微观压痕法测量Sn-Ag-Cu系无铅钎料的力学性能

Measurement of mechanical properties of Sn-Ag-Cu series lead-free solder alloy by using micro-indentation

Sn-Ag-Cu系合金是最有可能替代Sn-Pb钎料的无铅钎料。介绍了一种测量其力学性能的新方法,即通过微压痕仪精确测量不同加载速率下压子的压入深度h与加载载荷F的关系来确定钎料的弹性模量E和蠕变速率敏感指数m。结果表明加载速率对钎料蠕变压痕F-h曲线和压入深度有着重要的影响;OliverPharr方法确定的钎料弹性模量取决于卸载过程而与加载速率无关。基于压痕做功概念定义了压痕蠕变硬度和蠕变应变速率,从而给出钎料的蠕变速率敏感指数。Sn3.5Ag0.75Cu与Sn3.0Ag0.5Cu钎料蠕变压痕测试表明合金成分影响SnAgCu系无铅钎料的力学性能。

Sn-Ag-Cu series alloy is considered as the lead-free alternative to lead-tin alloys. A new method was introduced to measure the mechanical properties, i.e. modulus of elasticity and creep strain rate sensitivity by using depth-sensing micro-indentation with the influence of loading rates on load—displacement (Fh) relationship. The resulting indentation Fh curves are loading-rate-dependent and have varying creep penetration depths during the same hold time. The derived modulus of elasticity values with Oliver-Pharr method from unloading curves are loading rate-independent. The creep strain rate sensitivity can be determined from the relationship between the creep hardness and creep strain rate by the definition of “work of indentation”. Also, micro-indentation tests on two Sn-~3.5 Ag-0.75Cu and Sn-3.0Ag-0.5Cu lead-free solder alloys show a slight influence of alloy composition on mechanical properties for Sn-Ag-Cu series solder.