JPH03233923A - Manufacture of metallized film capacitor - Google Patents

Abstract

PURPOSE:To enhance a moistureproof characteristic as one of the reliability of a capacitor without lowering a small size and a withstand-voltage characteristic by a method wherein, immediately before a vapor decomposition process, the same outer circumference surface of a vapor-deposited drum used to execute a metal vapor deposition operation is irradiated with an electron beam. CONSTITUTION:A polyphenylene sulfide (PPS) film 10 is set on a delivery shaft B in an upper chamber 2; immediately before a vapor deposition operation, the side of a vapor-deposited face of the PPS film 10 is irradiated with an electron beam 20 on the outer-circumference surface of a vapor-deposited drum 14. That is to say, by this irradiation, the surface of the PPS film 10 is cleaned, and the bonding force of the PPS film 10 to an aluminum thin-film layer can be enhanced. Consequently, a metallized film capacitor using a winding-system vacuum vapor-deposition method can reduce sufficiently a deterioration with the passage of time at a moistureproof load life test even with an element single body without an outer package. Thereby, the moistureproof life characteristic can be enhanced sharply and the reliability can be increased without deteriorating a small size and a withstand-voltage characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing metallized film capacitors used in electronic and electrical equipment.

Background of the Invention In recent years, metallized film capacitors have been increasingly used in the industrial equipment field. For this reason, there is a strong demand for improvement in moisture resistance, which is one of the reliability characteristics of metallized film capacitors. Conventional techniques for solving this demand include a method of suppressing the infiltration of moisture into a capacitor element and a method of reducing deterioration of vapor-deposited electrodes over time. Specific methods to prevent moisture intrusion include increasing the thickness of the exterior resin;
The method used was to bury the capacitor element inside the case. Further, as a specific method for reducing the deterioration of the vapor deposited electrode over time, a method of increasing the thickness of the vapor deposited electrode has been used.

3 ＼ Problems to be Solved by the Invention However, the method of increasing the thickness of the exterior resin and burying the capacitor element inside the capacitor had the problem that the shape of the capacitor became large. Furthermore, the method of increasing the thickness of the vapor-deposited electrode has problems in that the self-healing property, which is a characteristic of metallized film capacitors, is poor and the withstand voltage characteristics of the capacitor are reduced.

In view of the above-mentioned problems, the present invention has been developed to further miniaturize the capacitor shape without making it thicker, and to improve the moisture resistance, which is one of the reliability characteristics of the capacitor, without reducing the withstand voltage characteristics of the capacitor. The object of the present invention is to provide a method for manufacturing a film capacitor.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a method for winding the film onto the surface of a polymeric MT film (polypropylene film, polyethylene terephthalate film, polyethylene naphthalate film, polyphenylene sulfide film). To form a thin aluminum film layer for electrodes using the vacuum evaporation method, an electron beam is used to heat, melt, and evaporate the aluminum, and the electron beam is applied to the entire surface of the polymer dielectric film immediately before the aluminum is deposited. It is characterized by irradiation.

Function: The present invention forms an aluminum thin film layer after irradiation with an electron beam to further reduce the size of the capacitor without increasing its size, and improves the reliability of the capacitor without reducing its withstand voltage characteristics. Certain moisture resistance properties can be improved.

EXAMPLE FIG. 1 shows a winding type vacuum evaporation machine for forming the aluminum electrode layer of the metallized film capacitor of the present invention.

The vacuum chamber 1 is divided by a partition plate 3 into an upper chamber 2 for unwinding and winding the film 9 and a lower chamber 23 for vapor depositing aluminum on the surface of the soil layer. The upper chamber 2 is an on-off valve 4
．． The exhaust pipe sf, shown in the figure, is normally reduced in pressure to 1σ25... (Pa) or less by an exhaust pump. The lower chamber 23 has an on-off valve 6,
The pressure is normally reduced to below 1O-3 (Pa) through an exhaust pipe 7 by an exhaust pump (not shown).

Polyphenylene sulfide (hereinafter referred to as pps)
The film was placed on the unwinding shaft 8 in the upper chamber 2.

The PPS film 10 passes through the free roll 11 and has a thickness of about 10 (
After running (in the direction of arrow A) along the outer circumferential surface of the evaporation drum 14 which has been cooled (in the direction of arrow A), it is wound up on the winding shaft 9 via a free-rotation v12.

