GB2039160A - Sockets for receiving electrical devices - Google Patents

Abstract

A socket for mounting to a printed circuit board (10) to receive a dual-in line integrated circuit (12) comprises a main body part (14) and a platform (40) which in the embodiment shown is slidably received by the part (14). The part (14) is fixed with respect to the board (10) by two straight rows of contact retaining devices (24) each soldered or otherwise secured to the board. Each device (24) comprises two resiliently deformable contacts (28, 30). To mount the integrated circuit (12), the platform (40) is raised to the position shown in Fig. 4 and the circuit (12) is seated thereon with contacts or pins (26) thereof each received in a respective one of the contact-retaining device (24), the pins (28, 30) of which are spaced to enable insertion of the pins (26). The integrated circuit (12) and the platform (40) are then pushed downwardly, whereupon cam surfaces (54) on the platform (40) push the pins (30) towards the pins (28) to clamp the pins (26) between the pins (28) and the pins (30). The integrated circuit (12) can be removed from the socket in a converse manner. With the construction described, the force required to insert and remove the integrated circuit (12) is minimal. Alternatively, the entire body of the socket (as opposed to just the platform (40)) is movable with respect to the contact-retaining devices (24) upon insertion and removal of the integrated circuit (12). <IMAGE>

Description

SPECIFICATION Sockets for receiving electrical devices This invention relates to sockets for mounting to base members to receive electrical devices having contacts extending therefrom. In particular, but not exclusively, the invention relates to sockets for mounting to printed circuit boards to receive dual in-line integrated circuits.

Sockets for mounting to printed circuit boards to receive dual in-line integrated circuits are known. The sockets comprise an individual contact-retaining means for each contact or pin of the integrated circuit. Although the force to insert an individual pin into its retaining means may not be large, since the integrated circuit has a reasonably large number of pins (typically about 10 to 40) the total insertion force can be quite high.

As is known in the art, this gives rise to serious problems. Attempts to overcome these problems, i.e. to provide a zero or ultra-low insertion force socket, have involved the provision of complex and not altogether satisfactory arrangements for opening the retaining means prior to insertion of the integrated circuit and for thereafter closing them. One such attempt involved the provision of a plastics bar extending through the socket and rotatable by a tool to open and close the retaining means. Not only is this arrangement expensive and complex to construct and not altogether simple to use, but the bar, being flexible, tends to rotate by a lesser and lesser extent in the direction away from the end engaged by the tool, whereby the contactretaining means farthest from the tool may be opened only partially.

According to the present invention there is provided a socket for mounting to a base member to receive an electrical device having a contact extending therefrom, the socket comprising a body having a surface against which the electrical device may be seated and contact-retaining means to engage the contact, the contact-retaining means being securable in place with respect to the base member and being capable of adopting closed and open conditions, in which, respectively, it grips and does not grip the contact, wherein at least a part of the body having said surface is movable with respect to the contact-retaining means between first and second positions in which, when the socket is mounted to the base member, it is respectively farther from and nearer to the base member, and wherein the body co-operates with the contact-retaining means such that in the first position the contact-retaining means is in the open condition and the electrical device can be seated on said surface, and such that when at least the part of the body is then moved together with the electrical device into the second position the contact is gripped by the contact-retaining means.

An electrical device can therefore be mounted to a socket embodying the invention in a simple manner and with a minimal amount of insertion force.

The socket preferably comprises a plurality of the contact-retaining means to engage a plurality of contacts of the electrical device, the body co-operating with each of the contact-retaining means. The plurality of contactretaining means may be arranged in two straight spaced rows to receive, for example, an electrical device in the form of a dual inline integrated circuit.

The contact-retaining means preferably comprises a pair of contact members of which at least one is movable towards and away from the other in the sense that it moves towards the other so that the contact is gripped as at least the part of the body of the socket is moved from the first position to the second position. In this case, the body preferably comprises a cam surface acting upon said one contact member to cause said movement thereof as at least the part of the body is moved with respect to the contact-retaining means. According to an embodiment of the invention the body includes a platform movable with respect to the contact-retaining means and having said cam surface thereon.

According to another embodiment the entire body is movable with respect to the contactretaining means. In the latter case, the cam surface may be on a central part of the body having the surface for seating the electrical device, the cam surface co-operating with an inner one of the pair of contact members; or the cam surface may be on a peripheral part of the body and co-operate with an outer one of the pair of contact members.

