DE9321275U1 - Component set for a housing made of plastic for receiving electrical components - Google Patents

Description

DD01 E022DEU2/Be97s0307TW/Be/10.04.1997

DODUCO GmbH + Co. Dr Eugen Dürrwächter, Im Altgefäl! 12, D-75181 Pforzheim

Arrangement consisting of a plastic housing, a circuit board for holding electrical components and supply lines

Description:

The invention is based on an arrangement with the features specified in the preamble of claim 1. Such an arrangement is known from WO 92/20096. In the known housing, rigid supply lines formed from a lead frame or punched grid lead straight into the housing by crossing a housing wall into which they were injected with the plastic during injection molding of the housing. An electronic component, e.g. an integrated circuit, is located on a carrier plate that is attached to the housing base, and its connection contacts are connected to the supply lines injected into the housing via thin wires by bonding. Bonding is a complex technique; bondable surfaces must be provided for both the circuit carrier plate and the injected supply lines. Another disadvantage is that bond connections are irreparable; even during assembly of the circuit carrier plate, the failure of just one bond connection leads to the failure of the entire product at a very high level of the added value. Since modern integrated circuits and

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Since numerous bond connections have to be made in hybrid circuits, this represents a cost risk that cannot be ignored.

Alternatively, it is known to solder the circuit board to the supply lines. The circuit board can be connected to the injected supply lines directly or via cables, which not only requires several work steps, but also results in an arrangement that is sensitive to vibrations, so that suitable measures for vibration damping must also be taken.

The present invention is based on the object of showing a way in which circuit carrier boards, in particular those which are only laminated on one side, can be installed in a housing of the type mentioned at the beginning with less effort and without the electrical connections between the supply lines and the circuit carrier board being sensitive to vibration.

This object is achieved by an arrangement with the features specified in claim 1. Advantageous further developments of the invention are the subject of the dependent claims.

According to the invention, the circuit board is not connected to the supply lines by soldering or indirectly by bonded wires, but by the end sections of the supply lines that protrude freely into the interior of the housing being passed through holes in the circuit board and thereby pressed into electrical contacts that are attached to the circuit board and surround the holes. This has a number of advantages:

♦ No bondable surfaces are required, to which otherwise increased

requirements must be met.
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♦ When installing the circuit board into the housing, no soldering is required.

♦ Mechanical fastening and electrical contacting are carried out in one operation.

♦ The circuit board can be inserted into the housing fully automatically.

♦ If the end sections of the supply lines that protrude freely into the interior of the housing are long enough, they can also accommodate several circuit boards arranged one above the other.

♦ Pressing in results in a very reliable electrical contact, which is less sensitive to vibrations than a soldered connection, since the pressing maintains a contact force over a long period of time.

♦ The circuit board does not need to come into contact with a housing wall to fix it in place, as it is not only electrically but also mechanically secured by pressing in the end sections of the supply lines. Vibrations that affect the housing are therefore not transmitted directly to the circuit board, but only indirectly via the end sections of the supply lines that protrude freely into the interior of the housing and therefore only reach the circuit board in a dampened manner, especially if the end sections of the supply lines are designed to be flexible.

The contact between the end sections of the supply lines and the contacts carried by the circuit board is particularly reliable when the supply lines are cold welded to the contact pieces when pressed into them, which can easily be achieved by welding the end sections of the

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Equip the supply lines with an insertion bevel and otherwise design them with sharp edges and a slight oversize.

The contact pieces themselves are preferably attached to the circuit board in a form-fitting manner, e.g. in the manner of hollow rivets, but can also be snapped into the holes in the circuit board. It is even sufficient to simply press them in and provide a flange on one side only, namely on the side of the circuit board on which the conductor tracks run, with which an electrical connection is to be made via the contact piece, most simply by having the flange rest on a corresponding conductor track, and if necessary soldered to it.

A further advantage of the invention is that the circuit board can be inserted with the component side facing upwards or downwards.

Embodiments of the invention are shown in the accompanying drawings.

