JPH0922635A - Push switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a soldering operation in such a way as to make heat unlikely to be transferred into a housing via a terminal. SOLUTION: A terminal 26 is insert molded in a hollow housing 12 made of an insulative resin, and contacts 14, 15 each connected to the terminal 26 are provided inside the housing 12. The terminal 26 insert molded in the housing 12 is partially narrowed to form a constricted part 28. The terminal 26 is formed by punching of an iron plate, with the constricted portion 28 formed near the side of the housing 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a push switch used as a contact for a keyboard of electronic equipment.

[0002]

2. Description of the Related Art Conventionally, a push switch used as a contact point of a keyboard has a fixed contact point and a movable contact point in a housing 2 formed of an insulating resin as shown in FIG. The stem provided on the upper surface in a protruding direction is in contact with the movable contact. A terminal 6 made of brass and having a constant width is integrally formed with the contacts 7 and 8 in the housing 2 and is insert-molded. The terminals 6 respectively extend from two side surfaces of the housing 2 near the bottom surface facing each other, are bent 90 degrees toward the bottom surface, and extend downward. When installing this push switch on the keyboard circuit board, first insert the push switch terminals into the terminal holes on the circuit board, and then at 45 ° C at 100 ° C.
After preheating for 2 seconds, the substrate and terminals are immersed in solder for 5 seconds using a flow soldering apparatus with a solder temperature of 250 ° C. to complete the process.

[0003]

In the case of the above conventional technique, when the push switch is soldered to the circuit board,
The heat of the solder is transmitted to the inserted terminal, the heat is transmitted to the movable contact and the stem in contact with the terminal, and the plastic stem may be melted by the heat and deformed.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to provide a push switch in which heat is less likely to be transferred to the inside of the housing through the terminals even when soldering.

[0005]

According to the present invention, a terminal is insert-molded in a hollow housing made of an insulating resin, and a contact connected to the terminal is provided in the housing, and the contact is inserted in the housing. Is a push switch in which a narrowed portion is formed by narrowing a part of the formed terminal. Further, the terminal is formed by punching out an iron plate, a fixed contact is integrally provided with the terminal in the housing, and the narrowed portion is formed near a side surface of the housing. Is.

[0006]

In the push switch of the present invention, when soldered to the circuit board, the heat of the solder is transmitted to the terminals, but the heat conduction is hindered by the narrowed portion provided at the terminals, and the push switch is connected to the terminals in the housing. The amount of heat transmitted to the moving contact and stem that are present is suppressed, and the influence of heat on the plastic stem is prevented.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show an embodiment of the present invention, the push switch 10 of this embodiment is
A switch mechanism such as fixed contacts 13 and 15 and movable contact 14 is built in a hollow box-shaped housing 12 made of insulating resin. The upper surface of the housing 12 is an opening and is covered with a cover 24. Cover 2
4 has a through hole 20 in the center, and a circular stem 16 is inserted into the through hole 20.

The lower end of the stem 16 contacts the movable contact 14 in the housing 12 and is biased in the protruding direction. Further, welding projections 18 formed integrally with the housing 12 are provided at the four corners of the upper surface of the housing 12, and the welding projections 18 are inserted into the through holes 22 at the four corners of the cover 24 and melted to form the housing 12.
The cover 24 is fixed to the.

A terminal 26 formed by punching an iron plate is insert-molded in the housing 12, and the terminal 26 projects from the vicinity of the bottom surfaces of the two side surfaces facing each other. A narrowed portion 28 having a length of 1 mm is provided at a portion of the terminal 26 inserted into the housing 12. The narrowed portion 28 is formed in the vicinity of the side surfaces of the housing 12 which face each other, and is formed by preliminarily cutting both side edges of the terminal 26 of the insert portion so that the terminal 26 having a width of 0.7 mm is 0.35 mm. To do.

Further, in the portion of the terminal 26 inserted into the housing 12, the fixed contacts 13 and 15 are exposed to the inside of the housing 12, and the movable contact 14 and the fixed contact 15 are constantly in contact with each other and the movable contact 14 is pressed. , Is provided so as to be able to contact the fixed contact 13. The terminal 26 is the housing 1
Immediately after projecting outward from the side surface near the bottom surface of 2, the terminal 26 is bent and extends downward, and the tip end portion of the terminal 26 is bent into a dogleg shape so that it can be inserted into and engaged with the terminal hole of the circuit board. There is.

To mount the push switch 10 of this embodiment on a circuit board, first, the terminal 26 of the push switch 10 is inserted into a predetermined terminal hole of the circuit board, and after preheating, soldering is performed as in the prior art. It is sent to the melted flow soldering furnace and the back side of the circuit board is dipped in a solder bath for a few seconds to perform soldering. At this time, the heat of the solder is transferred to the terminal 26, but the heat conduction is impeded by the narrowed portion 28 provided in the terminal 26, and the amount of heat transferred to the movable contact 14 in contact with the terminal 26 and the stem 16 is suppressed. Stem 16
Can be prevented from melting or being thermally deformed.

Here, the push switch 1 of this embodiment
0 is compared with the terminal 26 of this embodiment in the case of using a terminal made of iron and having the same shape as the conventional product in terms of heat conduction when soldering, the solder dip (260
The test was performed. As a result, the housing 1
The surface temperature of the contact point of 2 is 150 ℃ for the conventional shape.
The push switch 1 of this embodiment
In the case of 0, it was about 120 degreeC. Further, since the surface temperature of the contact portion was lowered by 30 ° C., it was possible to prevent the stem 16 from melting even if iron was used for the terminal 26. Further, the cost can be reduced by using the iron terminal 26.

In addition to iron, the terminal of the present invention can suppress the heat conduction similarly with the brass terminal and other materials as in the conventional case, and the effect of heat during soldering is effective. Can be suppressed.

[0014]

EFFECTS OF THE INVENTION The push switch according to the present invention is capable of suppressing the heat transmitted during soldering to the stem when soldering to a circuit board, and even if a terminal having high thermal conductivity is used, It is possible to eliminate the effect of heat when soldering.

[Brief description of drawings]

FIG. 1 is a bottom view of a push switch according to an embodiment of the present invention.

FIG. 2 is a partially cutaway plan view of the push switch according to this embodiment.

FIG. 3 is a partially cutaway front view of the push switch of this embodiment.

FIG. 4 is a bottom view showing a conventional push switch.

[Explanation of symbols]

 10 push switch 12 case 13 and 15 fixed contact 14 movable contact 26 terminal 28 narrowed portion

Claims (2)

[Claims] 1. A terminal is insert-molded in a hollow housing made of an insulating resin, a contact connected to the terminal is provided in the housing, and a part of the terminal inserted in the housing is provided. A push switch with a narrowed portion. 2. The push switch according to claim 1, wherein the terminal is formed by stamping an iron plate, and the narrowed portion is formed near a side surface of the housing.