13 shows a PPS film on which an aluminum thin film layer is formed. Aluminum 17 is placed in an alumina (A42o3) crucible 16, heated and melted by an electron beam 22 emitted from an electron gun 21, and evaporated into aluminum vapor 18. The electron beam 22 is deflected approximately 90 degrees above the aluminum by a deflector (not shown). The vapor deposition of aluminum onto the PPS film 10 is performed using PPS.
Immediately after the film 1o enters the deposition drum 14, the electron beam 20 emitted from the electron gun 19 is transferred to the PPS film 1o.
6・＼ on the entire surface of the vapor deposition side.

This is done by running the PPS film 10 without continuous irradiation and opening the shutter 16 while evaporating the aluminum vapor 18. Immediately before vapor deposition, the PPS film 10 is surface-treated by irradiating the vapor deposition surface side of the PPS film with an electron beam 20 on the outer peripheral surface of the vapor deposition drum 14, and at the same time, the evaporation source is heated.

Electron beam 2 emitted from electron gun 21 for melting and evaporation
PPS film 1 along with scattered electrons from 2 and secondary electrons.
Charge the PPS film 1o by injecting electrons into P
By strengthening the adhesion of the PS film 10 to the outer circumferential surface of the deposition drum 14 and quickly removing the heat of the PPS film 10 during aluminum deposition with the deposition drum 14, the temperature of the PPS film 7 rem 1o increases. An aluminum thin film layer with little heat damage was formed on the PPS film 10 by suppressing the heat damage. Additionally, the surface treatment of the PPS film performed by irradiating it with the electron beam 20 improved the adhesion between the PPS film 10 and the aluminum thin film layer. This is because by irradiating the surface of the PPS film 7 and film 10 with the electron beam 20, the surface cleaning action of the PPS film 10 improves the adhesion between the PPS film 10 and the aluminum thin film layer. The same effect was obtained when the surface of the PPS film 10 was irradiated with an ion beam. Improving adhesion is very effective in preventing oxidation of the aluminum thin film layer. Therefore, the metallized film capacitor made of metalized PPS film using the winding type vacuum evaporation method of the present invention can be used as a single element without an exterior. However, it is possible to provide a metallized film capacitor that can sufficiently reduce deterioration over time in a humidity load life test. In this example, in forming the metallized PPS film, aluminum was deposited on the edge 5oo (+g) of the PPS film 10 so that the surface resistance of the aluminum thin film layer was in the range of 2.5 to 4.0 (Ω/mouth), and In the normal margin forming method (not shown), 140 (
A margin of mm) was formed. FIGS. 2 and 3 show examples of the structure of metallized film capacitors. As shown in FIG. 2, the margin 34 is a metalized PPS film forming the left aluminum electrode 33, and the margin 32 is an aluminum (Ann electrode torque ps) alternately with a metalized PPS film forming the right aluminum electrode 31. After laminating 30 so that the films are in contact, lamination 30 is performed as shown in FIG.
An electrode 35 for external extraction was formed of metallicon at the end of the metallized PPS film where the machine was located, and both cross sections perpendicular to the electrode 35 were simply covered with resin sheets 36. With this structure, the length x width x height is 4.8X each.
I made a simple exterior type chip film capacitor using 3.3 x 1.8 (tomo) metallized PPS film. Among them, normal processing steps were used to make chip film capacitors. Table 1 shows a simple exterior type chip film capacitor using a metalized PPS film produced by the roll-up vacuum deposition method of the present invention as a dielectric material and a simple exterior type button using a metalized PPS film produced by another vacuum deposition method as described above. Comparison between the capacitor and the molded exterior type chip film capacitor is shown.

9 ・＼ 10-.

Figure 4 shows the test results of the humidity load life test.

The conditions for the humidity load life test are as follows.

