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This paper describes a technique that can obtain ternary Sn-Ag-In solder bumps with fine pitch and homogenous composition distribution.The main feature of this process is that tin-silver and indium are electroplated on copper under bump metallization(UBM) in sequence.After an accurate reflow process,Sn_(1.8)Ag_(9.4)In solder bumps are obtained.It is found that the intermetallic compounds(IMCs) between Sn-Ag-In solder and Cu grow with the reflow time,which results in an increase in Ag concentration in the solder area.So during solidification, more Ag_2In nucleates and strengthens the solder.
This paper describes a technique that can obtain ternary Sn-Ag-In solder bumps with fine pitch and homogenous composition distribution. The main feature of this process is that tin-silver and indium are electroplated on copper under bump metallization (UBM) in sequence. Sn_ (1.8) Ag_ (9.4) In solder bumps are obtained. It is found that the intermetallic compounds (IMCs) between Sn-Ag-In solder and Cu grow with the reflow time, which results in an increase in Ag concentration in the solder area. So during solidification, more Ag_2In nucleates and strengthens the solder.