Differential scanning calorimetry (DSC) technique was employed to understand the interfacial reactions during soldering by simulating the soldering process as well as analyzing the interfacial reactions. The measurement of peak temperatures and heat
involved provides useful information about the interfacial reactions such as the amount of intermetallic compounds (IMC) formed and that of Cu dissolved. Sn-plated Cu balls with a different Sn thickness were used to investigate the solder volume effect. As the Sn layer thickness decreases, the amount of IMC formed during reflow increases in general. This suggests IMC formation depends on the Sn volume. In addition, a Ni layer (electroless and electroplated) introduced as a diffusion barrier between Cu and Sn was found effective in reducing Cu out diffusion. The results from the DSC study were confirmed by the conventional metallography and SEM/EDX techniques.
By: Won Kyoung Choi, Sung K. Kang, Da-Yuan Shih
Published in: RC22331 in 2002
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