Technical Articles
Precision Resistors' Construction and TCR
Date:2019-04-24
Precision resistor here we mainly refer to thin film resistor. By depositing a thin film of resistive material, such as nickel-chromium on a silicon wafer, precision resistors for the hybrid are produced.  Microhm uses standard semiconductor technology etching away the unwanted resistive film  and leave the demanded resistor geometries on the silicon wafer.



 
Each circuit contains resistors from one to serveral dozen, which depending on the design. Thin film resistor's resistance value is determined by its structure and geometry. The larger the value of the resistor, the more area it occupies on the silicon die, so the total resistance value should be minimized in chip and wire hybrid.


Precision resistors is usually applicable in measurement and dividing down a stable voltage reference. Apart from tolerance, temperature coefficient is another most important parameters. The resistive tempco, expressed in parts per million per °C (ppm/°C). Standard metal film and chip resistors have tempcos of the order of ±50 to ±200 ppm/°C. The actual tempco depends on the manufacturing process and also on the value.


Besides thin film resistors, Microhm also produce high precision and low TCR metal foil resistors  MVR2321-4, MVR3825-4 and MVR4618-4 for power modules, current monitoring, frequency converters, switch mode.