Characteristic morphologies that cause failure of Au80Sn20/AlN substrate solder joint under combined temperature cycle a
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Characteristic morphologies that cause failure of Au80Sn20/AlN substrate solder joint under combined temperature cycle and current switch cycle tests Ping Lin1, Wensheng Liu1, Yunzhu Ma1, Yufeng Huang1,*
1
, and Siwei Tang1
National Key Laboratory of Science and Technology for National Defence on High–strength Structural Materials, Central South University, Changsha 410083, China
Received: 16 April 2020
ABSTRACT
Accepted: 5 September 2020
With the requirement of lead-free soldering technology in electronic industry for manufacturing lead-free electronic devices, Au80Sn20 solder has been developed and applied in high-power devices due to its excellent physical and chemical properties. However, the application of new type of chip in highpower devices leads to the exposure of the Au80Sn20 solder joints to the complex environment of temperature cycle and current switch cycle, which seriously affects the reliability of solder joints in practical applications. In this study, the solder joint structure and simulation platform were designed independently. The failure mechanism of Au80Sn20/AlN substrate solder joint under temperature cycle and current switch cycle was studied by analyzing the changes in morphological characteristics of solder joint and composition in different working times. It was found that the failure process of solder joint involved the generation of steps along the grain boundary and phase boundary, and the failure was caused by the gradual expansion of steps. Owing to the uneven distribution of Cu and Ni in Au5Sn and AuSn phases, the volume difference among different phases was generated, which promoted the formation of phase boundary steps. The grain boundary steps were formed due to the formation of Au3Cu phase at the grain boundary, resulting in the volume difference between grain boundary and grain. Based on the research results, the idea of improving solder joint reliability by adjusting microstructure of Au80Sn20 solder is put forward, which plays a theoretical guiding role in the optimization of targeted performance of Au80Sn20 solder.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
Address correspondence to E-mail: [email protected]
https://doi.org/10.1007/s10854-020-04438-9
J Mater Sci: Mater Electron
1 Introduction With the emergence of various new forms of electronic packaging, the number of pins on the chip increases significantly, which brings challenges for heat dissipation inside the chip [1, 2]. Dissipation of heat through metal structures such as solder joints and leads is highly desirable in order to improve the performance and prevent thermal fatigue of these joints [3]. Moreover, the reduction of area of solder joint leads to the increase in the current density flowing through the solder joint, and the high current density makes electromigration an important factor affecting the service life of solder joint [4–6]. Highpower chip encounters worse operating environment because of higher current passing through the solder joint and more severe
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