JPS6314347Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to the structure of a housing of an electronic device, such as a push button male switch, and its purpose is to prevent soldering flux from entering during an automatic soldering process.

FIG. 1 is a sectional view showing an example of a thin push button switch, in which fixed contacts 2,
2 and 3 and a movable contact 4 are arranged, and when the push button 5 is pressed, the contacts 2 and 3 are closed and the switch is turned on.In particular, the case 1 will be explained with reference to FIG. 2. , two sets of conductor strips 6 and 7 are embedded in the bottom wall 14 of the casing 1 by insert molding, and the fixed contacts 2 and 2 are formed integrally with the conductor strip 6, and are embedded in the outer wall of the casing 1. The protruding parts serve as terminals 8,8. Similarly, the fixed contact 3 and the terminals 9, 9 are formed integrally with the conductor strip 7. FIG. 3 is a cross-sectional view of essential parts showing the arrangement of molds during molding of the casing 1, with reference numeral 11 representing a lower mold and 12 representing an upper mold.

When synthetic resin for molding is injected in this state,
Since the lower surface of the fixed contact 2 is not supported by any part of the mold, it is in a state where it can easily move downward.
During the molding process, the height of the fixed contact 2 may drop to some extent, creating a slight gap between it and the upper mold. There are drawbacks such as the conductivity of the surface of the contact point 2 being inhibited.

Figure 4 shows the lower mold 1 in order to eliminate the above drawbacks.
A mold arrangement in which a pin 13 is provided protruding from the upper mold 1, and the fixed contact 2 is held between the pin 13 and the upper mold 12 to prevent the fixed contact 2 from moving up and down during molding. This shows that. However, in this molding method, a through hole 10 is formed in the lower surface of the housing 1 as shown in FIG. When soldering is performed using the device, the soldering flux sprayed from the bottom surface in a spouting state rises along the inner wall of the through hole 10,
It reaches the bottom surface of the fixed contact 2. There is a gap, although very small, between the lower surface of the fixed contact and the contact surface of the casing 1, and a liquid with low surface tension, such as flux, enters the bottom surface 1a of the casing through this gap and presses the push button switch. The disadvantage was that the functions of

In order to eliminate the above-mentioned drawbacks, the present invention forms the inner wall of the through hole in a step-like manner to lengthen the flux inflow path, thereby gradually lowering the inflow velocity and reducing the inflow amount. be.

FIG. 6 shows the shape of the through hole 15 of the present invention, where the through hole 15 has an opening 16 on the outer bottom surface 1b.
The inner diameter is made the widest, and the inner diameter is gradually narrowed stepwise until it reaches the innermost part 17. When flux enters along the inner wall of such a through hole 15, the inflow speed decreases as it rises along the inner peripheral surface, and the amount of inflow at the innermost part 17 decreases, so that the flux enters the lower surface of the fixed contact. The amount of flux that enters into the bottom surface 1a of the housing is extremely small, and the amount that enters the bottom surface 1a of the housing can be made to leave almost no trace.
This has the advantage that there is no need for preventive devices such as closing the through holes with adhesive or the like prior to the automatic soldering process.

[Brief explanation of drawings]

Figure 1 is a sectional view showing the structure of a conventional electronic device.
Figure 2 is a plan view of the casing, Figure 3 is a sectional view of the main part of the mold, Figure 4 is a sectional view of the main part of the mold in another conventional example, and Figure 5 is a sectional view of the main part of the casing. , FIG. 6 is a sectional view of the main part of the casing in the embodiment of the present invention. 1... Housing, 1a... Inner bottom surface, 1b... Outer bottom surface, 2, 3... Fixed contact, 14... Housing bottom wall, 1
5... Through hole, 16... Opening, 17... Innermost part.

Claims (1)

[Scope of utility model registration request] A terminal having a fixed contact is insert-molded into the housing so that the fixed contact is disposed on the inner bottom surface of a housing made of synthetic resin, and after inserting the terminal into a hole in a printed wiring board, the terminal is automatically removed. In the case of an electronic device that is soldered using a soldering device, the through hole on the lower surface of the fixed contact, which is created during insert molding, is formed so that the inner wall thereof is stepped and the inner diameter of the opening is the largest. A structure of a casing of an electronic device, characterized in that the casing is formed so as to become smaller as the size of the casing increases.