EP0455297A1

EP0455297A1 - Device comprising a plastics housing provided with channels for securing contact members

Info

Publication number: EP0455297A1
Application number: EP91200993A
Authority: EP
Inventors: Hermanus Smit; Adrianus Johannus Melis
Original assignee: Philips Gloeilampenfabrieken NV; Koninklijke Philips Electronics NV
Current assignee: Koninklijke Philips NV
Priority date: 1990-05-03
Filing date: 1991-04-25
Publication date: 1991-11-06
Also published as: NL9001061A; JPH04229571A

Abstract

The plastics housing (1) comprises a bottom portion (3) having a first surface (5) and a second surface (7). In the bottom (3) there are provided a number of channels which comprise a first section (9) and a second section (11) and which extend from the first surface (5) to the second surface (7). In at least one of the channels (9, 11) there is secured an electrically conductive contact member (12) which comprises a pin portion having a first section (21) and a second section (23) and a contact portion (27). The first section (21) has smooth side walls, the second section (23) being provided with a profile (25). In the prolongation of each channel (9, 11) there is provided a thin-walled bush (13) which projects from the first surface (5). The first section (21) of the pin (21, 23) fits tightly in said bush, so that flux migration in the direction from the first surface (5) to the second surface (7) is prevented. The contact members (12) are fixed in the plastics housing (1) by cooperation between the profile (25) on the second section (23) of the pin (21, 23) and the wall of the second section (1 1) of the channel (9, 11).

Description

The invention relates to a device comprising a plastics housing which includes a bottom portion having a mainly flat first surface and a second surface, said bottom portion being provided with a number of channels which extend from the first surface to the second surface, at least one of the channels, comprising an electrically conductive contact member which is secured in it and which consists at least partly of a pin which comprises at least a first section which is situated near the first surface and a second section which is situated near the second surface, the first section fitting tightly in a narrow opening adjoining the channel and the second section being retains in at least a portion of the channel by cooperation between the surface of the pin and the wall of the channel.
The device may be, for example a part of a connector where the plastics housing constitutes the part in which the pins forming part of the contact members of the connector are situated.
The device may also be a socket provided with channels with a corresponding number of contact members for receiving contact pins of an electronic housing. The electronic housing can thus be readily replaced.
A socket of this kind is known from US-A 4,010,992. The contact socket is mounted on a printed circuit board (PCB) by way of soldered joints between the portions of the contact members which are constructed as pins and the board. In order to realise these soldered joints use is made of liquid flux. This flux tends to flow between the pins and the wall of the channels, which may give rise to poor contacts and which may impede replacement of the housing.
The cited United States Patent Specification proposes to prevent flux migration by sealing the lower side of the channels by way of a flexible membrane comprising a narrow opening in which the pins fit tightly. However, it has been found that the sealing of this construction is not always adequate, which is probably due to the small thickness of the membrane. Because of the presence of the membrane, a smaller part of the bottom thickness is available for the channel, so that the channel length becomes comparatively short. As a result, the fixation of the pin in the channel is not always optimum.
It is an object of the invention to provide a device of the land set forth in which the pins are firmly secured in the channels and also provide suitable sealing against flux migration. To achieve this, the device in accordance with the invention is characterized in that at least a portion of the surface of the second section of the pin is provided with a profile which cooperates with the wall of the channel in order to retain the pin, and in that in the prolongation of the channels there is provided a thin-walled bush which projects from the first surface of the bottom portion and in which the first section of the pin fits tightly.
Because the bushes project from the bottom so that they do not claim any wall thickness of the bottom, if desirable the entire bottom thickness can be used for fixation which is further stimulated by the profile of the pins. As a result, the bottom may be comparatively thin, thus avoiding warping of the plastics housing after moulding.
Because the wall of the bushes is thin, the wall will yield when the pins are pushed through the bushes and will enclose the pins as a sleeve due to the elastic properties of the plastics material. A very tight seal against flux migration is thus achieved.
It is to be noted that from GB-A 2,005,929 it is known per se to provide a pin with a profile which introduces a given degree of fixation in cooperation with the wall of an opening and which constitutes a labyrinth which impedes liquid migration. However, the functions of sealing and fixation are then combined, so that they are difficult to optimize individually.
A preferred embodiment of the device in accordance with the invention is characterized in that the profile is a sawtooth profile.
A further preferred embodiment is characterized in that the second section of the pin has a mainly rectangular cross-section, the sawtooth profile being provided on the short sides of the rectangle.
The invention will be described in detail hereinafter with reference to the drawing.

Fig. 1 is a cross-sectional view of an embodiment of a portion of a plastics housing for a device in accordance with the invention,
Fig. 2 is a longitudinal sectional view of a channel of the housing shown in Fig. 1,
Figs. 3a and b are a front view and a side elevation, respectively, of an embodiment of an electrically conductive contact member which can be inserted into a channel of the housing shown in Fig. 1, and
Fig. 4 shows an embodiment of a device comprising an electrically conductive contact member arranged in a channel of the housing shown in Fig. 1.

