RESIN MOLDED SEMICONDUCTOR DEVICE

The trend toward higher integration degrees has caused the semiconductor pellets to have large sizes. In the resin molded semiconductor devices, in particular, cracks develop on the pellet due to contraction upon cooling that stems from the difference of coefficient of thermal expansion between the molding resin and the pellet. Cracks develop conspicuously under the ball of the wire that is bonded onto the bonding pad on the pellet. The area that receives the shearing stress increases with the increase in the ball portion, and the cracks develop easily. To decrease the shearing stress and to prevent the crack from developing according to the present invention, the breaking strength of the bonding portion is set to be greater than the bending moment that is received depending upon the shape of the ball. That is, the ratio d/l of the thickness d of the ball portion and the width l of the alloy layer formed by the pad and the wire at the time of bonding is selected to be smaller than 0.2.