Senju Metal Industry Co., Ltd.

Eietsu Hasegawa

Rikiya Kato

Sakari Tada

Seiichiro Hasegawa

Discarded printed circuit boards are sorted according to the alloying elements in solder used on the printed circuit boards. After sorting, the printed circuit boards are heated to melt the solder, and the molten solder is collected.

Method of recovering lead-free solder from printed circuit boards

Members to be soldered, such as printed circuit boards having electronic parts mounted thereon, are subjected to flow soldering in a solder bath with a Cu-containing lead-free solder. When the molten solder in the solder bath falls below a prescribed level, the molten solder is replenished with a material having a lower Cu content than the initial composition of the solder bath. Flow soldering can be continued for long periods with the Cu content of the solder bath being maintained substantially constant.

Soldering method using a Cu-containing lead-free alloy

A solder paste comprises a solder paste portion containing powdered solder and metallic spheres which are made of a material having a higher melting point than the solder paste portion and whose surface can be wet by molten solder. The metallic spheres have a diameter of 0.07-0.3 mm. The metallic spheres can comprise a single metal or two metals, one of which forms the center of the sphere and the second of which is plated on the surface of the first.

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Satte, Japan

Eietsu Hasegawa