Fig. 1 is a cross-sectional view of a plastics housing 1, comprising a bottom portion 3 having a first surface 5 and a second surface 7. In the bottom 3 there are provided a number of channels which comprise a first section 9 and a second section 11. The channels 9, 11 extend from the first surface 5 to the second surface 7, the second section 11 opening into the second surface 7.
Fig. 2 is a longitudinal sectional view of one of the channels 9, 11, taken along the line II-II of
Fig. 1. The channels 9, 11 are capable of receiving electrically conductive contact members 12 which will be described in detail hereinafter with reference to Fig. 3. A projecting thin-walled bush 13 is situated outside the mainly flat first surface 5 and in the prolongation of each channel 9, 11. The bush 13 is provided with an opening 15 which adjoins the first section 9 of the channel 9, 11.
The plastics housing 1 of the present embodiment forms part of a connector. The connector comprises two rows of juxtaposed channels. At the extremities of the housing 1 there is provided a connection portion 17 which is provided with a hole 19 (Fig. 2) in which, for example a screw can be inserted. Only one extremity is visible in the drawing.
The contact members 12 shown in Figs. 3a and 3b comprise a portion which consists of a pin having a first section 21 and a second section 23. Fig. 3a is a front view of such a pin 21,23. The first section 21 has smooth side walls, the second section 23 being provided with a profile 25. In the present embodiment the profile 25 is a sawtooth profile.
Fig. 3b is a side elevation of the contact member 12 which comprises a contact portion 27 in addition to the pin 21,23. The contact portion 27 of the present embodiment consists of a pin contact. However, it may alternatively be, for example a socket contact or a spring contact as described in Patent Speficiation US-A 4,010,992. The contact portion 27 can be bent through 90° with respect to the pin 21,23, but the contact members 12 may also remain entirely straight, depending on the application. In the present embodiment the pin 21,23 and the channels 9, 11 have a rectangular cross-section. The profile 25 is provided on the short sides of the rectangle of the pin 21,23. The pin may alternatively be, for example round or square. The advantage of rectangular pins consists in that they can be readily formed from metal sheets by punching, the profile 25 being formed during the same operation.
Fig. 4 shows a portion of the plastics housing 1 where a contact member 12 is secured in a channel 9, 11. The contact member 12 has been inserted into the channel 9,11 from the top downwards as denoted by the arrow 28 in Fig. 4. The first section 21 of the pin 21,23 enters the section 9 and the opening 15 of the thin-walled bush 13 upon insertion. The wall of the bush 13 is so thin that it will yield, due to the elastic properties of the plastics, when the first section 21 enters the opening 15. As a result, the internal dimension of the opening 15, originally being slightly smaller than that of the section 9, becomes approximately equal to the dimension of the section 9. Consequently, the bush 13 encloses the section 21 like a sleeve, so that migration of the flux used for soldering the pin section 21 is precluded.
The second section 23 of the pin 21,23 enters the second section 11 of the channel 9, 11 upon insertion. The pin 21,23 is secured in the channel by cooperation between the wall of the section 11 and the profile 25.
The orientation of the sawtooth profile is such that insertion of the pin 21,23 in the direction of the arrow 28 is comparatively easy but a comparatively large force is required for removal (for example, 100 N). This is the advantage of a sawtooth profile. The profile need not necessarily be a sawtooth, but may also be, for example a zigzag profile. The length of the channel section 11 determines the fixation to a given degree, but the section 11 is permitted to remain comparatively short due to the presence of the profile 25. Consequently, in the bottom 3 a space remains for the first section 9, having a slightly smaller dimension than the second section 11, in order to stimulate the guiding of the pin in the even narrower opening 15. Moreover, the section 9 also contributes to the fixation of the pin in the channel 9,11.
Because the bushes 13 which ensures sealing project from the bottom 3 the bottom thickness may be comparatively small. Worping of the plastics housing after moulding can thus be avoided. For the same reasons recesses 29 (Fig. 1) are provided in the bottom 3 of the plastics housing 1 between the rows of channels of the present embodiment.

Claims

A device comprising a plastics housing which includes a bottom portion having a mainly flat first surface and a second surface, said bottom portion being provided with a number of channels which extend from the first surface to the second surface, at least one of the channels comprising an electrically conductive contact member which is secured in it and which consists at least partly of a pin which comprises at least a first section which is situated near the first surface and a second section which is situated near the second surface, the first section fitting tightly in a narrow opening adjoining the channel and the second section being retained in at least a portion of the channel by cooperation between the surface of the pin and the wall of the channel, characterized in that at least a portion of the surface of the second section of the pin is provided with a profile which cooperates with the wall of the channel in order to retain the pin, and in that in the prolongation of the channels there is provided a thin-walled bush which projects from the first surface of the bottom portion and in which the first section of the pin fits tightly.
A device as claimed in Claim 1, characterized in that the profile is a sawtooth profile.
A device as claimed in Claim 2, characterized in that the second section of the pin has a mainly rectangular cross-section, the sawtooth profile being provided on the short sides of the rectangle.