JPH042113A - Aluminum electrolytic capacitor - 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 (Field of Industrial Application) The present invention relates to an aluminum electrolytic capacitor that uses an outer container in which a specific synthetic resin layer is provided on both sides of a bottomed cylindrical container body made of an aluminum plate. In particular, in view of the demand for thinner electronic devices, tubeless type aluminum with a colored exterior that has excellent heat resistance and insulation properties can be suitably used for types in which the lower part of the capacitor body is in direct contact with the surface of the printed wiring board. Regarding electrolytic capacitors.

(Prior Art and its Problems) In an aluminum electrolytic capacitor, a capacitor element is formed by connecting lead terminals to an anode foil and a cathode foil, respectively, and then winding the foils with electrolytic paper interposed therebetween.

Next, this capacitor element is impregnated with an electrolytic solution and stored in a bottomed cylindrical container, and then the open end of the container is sealed with a sealing body.

The above-mentioned container is usually a bottomed cylindrical container made of drawn aluminum plate, and the outer surface of the container is colored with various coloring agents to identify the capacitor element, and furthermore, symbols etc. are printed on it. These are covered with shrink tubing.

In recent years, electronic components mounted on the surface of printed wiring boards have become smaller, and aluminum electrolytic capacitors are also becoming smaller. This reduces the distance between the printed wiring board and the capacitor (lower height).
However, consideration is being given to eliminating wasted space and implementing high-density packaging.

As an example of the above-mentioned electrolytic capacitor, a small aluminum electrolytic capacitor with a reduced height is shown in a sectional view in FIG. 4. When the outer periphery of the capacitor outer container is used by covering the outer periphery with a conventionally used colored shrink tube 4 made of polyvinyl chloride resin or the like, soldering 8 to the printed wiring board 7 will cause the printed wiring board to Since the shrink tube 4 is in direct contact with the printed circuit board 7, it is easily affected by the solder temperature if the temperature of the solder is too high. There was a problem in that the aluminum case 1 was exposed due to heat conduction from the wiring board 7 and was re-shrinked or torn, and the aluminum case 1 directly contacted the printed wiring board 7, resulting in a decrease in insulation properties. Similarly, since the inner surface of the container is metal, there is a problem of poor insulation with the elements.

In addition, it has been considered to obtain a container having a resin layer on one or both sides by drawing process using a laminated plate in which one or both sides of an aluminum plate is coated with a synthetic resin layer, without using the shrink tube 4. Like the shrink tube 4, it has the problem of poor heat resistance and insulation, and a small aluminum electrolytic capacitor of the type that directly contacts the printed wiring board 7 has not been put into practical use.

(Means for Solving the Problems) The present invention is an aluminum electrolytic capacitor using an outer case formed by drawing a laminated plate having a specific synthetic resin layer on both sides, and a carboxylic acid-modified polyolefin resin layer on the inner surface of the outer case. It has been discovered that the above problems can be solved by providing a specific composite polyamide resin layer consisting of a layer containing a colorant and a layer not containing a colorant on the outer surface of the container.

The present invention will be explained below with reference to the drawings.

FIG. 1 is a cross-sectional view showing the state in which the aluminum electrolytic capacitor of the present invention is used, and FIG. 2 is an enlarged cross-sectional view of the section ■ in FIG. As shown in FIGS. 1 and 2, the aluminum plate 1 used for the outer container is preferably one of the 1000 series according to JISHoool, with an aluminum content of 99% by weight or more, and a thickness of 0. A material having a diameter of about 2 to 0.4 mm can be suitably used.

The outer container for an aluminum electrolytic capacitor of the present invention is made of a laminated plate having a carboxylic acid-modified polyolefin resin layer 2 on one side of the aluminum plate 1 and a composite polyamide resin layer 3 having a specific layer configuration on the other side. Obtained by processing. The carboxylic acid-modified polyolefin resin layer 2 is arranged on the inner surface of the container, and can improve the insulation between the capacitor element 5 and the inner surface of the container.

The above carboxylic acid-modified polyolefin resin is a polyolefin resin obtained by graft copolymerizing unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, and maleic acid, and carboxylic acid derivatives such as maleic anhydride and itaconic anhydride. As the polyolefin resin, polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, etc. can be suitably used. The thickness range of the carboxylic acid-modified polyolefin is preferably 10 to 100 μm, preferably 10 to 50 μm from the viewpoint of drawing processability.

