| 摘要 |
PROBLEM TO BE SOLVED: To prevent the generation of a break, a crack or the like in the edge parts of a ring varistor by a method wherein the square part on one side of square parts, which are constituted of the outer peripheral surface and the main surface of the ceramic varistor material, is covered with a resin extending over the entire periphery of the varistor. SOLUTION: Three fan-shaped electrodes 2 containing silver as its main component are printed on the main surface on one side of the main surfaces of a ring ceramic varistor material 1 and the electrodes 2 are baked to form a varistor. In the obtained varistor, the square parts, which are constituted of the outer peripheral surface and main surface of the varistor, and the outer peripheral surface are covered with an epoxy resin 3 extending over the entire periphery of the varistor and the resin 3 is thermoset to protect the edge parts of the varistor. The resin 3 covering the square parts is formed 5 to 100μm a thick. Moreover, as the resin 3, at least one kind of a resin selected from an epoxy resin, a phenolic resin, an urethane resin, a polyimide resin, a silicon resin and a polyester resin is used.
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