JPH07307243A - Manufacture of film capacitor - Google Patents

Abstract

PURPOSE:To improve adhesion of an internal resin layer to an electrode aluminum foil and improve the moisture resistance by a method wherein, before the internal resin layer is formed, a capacitor chip is dipped into solution containing a silane system coupling agent and pulled out of the solution and then the coupling agent is cured by heating. CONSTITUTION:Polyester films 1a and 1b and aluminum foils 2a and 2b are alternately laid one over another and wound into a cylindrical shape. Lead wires 4 and 4 made of CP wires are connected to the aluminum foils 2a and 2b by resistance welding in the middle of winding to from a capacitor chip which is formed flat. Then the flat capacitor chip is dipped into solution composed of ethanol as solvent and 0.1-1.9wt.% of beta-(3, 4epoxy cyclohexyl) ethyltrimethoxy silane added to it and, after it is lifted out of the solution, the silane system coupling agent is cured by heating. With this constitution, a film capacitor which has excellent moisture resistance, especially an excellent capacitance variation factor, can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a film capacitor, and more particularly to a method of manufacturing a plastic film capacitor which can have good moisture resistance.

[0002]

2. Description of the Related Art Plastic film capacitors are
Compared to paper capacitors and mica capacitors, they can be made smaller, have excellent electrical characteristics, and are highly reliable. Therefore, they can be used in consumer electronics such as televisions, radios, and audio equipment, as well as various industrial equipment. Widely used in.

Conventionally, plastic film capacitors are manufactured as follows. First, Fig. 1
As shown in FIG. 2, two dielectric films (for example, polyester films) 1a and 1b and two electrode aluminum foils 2a and 2b are alternately superposed and wound, as shown in FIG. A cylindrical capacitor element 3 having such a shape is formed.

During the winding, the lead wires 4 and 4 are attached to the electrode aluminum foils 2a and 2b. As the lead wire 4, for example, a solder-plated copper-coated steel wire (hereinafter referred to as a CP wire) is used. The lead wire 4 has one end formed flat, and the flat portion is fixed to the electrode aluminum foils 2a and 2b by resistance welding or the like.

Next, heat and pressure are applied to the capacitor element 3 from a direction orthogonal to the axis of the capacitor element 3 to flatten the capacitor element 3 as shown in FIG. Then, the capacitor element 3 is dipped in, for example, an epoxy resin solution, pulled up, and the resin is heated and dried to form an interior resin layer on the capacitor element 3. Then, for example, the resin is further dipped in an epoxy resin solution and pulled up to heat and dry the resin to form an exterior resin layer around the interior resin layer.

[0006]

Conventionally, the interior resin layer and the exterior resin layer are doubly formed on the capacitor element 3 as described above so as to maintain the moisture resistance characteristic. Since the adhesiveness of the interior resin layer to the foils 2a and 2b is not always good, moisture penetrates from that portion, which causes deterioration of the moisture resistance property, especially the capacitance change rate.

The present invention has been made to solve the above-mentioned conventional drawbacks, and an object thereof is to improve the adhesion of the interior resin layer to the electrode aluminum foil and to improve the moisture resistance of the film capacitor. To provide.

[0008]

In order to achieve the above-mentioned object, the present invention is a method in which two dielectric films and two electrode aluminum foils are alternately superposed and wound into a cylindrical shape, and the winding is performed. A lead wire was attached to each electrode aluminum foil in the middle of a turn to form a capacitor element, and the capacitor element was pressed from a direction orthogonal to its axis to be flattened and then immersed in a predetermined resin liquid, In the method for producing a film capacitor, which comprises drying the resin to form an interior resin layer and further forming an exterior resin layer around the interior resin layer, the capacitor element is flattened, and then the interior resin layer is formed. Before forming the, the capacitor element is immersed in a solution containing a silane coupling agent, and is pulled up to heat cure the silane coupling agent. There.

In this case, the silane coupling agent is β- (3,4epoxycyclohexyl) ethyltrimethoxysilane or γ-glycidoxypropyltrimethoxysilane, and the solvent of the silane coupling agent is silane coupling agent. Is preferably 0.5 to 1.9 wt%.

That is, if it is less than 0.5 wt%, the adhesiveness between the electrode aluminum foil and the interior resin layer is not improved. On the other hand, when it is 1.9 wt% or more,
Not only does the adhesiveness show no change, but the curing characteristics of the silane coupling agent itself deteriorate.

The silane coupling agent is soluble in water, but it is also soluble in most organic solvents such as alcohols, toluene and xylene. The curing conditions for the silane coupling agent are 100 to 11
A temperature of 0 ° C. for about 1 hour is suitable.

[0012]

[Function] Prior to the formation of the interior resin layer, the electrode aluminum foil is bonded to the silane coupling agent β- (3,4epoxycyclohexyl) ethyltrimethoxysilane or γ-.
By treating with glycidoxypropyltrimethoxysilane, the adhesion between the electrode aluminum foil and the interior resin layer becomes good, and the moisture resistance property is improved.

[0013]

EXAMPLES Examples according to the present invention will be described below together with comparative examples. The winding process and the flattening process of the capacitor element will be described with reference to FIGS.
Please refer to.