Figure 1 shows a device made up of the basic elements of an inventive

Housing formed from the kit in an exploded view in longitudinal section,

Figure 2 shows a vertical section through a modified plastic housing with built-in circuit board,

Figures 3 to 9 show different embodiments of contact pieces on a circuit board

a) in plan view and

b) in vertical section through the circuit board.

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Figure 1 shows, as an element of a component set according to the invention, a frame 1 made of injection-molded plastic as the basic element of the housing. This frame is open on its underside 2 and on its top side 3. On its underside, a shoulder 4 is formed from which a projection 5 projects downwards, the external dimension of which corresponds to the internal dimension d in the upper area of the frame, so that a similar frame 1 - as shown in Figure 4 - can be inserted with its extension 5 into the upper section of the other frame 1 without play. The top side 3 and the bottom side 4 thus have a complementary profile that enables them to be inserted together without play.

On one of the side surfaces of the frame, a projection 6 is formed with an outwardly open recess 7 in which the ends 8 of conductors 9 and 10 end, which form a connector strip and pass through the wall of the frame 1, in which they are embedded by injection molding. The conductors 9 and 10 are preferably made from a stamped grid and are stamped and bent parts that are bent at right angles so that their ends 11 and 12 located in the interior of the frame 1 point in opposite directions, namely downwards and upwards. On the wall of the frame 1 opposite the conductors 9 and 10, a projection facing the conductors 9 and 10 is formed, in which contact pins 14 are embedded, which, depending on the application, are connected to conductors 9, 10 in the projection 6 or not; in the latter case, they only serve as holding elements for a circuit board 15 on which electrical components 16 are located. For this purpose, the circuit board has holes 17 which are covered by spring clips 18 into which the pins 11, 12 and 14 can be pressed through the circuit board 15.

The frame 1 is closed at the bottom by a base 20, which has a projection 21 all around facing the frame 1, the inner dimension of which corresponds to the outer dimension of the projection 5 of the frame 1. Outside the projection 21 there are fastening holes 22 with which the

Base plate and with it the housing can be attached at the place of use. If desired, a plate-shaped heat sink 23 can be located in a recess in the base plate in order to absorb heat loss from components 16 and dissipate it to the outside. The heat sink 23 can be injected into the base plate 20 from the outset.

The frame 1 can be closed at the top by a cover 30 in the form of a relatively thin plate, which is expediently made of a hard plastic, but can also be made of another insulating material, e.g. ceramic. To accommodate the cover 30, a circumferential inner shoulder 19 is provided on the top 3 of the frame 1, which accommodates the cover 30 without play. The cover has a predetermined breaking point 31 all around, along which the edge 32 of the cover can be broken off. The width of the edge 32 corresponds to the width of the shoulder 19, so that the cover 30 can be pressed down over the shoulder 19 while breaking off the edge 32, whereby the edge 32 can remain on the shoulder 19. In order for the cover 30 to slide over the pins 12 and 13, it has point-shaped predetermined breaking points 33 at the corresponding locations, which can be pushed through by the pins 12 and 14. If this is done, the cover 30 takes up the position shown in Figure 3.

The fourth element of the component set is a cover 40, which, in contrast to the cover 30, is not flat on the underside, but is profiled in a similar way to the underside of the frame 1 and can therefore be joined to the frame 1 from above in a form-fitting manner, whereby the shoulders 41 provided on the underside of the cover can serve to fix a further circuit carrier plate 15a between the cover 40 and the frame 1, preferably with the thin cover 30 interposed, which in this case fulfills the function of an intermediate wall.

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Figure 2 shows a modified housing base made of plastic by injection molding, open at the top, in the base 102 of which electrical supply lines 103, 103a formed from a punched grid are embedded. The supply lines are placed in the injection mold before injection molding. To form a plug 104, a projection is molded onto the side of the housing with a recess 105 in which the ends of the supply lines 103, 103a serving as contact pins are located.

