Lock pin and electrical connector using the same

Abstract

 A lock pin (4,5) includes an arm to be inserted into a mounting aperture of a mounting plate and fixed to a metal portion around the mounting aperture by soldering, and an anchoring projection (3d) formed at an end of said arm. The arm is provided with a melted solder induction protrusion (7,8a,8b) for guiding melted solder to distribute it extensively on the metal portion. An electrical connector includes a connector main body (1), a front shell (2) surrounding the connector main body, and the lock pin to be secured to the connector main body and having an anchoring projection (3d), an arm (3c) electrically connected to the front shell and the melted solder induction protrusion (7,8a,8b). When a melted solder is positioned between the surface of the mounting plate and the induction protrusion, the induction protrusion is "wetted" with the melted solder. Therefore, the melted solder flows with the aid of its surface tension along surfaces of the induction protrusion to arrive at the arm of the lock pin and further flows along the arm of the lock pin to the back surface of the mounting plate with ease, whereby the mounting plate and the lock pin are fixed with great certainty.

Description

[0001] This invention relates to a lock pin for fixing an electrical element by means of soldering to a panel of an electronic appliance or a board therein (referred to hereinafter as a "mounting plate"), and more particularly to an electrical connector having such a lock pin utilized for grounding an electromagnetic shield of the connector. The electrical element in this case includes a relay, a switch, an electrical connector, an optical fiber connector, a light reception or emission module having a housing accommodating therein a semiconductor for receiving or emitting light beams, a terminal block for connecting lead wires and an electronic appliance, and the like.

[0002] In order to fix an electrical element to a mounting plate such as a panel or printed circuit board, lock pins are generally used (designated by numerals 3 and 4 in Fig. 1). Such lock pins are permanently fixed to the mounting plate by soldering. The lock pins are also often used as grounding lines of the electrical element.

[0003] In the case that the mounting plate is a printed circuit board, soldering operation is usually automatized. In many cases, a paste-like solder is previously coated on the metal pattern of a printed circuit board and an electrical element is arranged on the coated solder. Thereafter, the entire assembly is heated to cause the solder to flow into clearances between the portions to be soldered.

[0004] In order to solve the problem of disturbance of electromagnetic waves, particularly caused by development of electromagnetic devices, an electromagnetically shielded electrical connector has been used as an electrical element to be fixed to a mounting board, for example, shown in a perspective view of Fig. 1.

[0005] With such an electrical connector as shown in Fig. 1, a metal front shell 2 is fixed to a connector main body 1 to surround it so that both ends 1a of the connector main body 1 are embraced by both ends 2a of the metal front shell 2. A one-leg lock pin 3 and a two-leg lock pin 4 are arranged at and clamped to both ends 2a of the metal front shell 2 by means of set screws (not shown) extending through screw threaded apertures 3b and 4b formed in the lock pins 3 and 4, respectively. In this manner, the connector main body 1, the metal front shell 2 and the lock pins 3 and 4 are assembled as an integral unit. In this case, hook portions 3b and 4b of the lock pins 3 and 4 are engaged with the front shell 2 to ensure the electrical connections between the front shell 2 and the lock pins 3 and 4.

[0006] In mounting such an assembly or connector on a printed circuit board, as shown, for example, in Fig. 2a, the arm 3c of the one-leg lock pin 3 is inserted into one connector mounting aperture 5a provided in a ground wiring pattern of the printed circuit board 5 so that the anchoring projection 3d of the one-leg lock pin 3 at its free end is engaged with the ground wiring pattern on the rear side of the printed circuit board 5. Thereafter, the assembly is turned about the engaged portion of the one-leg lock pin 3 toward the printed circuit board to force the two-leg lock pin 4 into the other connector mounting aperture 5b provided in the ground wiring pattern 5c of the printed circuit board 5 as shown in Fig. 2b. As a result, the two arms 4c and 4c′ of the lock pin 4 are at once forced toward each other against their spring force during passing of the anchoring projections 4d and 4d′ of the lock pin 4 through the connector mounting aperture 5b. When the anchoring projections 4d and 4d′ have just passed through the connector mounting aperture 5b, the arms 4c and 4c′ are released and engaged with the ground wiring pattern 5c on the rear side of the printed circuit board 5 so that the connector is temporarily mounted on the printed circuit board 5.

