<p>Disclosed is a metal base substrate which comprises a low-temperature sintering ceramic layer formed on a metal substrate, and in which the low-temperature sintering ceramic layer is not prone to cracking or peeling at the interface with the metal substrate, and the anti-peeling strength of the surface conductor is improved while making it possible for the metal substrate to be configured from copper. In the metal base substrate (12) provided with a metal substrate (14) and a low-temperature sintering ceramic layer (15) formed thereon, the thermal expansion coefficient of the metal substrate (14) is greater than that of the low-temperature sintering ceramic layer (15); the average difference in thermal expansion coefficients between the metal substrate (14) and the low-temperature sintering ceramic layer (15) at 25-400C is 4-9 ppm/degree celsius; the Young's modulus of the low-temperature sintering ceramic layer (15) is less than 120 GPa; and the flexural strength is 200MPa or higher.</p>
