GB2239135A

GB2239135A - Mechanical retaining device for electrical connectors

Info

Publication number: GB2239135A
Application number: GB9022631A
Authority: GB
Inventors: Youichi Kashiwa; Takashi Kamono; Jun Saito; Yoshikazu Tanikawa
Original assignee: AMP Inc
Current assignee: TE Connectivity Corp
Priority date: 1989-11-02
Filing date: 1990-10-18
Publication date: 1991-06-19
Anticipated expiration: 2010-10-18
Also published as: KR970001032Y1; GB2239135B; KR910009968U; MY107281A; GB9022631D0

Abstract

A retaining device (24) for electrical connectors (14) is disclosed. The device is a metal latch (24) embedded in a groove (22) in a guide post (20) and having catch surfaces (32a, 32b) on flexible leg portions (30a, 30b) projecting laterally outwardly from the post (20). The device may be used to retain an electrical connector in a board. <IMAGE>

Description

RETAINING DEVICE FOR ELECTRICAL CONNECTORS The present model pertains to a retaining device for electrical connectors mounted on printed circuit boards such as edge connectors etc.

Along with the advances in the performance, speed and density of electronic components has come a steady increase in the number of electronic devices mounted on printed circuit boards. An electrical connector known as an edge connector has recently come into wide usage due to its effectiveness as a reciprocal connector of circuits formed by electronic devices mounted on main circuit boards (mother boards) and electronic devices mounted on secondary boards (daughter boards).

An example of how such a connector is structured is given in Figure 3. The electrical connector nonconductive housing 14 is mounted on the surface of a main circuit board possessing multiple openings or through holes 10a. The housing 14 has an opening along its extension. Flat, cut-out terminals 12 are inserted into multiple receiving holes 13 (contacts or terminal points) at right angles to the slot along the extension.

The terminals 12 have an abbreviated "C" shaped contact part 12a and a contact terminal part 25 which can be inserted into and soldered to through holes on the circuit board 10. Not shown in the drawing is how the contact terminal parts 25 project ~out from the underside of housing 14. On each end of the open slot 15 on the upper surface of housing 14 are flat extensions which form a latch with protruding part 16a and its continuing contiguous surface 16b. Further, perpendicular to the latch portion materials 16, flat catch materials are formed 18 with a stop projection portion 18a on the inner surface.

As is shown in the figure, the edge of a secondary circuit board 6 is inserted at an angle into the "C" shaped contact parts 12a of the multiple terminal connections 12 arrayed along the opening 15 or housing slot 14. Next, when the circuit board 6 is moved to a vertical orientation in the opening 15 of the housing 14, the edge of both sides of the board 6 makes contact with the protruding surface 16a of the latch material 16 forcing it to spread. As it is moved further, it meets contiguous surface 16b. At this time, the stop projection portion 18a of the catch 18 is inserted into the openings 6a on the secondary circuit board 6 thus completely fixing both circuit boards 6 and 10 in the housing 14.Simultaneously, the contact points 8 formed along the edge of the secondary printed circuit board 6 are electrically connected to the contact parts 12a of each of the terminal connections 12.

During the positioning and alignment of housing 14 on the main circuit board and during the soldering work a method of temporarily holding them in place is necessary. In particular, the alignment of electric connectors for high density packaging devices where the terminal pin pitch is approximately lmm is both critical and very difficult. For this reason, guiding devices near each end of the underside of housing 14, that is, guide posts 20a and 20b are formed as one unit with housing 14, are made to be inserted into guide openings lla and llb respectively on the main printed circuit board 10. Size differences in these guide posts 20a and 20b and the guide openings lla and llb make for correct positioning of the housing 14 on the main circuit board 10 by insuring correct orientation.

However, because guide posts 20a and 20b are extremely small posts with diameters of approximately 2mm, it is very difficult to obtain a sufficient difference in dimensions between these guide posts 20a and 20b as well as openings lla and llb. Nor is it easy to obtain sufficiently high dimensional and positional accuracy for guide posts 20a and 20b as well as openings lla and llb. Furthermore, since the guide posts 20a and 20b are generally not perfectly circular but right cylinders with v-shaped notches cut-out to provide some resiliency, they also had the problem of not maintaining enough hold power in the openings lla and llb of main circuit board 10.

Therefore, the objective of the present invention is to provide a new retaining device for electrical connectors with sufficient holding power to keep housing 14 together in openings lla and llb of circuit board 10 without requiring strict accuracy with respect to the dimensions of guide posts 20a and 20b as well as openings lla and llb.

In the device for electrical connectors of the present invention, a groove is formed in the guide post of housing 14 and a resilient metal clasp fixture is embedded in this groove. The catch formed at the top of the metal clasp passes through the opening of the circuit board and catches onto the underside of the board. If necessary, this metal clasp can be soldered to conductive pads around the openings of the circuit board.

The invention will now be described with reference to the drawings wherein: FIGURE 1 (A) and (B) shows enlarged cross sections of frontal and side views of Example 1 of a retaining device for electrical connectors according to the present invention; FIGURE 2 (A) and (B) shows enlarged cross sections of frontal and side views of Example 2 of a retaining device for electrical connectors according to the present invention; and FIGURE 3 is an isometric drawing of a prior art edge connector.

With reference to Figure 1 (A) and (B) and Figure 2 (A) and (B), an explanation of suitable examples of the retaining device for electric connectors according to the present invention is described below. As a matter of convenience, structural elements which correspond to the same structural elements as in Figure 3 are given the same reference number.

Figure 1 (A) shows an enlarged longitudinal cross section of the housing 14 including guide post 20 of the retaining device for electrical connectors of the present invention. Figure 1 (B) is a cross sectional view at a right angle to Figure 1 (A).