Furthermore, it is necessary to provide a composite polyamide resin layer 3 on the outer surface of the aluminum plate 1 on the opposite side of the carboxylic acid-modified polyolefin resin layer 2, but the polyamide resin used for this composite polyamide resin layer 3 has a melting point of 240°C. It is necessary to use the above substances, and the melting point is taken as the temperature value of the endothermic peak measured by a differential scanning calorimeter (DSC).

Polyamide resins having a melting point of less than 240° C. have a problem in that they have poor heat resistance when soldered. Specific examples of the resin include 6-row nylon, aromatic polyamide resin made of metaxylene diamine and adipic acid, and 46-nylon. In this case, all layers of the composite polyamide resin layer 3 may be composed of resins having the same composition, or may be composed of resins having different compositions.

Further, the composite polyamide resin layer 3 includes a transparent polyamide resin layer 31 containing no colorant (hereinafter referred to as "transparent layer") on both sides of a colored polyamide resin layer 32 containing a colorant (hereinafter referred to as "colored layer"). It is necessary to use a three-layer laminate.

With such a configuration, the colored layer 32 can be given a desired color tone using various coloring agents, and the aluminum plate 11F! ! Since I is a transparent layer 31, the adhesion to the aluminum plate 1 side is not inhibited.If the colored layer is provided directly on the aluminum plate side without providing this transparent layer, the coloring agent will improve the adhesion between the layers. There is a problem in that it inhibits the treatment and tends to cause peeling between the eyebrows.

Here, as shown in FIG. 2, the transparent layer 31 provided on the outside of the colored layer 32 is for protecting the colored layer 32, and the same content as the transparent layer 31 on the aluminum plate 1 side can be used. Further, it is preferable that the thickness of each of the transparent layers 31 provided on both sides of the colored layer 32 is approximately the same.Furthermore, the coloring agent used in the colored layer 32 is an organic pigment such as an azo type, a phthalocyanine type, an anthraquinone type, etc. , organic dyes and various inorganic pigments can be suitably used.

In addition, an antioxidant, an ultraviolet absorber, etc. can be appropriately added to either or both of the transparent layer and the colored layer, as required.

The thickness structure of the composite polyamide resin layer 3 is as follows:
The thickness ratio between the thickness of the transparent layer and the colored layer 32 needs to satisfy (transparent layer 31+transparent layer 31/colored layer 32)≧1.

If the thickness ratio is less than 1, there is a problem that the heat resistance and insulation properties are poor.

Also, the portion 6 that contacts the printed wiring board 7 after inserting the capacitor element into the container after drawing and curling the container.
The thickness is preferably 15 μm or more, and if it is less than 15 μm,
It tends to have poor heat resistance and insulation properties. As a method for laminating the carboxylic acid-modified polyolefin resin layer 2 and composite polyamide resin layer 3 on both sides of the aluminum plate 1, a carboxylic acid-modified polyolefin film previously formed by an extrusion method and a composite polyamide resin film formed in the same manner are used. A method may be used in which the resins are melted at a temperature higher than the melting temperature of each resin and laminated, or a method in which the resins are extruded and laminated onto an aluminum plate.

By providing a chemical conversion layer such as chromate treatment on the surface of the aluminum plate described above, the adhesion between the eyebrows can be further improved.

An outer container can be obtained by drawing the laminate having the above structure using a normal drawing machine so that the composite polyamide resin layer is on the outer surface. If the outer container obtained here is further heated to a temperature higher than the melting point of the resin, the adhesiveness and insulation between the eyebrows can be improved. Next, after storing the capacitor element impregnated with the electrolyte in the container, the open end is sealed with a sealing body to obtain the aluminum electrolytic capacitor of the present invention.

Hereinafter, the present invention will be explained in detail with reference to Examples.

(Example) Example aluminum plate (A 1100 P-HI3 thickness 0°3
mm) using a treatment solution containing phosphoric acid, chromic acid anhydride, and fluoride at a treatment temperature of 40 to 50°C to obtain a surface-treated aluminum plate with a chromate film amount of Lmg/rrr. It was done. A maleic anhydride-modified polypropylene film (
20μm thick) using the melt lamination method, and on the opposite side of the aluminum plate, the entire layer is coated with 66 nylon (
A three-layer composite polyamide resin film (transparent layer/colored layer/transparent layer = 10 μm/20 μm/
10 μm) was melt-laminated to obtain a laminate.

