JPS6014496B2 - How to undercoat electronic parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an undercoating method useful for manufacturing electronic components having a hollow portion in the element body.

The metallized plastic capacitor has the structure shown in FIG. First, as shown in FIG.
A capacitor foil on which aluminum vapor-deposited electrodes 3 are formed is sandwiched between lead wires 4 with solder balls 5,
The capacitor is obtained by rotating the lead wire 4 as an axis and winding it as shown in FIG. be. Now, many electronic components are manufactured by hardware that uses resin exteriors or metal cans to protect them from outside air pollution, especially moisture.
Currently, a metic seal is used.

This capacitor is no exception; in particular, a hermetic seal or resin exterior is indispensable in order to improve its green resistance. However, in this capacitor, there is a hollow part in the center of the element as shown in Figure 1B, so whether the exterior is made of powdered resin, dipping resin, or a combination of the case and Western-style resin,
It is extremely difficult to package the resin without pinholes on the resin surface or inside the resin. This results in poor green resistance. Therefore, in order to eliminate this pinhole, it is first necessary to fill the hollow part and eliminate the pinhole in the exterior. However, when the undercoat is in direct contact with the polysulfone or evaporated electrode, as in this capacitor, the electrical characteristics of the undercoat (tan6
(insulation resistance, etc.), and the primer must not attack the element. On this point, paraffin, polyethylene, or polypropylene waxes are inert and have good electrical properties, and polysulfone waxes do not corrode the deposited electrodes, so they are ideal as materials for filling hollow parts. However, after heating and melting these waxes 8 and dipping the element body 7 as shown in FIG. 2A, and adhering the wax to the lead wires as shown in FIG. It is thought that when the resin exterior is used as shown in C in the figure, resin moisture permeability is reduced. However, since the lead wire and the wax lack adhesiveness, moisture permeates through the interface between the two. The method of the present invention solves this problem, and as shown in FIG. When the element body 7 is pulled up after the wax is sucked into the hollow part of the lead wire, the wax 9 does not adhere to the lead wires, as shown in FIG.

When this is powder-packed using epoxy powder resin, it becomes as shown in Figure C, and since the adhesion between the lead wire and the resin is improved, interfacial moisture permeation from the lead wire is greatly improved. Incidentally, Ichikawa is a resin-coated body. Resin moisture permeability is considered to be inferior to when the resin is completely coated with wax, but the method of the present invention improves interfacial moisture permeability, resulting in improved moisture resistance.

When discussing moisture permeability here, whether the resin moisture permeability or the interface moisture permeability of the lead wire takes priority depends on the characteristics of the resin, but at least if the wax is attached to the lead wire, the moisture permeability will take priority. What happens at the wet lead interface is unavoidable. The type of wax used in the present invention is not limited as long as it has good properties and has a melting point equal to or higher than the guaranteed heat resistance temperature of the capacitor.

The present invention will be explained below using comparative examples and examples.

[Comparative Example 1] A metallized plastic capacitor was dipped in wax (softening point: 150 oo) heated and melted at 160° C. as shown in FIG. 2, so that the lead wire portion was covered with wax.

Thereafter, the capacitor was packaged with epoxy powder resin, and then left in an atmosphere at a temperature of 40°C and a relative humidity of 95%, and the moisture resistance of the capacitor was evaluated by the rate of change in capacitance (C) (ΔC/C). As a result, ΔC/C after 100 hours was 6%. [Comparative Example 2] A film capacitor was dipped in wax (softening point: 128 qo) heated and melted to 14 psi, as shown in Fig. 2, so that the lid wire portion was covered with wax.

Thereafter, the capacitor was wrapped in an outer bag using epoxy powder resin, and the moisture resistance of the capacitor was examined under the same conditions as in Comparative Example 1. As a result, ΔC/C after 10 field hours was 6.5%. [Example 1] A capacitor is dipped in wax (softening point 150 qo) heated and melted at 16,000 ℃ as shown in Fig. 3, and the wax is sucked into the hollow part by capillary action, and the wax is drawn into the lead wire part. was prevented from attaching.

This capacitor was packaged with the same powder gun resin as in Comparative Examples 1 and 2, and then the moisture resistance of the capacitor was examined under the same conditions. As a result, ΔC/C was 1%, which was six times higher than that of Comparative Example 1. [Example 2] As shown in Fig. 3, a capacitor is dipped in wax heated and melted to 140q0 (softening point 128oC) to the extent that it touches the surface of the wax, the molten wax is sucked into the hollow part, and the lead wire part is I tried not to let it stick.

After this was packaged using the same powdered resin as in Comparative Examples 1 and 2, the overflow resistance of the capacitor was examined under the same conditions. As a result, ΔC/C was 1.5%, which was four times higher than that of Comparative Example 2. If an undercoating method in which wax is not attached to the lead wires is used, as in the method of the present invention, the moisture resistance after resin coating is greatly improved. It should be noted that this priming method is not limited to metallized plastic film capacitors, but can also be applied to other electronic components that have similar hollow areas and yet require an inert priming agent.

[Brief explanation of drawings]

FIG. 1A is a developed view of a capacitor having a hollow portion in the element body, and FIG. 1B is a perspective view of the capacitor after winding. FIGS. 2A, B, and C are process diagrams for explaining a conventional example of resin coating of this capacitor, and FIGS. 3A, B, and C are process diagrams of resin coating to which the method of the present invention is applied. 7...Element body, 8...Melted wax, 9...
Solidified wax, 10...Resin coating. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1 The element body of an electronic component having a hollow part is immersed in the heated and melted wax surface to the extent that it touches the surface, and the hollow part is filled with wax due to capillary action of the wax, and then the element body is pulled up to directly A method of undercoating an electronic component, characterized by eliminating hollow parts of the electronic component without attaching wax to lead wires.