Cylindrical varistor and method of making the same

A varistor, the combination comprising:

• a cylindrical core made of a sintered varistor material and having an outer longitudinal surface;
• a pair of terminating layers, one being on each end of said core;
• an electrode film on the outer longitudinal surface of said core between said terminating layers, said electrode film being divided into a pair of electrode portions by a gap;
• each of said electrode portions being in communication with one of said terminating layers;
• the gap being formed in the peripheral surface of said electrode film in a closed path and being dimensioned to predetermine the properties of said varistor;
• and
• a pair of lead wires, each being attached to one end of said core and being in electrical contact with one of said terminating layers.

A method of making a varistor, comprising the steps of:

• formulating a varistor powder;
• pressing the powder into a cylindrical core having openings at its opposite ends and an outer longitudinal surface;
• heating the core at a temperature in the range from about 900.degree. to about 1400.degree. C until the core becomes sintered;
• applying a terminating layer to each end of the sintered core;
• applying an electrode film to the sintered core with each end of the film in electrical contact with one of the terminating layers;
• dividing the electrode film into a pair of electrode portions by forming a gap between the ends of the film;
• and
• inserting a lead wire into each end of the core in the core opening and in electrical contact with one of the terminating layers.

A method of making a varistor, comprising the steps of:

• formulating a varistor powder;
• pressing the powder into a cylindrical core;
• heating the core at a temperature in the range from about 900.degree. to about 1400.degree. C until the core becomes sintered;
• applying a terminating layer to each end of the sintered core;
• applying an electrode film to the sintered core with each end of the film in electrical contact with one of the terminating layers;
• dividing the electrode film into a pair of electrode portions by forming a gap between the ends of the film, the gap being formed by removing a part of the film in a closed path along the periphery thereof;
• the dimensions of the gap being adjusted to predetermine the properties of the varistor;
• and
• attaching a lead wire to each end of the core and in electrical contact with one of the terminating layers.