TY - JOUR
T1 - A fluxless process of producing tin-rich gold-tin joints in air
AU - Chuang, Ricky W.
AU - Kim, Dongwook
AU - Park, Jeong
AU - Lee, Chin C.
N1 - Funding Information:
Manuscript received September 5, 2002; revised April 15, 2003. This work was supported by UC-SMART (semiconductor manufacturing alliance for research and training), Uplink Communications, and UC MICRO. This work was recommended for publication by Associate Editor P. Garrou upon evaluation of the reviewers’ comments.
PY - 2004/3
Y1 - 2004/3
N2 - A soldering process performance in ambient air without the use of any flux is reported. We believe that this is the first time fluxless soldering process is successfully done in air without prior fluorine treatment. The fluxless process is implemented using Au-Sn binary system. It is based on Au-Sn multilayer design that is substantially tin-rich, namely, with 95 at.% Sn (91.8 wt.% Sn) and 5 at.% Au (8.2 wt.% Au). Over the past 15 years, we have developed numerous fluxless bonding processes. These processes require environments such as H2 or N2 during the bonding process to inhibit solder oxidation. This requirement is not compatible with the pick-and-place bonding machines widely employed in the industry. Thus, fluxless processing in air has been our lifelong endeavor. After many attempts, we finally achieved some initial success. The bonding process is carried out at 225°C. The resulting joints are nearly void-free as confirmed by scanning acoustic microscopy (SAM). To study the microstructure and composition of the samples, scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) spectroscopy was performed on the joint cros-section. The results show that the joint is composed of AuSn4 intermetallic grains embedded in a Sn matrix. Re-melting temperatures of the solder joint were measured to range from 214°C to 220°C, which are consistent with data on the Au-Sn phase diagram.
AB - A soldering process performance in ambient air without the use of any flux is reported. We believe that this is the first time fluxless soldering process is successfully done in air without prior fluorine treatment. The fluxless process is implemented using Au-Sn binary system. It is based on Au-Sn multilayer design that is substantially tin-rich, namely, with 95 at.% Sn (91.8 wt.% Sn) and 5 at.% Au (8.2 wt.% Au). Over the past 15 years, we have developed numerous fluxless bonding processes. These processes require environments such as H2 or N2 during the bonding process to inhibit solder oxidation. This requirement is not compatible with the pick-and-place bonding machines widely employed in the industry. Thus, fluxless processing in air has been our lifelong endeavor. After many attempts, we finally achieved some initial success. The bonding process is carried out at 225°C. The resulting joints are nearly void-free as confirmed by scanning acoustic microscopy (SAM). To study the microstructure and composition of the samples, scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) spectroscopy was performed on the joint cros-section. The results show that the joint is composed of AuSn4 intermetallic grains embedded in a Sn matrix. Re-melting temperatures of the solder joint were measured to range from 214°C to 220°C, which are consistent with data on the Au-Sn phase diagram.
UR - http://www.scopus.com/inward/record.url?scp=2442625278&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=2442625278&partnerID=8YFLogxK
U2 - 10.1109/TCAPT.2004.825757
DO - 10.1109/TCAPT.2004.825757
M3 - Article
AN - SCOPUS:2442625278
SN - 1521-3331
VL - 27
SP - 177
EP - 181
JO - IEEE Transactions on Components and Packaging Technologies
JF - IEEE Transactions on Components and Packaging Technologies
IS - 1
ER -