The invention will now be further described, by way of example, with reference to the accompanying schematic drawings, in which: Figure 1 is a perspective view from above of part of a first socket embodying the invention; Figure 2 is a perspective view from above of a platform for fitment to the structure of Fig. 1 to form the first socket embodying the invention; Figure 3 is a view of a larger scale of a part of the view of Fig. 2 within the circle Ill; Figure 4 is a sectional view of the assembled socket of Figs. 1 to 3 with the platform in a first, raised position so lhat a contactretaining device thereof is in an open condition, a dual in-line integrated circuit being seated on the platform;; Figure 5 is a view, corresponding to Fig. 4, of a second socket embodying the invention with a body thereof in a first, raised position so that a contact-retaining device thereof is in an open condition, a dual in-line integrated circuit being seated on the body; Figure 6 is a view of the socket of Fig. 5 with the body in a second, lowered position and with a pin of the integrated circuit gripped in the contact-retaining device; and Figures 7 and 8 are views corresponding to Figs. 5 and 6, respectively, of a third socket embodying the invention.

Referring firstly to Figs. 1 to 4, these show a socket for mounting to a printed circuit board 10 to receive a dual-in line integrated circuit 12.

The socket comprises a body including a moulded plastics main body part 14 comprising a base portion 16, a guide projection 1 8 extending upwardly from the centre of the base portion 16, and side portions 20 extending upwardly from opposite sides of the base portion 16. Two straight rows of apertures 22 are provided in the base portion 16, each row being adjacent a respective one of the side portions 20. A respective contact-retaining device 24, for receiving a respective one of two rows of pins 26 of the integrated circuit 12, are fixed in each of the apertures 22. For convenience, only one of the devices 24 is shown. The number of apertures 22 and devices 24 will depend on the number of pins 26.

As can best be seen from Fig. 4, each contact-retaining device 24 comprises two resiliently deformable contacts 28, 30 for example of phosphor-bronze or beryllium-copper secured to or integral with a base 32, which has a pin 34 extending therefrom.

The main body part 14 of the socket is secured to the printed circuit board 10 by insertion of the pins 34 through holes in the board and by soldering the pins to tracks such as 36 in the board.

The body of the socket further comprises a moulded plastics platform 40 having recesses 42 in its opposite ends to receive retaining clips 44 integral with the main body part 14.

The platform 40 further comprises a hole 46 therethrough in which the projection 18 is a sliding fit. Instead of a through hole 46, a blind hole in the base of the platform could be employed.

The platform 40 is fitted to the main body part 14 by pressing it downwardly on to the main body part so that teeth 48 on the clips 44 snap over shoulders (one of which is shown at 50 in Fig. 2) into the recesses 42.

The projection 18 is then disposed in the hole 46, and the inner contact 30 of each contactretaining device 24 is disposed in a respective one of a plurality of grooves 52 disposed along both sides of the platform 40. The base of each groove 52 has a rounded lower portion acting as a cam surface 54.

To fit the integrated circuit 12 to the assembled socket, the opposite ends of the platform 40 are gripped with the fingers (or possibly with a tool) and the platform is pulled upwardly to a first position shown in Fig. 2. The first position may be defined by abutment of the teeth 44 with the shoulders such as 50.

In this position, the contacts 28, 30 of each contact-retaining device 24 are spaced apart by an extent greater than the thickness of the pins 26 of the integrated circuit 12. The integrated circuit 12 is then seated on the upper surface of the platform 40 as shown in Fig. 2. Next, the integrated circuit 12 and platform 40 are pressed downwardly towards a second position, which may be defined by abutment of the lower surface of the platform 40 and the upper surface of the base portion 16. As the platform 40 moves downwardly, the cam surfaces 54 thereon move the contacts 30 outwardly towards the contacts 28 whereby each pin 26 becomes gripped be tween the associated pair of contacts 28, 30.

The integrated circuit 12 is thus secured in place in the socket with minimal insertion force and conductive connections between the pins 26 and the printed circuit board tO are established via the contact-retaining devices 24. The integrated circuit can likewise be removed with minimal withdrawal force by pulling the platform 40 back up to the first position, whereby the pins 26 are released, and then lifting off the integrated circuit Figs. 5 and 6 show a socket which closes resembles that shown in Figs. 1 to 4 and which will only be described in so far as it differs therefrom. In Figs. 5 and 6, reference numerals the same as those used in Figs. 1 to 4 designate like or similar items.

In the case of Figs. 5 and 6, the socket comprises a unitary plastics moulded body 60 comprising a peripheral part 62 and a central part 64. The central part 64 resembles the platform 40 of Figs. 1 to 4 except that it is not movable with respect to the remainder at the body 60. In particular, the central part of 64 includes the cam portions 54, which in this case are angular rather than rounded. > socket of Figs. 5 and 6 includes contact retaining devices 24 similar to those of the socket of Figs. 1 to 4, but in the case of Figs.

