JPH0345892B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a capacitor composed of an organic polymer film as a dielectric material.

Conventional configurations and their problems Recently, as the market demand for miniaturization of electric and electronic equipment increases, the miniaturization of electronic components is progressing rapidly. In such miniaturization, film capacitors whose main material is organic polymer film have a major problem in their heat resistance and reliability during soldering due to their characteristics.

In other words, while the short-term heat resistance temperature of general-purpose organic polymer film dielectrics is 140°C or less, the temperature of film capacitors during normal soldering is
This is because the temperature can reach over 180℃.

In order to overcome these problems, research has heretofore been conducted mainly on the use of highly heat-resistant organic polymer films as dielectric materials. Aromatic polyimide polymers were typical of such materials. However, such highly heat-resistant organic polymers have had problems such as being difficult to form into thin films and being unable to provide inexpensive capacitors due to extremely high raw material costs.

In addition, attempts have been made to solve the problem of solder heat resistance by providing long floats on the external lead-out electrodes, but such configurations require a large volume when attached to a printed circuit board, causing problems. .

Purpose of the invention The present invention uses polyester, polypropylene, etc., which have been widely used in the past, as a dielectric material,
It is an object of the present invention to provide a film capacitor having excellent soldering heat resistance.

Structure of the Invention In order to achieve the above object, the present invention provides a film capacitor in which an organic polymer film is used as a dielectric.
It has a part fitted with a lump of material that melts or evaporates after melting at temperatures below 200°C.

Effect With the above configuration, in the film capacitor of the present invention, the heat transmitted through the lead wire during soldering is removed as heat of fusion or heat of evaporation of the attached material.
The influence of heat on the capacitor body is significantly suppressed, and as a result, the film capacitor does not deteriorate.

That is, during normal soldering, the temperature at the base of the lead wire is 240°C or higher, but in the present invention, the temperature at that part is 200°C or lower, making it possible to suppress the temperature rise of the film capacitor to 140°C or lower.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below based on the drawings. FIG. 1 shows an example in which the present invention is applied to a polyester film capacitor covered with epoxy resin or the like by the dip method. In Fig. 1, 1 is the capacitor body, 2 is a lead wire drawn out to the outside, and 3 is a low molecular weight block with a melting point of around 100°C, which is fused to the base of the lead wire 2 drawn out to the outside. It is polyethylene terephthalate.

Figure 2 shows a polyester film capacitor in which a capacitor element is enclosed in a polyethylene terephthalate case and filled with epoxy resin.
This is an example to which the present invention is applied. In Figure 2, 4
1 is a capacitor main body, 5 is a lead wire drawn out to the outside, and 6 is a block of low molecular weight polyethylene terephthalate, which is the same as that shown in FIG. 1, potted on a filled epoxy resin.

In the above embodiments, the temperature rise of the film capacitor is suppressed to 130° C. or less.

In addition, in the embodiments shown in Figs. 1 and 2, if paraffin wax or solder having a melting point of around 100°C is fused to the bases of the lead wires 2 and 5 drawn out to the outside, soldering Because these substances sometimes melt and then partially evaporate, the temperature rise in film capacitors can be kept below 120°C.

Figure 3 shows cases in which the present invention is applied (A) and cases in which it is not applied (B) in which polyethylene terephthalate is used as the dielectric material and a film capacitor with a capacitance of 0.1 μF is dipped in epoxy resin and packaged. For each, samples were inserted directly onto a printed circuit board in a soldering bath at 260℃.
This shows the change in electrical characteristics when soldering is performed for 10 seconds. As shown in the results in FIG. 3, the present invention (A) exhibits superior soldering heat resistance compared to the conventional example (B).

Effects of the Invention As described above, the film capacitor according to the present invention can be obtained from inexpensive materials without using an expensive heat-resistant film, has extremely excellent solder heat resistance reliability, and has the ability to prevent bulk mounting materials from being exposed to the outside. There is no need to increase the thickness of the lead wire in the drawing direction, the film capacitor can be attached directly to the printed circuit board, and there is no need to provide a long float.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are block diagrams showing one embodiment of the present invention, respectively, and FIG. 3 is a solder heat resistance characteristic diagram showing a comparison between the present invention and the conventional method. 1, 4... Film capacitor body, 2, 5...
...Lead wires drawn out to the outside, 3, 6...100℃
Low molecular weight polyethylene terephthalate with melting points around.

Claims (1)

[Claims] 1. A film capacitor that uses an organic polymer film as a dielectric, and has a part attached to the base of an external lead wire that is attached with a lumpy substance that melts or evaporates after melting at 200°C or less.