JPH03101207A - Metallized plastic film capacitor and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a high quality capacitor without insulation degradation by applying wax to one end of a laminated capacitor opposite to its end having electrode terminals, and enclosing the capacitor with thermosetting epoxy resin. CONSTITUTION:Powder of polyphenylene oxide is dissolved in trichlene, and titanium oxide is added. After stirred and processed by a ball mill, this solution is applied to both metallized surfaces of a plastic film 21 to form coatings 23. This dielectric film is rolled and cut into thin rods. The end of each rod is provided with metal-flamed electrodes 24 to which leads 25 are welded. It is further cut into chips to produce capacitor elements. These elements are immersed in wax whose melting point is 80 to 150 deg.C to provide a wax coating 26, and then enclosed in thermosetting epoxy resin 27.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a metallized plastic film capacitor used in electronic circuits such as electronic equipment and information equipment, and a method for manufacturing the same.

Conventional technology In recent years, as electronic devices have become lighter, thinner, shorter, and more sophisticated, there has been an increasing demand for electronic components to be smaller and have higher performance.
Efforts to address these issues are becoming an urgent priority for metallized plastic film capacitors as well. In this trend, dielectric materials in which inorganic materials are dispersed have been developed in order to achieve miniaturization.

A conventional metallized plastic film capacitor will be explained below.

FIG. 3 is a diagram showing the exterior structure of a conventional metallized plastic film capacitor. Reference numeral 1 denotes an epoxy resin layer for undercoating to provide a stable exterior coating, and 2 an epoxy resin layer for exterior coating, which covers the entire multilayer capacitor element 3. This multilayer capacitor element 3 is made of aluminum (hereinafter referred to as 5e) formed by vacuum deposition on both sides of polyethylene terephthalate (hereinafter referred to as PET), which is a dielectric film. It has a dielectric coating layer (
At least one side of the dielectric coating layer is provided with a high dielectric constant dielectric coating layer in which an inorganic material is dispersed in an organic material. A lead wire is connected to the electrode for external extraction.

Here, we will talk about the self-healing function, which is one of the characteristics of metallized plastic film capacitors. Since a vapor-deposited metal film is used for the electrodes of the capacitor, there may be insulation defects in the dielectric coating layer or film, causing breakdown. When this occurs, an electric discharge occurs at the defective part, and the energy at that time scatters and annihilates the deposited metal near the defective part, restoring the insulation.This function restores and maintains the withstand voltage. It is.

Problems to be Solved by the Invention However, with the above-mentioned conventional configuration, it is difficult to uniformly disperse the inorganic material into the organic material, and as a result, thin areas occur in the coating layer and insulation defects occur frequently. . In addition, it is used as an undercoat material to ensure a stable exterior finish and has good adhesion to the capacitor element.

Due to the use of highly airtight epoxy resin, when an insulation defect breaks down, sufficient oxygen is not supplied for the complete self-healing function to work, making it difficult for the self-healing function to work.
It had the disadvantage that the melting resistance value decreased during high-temperature load tests.

The present invention solves the above-mentioned conventional problems, and achieves miniaturization by forming a high dielectric constant dielectric coating layer in which an inorganic material is dispersed in an organic material. The purpose is to improve the decrease in insulation resistance during high-temperature load tests by significantly improving the self-recovery function.

Means for Solving the Problems To achieve this object, the metallized plastic film capacitor of the present invention is characterized in that at least one side of the dielectric coating layer formed on both sides of the plastic film, which is metallized on both sides, is organic and inorganic. A multilayer capacitor element which is a high permittivity dielectric coating layer in which a material is dispersed, a wax layer applied to a cut surface different from the opposing cut surface on which the external extraction electrode of the multilayer capacitor element is provided; The present invention is characterized in that it includes an exterior part made of a thermosetting epoxy resin that includes the wax layer and covers the entire multilayer capacitor element.