[0007] Thereafter, the arms 3c, 4c and 4c′ of the lock pins 3 and 4 together with contact tails inserted in mounting apertures provided in a wiring pattern (not shown) are fixed by soldering to the ground wiring pattern provided in the mounting apertures 5a and 5b of the printed circuit board 5. In this manner, the electrical connector is permanently fixed to the printed circuit board, and at the same time the front shell 2 is grounded to shield the connector electromagnetically.

[0008] In soldering the electrical connector to the printed circuit board, for example, a paste-like solder is previously coated on the proximity of surfaces to be soldered and the whole assembly is then heated in a heating apparatus to cause the paste-like solder to flow so as to be distributed over the areas to be soldered. In this method, however, frequently the lock pins 3 and 4 are not electrically connected to or incompletely connected to the the ground wiring pattern of the printed circuit board 5.

[0009] This mainly results from the following fact. In this case, a paste-like solder is coated on around the connector mounting apertures 5b of the printed circuit board 5 as shown in Fig. 3a and heated to be melted in a heating apparatus. If the mounting apertures 5a and 5b of the printed circuit board 5 are comparatively larger than the lock pins 3 and 4, the melt solder tends to agglomerate with the aid of its surface tension to form risen formations which do not flow into the mounting aperture 5a or 5b as shown in Fig. 3b.

[0010] It is an object of the invention to provide a lock pin which eliminates the problem of the prior art described above and is able to guide a melted solder into a mounting aperture of a mounting plate in a reliable manner even if the mounting aperture is relatively larger than the lock pin.

[0011] It is another object of the invention to provide an electrical connector utilizing the lock pin so that an electromagnetic shield can be securely grounded even in an automatized soldering process for soldering the lock pin to a mounting plate.

[0012] These objects can be accomplished by providing a lock pin with an induction protrusion on an arm of the lock pin on the side of the surface of the mounting plate, for example, a printed circuit board for guiding the melted solder. The induction protrusion extends parallel with the surface of the mounting plate and substantially in contact with the surface of the mounting plate when the lock pin is secured to the mounting plate.

[0013] In other words, when a melted solder is positioned between the surface of the mounting plate and the induction protrusion, the induction protrusion is "wetted" with the melted solder. Therefore, the melted solder flows with the aid of its surface tension along surfaces of the induction protrusion to arrive at the arm of the lock pin. If the amount of the melted solder is sufficient, the melted solder further flows along the arm of the lock pin to the rear surface of the mounting plate with ease, whereby the mounting plate and the lock pin are fixed with great certainty.

[0014] In order that the invention may be more clearly understood, preferred embodiments will be described, by way of example, with reference to the accompanying drawings.

Fig. 1 is a perspective view of the connector of the prior art;

Figs. 2a and 2b and 3a and 3b are explanatory views for explaining operations for fixing the connector to a mounting plate;

Fig. 4 is a perspective view of one embodiment of the connector and the lock pin according to the invention; and

Figs. 5 and 6a and 6b are explanatory views for explaining operations for fixing the connector shown in Fig. 4 to a mounting plate.

[0015] Figs. 4-6 illustrate one embodiment of the electrical connector according to the invention. The lock pin according to the invention will be understood concurrently with understanding of the electrical connector according to the invention by referring to these drawings.

[0016] Referring to Fig. 4 illustrating in a perspective view the electrical connector according to the invention and Fig. 5 showing the state of the lock pin according to the invention inserted in a printed circuit board. The connector includes a connector main body 1 having both ends 1a and a front shell 2 having both ends 2a, a one-leg lock pin 3 and a two-leg lock pin 4. The one-leg lock pin 3 includes a hook portion 3a, a threaded aperture 3b, an arm 3c and an anchoring projection 3d. The two-leg lock pin 4 includes a hook portion 4a, a threaded aperture 4b, arms 4c and anchoring projections 4d. The above features are similar to those described in Fig. 1.

[0017] In order to prevent a solder from agglomerating, the lock pins 4 and 5 are provided with induction protrusions 7 and 8a and 8b, respectively, according to the invention. The induction protrusion 7 is provided on the arm 3c of the one-leg lock pin 3 and extends in the same direction as that of the anchoring projection 3d, while the induction protrusions 8a and 8b are provided on the arms 4c and 4c′ of the two-leg lock pin 4, respectively, and extending in the same directions as those of the anchoring projections 4d. These induction protrusions are so constructed that undersides of the protrusions 7, 8a and 8b are brought into contact with the surface of the printed circuit board 5 and extend in a horizontal direction beyond the outer circumferences of connector mounting apertures 5a and 5b of the printed circuit board 5 as shown, for example, in Fig. 5.

