Microstructural and mechanical evolution of silver sintering die attach for SiC power devices during high temperature applications
Microstructural and mechanical evolution of silver sintering die attach for SiC power devices during high temperature applications
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DOI：
10.1016/j.jallcom.2018.10.067
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发表时间：
2019-02-05
影响因子：
6.2
通讯作者：
Guo, Wei
中科院分区：
文献类型：
--
作者：
Zhang, Hongqiang;Wang, Wengan;Guo, Wei
银烧结是一种很有前途的芯片附着技术，以确保高的热可靠性。通过350 ℃空气和真空高温储存（HTS）工艺，对纳米Ag浆料烧结SiC器件的长期可靠性进行了评价。低温烧结后的纳米银浆料虽然可以将SiC芯片与直接键合铜（DBC）基板牢固地键合，但烧结后的芯片连接件的微观结构和剪切强度在高温超导过程中经历了巨大的演变。空气中高温处理后，芯片粘接层变得致密，部分气孔长大，气孔分布变得不均匀。而在真空高温合成过程中，残余有机物的存在抑制了气孔的生长和迁移，使胶层的致密化明显延迟。随着贮存时间的增加，粘片剪切强度先增加后缓慢下降。断口分析表明，Ni（P）层发生氧化，形成的NiO层为断裂提供了位置。结果表明，在长期高温下使用烧结芯片固定时，DBC基板的化学镀镍/浸金（ENIG）表面不是理想的金属化表面。(C)2018 Elsevier B. V.版权所有。
Silver sintering is a promising die attach technology to ensure high thermal reliability. The long-term reliability of SiC device sintered by nano-Ag paste has been evaluated by the high temperature storage (HTS) process at 350 degrees C in air and vacuum, respectively. Although the SiC chip and direct bonding copper (DBC) substrate could be bonded firmly by the nano-Ag paste after sintering at low temperature, the microstructure and shear strength of sintered die attachment experienced the huge evolution during HTS process. The bondline of die attachment became compact, and some pores grow up and pore distribution became nonuniform after HTS in air. While the densification of bondline was significantly delayed because residual organics inhibited the growth and migration of pores during HTS in vacuum. The shear strength of die attachment first increased then decreased slowly with the increasing of storage time. The fracture surface showed that the Ni(P) layer was oxidized, and the formed NiO layer provided the failure location. The results indicated that the electroless nickel/immersion gold (ENIG) surface of DBC substrate was not the ideal metallization when the sintered die attachment applied at the long-term high temperature. (C) 2018 Elsevier B.V. All rights reserved.