JPH0236263Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a chip type capacitor, and in particular,
This invention relates to a chip type capacitor with improved heat resistance during soldering etc. by forming a heat reflective layer and an air layer on the exterior member.

In recent years, with the miniaturization of electronic devices, the electronic components used therein have also been miniaturized and chipped, and capacitors are no exception.

In general, a chip type capacitor 1 using a capacitor element made of tantalum, aluminum electrolytic or film, etc., has a capacitor element 2 connected to a pair of external terminals 3, 3' made of minute metal pieces, as shown in FIGS. 1 and 2. are connected and covered with a synthetic resin exterior member 4 by molding, and symbols 7 such as ratings are stamped and displayed on the exterior member 4 as necessary. However, when incorporating the chip capacitor into an electronic device, when soldering is performed using the reflow method in which the chip capacitor is placed on a wiring board and passed through a high-temperature atmosphere, the thickness of the exterior member that covers the capacitor element is thin. , a large amount of heat will be applied to the capacitor element. For example, when the capacitor element is a plastic film capacitor element, the plastic film shrinks and deforms due to the above-mentioned thermal effects, causing a change in capacitance, and in extreme cases, the plastic film is damaged and the insulation deteriorates. and short circuits, which significantly deteriorate the electrical characteristics and reliability of such chip capacitors.

Conventionally, as a countermeasure to this problem, materials with low thermal conductivity or high heat reflectivity have been selected for exterior materials, but exterior materials are inherently good in electrical and environmental properties. The reality is that sufficient heat resistance effects cannot always be achieved due to the balance between these requirements and these various properties.

This invention was devised to solve the above problems, and even when heat is applied during soldering etc., the internal capacitor element is not affected by the heat, and the electrical The purpose is to provide a chip type capacitor with good characteristics and high reliability.

The above purpose is to form a heat reflective layer on the outer layer member and to form a heat reflective layer on the outer layer member, which is the gist of the present invention, in a chip type capacitor in which a capacitor element is covered with an exterior member and external terminals are led out. This is achieved by a chip-type capacitor characterized by having an air layer between the layers.An embodiment of the present invention will be described below with reference to the drawings.

3 to 5 show a chip type capacitor (in this case, an example using a plastic film capacitor element) according to an embodiment of the present invention. The capacitor element 2 is made by laminating and winding a polyester film, flattening it by heat pressing, and coating both end faces with metallized silicone.
It has a structure in which a pair of external terminals 3, 3' formed by punching a metal plate of approximately 1.0 mm in size are connected, and this is covered with an exterior member 4 of synthetic resin such as epoxy using a mold. In addition, the above external terminals 3, 3'
The portion led out of the exterior member 4 is arranged along the surface of the exterior member 4 to the end face and lower surface of the chip capacitor 1, and a plurality of recesses are formed on the upper surface of the exterior member 4, Furthermore, a heat reflective layer 5 is applied to the upper and side surfaces of the exterior member 4 to cover the recess, and an air layer 6 is formed between the exterior member 4 and the heat reflective layer 5.
is formed.

For example, a metal foil such as aluminum is suitable as a constituent material of the heat reflecting layer 5, and by applying an adhesive to one surface of the foil and adhering it to the exterior member 4 of the chip capacitor 1. The heat reflective layer 5 and the air layer 6 can be easily formed. In this case, if the shiny surface of the metal foil is the outer surface, a greater heat reflection effect can be obtained. In addition, if any symbol 7 such as a rating, mark, control symbol or other symbol is written on the heat reflective layer 5 by printing in advance and serves as a display label, the rating of the chip capacitor can be determined. This makes it possible to omit the stamping process.

However, when heat irradiation is applied to the chip type capacitor 1, the heat radiation from the heat source is reflected by the heat reflection layer 5, and some of the heat is not reflected but is absorbed by the heat reflection layer 5 and conducted inside. is weakened by the air layer 6 located under the heat reflective layer 5, and the heat conduction to the capacitor element 2 is small.

In order to measure the effect of this invention, the thickness is 1.5 μm and the width is
A capacitor element with a capacitance of 0.1 μF is formed by laminating and winding a metallized film with aluminum vapor deposited on 4.5 mm polyester, and a chip-type capacitor with an epoxy exterior with an average thickness of 0.8 mm is used to form a capacitor element based on the present invention. Heat resistance test (conditions;
230℃ for 10 seconds), the capacitance change rate was several tenths or less of the one with a heat reflective layer and air layer compared to the one without, and the insulation resistance also showed a high value. Ta.

In this embodiment, protruding pieces 8, 8' having a substantially U-shaped cross section are formed integrally with the external terminals 3, 3' and are arranged around the capacitor element 2, thereby also providing heat shielding. It is something that produces an effect. Furthermore, in this embodiment, an example using a plastic film capacitor element was shown, but the invention is not limited to this, and a chip type capacitor using other capacitor elements such as an electrolytic capacitor element may also be used. The same applies.

As detailed above, the chip-type capacitor of the present invention has a heat reflective layer and an air layer formed on its exterior member, so the applied heat is weakened by both layers and is reduced to a very small amount. Since heat is conducted to the capacitor element, there is no risk of reduction in capacitance or deterioration of insulation, resulting in good electrical characteristics and high reliability.

[Brief explanation of the drawing]

Figures 1 and 2 show a conventional chip capacitor, with Figure 1 being a perspective view of the product in progress, Figure 2 being a perspective view of the finished product, and Figures 3 to 5 showing the structure of the present invention. Fig. 3 is a perspective view of the finished product, Fig. 5 is a perspective view of the finished product, and Fig. 5 is a perspective view of the finished product.
FIG. 1... Chip type capacitor, 2... Capacitor element, 3, 3'... External terminal, 4... Exterior member,
5... Heat reflective layer, 6... Air layer, 7... Symbol.

Claims (1)

[Claims for Utility Model Registration] (1) In a chip-type capacitor in which a capacitor element is covered with an exterior member and external terminals are led out, a heat reflective layer is formed on the exterior member, and a heat reflective layer is formed on the exterior member. A chip-type capacitor characterized by having an air layer between it and the reflective layer. (2) The chip-type capacitor according to claim 1, wherein the heat reflective layer is a metal foil. (3) The chip-type capacitor according to claim 1 or 2, wherein the heat reflective layer also serves as a display label. (4) The chip-type capacitor according to any one of claims 1 to 3, wherein the air layer comprises a recess provided on the exterior member.