JPH0521862Y2 - - Google Patents

Description

[Detailed explanation of the idea] (Industrial application field) The present invention relates to a chip type capacitor.

(Prior Art) When an overvoltage is applied to a tantalum solid electrolytic capacitor or a film capacitor, when an overcurrent flows through the capacitor, or when the capacitor is heated to a high temperature, it smokes or catches fire along with the exterior.

In order to prevent smoke and ignition, a current fuse or a temperature fuse may be connected to the capacitor element and direct current.

(Problem that the invention aims to solve) However, when a capacitor such as a tantalum solid electrolytic capacitor is a chip type, it is difficult to manufacture it if the structure is such that a current fuse is connected in series with the capacitor element and covered with a resin jacket. Not only that, but the resin exterior becomes thinner, resulting in disadvantages such as a decrease in dielectric strength.

The object of the present invention is to improve the above-mentioned drawbacks and provide a chip-type capacitor having a safety function.

(Means for Solving the Problem) In order to achieve the above object, the present invention is characterized in that a resin layer that expands at a temperature higher than the heating temperature during connection is provided on the exterior surface that contacts the board to be connected. It provides chip-type capacitors.

(Function) If a resin layer that expands at a temperature higher than the heating temperature when connecting the board is provided on the exterior surface that contacts the board to be connected, an overcurrent will flow to the capacitor, causing the capacitor element to generate heat, and the resin layer will expand when the board is connected. When heated above the heating temperature, this resin layer expands. When the resin layer expands, it separates the capacitor body from the board and disconnects the circuit provided on the board and the terminals of the capacitor. Therefore, the capacitor is disconnected from the circuit.

(Example) Hereinafter, the present invention will be explained based on the illustrated example.

In FIG. 1, 1 is a chip type capacitor such as a tantalum solid electrolytic capacitor or a film capacitor. Reference numeral 2 denotes a resin layer provided on the exterior surface 3 of this chip-type capacitor that is in contact with the substrate, and is made of a material that expands when heated at a temperature higher than the heating temperature when soldering to the substrate. As for this material, for example, the resin material is polyphenylene sulfide resin, polyimide resin, polyimide amide resin, etc., and the foaming agents are aluminum hydroxide (decomposition temperature of about 450°C), magnesium carbonate (decomposition temperature of about 300°C - 500℃), iron carbonate (decomposition temperature
400-600℃), soda zeolite (decomposition temperature approximately 300℃),
Assume that ammonium chloride (decomposition temperature: approximately 350°C) is mixed.

This resin layer 2 is formed by kneading a foaming agent while heating and softening the resin, extrusion molding it into a sheet shape, cutting it into a suitable size, and adhering it to the exterior surface 3.

Next, the operation of the above embodiment will be described.

First, as shown in FIG. 2, the terminal 4 of the chip capacitor 1 is connected to the circuit 6 of the board 5 by soldering. Solder connections are made by reflow at a temperature of 200-260°C. The expansion temperature of the resin layer 2 is determined by the decomposition temperature of the foaming agent, and since the temperature is 300° C. or higher, the resin layer 2 does not expand during solder connection.

Next, when an overcurrent flows through the chip capacitor 1 and heats the capacitor element, the heat is transferred to the resin layer 2.

When the resin layer 2 is heated above the decomposition temperature of the foaming agent, the resin layer 2 expands and the terminal 4 is disconnected from the circuit 6, as shown in FIG.

(Effects of the invention) As described above, according to the invention, since a resin layer is provided on a part of the exterior surface and the resin layer expands when abnormal heat is generated, the capacitor can be disconnected from the circuit and smoke can be generated.・Can prevent ignition. In addition, a chip type capacitor which is easy to manufacture and whose dielectric strength can be improved can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a front view of the embodiment of the present invention, Fig. 2 is a front view of the embodiment of Fig. 1 connected to a board, and Fig. 3 is a front view of the state in which the resin layer is expanded in Fig. 2. shows. 1... Chip type capacitor, 2... Resin layer, 3
... Exterior surface, 5 ... Board.

Claims (1)

[Scope of utility model registration request] A chip-type capacitor characterized in that a resin layer that expands at a higher temperature than the heating temperature during connection is provided on the exterior surface that contacts the board to be connected.