In the base 102, end sections 106 and 107 of the supply lines 103, 103a are angled upwards and thus protrude from the base and extend freely into the interior 108 of the housing. They carry a circuit carrier plate 109, which has holes 110 for this purpose. The holes 110 are assigned contact pieces 111, which in the embodiment according to Figure 2 are clamps, which preferably consist of a spring material such as copper-beryllium and have holes that are aligned with the hole. The leg of the contact clamp 111 on the component side of the circuit carrier plate 109 - in the illustration according to Figure 2 the upper leg - is preferably soldered to a conductor track 114 of the circuit carrier plate. The soldering point is designated by the reference number 112. The circuit board carries electrical and/or electronic components 113, the type of which is not important within the scope of the invention.

The end sections 106 and 107 of the supply lines are chamfered at the tip, have a rectangular cross-section and are sharp-edged with a slight oversize compared to the clear width of the holes in the contact clamps 111, so that when pressed into the contact clamps 111 they cold-weld to them, whereby not only a reliable electrical contact is established, but the circuit carrier plate 109 is also mechanically held and fixed in a position in which it does not have any direct contact with any of the housing walls.

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The housing can be closed at the top in a conventional manner using a cover that can be glued or welded on.

With the appropriate height and length of the end sections 106 and 107 of the supply lines 103,103a, several circuit carrier plates 109,109a can also be mounted against each other on the same end sections 106 and 107.

Clamps as shown in Figure 2 and in detail in Figure 4 do not necessarily have to be used as contact pieces for the connection between supply lines and circuit board. Other contact piece options are shown in Figures 3 and 5 to 9, where identical or corresponding parts are each designated with the same reference numbers.

In Figure 3, the contact piece 111 has the shape of a through-hole with flanges on both sides of the circuit board 109, with one of the flanges 115 establishing the electrical connection to a conductor track 114 on the circuit board.

As a variation of this, Figure 5 shows a contact piece 111 with a flange 115 on the component side and barbs 116 on the opposite side of the circuit board. Such a contact piece can simply be snapped into the hole in the circuit board.

Figure 6 shows a contact piece 111, a sleeve with a flange 115 on the component side of the circuit board, where it makes contact with a conductor track 114. On the opposite side, the sleeve is flanged.

Figure 7 shows as contact piece 111 a sleeve with a flange 115 on the component side in contact with a conductor track 114; the sleeve is pressed in and can be soldered to the conductor track.

Figure 8 shows a contact piece in the form of a plate with a sleeve-like extension and next to it two barbs 118. For assembly, this contact piece requires in addition to the hole 110, which is used to press in the electrical supply line, two assembly holes 119 through which the barbs 118 are inserted.

Figure 9 shows a contact piece similar to that shown in Figure 8, but with only one barb 118 laterally next to the sleeve-shaped extension 117.

Claims (6)

-10-Protection claims: 1. Arrangement comprising a housing (101) made of plastic, a circuit carrier plate (109) fixedly arranged in the housing (101) for receiving electrical components and electrical supply lines (103, 103a) which pass through a wall (102) of the housing (101) and protrude freely into the housing interior (10()), characterized in that the circuit carrier plate (109) has holes (110) in an arrangement corresponding to the arrangement of the end sections (106, 107) of the supply lines projecting into the housing interior (108), 10 and that the holes (110) are surrounded by contact pieces (111) attached to the circuit board (109), into which the end sections (106, 107) of the supply lines (103, 103a) are pressed. 2. Arrangement according to claim 1, characterized in that the ends (106, 107) of the supply lines (103, 103a) are cold-welded to the contact pieces (111). 3. Arrangement according to claim 1 or 2, characterized in that the contact piece (111) is a sleeve inserted into the hole (110) which is connected to a conductor track (114) of the circuit carrier plate (109), in particular rests on it with a flange (115). 4. Arrangement according to one of the preceding claims, characterized in that the end sections (106, 107) have a rectangular profile and are sharp-edged. 5. Arrangement according to one of the preceding claims, characterized in that the circuit carrier plate (109) is held in the housing (101) solely by the supply lines (103, 103a). 6. Arrangement according to claim 5, characterized in that the circuit carrier plate (109) does not touch the housing (101).