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**Mumbai University > Electronics Engineering > Sem 8 > MEMS Technology**

**Marks:** 5M

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Define TCR thermal conductivity and its significance with respect to MEMS devices.

written 4.7 years ago by | • modified 4.7 years ago |

**Mumbai University > Electronics Engineering > Sem 8 > MEMS Technology**

**Marks:** 5M

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written 4.7 years ago by | • modified 4.6 years ago |

**TCR**

• TCR stands for Temperature Coefficient of resistance.

• Temperature coefficient of resistance is the measure of change in electrical resistance of any substance per degree of temperature change.

• In other words, ideally resistance should be zero but that does not happen practically. When heating comes into picture, the resistance changes in accordance with the heating and thus, the change of resistance per degree change in temperature is called Temperature Coefficient of resistance.

• For pure metals, it is positive, means the resistance increases with temperature whereas for non-metals this coefficient is negative, means the resistance decreases with increasing temperature.

• **Why this happens?**

• Consider example of pure metals where resistance increases with temperature, in this as the temperature increases number of collisions between charge carriers and atoms also increase resulting in increase in resistance.

• Ideally TCR should follow a linear relationship but that does not happen, the resistance effects resulting from the number of collisions is not always constant, particularly at low temperatures.

• If there is approximately no change in resistance with temperature, we can consider the value of this coefficient as zero. The alloy of constantan and manganin has the temperature coefficient of resistance nearly zero.

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