Harima Chemicals, Incorporated

Naoya Inoue

Keigo Obata

Takao Takeuchi

Kazuki Ikeda

Hiroshi Tanaka

Hisao Irie

Shunsuke Ishikawa

Takaaki Anada

A flux contains resin having film forming ability, activator, solvent and at least one complex selected from silver complex and copper complex. The flux is used when soldering is performed onto a circuit having electroless nickel plating or further having gold plating on the electroless nickel plating. Allowing a barrier layer of silver or copper to deposit on the surfaces of lands suppresses the diffusion of nickel into the melted solder alloy during soldering, and also prevents phosphorous concentration. This improves the bonding strength of soldering and suppresses the reduction deposition of silver and/or copper to portions other than circuit patterns.

Flux for soldering and circuit board

According to present invention, there is provided a lead-free solder precipitating composition comprising a tin powder, and a complex of silver ions and/or copper ions and aryl phosphines, alkyl phosphine, phosphines or azoles. The solder precipitating composition can form proper lead-free solder on lands of a circuit board, without forming silver and/or copper film on the circuit board.

Solder precipitating composition

Growing community of inventors

Akashi, Japan

Naoya Inoue