Searching for new Sn-Ag-Cu based lead free solders with low melting temperature using a thermodynamic modeling method

AIM焊料是一家总部位于蒙特利尔的公司，是电子行业锡铅和无铅焊料组装材料的全球领先制造商，该公司对无铅焊料的发展有着浓厚的兴趣。焊料在材料工业中扮演着重要角色，尤其是在电子封装应用中[1，2]。铅是锡基焊料中的传统合金元素，但对人体有害。因此，在世界上最重要的市场(美国、中国、欧盟和日本)，新的法律已经实施，禁止使用含铅焊料。因此，发展无铅焊料势在必行。目前商用的无铅焊料主要是以锡为基础，加入多种合金元素(银、铜、铋、镍、锌、锑等)。锡-银-铜合金(如SAC305)是最常用的无铅焊料。然而，与Sb-Pb焊料相比，锡-银-铜基合金的主要问题是其第一次熔化温度(称为共晶温度)较高。目的焊料需要我们团队的协助来解决这个问题，并找到具有较低共晶温度的锡-银-铜-X-Y多元合金。 本项目的目标是在5个月的时间内，以有效和可操作的方式，寻找和设计新的低共晶温度的锡-银-铜基焊料。

AIM Solders is a Montreal-based company leading the global manufacturing of tin-lead and lead-free solders assembly materials for the electronics industry, which has a strong interest for the lead-free solders development. Solders play an important role in the materials industry especially in the electronic packaging applications [1, 2]. Lead (Pb) is the traditional alloying element in Sn-based solders, but is harmful to human health. So in the most important markets of the world (USA, China, EU, and Japan), new laws banning the use of Pb containing solders have been imposed. Therefore, the requirement of development lead-free solders is imperative. Current commercial lead-free solders are mainly based on Sn with several alloying elements (Ag, Cu, Bi, Ni, Zn, and Sb etc.). Sn-Ag-Cu alloys (like SAC305) are the most used lead-free solders. However, the main problem of Sn-Ag-Cu-based alloys is its relatively high first melting temperature (called eutectic temperature) in comparison with Sb-Pb solders. AIM Solders requires the assistance from our group to solve this problem and find compositions of Sn-Ag-Cu-X-Y multicomponent alloys with lower eutectic temperatures. The present project will be aimed at searching and designing new Sn-Ag-Cu-based solders with low eutectic temperature in an effective and operable way within a period of 5 months.