Enhanced pressureless bonding by Tin Doped Silver Paste at low sintering temperature

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• 作者：Cheng-Xiang Yang^a ; ^b ; Xin Li^a ; ^{xinli@tju.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Guo-Quan Lu^a ; ^b ; Yun-Hui Mei^a
• 关键词：Transient liquid phase sintering ; Silver paste ; Pressureless bonding ; Second-phase strengthening ; Solid solution strengthening
• 刊名：Materials Science & Engineering A
• 出版年：2016
• 出版时间：13 April 2016
• 年：2016
• 卷：660
• 期：Complete
• 页码：71-76
• 全文大小：2641 K

文摘

The nanosilver sintering die-attach technique has been a promising alternative for wide band gap semiconductors. However, it is less preferable in industry because of its high sintering temperature. Recently research has been initiated to develop transient liquid phase sintering (TLPS) solder paste for use in electronics packaging. In this article, in order to lower the sintering temperature of nanosilver paste, we develop a novel tin (up to 10 wt%) doped silver paste (TDSP) and a sintering profile with the highest processing temperature of 235 °C based on TLPS. Sintered TDSP is Ag/Ag₃Sn/Ag–Sn solid solution composites. The composites have a microstructure of Ag matrix grains reinforced by Ag₃Sn and Ag–Sn solid solution within the matrix grains. And this microstructure endows the sintered Ag+4%Sn with a pressureless bonding strength of 23 MPa. The improved mechanical properties of sintered TDSP are attributed to second-phase strengthening and solid solution strengthening mechanisms. However, the overmuch formation of brittle Ag₃Sn phase is the main reason resulting in sharp decrease of bonding strength when the Sn content over 5 wt%. The new TDSP technology is expected to be applicable to a wide range of power semiconductors devices, such as organic devices and printed circuit boards. Furthermore, it provides new strategies for low-temperature sintering.