JPS59144118A - Film condenser - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is a chip electronic product having solder heat resistance necessary for mounting on a printed wiring board, similar to chip electronic components such as resistors, coils, and transistors. Regarding film chip capacitors.

Conventionally, capacitor chips have been commercialized based on relatively heat-resistant dielectric materials, such as ceramic tantalum and mica. However, in recent years, trends among set users have led to demand for chip components due to the trend toward thinner, smaller, and lighter equipment through high-density mounting on printed circuit boards, as well as labor-saving orientation through automatic mounting onto printed circuit boards. With film capacitors using plastic film (polyethylene terephthalate film, hereinafter referred to as PET film) as the dielectric material, soldering is not recommended when mounting on a printed circuit board due to the low heat resistance of PET film. It was considered extremely difficult to satisfy the conditions.

Therefore, as a measure against heat resistance, manufacturers have managed to provide heat resistance by using exterior materials with poor thermal conductivity, and by making the exterior part more than necessary, which is completely wasteful in terms of moisture resistance and insulation. The current situation is that there are.

The heat resistance level of conventional PET film capacitors will be explained below with reference to FIG.

FIG. 1 is a characteristic diagram showing the relationship between the mold exterior thickness and the heat resistance level of a conventional film capacitor composed of a PET film as a dielectric material and a thickness of 5 μm, and an aluminum foil as an electrode material and a thickness of 5 μm.

Epoxy resin for molding generally has high thermal conductivity even when the exterior thickness is increased.Thermal conductivity is 3 to 5 x 10/(
Cal-8ec・℃), and furthermore, since a single coating of only molding resin makes the resin thicker and the capacitor shape becomes larger, the heat resistance level is extremely less effective and in order to improve the heat resistance level. The exterior thickness is 1.
It turns out that 6 μm or more is required.

As is well known, this is a very disadvantageous method for reducing the size and weight of the capacitor and further reducing the cost.

Purpose of the Invention The present invention determines the relative thicknesses of the PET film condenser, aluminum foil, and mold exterior that make up the capacitor element body, making it smaller and lighter, greatly improving the heat resistance level, and making it easier to use than conventional chip electronics. The purpose is to enable automatic attachment to printed wiring boards as film capacitors for chip electronic components, similar to other parts.

Structure of the Invention In the present invention, the thickness of the dielectric polyethylene terephthalate film constituting the capacitor element is 15 to 16 μm. In terms of smell, the thickness of the aluminum foil, which is the electrode material, is 7 μm relative to the thickness of the polyethylene terephthalate film (T),
==(2) (±1) μm, and a capacitor element formed by winding the polyethylene terephthalate film, and tightly adheres to the capacitor element and has a minimum thickness of 0.3 μm.
It is characterized by having an exterior part of mm.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 2 to 5.

FIG. 2(a) is a sectional view of the structure of the film capacitor of the present invention, and FIG. 2(b) is a sectional view of the capacitor element body.

In Figure 2, (1) is a PET film which is a dielectric, (2) is an aluminum foil which is an electrode material, and (3) is a PET film which is a dielectric material.
) is a capacitor element main body composed of (1) and (2). (4) is an electrode comb connected to aluminum foil that is an electrode, (5) is a resin part covered with a mold,
The above structure is the same as that of a conventional film capacitor.

In the film chip condenser constructed as described above, the thickness relationship and heat resistance of the PET film (1) which is the dielectric material and the aluminum foil (2) which is the electrode material will be explained below.

Figure 3 is a diagram showing the relationship between aluminum foil thickness and heat resistance level when the PET film thickness is 3 μm and the molded resin exterior part is 0.3 mm.
It can be seen that the heat resistance is most improved at ~7 μm.

Furthermore, Fig. 4 is a diagram showing the relationship between aluminum foil thickness and heat resistance level when the PET film thickness is 4 μm and the mold resin exterior is 0.3 mm. It is clear that heat resistance is improved the most.

As described above, the inventors conducted experiments on aluminum foil thickness and heat resistance level by changing the P'ET film thickness and keeping the mold resin exterior part constant at 0.3 mm. The following conclusions were reached.

In other words, in order to improve the heat resistance level the most, the thickness of the aluminum foil that is the electrode material must always be 2x ± 1 μη for the thickness of the PET film that is the dielectric (X). It is.

In other words, if the thickness of the aluminum foil is less than 2x±1μm compared to the thickness of the PET film, then the aluminum foil is too bulky to hold the PET film firmly, and the shape of the capacitor formed accordingly. has very weak mechanical strength (l/). Therefore, in the heat resistance test, when heat is applied, the expansion and contraction of the film cannot be prevented, resulting in a significant change in capacity. In other words, the heat resistance level (well, it drops significantly).

On the other hand, for the PET film thickness X, the aluminum foil thickness T
If the thickness is more than (,2x-1l:1)μm, then the aluminum foil is thick, so it can hold the PET film and form a capacitor element with strong mechanical strength. Rather than being thick, heat conduction and absorption are large, and therefore, in heat resistance tests, when heat is applied, the capacitor margin shrinks due to the shrinkage of the PET film, resulting in frequent short-circuit failures. In the present invention, the margin part is usually 05 to 1.5 m.
Figure 5 shows the relationship between the thickness of PET film, which is a dielectric material that improves heat resistance the most, and the thickness of aluminum foil, which is an electrode material. The relationship between the thickness of aluminum foil and the thickness of aluminum foil is as follows: aluminum foil thickness μ = (PET film thickness x 2 ± 1) μ, and the thickness of aluminum foil that improves heat resistance is (2x +
1) μm % (2x 1 ) μm expressed by two straight lines. Therefore, in order to improve the heat resistance, it is sufficient to select aluminum foil having a thickness within these two linear ranges for each PK'I' film.

