“Alpha Electronics produces precision resistors in unparalleled Bulk Metal® Foil technology since 1978. They provide the lowest available TCR of 0.14ppm/℃ (typical), the tightest tolerance of ±0.005% and excellent long-term stability (5ppm/year, 10ppm/3 years). (Alpha Electronics, Vishay Foil Resistors, 2023) 

Definition of Bulk Metal® Foil Resistor technology

Unlike thin film or wirewound resistors, Bulk Metal® Foil resistors owe their superior precision to the use of a special alloy foil, with a thickness of several microns, as the resistive element. Use of this metal foil as the resistance element provides superior performance not found in any other resistor technology. In particular the temperature coefficient of resistance (TCR) has been reduced to an unprecedented, extremely low level of 0.14 ppm/°C thanks to strict quality control of the alloy composition and a newly developed foil stabilization treatment technology.” (Alpha Electronics, Vishay Foil Resistors, 2023)