Volume 36, Issue 5 (September 2008)
Solderability Testing of Lead-Free Solder Joints Using Miniature Specimens
A new method for mechanical testing of lead-free solder joints solderability is presented. Copper blanks are soldered with a known thermal cycle. Miniature tensile solder joints specimens are produced in large numbers from the blanks having a gage section made of lead-free solder alloy with dimensions that represent actual solder joints. Mechanical properties of Sn-3.5Ag-0.7Cu in tension at room temperature and strain-rates between 2.8×10−4–2.7×10−1s−1 have been studied. It is concluded that the solder section of the miniature joints is the weakest link in this complex structure. It was also found that the experimental results for solder strength and strain-rate sensitivity are in partial agreement with data obtained using solder bulk specimens. The role of microstructure across the joint, especially intermetallic compounds along the copper/solder interface is also discussed.