Figure 6 shows P when the thickness of the aluminum foil used as the electrode material is kept constant at ] μm and the thickness of the molded resin exterior is kept constant at 0.3 mm.
It is a diagram showing the relationship between the ET film thickness and the heat resistance level. When the film thickness is 7 μm or more, the heat resistance of the film itself is improved due to the thick film thickness. Thickness x
There is no need to consider the relationship between the PET film and the aluminum foil to improve the heat resistance of 2±1) μm. Therefore, the film chip capacitor of the present invention is The thickness of the lt body film is limited to a very thin range of 15 to 60 μm. Fig. 6 mtt; Tarchia 7121 F, i 7゜Furthermore, Fig. 7 shows the mold resin exterior thickness when the dielectric PET film thickness is 3 μm, and the electrode material aluminum foil thickness is constant 6 μm. It is a diagram showing the relationship with the heat resistance level,
It is clear that the heat resistance level is significantly improved when the mold resin outer thickness is 0.3 mm.

Therefore, the feature of the present invention is that the thickness of the dielectric film is extremely thin in the range of 15 to 60 μm, which is extremely important for reducing the size and weight of capacitors.At the same time, the thickness of the mold exterior is extremely thin. The ability to obtain sufficient heat resistance with a thickness of about 0.3 mm will have a significant impact on the capacitor industry.

In the heat resistance test, the film chip capacitor whose capacitance was measured was preheated in a hot air circulation oven at a temperature of 150 (°C) for 5 minutes, and then quickly immersed in a solder bath at a temperature of 230 (°C) for 10 seconds. After that, the capacitance was measured again with the capacitor taken out in equilibrium with room temperature, and the rate of change before and after the test was calculated.

Further, in the above embodiment, in the heat resistance test, the capacitance change rate, which is the main characteristic of the capacitor, was set within ±5 (%), and the survival rate due to short-circuit failure was set at 100 (%).

As described above, according to the present invention, in a PET film having a thickness of 1.5 to 6 μm, which is a dielectric material forming a capacitor element, the thickness of aluminum foil, which is an electrode material, is equal to the thickness of the aluminum foil for each film thickness. By setting = (PET film thickness x 2 ± 1) μm, there is no need to make the outer shell thicker than necessary, such as the mold outer thickness of 1.6 mm or more, which is the case with conventional heat-resistant products. Therefore, the capacitor can be made smaller and lighter. Moreover, a film chip capacitor with a high level of heat resistance can be obtained.

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram showing the relationship between the mold exterior thickness and heat resistance level of a conventional film chip capacitor, Figure 2 (A) is a cross-sectional view of the structure of the film chip capacitor of the present invention, and (B) Figure is a cross-sectional view of the capacitor element body, the third
Figures 4 to 4 are characteristic diagrams showing the relationship between the mold exterior thickness and the heat resistance level of a bright film chip capacitor made of PET film and aluminum foil, in which the embodiment of the present invention is most improved. 1: PET film 2: Aluminum foil as electrode material 3
: Capacitor element body 4 : Electrode comb 5 : Mold exterior resin part Patent applicant Matsushita Electric Industrial Co., Ltd. Agent patent attorney
Isao Abe Figure 1 Figure 2 Figure 5 Procedures Amendment (Method)■, Small case indication Patent Application No. 19065/1983 3 Relationship with the case of the person making the amendment Patent applicant address: 185 Tokyo 3-12-11-4 Minamimachi, Kokubunji City, Brief explanation of the drawings Figure 1 is a characteristic diagram showing the relationship between the mold exterior thickness and heat resistance level of a conventional film chip capacitor, and Figure 2 (a) is A cross-sectional view of the structure of the film chip capacitor of the present invention, (b) is a cross-sectional view of the capacitor element body,
4 is a characteristic diagram showing the thickness relationship and heat resistance level of PE"T film and aluminum foil according to an embodiment of the present invention,
(outside of Figure 3), Figure 4 (A,) is a short-circuit failure rate diagram, Figure 5
The figure shows the range of PET film and aluminum foil that improves the heat resistance level the most. Figure 6 (A) and (B) are P'
FIG. 7 is a characteristic diagram showing the relationship between E T film thickness, short-circuit failure rate, and capacitance change rate, and FIG. 7 is a characteristic diagram showing the relationship between the mold exterior thickness and heat resistance level of the film chip capacitor of the present invention. 1: PET film 2: Aluminum foil as electrode material
3: Capacitor element body 4: Electrode comb 5: Mold exterior resin part

Claims (1)

[Claims] When the thickness of the dielectric polyethylene terephthalate film constituting the capacitor element is 15 to 16 μm, the thickness T μm of the aluminum foil that is the electrode material is T−(2×
±1) μm and a capacitor element formed by winding the polyethylene terephthalate film, and an exterior part with a minimum thickness of 0.3 mm is provided in close contact with the capacitor element.