As clearly shown in Figures 1 (A) and (B), the retaining device for electrical connectors according to the present invention is not simply a guide post 20 formed as one unit with housing 14. A long narrow vertical groove 22 has been formed in guide post 20 running from the upper surface 14a of housing 14 to the tip of guide post 20. The groove is shaped so that a flat metal clasp fixture 24 can be inserted and held in place.

This metal clasp 24 including a main section 28 cut-out from a flexible metal sheet and held in place in the enlarged portion 22a of the groove 22 of the housing 14 by a barb 26 cutting into the side wall of 22a, and a pair of flexible leg portions 30a and 30b extending down from this main section 28 and separated from one another. The free tips of these legs are formed with sloping catch surfaces 32a and 32b. Parts of the catch portions 32a and 32b of the metal clasp 24 protrude beyond the external wall of the guide post 20 but the tips are designed to fit into the cavity 22b in the bottom of the groove 22.

Consequently, when the guide posts 20 of the electrical connector housing 14 are positioned and pushed down into the guide openings 11 on the circuit board 10, first the tips of the guide posts 20 are correctly guided into the entrance to the openings 11 of the circuit board 10. When further pressure is added the sloping catch surfaces 32a and 32b at the leading edge of flexible legs 30a and 30b of metal clasp 24 make contact with opening 11 and push flexible legs 30a and 30b inward, that is, in a mutually closer direction.As housing 14 is pressed down further, when the sloping surfaces of flexible legs 30a and 30b pass through the opening 11 of circuit board 10, these resilient legs return to their original condition and the relatively acute angle of the catch portions 32a and 32b catch on the lower surface of both sides of dening 11 of circuit board 10. If this metal clasp 24 ,4bricated from, for instance, approximately 0.5mm metal sheet, compared to the holding power of guide posts 20 molded with the same plastic materials as housing 14 taken alone, it is easy to understand why it would possess both sufficient holding strength and flexibility. Further, it is possible to increase the holding strength by forming a conductive pad around opening 11 on circuit board 10 and soldering.

In addition, to provide housing 14 with directional orientation, the size of the metal clasp 24 can be differentiated to correspond to the dimensions of guide posts 20a and 20b. Although in the embodiment shown in Figure 1, the grooves 22 for metal fittings 24 were formed for insertion at guide post 20 positions through the upper surface 14a of housing 14, it is also possible to form the grooves from the lower tip of guide post 20 to lower surface of housing 14. In this case, the metal fitting 24 is inserted vertically into the tip of the guide post 20. Also, since the guide posts 20 are formed near each end of housing 14, the slot can be formed along the length of housing 20 up to the guide post 20 position and the metal clasp inserted tangentially. Guide posts 20 may be located at multiple fixed intervals along the length of housing 14, not only at both ends.

Figure 2 (A) and (B) shows a second embodiment of the retaining device for electrical connectors in enlarged cross sections from both frontal and side views, one at right angle to the other. The same reference numbers are used for structural elements corresponding to those in Figure 1 (A) and (B). The following explanation only treats the differences with respect to the first embodiment.

The top (or head) of the main section 28' of metal fitting 24' is fashioned to protrude from the surface of the housing 14. This is in order to permit it to be hit into groove 22 of housing 14 with a hammer or other tool if necessary. The flexible legs 30a' and 30b' are not straight; rather, they are bent so as to improve their resiliency and spring as well as to achieve full contact with the opening in circuit board 10. Further, the catch portions 32a' and 32b' take on an overall slippery form.

The retaining device in this second embodiment is characterized by having a greater degree of permissible error with regard to the position and dimensions of housing 14 and the openings of printed circuit board 10 as well as greater holding strength.

Due to the present invention for a retaining device for electrical connectors, because a metal clasp fitting is deftly combined with guide posts formed as one unit with the housing, strict precision is not essential with respect to the position and dimensions of the guide openings in the circuit board or the housing guide posts. Moreover, compared to prior plastic guide posts only, it is possible to greatly increase the flexibility and durability of the guiding device. Furthermore, to remove an electrical connector once inserted into a main circuit board, it is only necessary to apply pressure to catch portions 32a and 32b forcing them inward with the same tool used for insertion, while either pushing the guide posts 20 or pulling the housing 14. The device can easily withstand multiple insertions and removals.

Claims

CLAIMS:

1. A retaining device for electrical connectors having guide posts extending outwardly from one surface for insertion into openings of a printed circuit board characterized in that the guide posts are provided with a groove therein and a metal clasp having catch surfaces thereon are disposed in groove with. the catch surfaces projecting laterally outwardly therefrom.

2. The retaining device of Claim 1 characterized in that the catch surfaces are on flexible leg portions.

3. The retaining device of Claim 2 characterized in that the metal clasp has barbs on a main section.

4. The retaining device of Claim 3 characterized in that the guide posts have a cavity for receiving the tips of the leg portions.

5. The retaining device of Claim 4 characterized in that the leg portions diverge from each other.

6. A retaining device for electrical connectors, constructed and adapted to operate substantially as hereinbefore described with reference to Figures lA,lB or Figures 2A,2B of the accompanying drawings.

6. A retaining device for electrical connectors, constructed and adapted to operate substantially as hereinbefore described with reference to Figures#lA,lB or Figures 2A,2B of the accompanying drawings.

Amendments to the claims have been filed as follows

1. A retaining device for electrical connectors having guide posts extending outwardly from one surface for insertion into openings of a printed circuit board characterized in that the guide posts are provided with a groove therein and a metal clasp having catch surfaces thereon is disposed in the groove with the catch surfaces projecting laterally outwardly therefrom.