Furthermore, the method for manufacturing the metallized film capacitor of the present invention is as follows:
At least one side of the dielectric coating layer formed on both sides of a plastic film metallized on both sides is a high dielectric constant dielectric coating layer in which an inorganic material is dispersed in an organic substance. A step of forming an external extraction electrode on the cut surface of the electrode and joining a lead wire to the external extraction electrode, and a step of applying wax to the opposite cut surface different from the predetermined cut surface after this step, The present invention is characterized by comprising a step of forming an exterior portion made of a thermosetting epoxy resin over the entire multilayer capacitor element after the step.

Here, the high dielectric constant dielectric coating layer is selected from polyphenylene oxide as the organic material and titanium oxide, barium titanate, strontium titanate, and lead titanate as the inorganic material or a mixture of two or more thereof. It is.

In addition, the wax used is a wax with a melting point of 80°C or more and 150'C or less, which has weak adhesion to the film and low airtightness.For example, synthetic waxes such as synthetic hydrocarbon Warnox, modified wax, and hydrogenated wax, and wax, animal wax.

Mineral Wax 1 This is selected from natural waxes such as petroleum waxes. If a wax with a melting point of less than 90'C is used, wax and wax tend to flow out during packaging, making it impossible to form a homogeneous layer and resulting in poor workability.

On the other hand, if a wax with a melting point higher than 150° C. is used, the capacitor element will be seriously damaged by heat, and the purpose cannot be met.

Function: The metallized plastic film capacitor of the present invention has a complete self-healing function when it breaks at an insulation defect by coating at least the cut surface of the multilayer capacitor element with a wax that has weak adhesion to the film and low airtightness. Sufficient oxygen can be supplied for the self-healing function to work, and the heat and gas generated when the self-healing function works can be easily dissipated, so the self-healing function can be performed efficiently. As a result, it is possible to improve the reduction in insulation resistance value during high-temperature load tests.

Further, in the method for producing a metallized plastic film capacitor of the present invention, at least one side of the dielectric coating layer formed on both sides of a plastic film whose both sides are metallized has a high dielectric constant dielectric layer in which an inorganic material is dispersed in an organic material. The process of applying wax to the cut surfaces of the multilayer capacitor element, which is the body coating layer, is carried out after the lead wires are joined to the external lead electrodes provided on the opposing cut surfaces of the multilayer capacitor. Lead wires can be joined to electrodes without being affected by wax, and wax can be applied easily.

Example The present invention will be explained below with reference to Examples and Comparative Examples.

Example 1 After uniformly dissolving 40 g of powder of polyphenylene oxide (hereinafter referred to as PPO) in 400 g of Wotriclean, titanium oxide (hereinafter referred to as ?i0□) with an average particle size of 0.21 μl was dissolved.
was added, stirred and mixed, and further milled in a ball mill for 40 minutes.
It was subjected to Hr treatment to obtain a coating liquid.

This coating solution was applied to both sides of a double-sided metallized plastic film to obtain an entire coating layer with a thickness of 0.7 μm.

After winding and laminating this dielectric film flatly, it is cut into thin rods, external lead electrodes are formed on the cut surfaces using metallized silicone, and lead wires are connected, and further cut into chips to form a capacitor element with a capacitance of 20 μF. It was created. This capacitor element is heated and immersed in melted Wank's liquid to coat at least the cut surface of the capacitor element with wax.To remove excess wax, the capacitor element is heated and placed in a centrifuge to reduce the wax to 0.1 to 0.6 μm. A thick wax layer was formed. It was then covered with thermosetting epoxy resin. Here, polyethylene wax is used as the wax.

FIG. 1 shows a cross-sectional view of the metallized film capacitor of this example. In FIGS. 1 and 2, 21 is a frame film, 22 is a mu e electrode, 23 is a dielectric coating layer,
24 is an external extraction electrode, 26 is a lead wire, 2e is a wax layer, and 2 is an exterior part.