5 and 6 the devices 24 are slidable in the vertical sense within the body 60. The pins 34 are soldered to the printed circuit board 10 in the same manner as described with reference to Figs. 1 to 4. Insertion and with drawal of the integrated circuit 12 are carried out as before, except that in this case the whole body 60 (rather than just the platform 40) is moved between the first position (Fig.

5) and the second position (Fig. 6).

Figs. 7 and 8 show a socket which closely resembles that shown in Figs. 5 and 6 and which will only be described in so far as it differs therefrom. In Figs. 7 and 8, reference numerals the same as those used in Figs. 1 to 6 designate like or similar items.

In the case of Figs. 7 and 8, the cam surfaces 54 are provided on the peripheral part 62 rather than the central part 64 and co-operate with the outer contacts 28 rather than the inner contacts 30. The inner contacts 30 are each provided with a terminal portion 70 that co-operates with a shoulder 72 on the central part 64 to define the first position of the body 60 (Fig. 7) by abutment of each terminal portion 70 with its shoulder 72.

In the various figures, the arrangement of the pins 26 of the integrated circuits 1 2 is shown only schematically. As is known to those skilled in the art, the major portions of the pins 26 may be inclined to the vertical by an angle a (see Fig. 5) which may typically be between about 0 and 1 5'. As will be evident, the above-disclosed sockets will be able to receive the pins 26 over a wide variation in value of the angle a.

For convenience, the above disclosure of various embodiments of the invention assumed that the printed circuit board 10 is disposed horizontally and that, therefore, the various components of the socket and integrated circuit are oriented correspondingly.

However, as will be evident, the above-described sockets can be mounted to printed circuit boards oriented in any other way.

As will be evident, the above-described sockets are not restricted to mounting dual inline integrated circuits, but can be used to mount other electrical devices of similar configuration, or modified to mount integrated circuits or other electrical devices of different configurations.

Although the contact-retaining devices 24 are described above, by way of example, as being secured to the printed circuit board 10 by soldering, they may instead be secured to the board in any other suitable way, for instance by a wire wrapping technique or by their being provided with solder eyelet tails.

Claims (11)

1. A socket for mounting to a base member to receive an electrical device having a contact extending therefrom, the socket comprising a body having a surface against which the electrical device may be seated and contact-retaining means to engage the contact, the contact-retaining means being securable in place with respect to the base member and being capable of adopting closed and open conditions in which, respectively, it grips and does not grip the contact, wherein at least a part of the body having said surface is movable with respect to the contact-retaining means between first and second positions in which, when the socket is mounted to the base member, it is respectively farther from and nearer to the base member, and wherein the body co-operates with the contact-retain ing means such that in the first position the contact-retaining means is in the open condition and the electrical device can be seated on said surface, and such that when at least the part of the body is then moved together with the electrical device into the second position the contact is gripped by the contact-retaining means.

2. A socket according to claim 1, which comprises a plurality of the contact-retaining means to engage a plurality of contacts of the electrical device, the body co-operating with each of the contact-retaining means.

3. A socket according to claim 2, wherein the plurality of contact-retaining means are arranged in two straight spaced rows.

4. A socket according to any one of claims 1 to 3, wherein the or each contact-retaining means comprises a pair of contact members of which at least one is movable towards and away from the other in the sense that it moves towards the other so that the contact is gripped as at least the part of the body of the socket is moved from the first position to the second position.

5. A socket according to claim 4, wherein the body comprises a cam surface acting upon said one contact member to cause said movement thereof as at least the part of the body is moved with respect to the contactretaining means.

6. A socket according to any one of claims 1 to 5, wherein the body includes a platform movable with respect to the contact-retaining means and having said cam surface thereon.

7. A socket according to claim 5, wherein the entire body is movable with respect to the contact-retaining means and the cam surface is on a central part of the body having the surface for seating the electrical device, the cam surface co-operating with an inner one of the pair of contact members.

8. A socket according to claim 5, wherein the entire body is movable with respect to the contact-retaining means and the cam surface is on a peripheral part of the body, the cam surface co-operating with an outer one of the pair of contact members.

9. A socket for mounting to a base member to receive an electrical device having a contact extending therefrom, the socket being substantially as herein described with reference to Figs. 1 to 4, Figs. 5 and 6 or Figs. 7 and 8 of the accompanying drawings.

10. The combination of a socket according to any one of the preceding claims and an electrical device received by the socket.

11. A combination according to claim 9, wherein the electrical device is an integrated circuit.