COMPOSITE MEMBER

In a composite member (1), a heat dissipating base substrate (30) is bonded to a heat generating member (10) with a thermoconductive insulating adhesive film (20) interposed therebetween, and the composite member (1) satisfies the following expressions. X/(E×|CTE(B)-CTE(A)|) ≥ 50, X/(E×|CTE(B)-CTE(C)|)≥50, Y/|CTE(B)-CTE(A)|×L(BA)≥ 50, and Y/CTE(B)-CTE(C)×L(BC)≥50. X: shear bond strength (MPa) between the heat dissipating base substrate and heat generating member, Y: fracture elongation (-) of the thermoconductive insulating film, E: modulus of elasticity (MPa) of the thermoconductive insulating film, CTE(A): linear expansion coefficient (°C-1) of the heat dissipating base substrate, CTE(B): linear expansion coefficient (°C-1) of the thermoconductive insulating film, CTE(C): linear expansion coefficient (°C-1) of the material of the surface of the heat generating member in contact with the thermoconductive insulating film, L(BA): initial contact length (m) between the thermoconductive insulating film and the heat dissipating base substrate, and L(BC): initial contact length (m) between the thermoconductive insulating film and the heat generating member.