Flux for lead-free solder and soldering method
A soldering flux which is suitable as a no-clean post flux in flow soldering and which can prevent the formation of whiskers which tends to occur when soldering electronic parts to a printed circuit board using a lead-free solder (such as Sn-3.0Ag-0.5Cu) having a higher Sn content and a higher melting point than the eutectic solder contains, in addition to a rosin as a base resin and an activator, 0.2-4 mass % of at least one compound selected from acid phosphate esters and derivatives thereof. The formation of whiskers can be more effectively prevented by carrying out soldering in a nitrogen atmosphere.
Denso Corporation Senju Metal Industry Co., Ltd.
B B B B B H B
B23K B23K B23K B23K B23K H05K B23K
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Yuji Takashi Hiroyuki Kazuyuki
Kawamata Hagiwara Yamada Hamamoto