The effect of a concentration gradient on interfacial reactions in microbumps of Ni/SnAg/Cu during liquid-state soldering

We report new findings in Ni/SnAg–solder/Cu microbumps having a reduced solder thickness in the range of 40–10 μm; the growth rate of the intermetallic compounds depends strongly on the solder thickness. In the Ni/40 μm solder/Cu samples, the compound which grew on the Ni side grew slightly faster than that on the Cu side. However, the growth reverses as the solder thickness decreases below 20 μm due to the change in Cu and Ni concentration gradients in the solder.

[1]  Chih Chen,et al.  Cross interactions on interfacial compound formation of solder bumps and metallization layers during reflow , 2004 .

[2]  Cheng-Yi Liu,et al.  Asymmetrical solder microstructure in Ni/Sn/Cu solder joint , 2006 .

[3]  N. Chawla,et al.  Creep deformation behavior of Sn–3.5Ag solder/Cu couple at small length scales , 2004 .

[4]  Y. C. Chan,et al.  Solid-state growth kinetics of Ni3Sn4 at the Sn–3.5Ag solder∕Ni interface , 2005 .

[5]  C. Y. Liu,et al.  Evolution of Ag3Sn compound formation in Ni/Sn5Ag/Cu solder joint , 2008 .

[6]  Y. C. Chan,et al.  Growth mechanism of Ni3Sn4 in a Sn/Ni liquid/solid interfacial reaction , 2009 .

[7]  K. H. Chen,et al.  Metallurgical reactions of Sn-3.5Ag solder with various thicknesses of electroplated Ni/Cu under bump metallization , 2005 .

[8]  Remo Guidieri.  Res , 1995, RES: Anthropology and Aesthetics.

[9]  Christopher Mark Johnson,et al.  Interfacial reaction in Cu/Sn/Cu system during the transient liquid phase soldering process , 2011 .

[10]  K. Tu,et al.  Six cases of reliability study of Pb-free solder joints in electronic packaging technology , 2002 .

[11]  Sinn-wen Chen,et al.  Phase equilibria of the Sn-Ag-Ni ternary system and interfacial reactions at the Sn-Ag/Ni joints , 2004 .

[12]  Wen-Tai Chen,et al.  Effect of Cu concentration on the interfacial reactions between Ni and Sn–Cu solders , 2002 .

[13]  R. Arróyave,et al.  Early stages of intermetallic compound formation and growth during lead-free soldering , 2010 .

[14]  K. N. Tu,et al.  Reliability challenges in 3D IC packaging technology , 2011, Microelectron. Reliab..