Conditions Temperature: 60 (T) Humidity: 9tsfA Applied voltage: Rated voltage DC = 25■ In the humidity load life test as shown in Figure 4, 100
Example 1 after hours. Comparative example 1. In both Comparative Example 2, the characteristic values of capacitance, dielectric loss tangent, and insulation resistance showed little change compared to the initial values. However, although the capacitance change after 500 hours was 3-6% decrease compared to the initial capacity in Comparative Example 1, in Comparative Example 2 of Example 1 of the present invention and exterior type, there was almost no change in capacitance. It didn't change. Furthermore, the dielectric loss tangent ranged from 0.04 to 0.05% in Comparative Example 1 to 0.00% after 500 hours.
6~O,S% compared to Example 1. In Comparative Example 2, it increased only to 0.1%. Regarding insulation resistance, Example 1. Comparative example 1. The difference in Comparative Example 2 was small. Further, after 1,000 hours, the characteristics of Example 1 did not change by 11.-- compared to 500 hours. The capacitance change in Comparative Example 2 is -2
~-4%, dielectric loss tangent 02%, insulation resistance 1011~1o1
At 2Ω, there was some deterioration over time. In Comparative Example 1, the deterioration over time was large and was outside the range shown in FIG. 4.

Figure 6 shows the high temperature load life test results.

High temperature load life test conditions Temperature: 126°C Applied voltage: 1.25 times the rated voltage - 31,25V As shown in FIG. Comparative example 2
Similarly, the capacitance after 1000 hours of high temperature load life test,
Deterioration of dielectric loss tangent and insulation resistance over time was extremely slight.

From the above results, chip film capacitors using metallized PPS film by vacuum evaporation, which have been conventionally done, are of the type with an exterior, and the deterioration over time in the humidity load life test is small, but with the simple exterior type, Deterioration over time in the humidity load life test was significant. On the other hand, the simple exterior type chip film capacitor using the metallized PPS film produced by the winding vacuum evaporation method of the present invention shows almost no durability deterioration in the humidity load life test and the high temperature load life test, and has a highly reliable metallization. It turned out to be a film capacitor.

In the detailed description of this embodiment, specific shapes and dimensions have been cited, but the present invention is not limited to these. In addition, although a PPS film was used as the polymer dielectric film in this example, the same effect can be achieved by using a polypropylene film, a polyethylene terephthalate film, a polyethylene naphthalate film, etc. can be obtained. Furthermore, although a single-sided metalized film is used in this embodiment, the present invention is not limited to this, and the same effect can be obtained by using a double-sided metalized film or a double-sided metalized coating film.

Effects of the Invention As described above, a metallized film capacitor using a metallized film in which a thin aluminum film is formed on the polymer dielectric film of the present invention using electron beam irradiation and electron beam heating evaporation method is 0). This is a highly reliable metallized film capacitor with significantly improved moisture resistance and life characteristics without degrading withstand voltage characteristics.

(2) Since the capacitor element alone has significantly improved moisture resistance and life characteristics, there is no need to increase the thickness of the exterior to prevent moisture intrusion or use an exterior case, and even a simple exterior is sufficient. This is a metallized film capacitor that can be significantly downsized.

(3) The winding vacuum evaporation method is a highly productive method, and therefore can provide low-cost capacitors, and is highly industrially viable.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing a winding type vacuum evaporation machine used for forming aluminum thin film layered dielectric films of metallized film capacitors of the present invention, and Fig. 2 is a perspective view of the configuration showing the capacitor element of the metallized film capacitors. Fig. 3 is a perspective view of the structure of a simple exterior type metallized film capacitor □ Fig. 4 is a characteristic diagram showing changes in each characteristic in the humidity resistance 14 ＼ load life test, Fig. 5
The figure is a characteristic diagram showing changes in each characteristic during a high-temperature load life test, and FIG. 6 is a partially cutaway perspective view showing an exterior type metallized film capacitor. 1o...Film, 14...Z Wearing drum 15...Shutter, 16...
Crucible, 18... Aluminum vapor, 20.2
2...Electron beam 19, 21...Electron gun.

Claims (3)

[Claims] (1) In a method for manufacturing a vapor-deposited electrode type film capacitor using a metallized film formed by forming a metal thin film layer on the surface of a polymer dielectric film, an electron beam is used to heat the evaporation source on the surface of the polymer dielectric film. A metallized film characterized in that when a metal thin film layer is formed by a roll-up vacuum evaporation method using a metallized film, electron beam irradiation is performed on the same outer peripheral surface of a evaporation drum for metal evaporation immediately before the evaporation process. Method of manufacturing capacitors. (2) The method for manufacturing a metallized film capacitor according to claim 1, wherein the polymer dielectric film is selected from polypropylene film, polyethylene terephthalate film, polyethylene naphthalate film, and polyphenylene sulfide film. (3) The method for manufacturing a metallized film capacitor according to claim 1, wherein the vapor-deposited metal layer is aluminum.