A module is provided that has high reliability in the junction between a
ceramic circuit board and a heat sink, undergoes small changes in shape
and warp of a module structure comprising a ceramic circuit board and a
metal heat sink event under a temperature history during power module
assembly and power module actual use, eliminates an unfavorableness
during power module assembly, and maintains high reliability over a long
period of time. A module structure characterized in that in a module
member formed by bonding the ceramic circuit board to the metal heat sink
via a metal plate (A) the main component of which is aluminum, the metal
plate (A) has a thickness of 400 .mu.m or more and 1,200 .mu.m or less.