The development of lead-free solder alloys is necessary for environmental protection. We have focused on binary alloys based on tin-siver, and have found that the Sn-Ag system doped with a very little germanium drastically improves solder ability and reliability. The new type of solder alloy is composed of Sn-2.0Ag-4.0Bi-0.Cu-0.1Ge. The melting point of our solder is 217 deg C, higher than that of conventional Pb solder (183 deg C). We confirmed that it is in higher in solderability and reliability than conventional Pb solder, and that conventional soldering equipment can be used.
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