In the big data era, Si chips are integrated more and more to satisfy the fast growing demand from customers. In addition, in the post-COVID-19 virus era, the trend of distance teaching and home office has increased greatly the need of advanced consumer electronic products. To provide more processing tolerance and to build a wider temperature window in manufacturing, it becomes necessary to develop low melting temperature solders because a hierarchy of solders is needed in the packaging technology. Much research has been on Pb-free and Sn-based solders with a melting point from 180 to 230 °C. In this review, we will concentrate on low melting point solder alloys with a melting point lower than 180 °C and even below 100 °C. We review eutectic SnBi, eutectic SnIn, and the alloys with trace addition of a third element to them. Eutectic Sn-Bi solder is too brittle, and Sn-In solder is too soft. However, third element addition can only improve the solder properties partially; thus, we will further review the properties of Sn-Bi-In ternary alloys and the effect on the addition of a fourth element to them. This approach, when we include the Cu substrate, becomes a 5-element system, which leads us to consider high entropy alloys for soldering. With these Sn-, Bi-, and In-based alloys, we hope to develop new ways to design industrial applicable low melting point solders.

在大数据时代，越来越多地集成了Si芯片，以满足客户快速增长的需求。此外，在后COVID-19病毒时代，远程教学和家庭办公的趋势大大增加了对高级消费电子产品的需求。为了提供更大的加工公差并在制造过程中建立更宽的温度范围，有必要开发低熔点的焊料，因为包装技术中需要焊料的层次结构。对于无铅和锡基焊料，其熔点从180到230°C，已有很多研究。在本文中，我们将重点研究熔点低于180°C甚至低于100°C的低熔点焊料合金。我们回顾了共晶SnBi，共晶SnIn以及向合金中添加微量元素的合金。共晶Sn-Bi焊料太脆，Sn-In焊料太软。但是，添加第三种元素只能部分改善焊接性能。因此，我们将进一步审查Sn-Bi-In三元合金的性能及其对添加第四元素的影响。当我们包括铜基板时，这种方法成为5元素体系，这使我们考虑使用高熵合金进行焊接。我们希望借助这些Sn，Bi和In基合金，开发出设计工业适用的低熔点焊料的新方法。成为由5种元素组成的系统，这使我们考虑使用高熵合金进行焊接。我们希望借助这些Sn，Bi和In基合金，开发出设计工业适用的低熔点焊料的新方法。成为由5种元素组成的系统，这使我们考虑使用高熵合金进行焊接。我们希望借助这些Sn，Bi和In基合金，开发出设计工业适用的低熔点焊料的新方法。