[0018] With this arrangement, when the connector according to the invention is mounted on the printed circuit board 5 and heated, a solder paste 6 (shown on an exaggerated scale in Fig. 6) provided, for example, between melted solder induction protrusions 8a and 8b of the two-leg lock pin 4 and ground wiring pattern surface 5c of the printed circuit board 5 is melted. On the other hand, the melted solder induction protrusions 8a and 8b are substantially in contact with the ground wiring pattern surface 5c of the printed circuit board 5 as described above. Therefore, the induction protrusions 8a and 8b prevent the solder from agglomerating and introduce the melted solder 6 in a flowing condition into clearances between wall surface of the connector mounting aperture 5b and the arms 4c and 4c′ of the two-leg lock pin 4 so that the melt solder flows along the arms 4c and 4c′ and arrives on the underside of the printed circuit board 5. Accordingly, by cooling the connector under this condition, the arms 4c and 4c′ of the lock pin 4 and hence the front shell 2 are electrically connected to the ground wiring pattern surface 5c in a reliable manner. The soldering operation with the one-leg lock pin 3 is effected in the same manner as that described above.

[0019] While one of the lock pins includes one leg and the other lock pin includes twin legs in the above embodiment, it is apparent that all the lock pins may be provided with single legs or twin legs to bring about the same effect. Moreover, instead of both the lock pins being soldered, either of the lock pins may be soldered in the connector according to the invention. In the case of the one-leg lock pin, the induction protrusion may be provided so as to extend in the direction opposite to the extending direction of the anchoring projection 3d.

[0020] As can be seen from the above explanation, the melted solder induction protrusions are provided on the arms of the lock pins according to the invention. With such a simple construction, it is possible to cause the solder to flow along the arms without any agglomeration so as to arrive, for example, on the rear side of the printed circuit board with great certainty.
Consequently, the lock pins of the connector and ground portions of the printed circuit board are electrically connected in a reliable manner to ensure the connection between the front shell of the connector and the ground circuit of the printed circuit board, thereby obtaining the desired electromagnetic shield effect.

[0021] It is further understood by those skilled in the art that the foregoing description is that of preferred embodiments of the disclosed invention and that various changes and modifications may be made in the invention without departing from the spirit and scope thereof.

Claims

1. A lock pin including an arm to be inserted into a mounting aperture of a mounting plate and fixed to a metal portion around said mounting aperture by soldering, and an anchoring projection formed at an end of said arm, wherein said arm is provided with a melted solder induction protrusion for guiding melted solder to distribute it extensively on said metal portion.

2. A lock pin as set forth in claim 1, wherein said mounting plate is a printed circuit board, said metal portion around said mounting aperture is a wiring pattern of said printed circuit board, and said mounting aperture is for mounting an electrical element on said printed circuit board.

3. A lock pin as set forth in claim 2, wherein said melted solder induction protrusion is located on said arm so that said melted solder induction protrusion is brought into contact with the surface of said printed circuit board when said lock pin is mounted in said printed circuit board as said mounting plate, and said melted solder induction protrusion has a length which extends beyond the outer diameter of said mounting aperture of said printed circuit board over the outer circumference of the mounting aperture.

4. A lock pin as set forth in claim 3, wherein said electrical element is any one selected from a relay, a switch, an electrical connector, an optical fiber connector, a light reception or emission module and a terminal block.

5. A lock pin as set forth in claim 3, wherein said electrical element is an assembly of those selected from a relay, a switch, an electrical connector, an optical fiber connector, a light reception or emission module and a terminal block.

6. A lock pin as set forth in claim 2, wherein said melted solder induction protrusion is located on said arm so that said melted solder induction protrusion is brought into contact with the surface of said printed circuit board when said lock pin is mounted in said printed circuit board as said mounting plate, and said melted solder induction protrusion has a length which extends beyond the outer diameter of a connector mounting aperture of said printed circuit board over the outer circumference of the connector mounting aperture.

7. An electrical connector including a connector main body, a front shell surrounding said connector main body, and a lock pin to be secured to said connector main body and having an anchoring projection and an arm electrically connected to said front shell, wherein said arm of the lock pin is provided with a melted solder induction protrusion for guiding melted solder to distribute it extensively on a portion to be soldered.

Drawing