Method for manufacturing power module substrate

A method for manufacturing a power module substrate including a ceramic substrate, a circuit layer formed of a copper sheet bonded onto one surface of the ceramic substrate, and a metal layer formed of an aluminum sheet bonded onto the other surface of the ceramic substrate, the method comprising:

• a first lamination step of laminating the copper sheet on the one surface of the ceramic substrate through an active metal material and a filler metal, the filler metal having a melting point of 600° C. or lower;
• a second lamination step of laminating the aluminum sheet on the other surface of the ceramic substrate through a bonding material;
• and
• a heating treatment step of heating the ceramic substrate, the copper sheet, and the aluminum sheet laminated together at a heating temperature of 650° C. or lower, wherein
• the ceramic substrate and the copper sheet, and the ceramic sheet and the aluminum sheet are bonded at the same time;
• wherein at the first lamination step of laminating the active metal material is disposed on the copper sheet, and the filler metal is disposed on the ceramic substrate;
• the active metal material is selected from a group consisting of one or more active elements of Ti, Zr, Nb, and Hf, and
• the filler metal does not come into direct contact with the copper sheet.