JPH0215973B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a contact joining method for joining a contact member (hereinafter simply referred to as a contact) to a pedestal using a spot welding machine.

When a contact is joined to the end of a pedestal of a predetermined length using an ordinary spot welding machine, according to the conventional contact joining method, a contact failure occurs due to uneven temperature rise at the joining interface. It was easy. Figure 1 is a side view showing such a poor bonding state.
1 is the upper electrode of the spot welding machine, 2 is the lower electrode,
3 is a contact for joining to the free end of the pedestal 4 of a predetermined length, 5 is a joining alloy layer formed between the contact 3 and the pedestal 4, and 6 is an eluted alloy layer eluted from this joining alloy layer 5. , 7 is a gap-like bonding defect formed between the pedestal 4 and the contact 3.

Therefore, in the conventional contact bonding method, the bonding alloy layer 5 is formed only on the free end side of the pedestal 4, and a large amount of the eluted alloy layer 6 drips down.
Moreover, on the opposite side of the bonding alloy layer 5, that is, on the non-free end side of the pedestal 4, void-like bonding defects 7 are likely to occur. FIG. 2 is a side view for explaining the cause of such a joint failure. As shown by the arrow X, the heat inside the pedestal 4 is reflected by its end surface, and In this case, heat escapes in the longitudinal direction of the base 4 as shown by arrow Y. Therefore, the temperature distribution from point A to point _B at the bonding interface between pedestal 4 and contact 3 exhibits a gradient as shown in _FIG . As shown in the figure, on the free end side of the pedestal 4, the temperature is high, so that the amount of the eluted alloy layer 6 eluted from the bonding alloy layer 5 drips down, and on the non-free end side of the pedestal 4, the temperature is high. Because of the low temperature, void-like bonding defects 7 are likely to occur.

This invention was made with attention to this point, and the temperature distribution at the bonding interface between the contact and the pedestal is made uniform throughout, thereby preventing the eluted alloy layer from dripping,
It is an object of the present invention to provide a contact bonding method that prevents the occurrence of void-like bonding defects.

The first invention of the present application is such that a pair of contact members to be joined to each other and a pedestal of a predetermined length are sandwiched between a pair of electrodes with the contact members facing each other at the end of the pedestal. A method of joining the contact member to the end of the pedestal by energizing the pedestal, and in order to achieve the above purpose, a heat dissipation member extending in the opposite direction to the pedestal is provided between the pedestal and one electrode. This is a contact joining method characterized by inserting a metal plate.

In the second invention of the present application, two sets of contact members to be joined to each other and a set of a pedestal of a predetermined length are sandwiched between a pair of electrodes with the contact members facing each other at the end of the pedestal, and the electrode A method of joining the contact to the end of the pedestal by applying electricity between the two pairs of contact members and the pedestal, in order to achieve the above object, the two sets of contact members and the pedestal are connected to the side of the pedestal where the contact member is not joined. This is a contact bonding method characterized by arranging the two sets of pedestals so that their ends are overlapped so that their surfaces face each other and the extending directions of the two sets of pedestals are opposite.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 5 is a side view showing an embodiment of the first invention. In the figure, between a pair of spot welding electrodes (upper electrode 1, lower electrode 2) arranged oppositely, there is an end of the base 4 (free end side; a side that is not fixed when attached to an electronic device, etc.). The contact point 3 is placed on the end portion) and held, and the pedestal 4 extends to the left in the drawing. In addition, the pedestal 4 and the lower electrode 2
A heat dissipating metal plate 8 is disposed so that its end portion overlaps the free end portion of the pedestal 4 and extends in the opposite direction to the pedestal 4 (ie, to the right in the drawing).

In this state, when electricity is applied between the electrodes 1 and 2, the temperature of each member sandwiched between them increases due to Joule heat, and the contact 3 and the pedestal 4 are welded (eutectic metal plate 8 and the pedestal 4 are welded). metal plate 8 to prevent a reaction from occurring.
It goes without saying that the metals that make up the material must be selected).

