Analysing the growth of intermetallic compounds in lead-free solder joints by differential scanning calorimetry measurements

摘要

The article in hand discusses the development of a method to determine the growth of intermetallic compounds by means of differential scanning calorimetry measurements, which can be used as an alternative method to the currently used long-term tempering of samples. 96.5Sn-3.0Ag-0.5Cu/Cu solder joints were tempered at 200 C and subsequently metallographically examined, and the growth of the copper-tin phases was determined. From the results of our experiments, we are able to calculate a growth rate constant, D, of 427 × 10 ~(-15) cm~2/s and identify a linear relationship between the growth of the intermetallic compounds and the enthalpy difference determined by calorimetric measurements before and after tempering. Based on the experimental results of the examined material set, the thickness of the solder joint's intermetallic compound can be calculated from the enthalpy difference of the calorimetrical examinations via the conversion factor 19.48 mJ/μm.