JPH04377B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of packaging a capacitor using a plastic film.

Conventional configurations and their problems Conventional methods for packaging capacitors using the dip method include packaging with a porous liquid epoxy resin and then impregnating it with wax, etc., or wrapping the capacitor element with an epoxy resin with a relatively low viscosity. A common method is to impregnate it with resin and then cover it with powdered or liquid epoxy resin.

Capacitors having the above-mentioned exterior structure have a proven track record in the past because they can provide electrically and mechanically very stable and high quality characteristics.

However, in recent trends in electronic components, miniaturization has been advocated, and the above-mentioned packaging method has been limited to changes over time in the packaging material (e.g., viscosity, melting point, etc.) or changes in packaging conditions (e.g., the surface of the capacitor element). Variations in capacitor exterior thickness are likely to occur due to factors such as temperature, work environment temperature, exterior material temperature), etc. Therefore, in order to make the exterior thickness uniform, manufacturers must adequately manage exterior materials and coating conditions. Therefore, the manufacturing conditions for capacitors were extremely narrow.

Hereinafter, with reference to FIG. 1, the thickness of the conventional capacitor packaging method will be described.

FIG. 1 is a diagram showing the relationship between the average exterior thickness and the variation in exterior thickness in a conventional capacitor exterior packaging method. It can be seen that even if sufficient control of coating conditions is carried out, the exterior thickness fluctuates significantly.

This means that in order to maintain the minimum capacitor thickness, the capacitor must be made thicker than necessary, which is completely wasteful considering the capacitor's moisture resistance, insulation properties, and mechanical strength. This is a very disadvantageous method for making capacitors lighter, thinner and smaller, and further reducing costs.

Purpose of the Invention The present invention solves these problems, and by significantly reducing variations in the thickness of the exterior capacitor, it is possible to make the capacitor lighter, thinner, and smaller, and moreover, compared to capacitors with a conventional exterior structure. The purpose is to obtain capacitor characteristics that are equivalent or better than those of other capacitors.

Structure of the Invention In order to achieve this object, the present invention covers a capacitor element with a heat-shrinkable tube-shaped covering material having a thickness of at least 90 μm, and also covers a capacitor element with a heat-shrinkable tube-shaped covering material having a thickness of at least 90 μm. It is heat-shrinked so as to protrude by 0.5 mm or more and cover the electrode end face of the capacitor element, and is dipped in thermosetting epoxy resin two or more times.

DESCRIPTION OF EMBODIMENTS Hereinafter, one embodiment of the present invention will be described in FIGS. 2 to 6.
This will be explained with reference to the drawings in the figures.

FIG. 2 is a sectional view of the structure of a capacitor according to the present invention. In Fig. 2, 1 is a capacitor element;
2 is an electrode part, 3 is a lead wire drawn out from the electrode part 2, and 4 is a lead wire 0.5 from the top of the element body in the direction of the 3 direction.
The tube is heat-shrinked so as to insulate and protect the end face of the capacitor electrode which protrudes by more than 1 mm, and 5 is a resin part which is depressed.

In the capacitor configured as above,
Figure 3 is a diagram showing the relationship between the heat-shrinked tube thickness and the capacitor lead wire tensile tube fracture strength level.
It can be seen that the above results greatly improve the fracture strength level.

Furthermore, Figure 4 shows the thickness of the heat-shrinked tube.
It is a diagram showing the relationship between the length of the tube protruding from the top of the element body in the direction of the lead wire and the torsional strength level with the capacitor lead wire when liquid epoxy resin is dipped once and twice with a constant 90 μm. The length of the tube protruding from the top of the capacitor element body after 2 times is 0.5mm.
From the above, it can be seen that there is a significant improvement.

Here, if the epoxy resin is dipped once, no matter how long the protruding tube is 0.5 mm or more, the dipped epoxy resin will penetrate into the gap between the capacitor element body and the heat-shrinked tube. Therefore, very little resin accumulates in the tube that protrudes in the direction in which the lead wires are pulled out at the top of the capacitor element main body, and the lead wire torsion strength becomes extremely weak.

That is, by dipping the liquid epoxy resin twice, in the first dip, the gap between the capacitor element body and the heat-shrinked tube is filled, and in the second dip, the liquid epoxy resin is applied to the leads on the top of the capacitor element body. The lead wire strength is improved by collecting in the protruding tube in the wire drawing direction.

