Material properties: Different metal oxide materials have different temperature coefficients. For example, resistors made of materials such as tin oxide have relatively low temperature coefficients. The selected substrate materials, electrode materials, etc. will also affect the temperature coefficient due to differences in thermal expansion coefficients.
Manufacturing process: The parameter control of thin film deposition processes, such as vacuum evaporation and sputtering, will affect the microstructure and performance of the oxide film, and thus affect the temperature coefficient. In addition, improper processing such as cutting, doping, and annealing will also lead to unstable temperature coefficients.
Resistor structure: In terms of geometric shape and size, larger resistors have large heat capacity, good heat dissipation, and relatively low temperature coefficients. The contact condition between the electrode and the resistor film also has an impact. Poor contact will produce contact resistance, which will affect the overall temperature coefficient with temperature changes.
Environmental conditions: Too high or too low ambient temperature, high humidity, etc. will change the material properties of the resistor, resulting in changes in the temperature coefficient. In addition, if it is in a harsh environment such as corrosive gas, it will accelerate the aging of the resistor and affect the stability of the temperature coefficient.
Power consumption: The resistor consumes power in the circuit and generates heat, which increases its own temperature. The greater the power consumption, the higher the temperature rise and the more obvious the change of temperature coefficient. Good heat dissipation can reduce this effect.
Welding process: If the temperature, time, flux and other factors during welding are not properly controlled, the resistor will be overheated locally, resulting in thermal stress and microstructural changes, thus affecting the temperature coefficient.
Protective coating: If the material and thickness of the protective coating are not properly selected, the thermal conductivity, thermal expansion coefficient and other factors may not match the resistor body, resulting in stress when the temperature changes, affecting the temperature coefficient of the resistor.
Aging of resistors: After long-term use, the material of metal oxide film resistors will age and the internal structure will change, such as cracks and shedding of the oxide film, resulting in changes in resistance value and temperature coefficient.
Circuit board design: If the layout and heat dissipation design of the circuit board are unreasonable, the heat flow around the resistor will be unevenly distributed, affecting its heat dissipation effect, and then affecting the temperature coefficient.
Rated power consumption: If the resistor is used beyond the rated power consumption, the temperature of the resistor film will rise rapidly, accelerating aging and resistance value changes, resulting in changes in the temperature coefficient.
