| 摘要 |
<p>PROBLEM TO BE SOLVED: To achieve solder composition where a joint cannot cause release easily by adding Sn, Ag, Cu, In, and Bi with a specific range of weight as solder or adding other small amount of elements to them when connecting a chip to an insulation substrate by lead-free solder. SOLUTION: An Mo plate 2 (a thermal diffusion plate with low thermal expansion and Ni plating 5) and a Cu plate heat sink 9 (Ni plating) are soldered at a maximum of 270 deg.C in an inactive atmosphere using a solder foil 8 where the melt point of Sn-7Sb of 0.15 mmt ranges from 235 to 244 deg.C so that an alumina substrate 3 can be sandwiched in a power device. Then, an Si chip 1 is placed on the rear side (Ni plating) of the joined Mo by a solder foil 7 of Sn-3 Ag-0.7Cu-3In-3Bi for soldering in an inactive atmosphere similarly at a maximum of 230 deg.C, thus forming a solder composition for preventing a joint from being released easily.</p> |