Each of the obtained laminates was subjected to seven stages of drawing using a lance progressive drawing machine to produce a cylindrical container with a height of 4 mm x 5 mm. The thickness of the composite polyamide resin layer at the contact portion with the printed wiring board after storing the capacitor element and curling sealing was measured and found to be 16 μm, and the thickness ratio of the transparent layer and the colored layer was the same as above. Next, insulation and heat resistance were evaluated using a capacitor in which a capacitor element was housed in the container.

The insulation was evaluated by measuring the dielectric breakdown voltage and insulation resistance of the curled sealing end face 6 on the open end side of the container using the test method shown in FIG. In this dielectric breakdown voltage test, the upper electrode 11 with a load of 500 g was placed on the aluminum plate 10 from which the laminated resin 9 on the top side of the container had been peeled off in advance. Further, in the insulation resistance test, a DC voltage of 500 V was applied according to the above test method, and the insulation resistance was measured after charging for 1 minute. As the measuring device 14,
For the dielectric breakdown voltage test, we used a voltage tester T manufactured by Kikisui Denshi Kogyo ■.
O38750 type was used, and Kyokucho Megohmmeter 5M-10E manufactured by Toa Denpa Kogyo ■ was used for the insulation resistance test. ! The material of the electrode plates was stainless steel for both Upper and Lower Toden @11 and 12.

In addition, for the evaluation of heat resistance, a capacitor element 1 is placed in the above container.
3 was directly attached to a printed wiring board made of glass epoxy resin with a thickness of 0.8 mm (the curled seal end face 6 on the open end of the container was in contact with the surface of the printed wiring board), and the capacitor was soldered at a soldering temperature of 260°C. A solder dip was performed for 1 minute, and the insulation properties after the heat resistance test were evaluated as described above.

The above measurement results are shown in Table 1.

Table 1 The layer structure of the composite polyamide resin film used in the comparative example laminate is transparent layer/colored layer/transparent layer=+=3 μm/20 μm/
A container (the thickness of the composite polyamide resin layer at the part in contact with the substrate is 10 μm) was prepared with the same contents as in the example except that the thickness was 3 μm, and the same evaluation as in the example was performed. The measurement results are shown in Table 2.

As is clear from Clothing 1 and Table 2 above, according to the Examples and Comparative Examples, it can be confirmed that the ratio of the thickness of the transparent layer to the thickness of the colored layer is 1 or more is superior, and the above-mentioned problems can be solved. .

(Effects of the Invention) As described above, according to the aluminum electrolytic capacitor of the present invention, even when exposed to high temperatures during soldering, the resin on the outer surface of the outer container does not deteriorate and the insulation is maintained. ,
This has a great practical effect on aluminum electrolytic capacitors, where the lower part of the capacitor is in direct contact with the printed wiring board.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing how the aluminum electrolytic capacitor of the present invention is used, Fig. 2 is an enlarged sectional view of the section ■ in Fig. 1, Fig. 3 is a configuration diagram showing a test method for the aluminum electrolytic capacitor, FIG. 4 is a sectional view showing a conventional aluminum electrolytic capacitor in use. 1... Aluminum plate 2... Carboxylic acid modified polyolefin resin layer 3...
Composite polyamide resin layer 1...Transparent polyamide resin layer 2...Colored polyamide resin layer

Claims (1)

[Claims] A carboxylic acid-modified polyolefin resin layer (2) is laminated on one side of an aluminum plate (1), and a composite polyamide resin layer (3) made of a polyamide resin with a melting point of 240° C. or higher is laminated on the other side. The capacitor element is housed in an outer container made by drawing the stacked laminates so that the composite polyamide resin layer (3) is on the outside, and the curled and sealed portion of the composite polyamide resin layer (3) at the opening of the container is used as a printed wiring board. The composite polyamide resin layer (3) is an aluminum electrolytic capacitor that is mounted in contact with a transparent polyamide resin layer (31) that does not contain a colorant on both sides of a colored polyamide resin layer (32) that contains a colorant. The total thickness of the transparent polyamide resin layer (31) and the thickness ratio of the colored polyamide resin layer (32) are as follows: [Transparent polyamide resin layer (31) + transparent polyamide resin layer (31)/colored polyamide An aluminum electrolytic capacitor characterized in that resin layer (32)]≧1.