JPS633153Y2 - - Google Patents

Description

[Detailed explanation of the idea]

This invention relates to capacitors such as electrolytic capacitors, and more specifically, it holds and fixes the external lead wire drawn out from the capacitor element so as to withstand external shocks, and also prevents the wire from adhering to the printed circuit board when it is installed on the printed circuit board. The purpose of this is to prevent the halogenated organic solvent from penetrating into the capacitor and corroding and breaking the capacitor element when cleaning solder flux with a halogenated organic solvent. Generally, an electrolytic capacitor is constructed as shown in FIG. That is, the capacitor element 1 is housed in the case 2, and the internal lead wire 3 of the capacitor element 1 is
An electrolytic capacitor is obtained by sealing an elastic sealing body 5 to the opening of the case 2 through which an external lead wire 4 is passed. Note that 6 is an insulating tube that is tightly placed over the outer circumference of the case 2. In such a configuration, when an external impact is applied to the external lead wire 4 during transportation or installation into a printed circuit board, the external impact is transmitted from the external lead wire 4 to the internal lead wire 3 and is applied to the capacitor element 1. This has resulted in a disadvantage that the leakage current has an adverse effect on the connection between the internal lead wire 3 and the capacitor element 1, thereby adversely affecting the leakage current characteristics as shown in FIG. Additionally, after a capacitor is mounted on a printed circuit board, the solder flux adhering to the board is generally cleaned with a detergent in order to improve the reliability of the circuit, and at this time, there is a problem in that the detergent gets into the inside of the capacitor element 1. It was happening. Furthermore, in recent years, halogenated organic solvents have been most widely used as detergents in the market due to their safety, flame retardance, cost, and cyclical reuse. Therefore, the detergent that has entered the inside of the capacitor through the elastic sealing body 5 comes into contact with the Al metal of the electrode.
The halogen ions were decomposed and released, and reacted with the Al electrode, causing corrosion of the electrode, causing the capacitor element 1 to become disconnected and no longer functioning as a capacitor. In order to increase the reliability of such electrolytic capacitors and prevent defects, as shown in Figures 3 and 4, resin is filled on top of the elastic sealing body 5 to fix the external lead wire 4 and the case 2. At the same time, the airtightness of the seal is increased, and the external impact applied to the external lead wire 4 is absorbed and prevented by the resin layer 7, and the halogenated organic solvent permeates through the elastic seal member 5. A capacitor has been developed in which the resin layer 7 prevents the wire from entering the capacitor, thereby preventing corrosion and breakage of the capacitor. However, if case 2 is made higher as shown in Figure 3, a new case 2 must be made, and case 2
The aperture and assembly method had to be modified, and there was also the problem that it was difficult to fix the position of the elastic sealing body 5. Furthermore, if the resin is piled up as shown in Figure 4, it will be piled up on the insulating tube 6, which will prevent the case 2 and the resin layer 7 from coming into close contact with each other. As a result, the solvent enters the elastic sealing member 5, and the halogenated organic solvent ends up entering the inside of the capacitor, resulting in a problem that the capacitor does not sufficiently prevent the infiltration of the solvent. Furthermore, when applying resin, if the resin has a low viscosity, it will flow before it hardens, making it impossible to fill it into a uniform shape and making it difficult to create a sufficient thickness of the resin layer.
Furthermore, the surface of the resin layer 7 is not flat, and the resin surface is curved during and after mounting on a printed circuit board, resulting in insufficient fixation, poor stability, poor installation workability, and reduced reliability. However, the disadvantage was that it was inferior. The present invention has been developed in view of these conventional problems, and will be described in detail below with reference to FIG. 5, which shows an embodiment of the present invention. The electrolytic capacitor according to this invention has a thermal shrinkage rate of
A low insulation tube 8 of 15% to 25% is used, and the case 2 is attached to the sealing part side where the elastic sealing body 5 of the case 2 is inserted.
Case 2 is made by increasing the length and heat shrinking.
As shown in FIG. 5, as shown in FIG. It covers the According to the structure of the present invention, since the thermal shrinkage rate of the insulating tube 8 is low, the filling resin will not be deformed by heat during filling, regardless of whether it is room temperature curable, thermosetting, or ultraviolet curable. It can be used satisfactorily even when filled with a curable resin and thermosetted at high temperatures. Furthermore, since the resin layer portion 9 is in direct contact with the case 2 and the elastic sealing body 5, the adhesion between them is desirable and good. By the way, conventional insulating tubes are made of materials such as polyvinyl chloride and polyethylene terephthalate and have a limited thickness.
A heat shrinkable tube with a heat shrinkage rate of approximately 35% to 45% is used, with a thickness of about 0.1 mm to 0.5 mm, and when it is heat shrunk, it will stick tightly to the case 2, and a part of the insulating tube will be removed as shown in Figure 5. It is very difficult to stand. It is also possible to form a concave portion by increasing the length of the heat-shrink tube so that the tip part does not come into close contact with the case 2, but in this case, the heat-shrink tube is formed into a conical shape, and the tube Since the dimensions become longer by the length of , it is not possible to fill with resin as is, and it is necessary to cut off the excess portion after heat shrinking. On the other hand, in the present invention, a low heat shrink tube with a heat shrink rate of 15% to 25% is used in the radial direction of the insulating tube, and as described above, it is heat shrunk to form the case 2.
When the insulation tube 8 is brought into close contact with the insulation tube 8, a part of the insulation tube 8 can be erected. In addition, in the present invention, if the thickness of the insulating tube 8 is thin, there is a risk that the insulating tube 8 may be deformed by the load caused by the resin when it is filled with resin.
It needs to be about 1.5 to 2 times thicker. Also,
The material of the insulating tube 8 may be the same as conventional ones such as polyvinyl chloride or polyethylene terephthalate, or another material may be used. The following table shows, as a specific example, the conventional products shown in Figs. 1, 3, and 4 and the invented product shown in Fig. 5, in which thermosetting epoxy resin is used as the resin to be filled and hardened in the sealing part. This figure shows the results of investigating the occurrence of corrosion and disconnection in capacitor elements when As for the test method, each of the conventional product and the invented product was placed in 1,1,1-trichloroethane at 50°C.
After soaking for a minute, apply a DC voltage of 50V and raise the temperature to 105℃.
The state of corrosion was examined by placing it in a constant temperature bath. The number of samples for each is 100, and the product ratings are 50W・V., 100μF.

