X-MINING Stabilizing Electronics in Harsh Temperatures Thick Film Paste

Electronic components used in mobility devices, which are often used in harsh temperature conditions, are required to function stably even if the usage environment changes. Especially, the change of the characteristics with respect to temperature must be small.

In case of passive resistors, the temperature coefficient of resistance, TCR, is used as an indicator of change in characteristics against temperature.

A resistor whose TCR is close to zero is a stable resistor that is not affected by temperature.

TCR is expressed by the following equation as the change in resistance (RT) at temperature T relative to the resistance value (RTa) at the reference temperature (Ta).

TCR(ppm/℃)=(R_T-R_Ta) /R_Ta/(T-Ta)×10⁶

The reference temperature is usually 25℃, but in some cases, a temperature of 20℃ is used.

Based on the reference temperature, TCR on the low temperature side is called Cold-TCR and TCR on the high temperature side is called Hot-TCR. They are often used separately.

As described above, a resistor that is close to zero for both Cold-TCR and Hot-TCR can be said to be a stable resistor, but it is very difficult to design such a resistor.

For this reason, resistors are usually designed with focusing on either Cold-TCR or Hot-TCR, and the material is selected accordingly.

Materials used in resistors include those with metallic conductive properties and those with semiconducting conductive properties.

The resistance value RT at temperature T for a material of metallic conductive properties is expressed by following.

R_T=R₀(1+αδT)

Since α takes a positive value, RT becomes positive and TCR also becomes positive.

The resistance value RT at temperature T of a material that exhibits semiconductive properties is expressed by following.

R_T=βexp(E/kT)

Since E takes a positive value, RT becomes negative and TCR also becomes negative.

*R0: Resistance at reference temperature,
α: Temperature coefficient of resistivity,
β: Material-specific constant
E: Activation energy,
k: Boltzmann constant

Sumitomo Metal Mining’s high-quality low TCR thick film resistive paste contains metallic conductive components and semiconductive components. It is optimally designed to keep both Cold-TCR and Hot-TCR within ±50ppm/℃ (Reference temperature 25℃).

Example: When the behavior is based on 25°C.

Sumitomo Metal Mining’s high-quality low TCR thick film resistive paste is a thick film resistive paste that has been adjusted to ±50ppm/°C for both Cold-TCR, Hot-TCR by optimizing the distribution composition.

Sumitomo Metal Mining’s high-quality low TCR thick film resistive paste is a material that suppresses changes in resistance values over a wide temperature range.

This material is suitable for electronic components used in mobility. Furthermore, this material can be used in a variety of applications based on its characteristics and your diverse ideas.