| 摘要 |
PROBLEM TO BE SOLVED: To improve the power cycle resistance and reliability by self-repairing the heat deterioration and crack caused in a solder layer, in a solder joint part between a semiconductor element and an insulating substrate joined with a lead free solder. SOLUTION: In a semiconductor device wherein a semiconductor element 3 is solder-mounted on a copper circuit pattern 2b of an insulating substrate 2, after a solder joint surface area A between the semiconductor element and the copper circuit pattern is divided in two of a center surface part B corresponding to the underpart of a center of a semiconductor chip and an outer peripheral surface part C surrounding the center surface part, the center surface part B is joined by selecting a lead free solder 8 whose melting point is not over a maximum proof temperature of the semiconductor element 3 (for example, 150°C), and the outer peripheral surface part C is joined with a lead free solder 9 whose melting point is higher than the maximum proof temperature of the semiconductor element 3. To be more precise, the insulating substrate and the semiconductor element are piled while sandwiching plate solders of the lead free solders 8 and 9 cut out according to a pattern of the joint surface area. By reflowing at the temperature not over the melting point of the lead free solder 9 under such a condition as above, the center and the outer peripheral surface parts are solder-joined at the same time. COPYRIGHT: (C)2007,JPO&INPIT |
