首页|In-situ isothermal aging TEM analysis of a micro Cu/ENIG/Sn solder joint for flexible interconnects

In-situ isothermal aging TEM analysis of a micro Cu/ENIG/Sn solder joint for flexible interconnects

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Sn/ENIG has recently been used in flexible interconnects to form a more stable micron-sized metallurgical joint,due to high power capability which causes solder joints to heat up to 200 ℃.However,Cu6Sn5 which is critical for a microelectronic interconnection,will go through a phase transition at temperatures between 186 and 189 ℃.This research conducted an in-situ TEM study of a micro Cu/ENIG/Sn solder joint under isothermal aging test and proposed a model to illustrate the mechanism of the microstructural evolution.The results showed that part of the Sn solder reacted with Cu diffused from the electrode to form η'-Cu6Sn5 during the ultrasonic bonding process,while the rest of Sn was left and enriched in a region in the solder joint.But the enriched Sn quickly diffused to both sides when the temperature reached 100 ℃,reacting with the ENIG coating and Cu to form(NixCu1-x)3Sn4,AuSn4,and Cu6Sn5 IMCs.After entering the heat preservation process,the diffusion of Cu from the electrode to the joint became more intense,resulting in the formation of Cu3Sn.The scallop-type Cu6Sn5 and the seahorse-type Cu3Sn constituted a typical two-layered structure in the solder joint.Most importantly,the transition between η and η'was captured near the phase transition temperature for Cu6Sn5 during both the heating and cooling process,which was accompanied by a volume shifting,and the transition process was further studied.This research is expected to serve as a reference for the service of micro Cu/ENIG/Sn solder joints in the electronic industry.

In-situ TEM observationIsothermal agingMicro Cu/ENIG/Sn solder jointCu6Sn5 phase transition

Jinhong Liu、Jianhao Xu、Kyung-Wook Paik、Peng He、Shuye Zhang

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State Key Laboratory of Advanced Welding and Joining,Harbin Institute of Technology,Harbin,150001,China

Department of materials science and engineering,KAIST 291 Daehak-ro,Yuseong-gu,Daejeon,305-338,Republic of Korea

opening fund of National Key Research and Development Program of ChinaKey Laboratory of Science and Technology on Silicon Devices,Chinese Academy of SciencesChongqing Natural Science Foundation of China中央高校基本科研业务费专项

2020YFE0205300KLSDTJJ2022-5cstc2021jcyjmsxmX1002AUGA5710051221

2024

10.1016/j.jmst.2023.06.020

材料科学技术(英文版)
中国金属学会 中国材料研究学会 中国科学院金属研究所

材料科学技术(英文版)

CSTPCD
影响因子：0.657
ISSN：1005-0302
年,卷(期)：2024.169(2)
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