Example A dielectric film having a thickness of 4
A polyester film with a width of 9 μm, a width of 9 mm, and a length of 1290 mm is used. The thickness of the electrode aluminum foil is 5 μm.
An aluminum foil with m, a width of 7.5 mm and a length of 1040 mm was prepared.

Two pieces of these polyester films and two pieces of aluminum foil are alternately laminated and wound into a cylindrical shape, and a lead wire made of a CP wire is attached to each of the aluminum foils by resistance welding in the middle of the winding to form a capacitor. An element was formed, and heat and pressure were applied to the capacitor element to flatten it.

Next, the flattened capacitor element was added with 1.0 wt% of β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane in ethanol as a solvent.
% Soak in the added solution and pull up to 100-110 ° C
The mixture was heated for 1 hour to cure the silane coupling agent.

Thereafter, the capacitor element was dipped in an epoxy resin liquid, pulled up and heated at 120 ° C. for 1 hour to be cured to form an interior resin layer. Then, the capacitor element was dipped in an epoxy resin solution, pulled up, heated at 120 ° C. for 1 hour to be cured, and an exterior resin layer was formed around the interior resin layer.

In this way, 50 film capacitors having a rated voltage of 50 V and 0.1 μF were produced, and the temperature was 40 ± 2 ° C.
When a humidity resistance characteristic test was conducted for 1000 hours under the condition of relative humidity of 90 to 95%, the capacitance change rate was 2.5% on average.

Comparative Example 1 The same polyester film and aluminum foil as in Example 1 were alternately superposed on each other and wound in a cylindrical shape, and a lead wire made of a CP wire was wound around each aluminum foil during the winding. Was attached by resistance welding to form a capacitor element, and heat and pressure were applied to the capacitor element to perform flat processing.

Without treating with a silane coupling agent, the capacitor element is dipped in an epoxy resin solution, pulled up, and heated at 120 ° C. for 1 hour to cure,
An interior resin layer was formed. Then, the capacitor element was dipped in an epoxy resin solution, pulled up, heated at 120 ° C. for 1 hour to be cured, and an exterior resin layer was formed around the interior resin layer.

In the same manner as in Example 1, 50 film capacitors having a rating of 50 V and 0.1 μF were manufactured, and the humidity resistance test was conducted for 1000 hours under the conditions of temperature 40 ± 2 ° C. and relative humidity 90 to 95%. When I did
The rate of change in capacitance was 3.2% on average.

For reference, the rate of change in capacitance according to Example 1 and Comparative Example 1 is shown in Table 1. According to the present invention, the rate of change in capacitance is improved by about 0.7%. Admitted.

[0023]

[Table 1]

Although in Example 1 β- (3,4epoxycyclohexyl) ethyltrimethoxysilane was used as the silane coupling agent, similar results were obtained with γ-glycidoxypropyltrimethoxysilane. Was given.

[0025]

As described above, according to the present invention,
Two dielectric films and two electrode aluminum foils are alternately laminated and wound into a cylindrical shape, and lead wires are attached to each electrode aluminum foil in the middle of the winding to form a capacitor element. The capacitor element is pressed from a direction orthogonal to its axis to be flattened, and the capacitor element is treated with a solution containing a silane coupling agent (preferably 0.5 to 1.9 wt% β).
-(3,4 Epoxycyclohexyl) ethyltrimethoxysilane solution or γ-glycidoxypropyltrimethoxysilane solution), and pull up to heat-cure the silane coupling agent, and then in a prescribed resin liquid A film capacitor with excellent moisture resistance, especially good rate of change in capacitance, by immersing in the resin and drying the resin to form an interior resin layer and then forming an exterior resin layer around the interior resin layer. Can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view for explaining a winding process of a film capacitor.

FIG. 2 is a perspective view showing a capacitor element wound in a cylindrical shape.

FIG. 3 is a perspective view showing a flattened capacitor element.

[Explanation of symbols]

 1a, 1b Dielectric film 2a, 2b Electrode aluminum foil 3 Capacitor element 4 Lead terminal

Claims (3)

[Claims] 1. A capacitor element in which two dielectric films and two electrode aluminum foils are alternately superposed and wound into a cylindrical shape, and a lead wire is attached to each electrode aluminum foil during the winding. Is formed, and the capacitor element is pressed from a direction orthogonal to its axis to be processed into a flat shape, then dipped in a predetermined resin liquid, and the resin is dried to form an interior resin layer. In a method of manufacturing a film capacitor having an outer resin layer formed around an inner resin layer, after the flattening of the capacitor element and before forming the inner resin layer, the capacitor element is treated with a silane coupling agent. A method for producing a film capacitor, which comprises immersing the film in a solution containing the above and pulling it up to heat-cure the silane coupling agent. 2. The silane coupling agent is β-
The method for producing a film capacitor according to claim 1, wherein the film capacitor is (3,4 epoxycyclohexyl) ethyltrimethoxysilane or γ-glycidoxypropyltrimethoxysilane. 3. The method of manufacturing a film capacitor according to claim 1, wherein the content of the silane coupling agent in the solvent is 0.5 to 1.9 wt%.