Temperature sensor with heat-sensitive paste

1. A circuit comprising a support and, on the support, a heat-sensitive resistor of negative or positive temperature coefficient, respectively comprising a resistive element based on antimony tin oxide, said resistive element also containing a polymer having a dielectric constant between 2 and 3, a molar mass between 50,000 and 150,000 g/mol, and a glass transition temperature Tg between 40 and 100° C., and wherein the polymer belongs to the family of styrenic polymers or to the family of fluorinated polymers.

2. The circuit of claim 1 , wherein the resistive element comprises from 5% to 40% by mass of dry extract of the polymer with respect to the total mass of the resistive element.

3. The circuit of claim 1 , wherein the heat-sensitive resistor further comprises a resistive element based on carbon black, said resistive element also containing a polymer having a dielectric constant between 2 and 3, a molar mass between 50,000 and 150,000 g/mol, and a glass transition temperature Tg between 40 and 100° C.

4. The circuit of claim 3 , wherein the heat sensitive resistor is of positive temperature coefficient having an adjustable threshold temperature with a resistance which is constant below said threshold and which increases along with temperature above said threshold comprising a first resistive track made of a heat-sensitive paste of positive temperature coefficient, PTC, arranged in electrical series with a second resistive track made of a heat-sensitive paste of negative temperature coefficient, NTC.

5. A method of manufacturing a heat-sensitive resistor of negative or positive temperature coefficient, comprising the steps of:

forming a first solution comprising antimony tin oxide, said first solution also containing a polymer having a dielectric constant between 2 and 3, a molar mass between 50,000 and 150,000 g/mol, and a glass transition temperature Tg between 40 and 100° C., and wherein the polymer belongs to the family of styrenic polymers or to the family of fluorinated polymers;

forming portions of the first solution on a support; and

heating the portions.

6. The method of claim 5 , wherein the step of manufacturing the first solution comprises the step of:

providing a second solution comprising antimony tin oxide or carbon black and a first solvent;

providing a third solution comprising the polymer and a second solvent; and

mixing the second and third solutions to provide the first solution.

7. The method of claim 6 , wherein the third solution is by a mass proportion smaller than 30%, preferably from 10 to 30% with respect to the total mass of the first solution.

8. The method of claim 6 , the third solution comprises from 15 to 30% by mass, for example, 25%, of the polymer in from 85 to 70% by mass, for example, 75%, of the second solvent.

9. The method of claim 6 , wherein the first solvent is selected from the group comprising cyclopentanone, ethyl acetate, tetrahydrofuran, acetone, 3-hexanone, and 2-pentanone for antimony tin oxide or the group comprising cyclopentanone, dibutyl carbitol, and ethylene glycol diacetate for carbon black.

10. The method of claim 6 , wherein the second solvent has an evaporation temperature in the range from 100 to 170° C.

11. The method of claim 6 , wherein the second solvent is selected from the group comprising toluene or butyl acetate for styrenic polymers or perfluorotributylamine (FC43) for fluorinated polymers.

12. The method of claim 6 , wherein the evaporation temperature of the first solvent is greater than the evaporation temperature of the second solvent.

13. The method of claim 5 , further comprising the steps of:

forming a fourth solution comprising carbon black containing a polymer having a dielectric constant between 2 and 3, a molar mass between 50,000 and 150,000 g/mol, and a glass transition temperature Tg between 40 and 100° C., and wherein the polymer belongs to the family of styrenic polymers or to the family of fluorinated polymers;

forming portions of the fourth solution on a support; and

heating the portions.

14. The method of claim 13 of manufacturing a heat-sensitive resistor of positive temperature coefficient having an adjustable temperature threshold with a resistance which is constant below said threshold and which increases along with temperature above said threshold, comprising the steps of:

forming in series on the support a first portion made of a heat-sensitive paste of positive temperature coefficient, PTC, and a second portion made of a heat-sensitive paste of negative temperature coefficient, NTC, the first and/or the second portion being formed with the first solution; and

heating the first and second portions to form first and second resistive tracks.