JPS6116682Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a resin-sealed electrolytic capacitor, and particularly to a structure that prevents the intrusion of cleaning liquid during assembly of a printed wiring board (hereinafter referred to as a board).

Electrolytic capacitors and other electronic components are often attached to circuit boards. When assembling this board, after attaching the components to the board and performing soldering, the entire board is cleaned with a chloride-based cleaning solution such as trichlorethylene or trichlorethane to remove soldering flux and other contaminants. It is usually done. However, electrolytic capacitors are sensitive to chlorine, and if even a small amount of the above-mentioned chlorine-based cleaning solution infiltrates through the gap in the sealing part, the capacitor will gradually corrode, causing accidents such as valve opening and wire breakage, and reducing the reliability of the equipment. This will result in a loss. For this reason, in the past, the capacitor's elastic sealing body was covered with thermosetting epoxy resin as a countermeasure against cleaning fluids. Bending or other forces on the lead wire may cause separation between the lead wire and the resin, or the contact surface between the lead wire and the resin may separate due to a difference in expansion coefficient due to heat during soldering. Therefore, during cleaning, the cleaning liquid may enter through the lead wire portions that are insufficiently bonded, and this cannot be said to be a sufficient measure against cleaning liquid. Also, with epoxy resin, as shown in Fig. 1, if the epoxy resin layer 5 is made sufficiently thick (several mm or more), the lead wire 3 and the resin layer 5 will be difficult to separate due to bending of the lead wire 3, etc. This is by no means a good measure in today's electronic components, where the overall length of the capacitor is long and miniaturization is required.

Therefore, as shown in FIG. 2, the present invention has a structure in which the elastic sealing member 4 of the electrolytic capacitor is covered with a silicone resin 6 that hardens at room temperature, and is cured at room temperature.

In the drawing, 1 is an electrolytic capacitor element, 2 is a case, and 3 is a lead wire.

The room-temperature curable silicone resin 6 of the present invention remains elastic even after curing, so it has sufficient ability to follow the bending and pulling of the lead wire 3, and the silicone resin itself has superior adhesion to metal compared to epoxy resin. At the same time, the resin and lead wire will not peel off. Furthermore, the silicone resin has excellent heat resistance, and the resin will not melt due to the heat generated by soldering. Furthermore, due to its elasticity, the silicone resin layer only needs to be about 0.5 mm thick to achieve its purpose, so it is sufficient to cover the sealing fold part of case 2 with resin as shown in Figure 2, and the case can be made longer. do not have to.

In this way, the present invention reliably prevents the intrusion of substrate cleaning liquid, eliminates the risk of corrosion, and has an effect on the lifespan and reliability of electrolytic capacitors. Moreover, it does not have the disadvantage of having a larger case than conventional capacitors. do not have.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional front view of a conventional electrolytic capacitor.
FIG. 2 is a longitudinal sectional front view of the electrolytic capacitor of the present invention. 1... Electrolytic capacitor element, 2... Case, 3
... Lead wire, 4 ... Elastic sealing body, 5 ... Epoxy resin layer, 6 ... Silicone resin layer.

Claims (1)

[Scope of utility model registration request] An electrolytic capacitor sealed with an elastic sealing body made of rubber or the like, characterized in that the outer surface of the elastic sealing body is covered with a layer of a room-temperature curable silicone resin applied and cured.