It should be noted that regardless of the viscosity of the dipping resin, resin will always accumulate in the tube that protrudes from the top of the capacitor element body by the length of the protruding tube with a constant thickness by dipping twice. The inventors confirmed this.

Furthermore, Figure 5 shows the tube thickness of 90 μm and the length of the tube protruding from the top of the element body in the direction of the lead wire.
This is a diagram showing the relationship between the epoxy resin viscosity and the moisture resistance characteristics of a capacitor when the number of dips is 1 and 2 with a constant value of 0.5 mm. Although the improvement is greater than that of DIP, it can be seen that it is almost unaffected by resin viscosity.

This means that the resin thickness at the top of the element body in the direction of the lead wires is affected by the moisture resistance due to the infiltration of moisture through the lead wires, but it is almost unaffected by the resin thickness at the bottom of the capacitor. be.

Therefore, a heat-shrinkable tube-shaped covering material of a constant thickness is always protruded by 0.5 mm or more from the top of the element body in the direction of the lead wire drawn out from the end face of the capacitor electrode.
By heat-shrinking the end surface of the capacitor electrode and dipping it twice with thermosetting epoxy resin, the dip resin is stored in the tube-shaped covering material that protrudes from the top of the capacitor, improving the mechanical strength and moisture resistance of the capacitor. Of course, it is possible to form an exterior structure with very little variation in resin thickness, which makes it possible to make capacitors lighter, thinner, and smaller, and also allows for a wide range of manufacturing conditions.

FIG. 6 is a diagram showing the relationship between capacitance value and capacitor volume of a capacitor with an exterior structure according to the present invention and a capacitor with a conventional exterior structure,
The capacitor volume of the exterior structure of the present invention is approximately 25% compared to the capacitor volume of the conventional exterior structure.
It is clear that the size has been reduced by ~50%, and that variations in capacitor volume due to variations in exterior thickness are also extremely small.

The lead wire tensile sheath strength test and lead wire torsion test described in the above examples were conducted in accordance with JISC-
The experiment was conducted based on the test method specified in 5102.

Furthermore, in the lead tensile sheath strength test, the sheath breaking strength value was targeted at 2.0 kg or more, and the lead wire twist test was targeted at 20 times or more.

Furthermore, moisture resistance characteristics are determined by measuring the initial capacitance value of the capacitor at room temperature, leaving it for 100 hours in an atmosphere with a temperature of 85°C and a humidity of 95% or more, cooling it to room temperature, and measuring the capacitance value again. Measure and find the rate of change, 14%
The goal was to be within.

Effects of the Invention As described above, according to the present invention, at least the thickness
A heat-shrinkable tube-shaped covering material of 90 μm or more is protruded by 0.5 mm or more from the top of the element body in the direction of the lead wire drawn out from the end face of the capacitor electrode, and is heat-shrinked so as to insulate and protect the end face of the capacitor electrode. By dipping twice with a curable epoxy resin, it is possible to form an exterior structure with less variation in resin thickness, and as a result, the capacitor can be made lighter, thinner, and smaller, and a great effect can be obtained.

[Brief explanation of drawings]

Figure 1 is a characteristic diagram showing the average exterior thickness and variation in exterior thickness in a conventional packaging method, Figure 2 is a sectional view showing the structure of a capacitor according to the present invention, and Figure 3 is a diagram showing a capacitor according to an embodiment of the present invention. Figure 4 is a characteristic diagram showing the tube thickness of the exterior packaging method and the lead wire tensile strength of the tube. Figure 4 is a characteristic diagram showing the length of the tube protruding from the top of the capacitor element body in the lead wire drawing direction and the lead wire torsional strength depending on the number of dips. , FIG. 5 is a characteristic diagram showing the liquid resin viscosity and moisture resistance characteristics depending on the number of dips, and FIG. 6 is a diagram comparing the capacitor volumes of a capacitor according to the present invention and a conventional capacitor. 1... Capacitor element, 2... Electrode part, 3...
Lead wire, 4...tube, 5...resin part.

Claims (1)

[Claims] 1 Cover the capacitor element with a heat-shrinkable tube-shaped covering material with a thickness of at least 90 μm, and protrude by 0.5 mm or more from the top of the capacitor element in the direction of the lead wire drawn out from the electrode end surface of the capacitor element to cover the electrode end surface of the capacitor element. 1. A method for packaging a capacitor, which is characterized by shrinking the capacitor by heat and dipping it with thermosetting epoxy resin two or more times.