Metal film resistor is a special metal or alloy as resistance material, using high temperature vacuum coating technology, heating alloy in vacuum, alloy evaporation, forming resistance film on the ceramic or glass matrix resistor. Resistance can be controlled by grooving and changing the thickness of the metal film. Compared with carbon film resistors, metal film resistors have smaller volume, lower noise, better temperature coefficient and voltage coefficient, but higher cost. Common metal film resistors include pin type and patch type, among which, wafer type metal film resistors are more common, wafer resistance combines the advantages of pin type and patch type, and small size, can achieve a small size of high power.