| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent occurrence of poor soldering at ends of a semiconductor element by ensuring that molten solder is in contact with the entire joining face of a semiconductor element. <P>SOLUTION: A solder 30 is adapted to be a laminate consisting of, from a heat sink 20 side, a low-temperature holder layer 31 composed of Pb free solder and a high-temperature solder layer 32 composed of Pb free solder which is higher in melting point than the low-temperature holder layer 31 and whose joining face with a semiconductor element 10 is flat. When soldered, a first melting process is carried out in which the high-temperature solder layer 32 is kept in a solid state in order to maintain the flatness of the joining face thereof, while the low-temperature solder layer 31 is entirely in a molten state. After that, a second melting process is carried out in which a semiconductor element 20 is placed on the joining face of the high-temperature solder layer 32 and then the high-temperature solder layer 32 is also melted along with the low-temperature solder layer 31 to complete soldering. <P>COPYRIGHT: (C)2012,JPO&INPIT |
