JPH027457Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to improvements in chip-type film capacitors.

In general, chip capacitors are mounted by installing them on a mounting board together with other electronic components, and then placing the board in a molten solder bath, or by passing it through an atmospheric furnace with a belt, etc., and fixing it with solder. There is. Therefore, the entire exterior surface of the capacitor is affected by heat during soldering. A film capacitor element is composed of an organic polymer film as a dielectric material, and an element in which the film is provided with a metal vapor-deposited electrode, or the film is wound together with two opposing electrodes of metal foil.Such a capacitor element If the capacitor is made into a chip as is, the film will shrink or fuse due to the soldering heat during mounting and soldering, which will not only impair the excellent characteristics inherent to film capacitors, but also cause the problem that it will no longer function properly as a capacitor. This makes it difficult to make film capacitors into chips.

A recently proposed chip-type film capacitor (Utility Application No. 106336/1982) has an improved exterior casing to make it resistant to the soldering heat. That is, as shown in FIG. 1, a fibrous sheet with high porosity is wrapped around the outer periphery of a wound film capacitor element 1, a heat insulating layer 2 is provided to retain air-containing voids, and a heat-resistant resin is 3
This is a chip-type film capacitor that is designed to block soldering heat conducted from the capacitor exterior surface to the internal capacitor element during mounting soldering. In a capacitor configured in this way, conduction of solder heat from the exterior surface is blocked, but since the solder heat is conducted to the element through the external terminal 4, the insulation of the element is insufficient, resulting in a high temperature when mounted in an electronic device. There are drawbacks that make it difficult to obtain a chip-type film capacitor of high quality and reliability.

The present invention has been improved to solve the above drawbacks. In other words, do not connect the external terminal directly to the element, but connect the terminal and the capacitor element with a thin wire of at least 0.2φmm or less to reduce the influence of heat from the terminal during soldering, and provide a heat insulating layer around the outer periphery of the capacitor element. It is characterized by a structure in which it is coated with a heat-resistant resin, which minimizes the conduction of soldering heat to the capacitor element, making it possible to make a film capacitor into a chip.

The present invention will be explained below with reference to the drawings. FIG. 2 is a sectional view of a chip-type film capacitor according to an embodiment of the present invention, in which 1 is a capacitor element, 2 is a heat insulating layer,
3 is a heat-resistant resin; 4 is a plate-shaped external terminal connected to a capacitor element by a thin wire 5; As shown in the figure, a film capacitor element 1 is composed of two electrodes facing a metallized film or metal foil using an organic polymer film as a dielectric.
A thin wire 5 with a wire diameter of at least 0.2φmm, for example a copper wire of 0.1φmm, is connected to the electrodes at both ends of the capacitor element 1, and a fibrous sheet with high porosity, for example, is wrapped around the outer circumference of the capacitor element 1 to form a heat insulating layer 2. are provided, connected to each one of the external terminals 4 of the thin wires 5, and molded and packaged with heat-resistant resin 3 so that the external attachment portions of the external terminals are located outside the package.

As a specific example, connect the external terminal of a chip-type film capacitor (0.1μF-100V) and the wound element.
Connected with 0.1φ to 0.5φmm copper wire, each wound element was wrapped with 50μ manila paper 2 to 3 times and then molded with epoxy resin (7.6 x 4.5 x 3.2 mm).
Figure 3 shows a comparison of capacitance changes after natural cooling of a sample of a chip capacitor (chip capacitor) immersed in molten solder (250°C) for 10 seconds. into a thin line
In the sample using a 0.1φmm copper wire, there was almost no change in capacitance, and as the wire diameter became thicker, the rate of change in capacitance increased. The sample with a wire diameter of 0.5φmm has a large capacitance change rate of -6 to -14% and is unstable, but by making the wire diameter of the thin wire at least 0.2φmm or less, it can be immersed in solder at 250℃. It can be seen that the capacitance change rate is small even when soldering, and the influence of heat during soldering is reduced. From this result, it is appropriate that the thickness of the thin wire be at least 0.2φmm or less.

By the means described above, conduction from the capacitor exterior surface to the internal film capacitor element can be achieved even when the capacitor is mounted on a printed circuit board using a solder dip method using a solder dip tank or a method of soldering through an atmosphere furnace. The soldering heat generated is blocked by the heat insulating layer, and the soldering heat conducted from the external terminals is reduced by connecting the film capacitor element and the external terminal with a thin wire of at least 0.2φmm. The effect of the soldering heat received is extremely small, and the characteristics of the film capacitor are not impaired, making it possible to provide a high-quality, highly reliable chip-type film capacitor.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional embodiment. FIG. 2 is a sectional view of an embodiment of the present invention. FIG. 3 is a relationship diagram showing the wire diameter of the thin wire and the change in characteristics after capacitor mounting. 1... Capacitor element, 2... Heat insulation layer, 3...
Heat-resistant resin, 4...external terminal, 5...thin wire.

Claims (1)

[Scope of utility model registration request] In chip-type film capacitors, in which a high-porosity fibrous sheet is wrapped around the outer circumference of the capacitor element, a heat-insulating layer is provided to maintain air-containing voids, and the capacitor is coated with heat-resistant resin, the gap between the capacitor element and the external terminals is A chip-type film capacitor characterized by being connected with a conductor wire of at least 0.2φmm or less.