【table】

[Table] As is clear from this table, the structure of the present invention makes it possible to obtain a highly reliable capacitor that is less susceptible to corrosion and breakage caused by halogenated organic solvents used to clean solder flux than conventional capacitors. Also, in terms of labor, it is only necessary to change the insulating tube, so there is no deterioration in workability and no increase in cost. Furthermore, the lead wires of the capacitor element can be held and fixed firmly enough, making it possible to obtain a capacitor that is stable against external shocks. As described above, the present invention is extremely effective in improving the characteristics of a capacitor, and its practical value is very great.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a typical electrolytic capacitor, Figure 2 is the capacitor (rated at 50V, 47μF)
FIGS. 3 and 4 are cross-sectional views showing conventional electrolytic capacitors, and FIG. 5 is a cross-sectional view showing an electrolytic capacitor according to an embodiment of the present invention. 1... Capacitor element, 2... Case, 3...
Internal lead wire, 4... External lead wire, 5... Elastic sealing body, 8... Insulating tube, 9... Resin layer portion.

Claims (1)

[Scope of utility model registration request] The outer periphery of the case, which houses a capacitor element inside and seals the opening from which the lead wire of the capacitor element is drawn out with a sealing material, has a heat shrinkage rate of 15% to 25%.
% insulating tube is placed tightly over the outer periphery of the case, and a recess formed by a portion of the insulating tube protruding toward the sealing portion of the case and the sealing portion is filled with resin. capacitor.