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Home  >  Journal list  >  MATERIALS TRANSACTIONS  >  Vol.42  No.5 (2001)  >  pp.820-824

<<Previous article Vol.42  No.5 (2001)   pp.820 - 824 Next article>>

A Study on the Fluxless Soldering of Si-Wafer/Glass Substrate Using Sn-3.5 mass%Ag and Sn-37 mass%Pb Solder

Chang-Bae Park1), Soon-Min Hong2), Jae-Pil Jung1), Choon-Sik Kang2) and Yong-Eui Shin3)
1) Department of Materials Science & Engineering, University of Seoul
2) School of Materials Science and Engineering., Seoul National University
3) Department of Mechanical Engineering, Chung-Ang University

UBM-coated Si-wafer was fluxlessly soldered with glass substrate in N2 atmosphere using plasma cleaning method. The bulk Sn-37 mass%Pb and Sn–3.5 mass%Ag solders were rolled to the sheet of 100 \micron thickness in order to achieve bonding to Si-wafer by fluxless 1st reflow process. The oxide layer on the solder surface was analyzed by AES (Auger Electron Spectroscopy). After 1st reflow the Si-wafer with a solder disk was plasma-cleaned, and soldered to glass by 2nd reflow soldering process without flux in N2 atmosphere. The thickness of oxide layer decreased with increasing plasma power and cleaning time. The optimum plasma treatment condition in this study was 500 W for 12 min and at this condition, 100% bonding ratio for Sn–3.5 Ag and over 80% bonding ratio for Sn–37Pb solder were achieved. The intermetallic compound of continuous Cu6Sn5 was observed along the Si-wafer/solder interface but discrete Cu6Sn5 along the glass/solder interface and the different shapes of Cu6Sn5 were caused by different thickness of Cu as a pad. The fracture of the tensile test specimen occurred at not only solder/UBM and solder/TSM interface but also in Si-wafer and glass substrate.

fluxless soldering, plasma cleaning, Silicon-wafer, glass substrate, oxide layer

Received: November 20, 2000
Accepted: January 16, 2001 , Published online: September 06, 2005
Copyright (c) 2005 The Japan Institute of Metals



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