JPS6120126B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a thin capacitor in which a plurality of electric double layer capacitance cells are connected in series. Conventionally, capacitors that have been used in general have utilized the space charge of semiconductors or the charges induced on both sides of a dielectric material. Among these, those with very small capacitance are built on the same circuit board like integrated circuits, while those with large capacitance are used externally to the circuit. The electric double layer capacitor has a higher capacitance density than these capacitors, and there is a possibility that the capacitor can be made smaller. Recently, devices using an electric double layer formed at the interface between a polarizable electrode and a solid electrolyte have been studied and commercialized. However, all of these are used as functional elements such as timers and integral elements, and are not used as a capacitor incorporated on the same substrate. The reason for this is thought to be that silver and silver salts are used for the electrodes and electrolyte, which are expensive, and the decomposition voltage is low, making it impossible to achieve a high withstand voltage. The inventors added a predetermined amount of methyl halide of triethylenediamine or hexamethylenetetramine to cuprous halide, heated the reaction at a predetermined temperature, and then rapidly cooled the resulting solid electrolyte. It has been found that it exhibits high ionic conductivity, little deterioration over time, and a high decomposition voltage of 0.72V (silver salt 0.67V). Furthermore, simply replacing the electrolyte and counter electrode of a conventional silver salt element with the copper salt solid electrolyte and copper does not provide a device that can withstand repeated use and has a small leakage current. We have found that it is effective to use carbon for both electrodes. The present invention provides a thin capacitor that can be built into a circuit by using the above-described capacitor components. Examples of the present invention will be described below. 1 and 2 show an example of the structure of a capacitor according to the present invention. 1 and 2 are sheets made of heat-resistant resin such as phenol resin, polyester, epoxy resin, polyimide, etc. A capacitor element is arranged inside these resin sheets, and the resin sheets are sealed by pasting them together using double-sided adhesive tapes 3, 4 or the like. When a capacitor is built into a circuit, the sheet 1 becomes a circuit board. To explain in detail the manufacturing method of the capacitor, first, double-sided adhesive tapes 3 and 4 with a paper surface are attached to resin sheets 1 and 2, respectively. The tape is provided with through holes into which layers 5 and 6 of chemically and electrochemically stable metals such as nickel, stainless steel, gold or platinum are applied by vapor deposition or sputtering. These metals are usually economically inexpensive nickel or stainless steel. This forms the current collector portion of the electrode and a portion of the connector. Reference numerals 7 and 8 designate electrode portions made of carbon coating layers provided on metal layers 5 and 6, respectively. These electrode parts were made by mixing 100 parts by weight of a mixture of activated carbon and electrolyte at a weight ratio of 3:7 with the addition of butyl cellosolve containing 15 parts by weight of epoxy resin or resol type binder. Fill the paste on layer 5 or 6 and dry it naturally at 130℃.
by hot pressing for 5 minutes. After that, the surface paper of the tapes 3 and 4 is peeled off, and a double-sided adhesive tape 10 with a through hole for filling the electrolyte is pasted so as to cover the electrodes on one sheet, and 100 parts by weight of electrolyte is added to the through hole. A paste prepared by adding and kneading butyl cellosolve containing 15 parts by weight of a binder is filled, and the electrolyte layer 9 is formed by air drying. After that, the surface paper of the tape 10 was peeled off, and the resin sheets 1 and 2 were pasted together so that the carbon electrodes 7 and 8 faced each other with the electrolyte layer 9 in between.
Hot press for a minute. The through holes of the double-sided adhesive tape are accurately aligned so that the individual cells are connected in series by pasting. In addition, the electrolyte includes, for example, methyl bromide of triethylenediamine in cuprous halide.
C ₆ H ₁₂ N ₂・(CH ₃ Br) ₂ or the methyl bromide of hexamethylenetetramine C ₆ H ₁₂ N ₄・CH ₃ Br
The mixture was mixed at a ratio of 12.5 mol%, reacted by heating at 230°C or 150°C, and then rapidly cooled. Next, 56 cells were connected in series with 10 cells as described above.
The characteristics of capacitor A of the present invention with μF and 7.2V are 10
μF, 16V aluminum electrolytic capacitor B for timer
The results of the comparison are shown in the table. In capacitor A of the present invention, the electrodes of each cell had a size of 2 mm x 2 mm, and the filling thickness was adjusted by setting the thickness of the double-sided adhesive tape to 50 μm. In addition, the size of the electrolyte was 2.6 mm x 2.6 mm, and the filling thickness was adjusted by setting the thickness of the double-sided adhesive tape to 20 μm. The spacing between the electrolyte filled layers was 1 mm to allow for cutting, and the spacing between the electrodes was 1.6 mm.

【table】

[Table] From the above results, it can be seen that the capacitor of the present invention is small in size, has a high stored energy density, has a small leakage current, and can be used up to high temperatures. In addition, during manufacturing, if double-sided adhesive tape is used for the attachment and filling pattern of the metal layer, carbon electrode, and solid electrolyte, not only can the amount of filling be accurately controlled by the tape thickness, but also the amount of filling can be easily controlled. Even when hot-pressing to achieve a tight bond, the filling is pressed without spreading, and when bonding, all areas other than the filling are affixed, increasing the adhesion strength and ensuring that each layer of the filling is Peeling is less likely to occur. With other means, such as screen printing, it is difficult to press without spreading the filler, and with photoresist, even pressing is difficult. Furthermore, these other means have the drawback that it is difficult to apply the adhesive to areas other than the filling, and it is not possible to reduce the series resistance without variation. The capacity is proportional to the weight of the carbon mixture of the electrode as shown in FIG. 3, but by changing the size and thickness of the through holes in the double-sided adhesive tape, it is possible to create an arbitrary capacity. As described above, according to the present invention, it is possible to provide a capacitor that is small and has a high storage energy density.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of a capacitor according to an embodiment of the present invention, Fig. 2 is a plan view with essential parts removed, and Fig. 3 shows the relationship between the weight of carbon in the electrode of the capacitor and the capacity of a single cell. The characteristic diagram shown in FIG. 4 is an equivalent circuit diagram of the capacitor. 1, 2... Resin sheet, 3, 4... Double-sided adhesive tape, 5, 6... Metal layer, 7, 8... Carbon electrode, 9... Electrolyte, 10... Double-sided adhesive tape.

Claims (1)

[Scope of Claims] 1. Two resin sheets, each having a plurality of metal layers forming a current collector part and a connector part on their surfaces and electrode parts made of a carbon coating layer formed on the metal layers, are made into a solid state. A capacitor in which the electrode parts are bonded together so as to face each other with an electrolyte layer in between to form a plurality of electric double layer capacitance cells connected in series, and these cells are sealed. 2. Claim 1, wherein the metal layer on the resin sheet is formed in a through-hole portion of a double-sided adhesive tape bonded on the resin sheet, and is separated from an adjacent metal layer by the adhesive tape. Capacitor described in section. 3. Claim 1, wherein the electrolyte layer is formed in a through-hole portion of a double-sided adhesive tape that bonds the electrode portion forming surfaces of both resin sheets, and is separated from an adjacent electrolyte layer by the adhesive tape. Capacitor as described.