Effects of Sn-Ag-x leveling layers on the microstructure and mechanical properties of SnBi low-temperature solder joints,Soldering & Surface Mount Technology

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Effects of Sn-Ag-x leveling layers on the microstructure and mechanical properties of SnBi low-temperature solder joints
Soldering & Surface Mount Technology ( IF 1.7 ) Pub Date : 2021-11-01 , DOI: 10.1108/ssmt-08-2021-0052
Yang Liu ₁ , Yuxiong Xue ₁ , Min Zhou ₁ , Rongxing Cao ₁ , Xianghua Zeng ₁ , Hongxia Li ₁ , Shu Zheng ₁ , Shuang Zhang ₂

Affiliation

Purpose

The purpose of this paper is to investigate the effects of Sn-Ag-x leveling layers on the mechanical properties of SnBi solder joints. Four Sn-Ag-x (Sn-3.0Ag-0.5Cu, Sn-0.3Ag-0.7Cu, Sn-0.3Ag-0.7Cu-0.5 Bi-0.05Ni and Sn-3.0Ag-3.0 Bi-3.0In) leveling layers were coated on Cu pads to prepare SnBi/Sn-Ag-x/Cu solder joints. The microstructure, hardness, shear strength and fracture morphology of solder joints before and after aging were studied.

Design/methodology/approach

The interfacial brittleness of the SnBi low-temperature solder joint is a key problem affecting its reliability. The purpose of this study is to improve the mechanical properties of the SnBi solder joint.

Findings

Owing to the addition of the leveling layers, the grain size of the ß-Sn phase in the SnBi/Sn-Ag-x/Cu solder joint is significantly larger than that in the SnBi/Cu eutectic solder joint. Meanwhile, the hardness of the solder bulk in the SnBi/Cu solder joint shows a decrease trend because of the addition of the leveling layers. The SnBi/Cu solder joint shows obvious strength drop and interfacial brittle fracture after aging. Through the addition of the Sn-Ag-x layers, the brittle failure caused by aging is effectively suppressed. In addition, the Sn-Ag-x leveling layers improve the shear strength of the SnBi/Cu solder joint after aging. Among them, the SnBi/SACBN/Cu solder joint shows the highest shear strength.

Originality/value

This work suppresses the interfacial brittleness of the SnBi/Cu solder joint after isothermal aging by adding Sn-Ag-x leveling layers on the Cu pads. It provides a way to improve the mechanical performances of the SnBi solder joint.

中文翻译：

Sn-Ag-x整平层对SnBi低温焊点组织和力学性能的影响

目的

本文的目的是研究 Sn-Ag-x 整平层对 SnBi 焊点机械性能的影响。四个 Sn-Ag-x（Sn-3.0Ag-0.5Cu、Sn-0.3Ag-0.7Cu、Sn-0.3Ag-0.7Cu-0.5 Bi-0.05Ni 和 Sn-3.0Ag-3.0 Bi-3.0In）整平层将其涂在铜焊盘上以制备 SnBi/Sn-Ag-x/Cu 焊点。研究了时效前后焊点的显微组织、硬度、剪切强度和断裂形貌。

设计/方法/方法

SnBi低温焊点的界面脆性是影响其可靠性的关键问题。本研究的目的是提高 SnBi 焊点的机械性能。

发现

由于添加了整平层，SnBi/Sn-Ag-x/Cu 焊点中 ß-Sn 相的晶粒尺寸明显大于 SnBi/Cu 共晶焊点中的晶粒尺寸。同时，SnBi/Cu 焊点中焊料块的硬度由于整平层的增加而呈现下降趋势。SnBi/Cu焊点时效后出现明显的强度下降和界面脆性断裂。通过添加 Sn-Ag-x 层，有效抑制了时效引起的脆性破坏。此外，Sn-Ag-x 整平层提高了 SnBi/Cu 焊点在老化后的剪切强度。其中，SnBi/SACBN/Cu 焊点的剪切强度最高。