Pb free solder is used in die bonding. A thermal stress reduction plate is disposed between a semiconductor chip and a die pad made of a Cu alloy. The semiconductor chip and the thermal stress reduction plate are joined and the thermal stress reduction plate and the die pad are joined by a joint material of Pb free solder having Sn--Sb--Ag--Cu as its main constituent elements and having a solidus temperature not lower than 270.degree. C. and a liquidus temperature not higher than 400.degree. C. Thus, die bonding can be performed using the Pb free solder without generating any chip crack.