Interfacial reaction between Sn-0.7Cu (-Ni) solder and Cu substrate

The interfacial reaction between Sn-0.7mass%Cu-(Ni) solders and a Cu substrate was investigated to reveal the effect of the addition of Ni to Sn-Cu solder on the formation of intermetallic compounds (IMCs). Sn-0.7Cu-xNi solders (x=0, 0.05, 0.1, 0.2 mass%) were prepared. For the reflow process, specimens were heated in a radiation furnace at 523 K for 60 sec, 300 sec, and 720 sec to estimate the interfacial reaction between the molten solder and Cu substrate. Then, for the aging process, some specimens were heat-treated in an oil bath at 423 K for 168 h and 504 h. The cross sections of soldered specimens were observed to measure the dissolution thickness of the Cu substrate and the thickness of the IMC and to investigate the microstructures of IMC. The results showed that, just after the reflow process, the dissolution thickness of the Cu substrate increased with the increase of Ni content in the Sn-0.7Cu-xNi solder and the thickness of the IMC between the solder and Cu substrate was the minimum in the Sn-0.7Cu-0.05Ni solder. After the aging process, the IMC grew with the increase of aging time. In the case of 0.05% Ni, the IMC thickness was the thinnest regardless of aging time. It is clear that 0.05% Ni addition to Sn-0.7Cu solder very effectively inhibits the formation and growth of the IMC between solder and Cu substrate. Electron probe microanalysis of the IMC showed that the IMC layer in the Sn-0.7Cu-Ni solder contained Ni, and the IMC was expressed as (Cu1−y,Niy)6Sn5.

[1]  Hyuck-Mo Lee,et al.  Effect of In Addition on Sn-3.5Ag Solder and Joint with Cu Substrate , 2001 .

[2]  Sinn-wen Chen,et al.  Phase equilibria and solidification properties of Sn-Cu-Ni alloys , 2002 .

[3]  Yee-Wen Yen,et al.  Interfacial reactions in Ag-Sn/Cu couples , 1999 .

[4]  James C. Foley,et al.  Alloying effects in near-eutectic Sn-Ag-Cu solder alloys for improved microstructural stability , 2001 .

[5]  Sinn-wen Chen,et al.  Interfacial reactions in the Sn-Ag/Au couples , 2001 .

[6]  Sinn-wen Chen,et al.  Interfacial reactions in the Sn-(Cu)/Ni, Sn-(Ni)/Cu, and Sn/(Cu,Ni) systems , 2003 .

[7]  Y. G. Lee,et al.  Phase Analysis in the Solder Joint of Sn-Cu Solder/IMCs/Cu Substrate , 1999 .

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

[9]  K. Bae,et al.  Interdiffusion analysis of the soldering reactions in Sn-3.5Ag/Cu couples , 2001 .

[10]  T. Takemoto.  Lead-free Solder and Micro-joining. , 1996 .

[11]  Hwa-Teng Lee,et al.  Influence of intermetallic compounds on the adhesive strength of solder joints , 2002 .

[12]  Katsuaki Suganuma,et al.  Effect of Ag Addition on the Microstructural and Mechanical Properties of Sn-Cu Eutectic Solder , 2001 .

[13]  Y. L. Lin,et al.  Effect of Cu concentration on the reactions between Sn-Ag-Cu solders and Ni , 2002 .

[14]  Ikuo Shohji,et al.  Tensile Properties of Sn-3.5Ag and Sn-3.5Ag-0.75Cu Lead-free Solders , 2002 .

[15]  T. Takemoto,et al.  Effect of Excess Temperature above Liquidus of Lead-Free Solders on Wetting Time in a Wetting Balance Test , 2001 .

[16]  Sinn-wen Chen,et al.  Mechanical properties and intermetallic compound formation at the Sn/Ni and Sn-0.7wt.%Cu/Ni joints , 2003 .

[17]  J. Pang,et al.  Low cycle fatigue study of lead free 99.3Sn–0.7Cu solder alloy , 2004 .

[18]  Xin Ma,et al.  Development of Cu-Sn intermetallic compound at Pb-free solder/Cu joint interface , 2003 .

[19]  T. Takemoto,et al.  Role of electrode potential difference between lead-free solder and copper base metal in wetting : Lead-free electronics packaging , 2002 .

[20]  Kwang-Lung Lin,et al.  Effect of microelements addition on the interfacial reaction between Sn-Ag-Cu solders and the Cu substrate , 2003 .

[21]  Chang-Da Tsai,et al.  A study on the reaction between Cu and Sn3.5Ag solder doped with small amounts of Ni , 2003 .

[22]  M. Abtew,et al.  Lead-free Solders in Microelectronics , 2000 .