At this time, the heat generated at the free end of the pedestal 4 does not reach saturation, and the heat dissipating metal plate 8 that is pressed against the back surface of the pedestal 4 does not reach saturation.
Since the water flows toward the pedestal 4, only the free end side of the pedestal 4 does not become high temperature. That is, since the pedestal 4 and the heat dissipating metal plate 8 are arranged symmetrically in the longitudinal direction, the temperature of the joint surface between the contact point 3 and the pedestal 4 is almost uniform throughout, and there is no chance of dripping of the eluted alloy layer or bonding defects such as voids. does not occur.

3 and 4 show an embodiment of the second invention, in which the free end sides of a pair of pedestals 4, 4' of a predetermined length are overlapped with each other, and their longitudinal directions are symmetrical to each other. and both pedestals 4,
4' and the upper and lower electrodes 1, 2, after sandwiching the contacts 3, 3' to be joined, the upper and lower electrodes 1,
When a predetermined voltage is applied to 2, the heat at the respective free end sides of both pedestals 4, 4' flows in the longitudinal direction of both pedestals 4, 4' which are in overlapping contact with each other,
Without saturation, as shown in Figure 3, from point A to point B at each bonding interface, and
The temperature distribution from point A' to point B' is shown in Figure 3 as T _A - T _B and T _A '- T _B ', and the temperature difference is extremely small, similar to the conventional one mentioned above. As shown in Fig. 4, there is no dripping of the eluted alloy layer or generation of void-like bonding defects, and as shown in Fig. 4, one pedestal 4 and contact 3, and the other pedestal 4' and contact 3' are The bonding alloy layers 5, 5' can ensure reliable bonding. In addition, in the contact joining method of the invention as described above, the pedestal 4,
4' and the contacts 3, 3' are bonded to each other, and no bonding reaction occurs between the overlapping pedestals 4 and 4' because the materials of the contacts 3, 3' and the pedestals 4, 4' are, for example, This is due to the formation of a low melting point alloy through a eutectic reaction, such as in silver and copper systems.

As described above, in the first invention, since the heat dissipation metal plate extending in the opposite direction to the base is interposed between the base and the electrode, the heat at the free end of the base is not saturated and the heat dissipation metal plate is disposed between the base and the electrode. It flows in the direction of extension, and the temperature distribution at the joint surface between the pedestal and the contact point becomes almost uniform throughout.

Further, in the second invention, the two sets of contacts and the pedestals are arranged with the ends of the pedestals overlapping each other so that the back surfaces of the pedestals face each other and the extending directions of the two sets of pedestals are opposite. Therefore, the heat at the free end of the pedestal flows in the direction of extension of the other pedestal without being saturated, and the temperature distribution at the joint surface between the pedestal and the contact point becomes almost uniform throughout both sets.

Therefore, according to the method of the present invention, it is possible to reliably join the contact to the end of the pedestal without causing the eluted alloy layer to sag or to create a void-like joining defect. Furthermore, the second invention has the advantage that two sets of contacts and pedestals can be joined at once.

[Brief explanation of drawings]

FIG. 1 is a side view showing a poor bonding state by a conventional contact bonding method, FIG. 2 is an explanatory diagram thereof, FIGS. 3 and 4 are side views for explaining the second invention, and FIG. FIG. 2 is a side view for explaining the first invention. In the drawing, 1 and 2 are the electrodes of the spot welding machine, 3,
3' is a contact, 4 and 4' are pedestals, and 8 is a heat dissipation metal plate. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A pair of contact members to be joined to each other and a pedestal of a predetermined length are sandwiched between a pair of electrodes with the contact members facing each other at the end of the pedestal, and A method of joining the contact member to the end of the pedestal by applying electricity, the method comprising interposing a heat dissipating metal plate extending in the opposite direction to the pedestal between the pedestal and one electrode. Characteristic contact joining method. 2. By sandwiching two sets of contact members to be joined to each other and a pedestal of a predetermined length between a pair of electrodes with the contact members facing each other at the ends of the pedestals, and applying electricity between the electrodes. A method of joining the contact point to an end of the pedestal, the two sets of the contact member and the pedestal being arranged such that the surfaces of the pedestals on the side where the contact members are not bonded face each other, and the extension directions of the pedestals are opposite to each other. A contact joining method characterized by arranging the ends of the pedestals so that they are oriented in the same direction.