PTC thermistor and method for protecting circuit

1. A polymeric PTC thermistor comprising:

a conductive member comprising a conductive polymer having PTC characteristics; and

two electrodes each placed in two different locations on the conductive member;

wherein the conductive member and at least one of the two electrodes are bonded via an adhesive which (i) comprises a synthetic resin, (ii) has conductivity, and (iii) deteriorates in an overheated state in a temperature range in which the conductive polymer thermally expands and irreversibly increases the electrical resistance.

2. A thermistor according to claim 1 , wherein both of the two electrodes are bonded via the adhesive.

3. A thermistor according to claim 1 , wherein another of the two electrodes is bonded to the conductive member via a weld.

4. A thermistor according to claim 1 , wherein another of the two electrodes is bonded to the conductive member via solder.

5. A thermistor according to claim 1 , wherein the synthetic resin comprises a thermoplastic resin.

6. A thermistor according to claim 5 , wherein the thermoplastic resin comprises vinyl acetate resin, polyvinyl alcohol resin, acrylic resin, vinyl urethane resin, or mixtures thereof.

7. A thermistor according to claim 1 , wherein the synthetic resin comprises a thermosetting resin.

8. A thermistor according to claim 7 , wherein the thermosetting resin comprises urea resin, melamine resin, phenol resin, resorcinol resin, epoxy resin, silicone resin, α-olefin maleic acid anhydride resin, polyamide resin, polyimide resin, or mixtures thereof.

9. A thermistor according to claim 1 , wherein the adhesive comprises a conductive powder.

10. A thermistor according to claim 9 , wherein the conductive powder comprises gold, silver, nickel, or copper.