Patent ID: 6852569

Claim:
A method of fabricating a multilayer ceramic substrate comprising: stacking one or a plurality of unfired ceramic greensheets on one or both sides of a previously fired ceramic substrate, thereby forming a stack, each unfired ceramic greensheet having a firing temperature substantially equal to or lower than a firing temperature of the previously fired ceramic substrate; stacking a restricting greensheet on the unfired ceramic greensheet composing an outermost layer of the stack, the restricting greensheet having a higher firing temperature than each unfired ceramic greensheet; firing the stack at the firing temperature of the unfired ceramic green sheets with or without pressure applied via the restricting greensheet while the stack is under restriction by the restricting greensheet, thereby integrating the stack; and eliminating remainders of the restricting greensheet after the firing step, wherein the previously fired substrate and the unfired ceramic greensheets are made from different ceramic materials from each other.