A foil resistor consists of a supporting ceramic body, the surface of which is coated with a foil alloy of nickel-chromium. The properties of the foil alloy are mainly determined by its resistivity and temperature coefficients.
In the production of foil resistors, exact meandering resistivity patterns are etched into a foil by photoetching. The exact resistivity value is increased by gradually adding progressively smaller resistivity values or reduced by short-circuiting junctions that remove resistive loops.
The ceramic-foil interconnect provides high stability in terms of temperature dependence and power coefficient of the resistor. Also positive are the characteristic values for long-term stability, freedom from induction, thermoelectric voltage, ESD resistance and low noise. Foil resistors achieve temperature coefficients of +/- 1 ppm/°C in the operating range.