The formation of intermetallic compound (IMC) layer at the interfaces of pad finishes has been studied.
The growth of IMC layer as a reflow process and its properties were also discussed. In this study, solder
alloy SAC237 (Sn: 99 wt.%, Ag: 0.3 wt.%, Cu: 0.7 wt.%), reinforced with 0.01 wt.% Multi-Walled
Carbon Nanotubes (MWCNTs), was mixed to form a composite solder paste and soldered on Electroless
Nickel Immersion Gold (ENIG) and Immersion Tin (ImSn) pad finishes. Reflow process was conducted
in oven with specific reflow profile. The growth and properties of IMC layer were analysed using optical
microscope with image analyser. Results showed that the thickness of IMC layer for ENIG and ImSn
were 1.49 and 2.51 µm, respectively. Floating IMC and voids within the solder bulk and IMC layer
were also identified in the samples. In addition, the measured wetting angle for ENIG and ImSn were
16.21° and 34.32°, respectively.