To produce a coefficient of linear thermal expansion (CTE)-matching metalized film that would be suitable as the packaging for next generation power semiconductor devices, we examined the electroless Fe–Ni alloy deposition using DMAB as the reducing agent. Electroless deposited Fe–Ni alloy films with Fe content of 0–70 wt% were obtained and were found to be free of any cracks. Compared with an electroless deposited Ni–B alloy film, the absolute value of the thermal stress change dropped to less than half in electroless deposited Fe–Ni alloy films with Fe content of 55 and 64 wt% in the Invar composition range, while the CTE was approximately 8 ppm/°C. In the future, using an electroless deposited Fe–Ni alloy film in the range of Invar composition for packaging, we expect the implementation of next generation power semiconductors that are highly reliable even under high-temperature conditions.