Example 2 After uniformly dissolving PPO powder 401 in 400 g of trichlene, TlO2 with an average particle size of 0.21 fi m was added, stirred and mixed, and further treated with a ball mill for 4 ° Hr to form the first coating. I got the liquid. This first coating liquid was applied to one side of a single-sided metallized plastic film using a gravure coater to obtain a coating layer with a thickness of 0.7 μm. On the other hand, p
A second coating solution was obtained by uniformly dissolving Po powder 409 in 40 oy of Triclean, and this second coating solution was applied to one side of a double-sided metallized plastic film using a gravure coater to obtain a film thickness of 0. A coating layer of .7 μm was obtained. After winding and laminating this dielectric film flatly, it is cut into thin rods, external lead electrodes are formed on the cut surfaces using metallized silicone, and lead wires are connected, and further cut into chips to form a capacitor element with a capacitance of 20 μF. was prepared, and the exterior was applied after wax application in the same manner as in Example 1.

The performance of the capacitor of this example will be compared with that of a conventional capacitor and will be explained using FIG. Conventional Example 1 is a capacitor having a high dielectric constant dielectric coating layer on both sides, and Conventional Example 2 is a capacitor having an organic dielectric coating layer on one side and a high dielectric constant dielectric coating layer on the other side. The exterior is an epoxy resin for undercoating, and an epoxy resin for exterior coating is applied on top of this.

Figure 2 shows the capacitors of the embodiment and conventional example at a temperature of 86°C.
The graph shows the insulation resistance value measured after applying a current esV in the atmosphere, taking out the sample at room temperature after a predetermined period of time, and leaving it for 1 hour.

The example overcomes the drawbacks of the conventional example since no decrease in insulation resistance value was observed during the high-temperature load test.

Effects of the Invention As described above, the present invention provides a multilayer capacitor element in which at least one side of the coating layers formed on both sides of a double-sided metallized plastic film is a high dielectric constant dielectric coating layer in which an inorganic material is dispersed in an organic substance. Since it has a wax layer on the cut surface,
It is possible to realize a high-performance metallized plastic film capacitor whose insulation resistance value does not decrease during high-temperature load tests by being packaged with thermosetting epoxy resin.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing one embodiment of the metallized glass film capacitor of the present invention, Fig. 2 is a comparative characteristic diagram of insulation resistance values of the same capacitor and a conventional capacitor, and Fig. 3 is a conventional metallized plastic film capacitor. FIG. 2 is a cross-sectional view of a film capacitor. 21...Flastic film, 22...Out...
Ae electrode, 23...dielectric coating layer, 24...
・・External lead-out electrode (Metallicon), 26・・・・
...Leet wire, 26...wax layer, 27...exterior part.

Claims (3)

[Claims] (1) A multilayer capacitor element, in which at least one side of a dielectric coating layer formed on both sides of a plastic film metallized on both sides is a high dielectric constant dielectric coating layer in which an inorganic material is dispersed in an organic substance; A wax layer coated on a cut surface different from the opposing cut surface on which the external extraction electrode of the multilayer capacitor element is provided, and a thermosetting epoxy resin provided so as to cover the entire multilayer capacitor element including the wax layer. A metallized plastic film capacitor characterized by having an exterior portion made of (2) The metallized plastic film capacitor according to claim 1, wherein the wax is a wax having a melting point of 80° C. or higher and 150° C. or lower. (3) Opposite orientation of a multilayer capacitor element in which at least one side of the dielectric coating layers formed on both sides of a plastic film whose both sides are metallized is a high dielectric constant dielectric coating layer in which an inorganic material is dispersed in an organic substance. a step of forming an external extraction electrode on a predetermined cut surface and joining a lead wire to the external extraction electrode, and a step of applying wax to an opposite cut surface different from the predetermined cut surface after this step. ,
A method for manufacturing a metallized plastic film capacitor, which comprises the step of forming an exterior portion made of a thermosetting epoxy resin over the entire multilayer capacitor element after this step.