practice, and in particular to a magazine for the reception of a number ofclosely-spaced parallel mounted circuit boards, usually of the printed circuit type.

With such an arrangement one difficultywhich arises is the problem of heat; since the boards, often crowded with circuitry, are close together a great deal of heat is developed. To get rid of this heat harmlessly, good cooling is essential. Figure 1 is a partial representation of a conventional arrangement for such a magazine, which is adequate to indicate the basic principles on which its operation is based. The magazine is an open-fronted box with a back-plane indicated at 1 on which are mounted socket connectors which receive plug connectors on the innermost edges of the circuit boards, such as 2, to be received in the magazine. The side plates ofthe magazine are not shown.

The top and bottom members of the box are of lamina construction and we now describe the bottom, the top being similar. The two plates or laminae 3, 4 are mounted parallel to each otherwith the upper lamina 3 having down-turned front and rear ends, to which the edges of the lamina 4 are secured. The upper lamina 3 has slots such as 5for the reception of the edge of a circuit board such as 2, splayedatthefrontendtoassistinsertion ofthe board. Although the laminae have many holes such as 6, the open area percentage may not prove adequate to give proper cooling of the electronics mounted on the circuit boards.

An object of the invention is to provide a magazine for circuit boards in which cooling ofthe boards and the components supported by them is improved as compared with that provided by the conventional devices.

According to the present invention there is provided a printed circuit board magazine of generally parellellepipedal configuration, wherein one rectangular face is a back-planeforthe magazine, which back-plane has sockets forthe reception of plugs atthe edges of printed circuit boards to be inserted into the magazine, which boards when inserted are closely spaced and parallel to each other, wherein each circuit board thus inserted is guided at its parallel edges by two parallel members ofthe magazine, wherein said parallel members are each of laminar construction and gappedthroughoutsoastoallowtheflowofair therethrough, wherein each said laminar surface includes two parallel plate-like members secured close together, and wherein the configuration of the plate-like members are such asto guide a circuit board on insertion into the magazine, at least one of the said plate-like members being so formed as to guide the board being inserted at spaced points along the length of the board, whereby a large open area in the parallel surface is attained.

Embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 2 is a plan view of one of two laminae used tomakeabottom ortopsurfaceforamagazine, Figure3is a plan viewofthe other lamina to be used with that of Figure 1, Figure4is a top plan view of laminae such as shown in Figures 2 and 3, when fitted together, FigureS is a front view ofthe assembly of Figure4, Figure 6 is a plan view of the inner lamina for a second form of bottom or top surface for a circuit board magazine, Figure 7is afrontviewofthe lamina of Figure6, Figure 8 is a plan viewofthe outer laminato be used with the lamina of Figures 6 and 7, Figure9is a plan view of laminae such as shown in Figures 6, 7 and 8, when fitted together, Figure 10 is a front view of the assembly of Figure 9.

Figures 11 and 12 are simplified The drawings show the construction ofthe top and bottom surface members for use in magazines which embodythe invention. In each case the surface member consists of two parallel plate-like members, the innerofwhich has bent down parallel edges, which enclose the outer member.

In Figure 2the lamina is slotted in a zig-zag manner with the ends of the zig-zag joined at each end ofthe lamina. The edges of this lamina shown at top and bottom in Figure 1 are bent down. They are also jointed at a number of points throughouttheir lengths, but so as to define zig-zag slots such as 1 0to receive a printed circuit board edge. Although not shown the parallel sides -vertical on the page - are also of linear form. Further, the lower-most edge at which the board is inserted can be splayed out in a similarwaytothatshownin Figure 1.

The outer lamina (as 'seen' by a printed circuit board) is generally similar, but not slotted - see Figure 3. As fitted together, the result is as shown in Figures 4 and 5, where the lines such as 11 indicate where the 'slots' to receive boards lie. The bent-down front end is shown at 12, Figure 5. Here the portion 13 is a 'zig' of the zig-zag of part ofthe inner lamina. The portion 14is an end-on view of part ofthe lamina of Figure 3, e.g. a portion thereof such as shown at 15 which fits into a slot in the portion 12.

The laminae can be secured togetherfurther by bolts with spacers between them at the edges.

Two laminar assemblies such as shown in Figures 4and Swould, in effect, replace the top and bottom members of the magazine shown partially in Figure 1. It will be seen that the percentage of open area of such a laminar assembly is higherthan forthe assembly of Figure 1. The edges of the boards when inserted are supported at a number of points throughoutthe length, these support points being on opposite faces of the board and being provided by the apices of the 'zigs' and the 'zags'.

The configuration of the laminae could be modified without departing from the principles of support on the faces at separated points instead of throughout the entire length of the board. Thus the strip portion could be sinusoidal in form instead of zig-zag, ifthis proved to be easter to manufacture.

In the second embodiment, the structure of the laminae is basically linear in form, unlike the arrangement of Figures 2 to 5, where the structure is basically undulatory in form. This is shown in Figures 6to 10. The innermost lamina, Figure 6, has its two ends bent down, see the end-on view in Figure 7, and it includes a set of parallel straight portions such as 20, each with a number offingers such as 21 projecting from one side of the straight portion. Atthe front end there are bevelled portions such as 22, to guide the entry of a circuit board. The other lamina, Figure 8, is a relatively simple grid-like structure with a number of tabs such as 23 at its ends.

When the two laminae are assembled, see Figures 9 and 1 0,these tabs are received in slots such as 24 (Figure 7) in the bent down portions.

In this arrangementthe circuit board as it is inserted is guided on one side bythe straight edge of one of the portions 20, and on the other side by a set of fingers such as 21. However, as 'seen' by the user, this arrangement functions in the same way as does the arrangement of Figures 2 to 5.

A magazine for printed circuit boards embodying the invention is an open-fronted parallellepipedal box with the face opposite the open front forming a back plane. This back-plane carries electrical connections in the form of printed circuittracks, and also socket connections with which plug connections on the inner ends ofthe circuit boards mate. The two side panels of the box, i.e. the ones which interconnect the laminar assemblies, are also perforated, e.g. with a network of row and columns of 'sausage-shaped' holes. Thus airflow through the whole engagement is facilitated.

Figures 11 and 12 show another arrangement of the laminar structure used atthetop and bottom of an equipment box. This consists oftwo plates, one as shown in Figure 11, which consists of parallel straight portions 30,31, adjacent ones of which are interconnected by zig-zags such as 32. The other lamina is as shown in Figure 12 and consists of another set of zig-zags which extend between end strips (not shown).

Thus both members have end strips, with angled lead-ins at one side, andthetwo are mounted one on top of the other, with the zig-zags connecting. The POCB's are inserted in at the lead-ins (notshown) and move along aligned straight portions such as 31, and are located by the ends ofthezig-zags.

Thisarrangementgivesagreateramountof open-ness than the other arrangements.

Claims (8)

1. A printed circuit board magazine of generally parallellepipedal configuration, wherein one rectangularface is a back-planeforthe magazine, which back-plane has sockets for the reception of plugs atthe edges of printed circuit boards to be inserted into the magazine, which boards when inserted are closely spaced and parallel to each other, wherein each circuit board thus inserted is guided at its parallel edges bytwo parallel members ofthe magazine, wherein said parallel members are each of laminar construction and gapped throughout so as to allow the flow of airtherethrough,wherein each said laminar surface includes two parallel plate-like members secured close together, and wherein the configuration ofthe plate-like members are such asto guide a circuit board on insertion into the magazine, at least one of the said plate-like members being so formed as to guide the board being inserted at spaced points along the length of the board, whereby a large open area in the parallel surface is attained.

2. A printed circuit board magazine as claimed in claim 1,wherein each said lamina is formed of undulatory, e.g. zig-zag or sinusoidal, strip-like portions, each such strip like portion extending from the front edge of the lamina to the back-edge thereof, so that a board is guided on insertion by the crests of the zig-zag or of the sinusoids.

3. A printed circuit board magazine as claimed in claim 1, wherein the innermost laminae of each said pair has extending between its front-edge and its back-edge, straight strip like members, each with a set offingers projecting from one side towards an adjacent strip-like member such thaton insertion is guided by the edges of said strip-like members and by the ends of said fingers.

4. A printed circuit board magazine as claimed in claim 3, wherein the outermost lamina of each said pair is a plain grid with the strips between the front and back edges aligned with and staggered slightly with respecttothestrip-like member of the outermost laminae.

5. A printed circuit board magazine as claimed in claim 1,2,3 or 4, wherein the innermost lamina of each pair has bent-overfrontand backedge portions, the outermost lamina of each said pair being secured to the bent down edge portion.

6. A printed circuit board magazine as claimed in claim 5, wherein the outermost lamina of each said pair has tabs at its front and back edges which fit when the laminae are assembled together into slots in the bent-down portions of the innermost laminae.

7. A printed circuit board magazine, substantially as described with reference to Figures 2 to 5, or Figures 6 -10 ofthe accompanying drawings.

8. A printed circuit board magazine of generally parallellepipedal configuration, wherein one rectangularface is a back-plane for the magazine, which back plane carries connector elements for mating with corresponding connector elements on the edges of printed circuit boards to be inserted into the magazine, which boards are substantially vertical and closely spaced when thus inserted, wherein each circuit board when thus inserted is guided atitsupperand loweredges bytwo parallel members which respectively form the top and bottom sides of the magazine, wherein said parallel members are of laminar construction and are each gapped throughout their areas so as to allowthe flow of air or other coding fluid therethrough, wherein each said parallel member includes two parallel open-workflat sheets secured close together, the distance between the two sheets of a parallel member being small comparedwiththe length and width of a said sheet, wherein each said open-work flat sheet is in the form of narrow strips which are spaced apart by distances wider than the strips, so as to give a grid-like or net-like structure, and wherein the configuration oftheinnermostflat sheet of each said parallel member is such asto guide circuit boards on insertion into the magazine, each said innermost flat sheet being so formed asto guide the edges of the circuit boards being inserted at spaced points along the length of each such board, whereby each such parallel member provides an open area which is a substantial proportion of the actual area ofthatmember.