Study on IMC morphology and impact to solder joint performance for different halogen free (HF) flux in semiconductor application

With increased social governance awareness on the usage of halogen products, studies on halogen free (HF) products as replacements are now becoming highly important among semiconductor industry players as well as researchers. In this study, IMC morphology of SAC305 on NiP substrate was used to study or compare the performance for different HF fluxes and halogenated flux candidates. On top of this, the activator used within the flux candidates is also being identified in order to understand the impact on fluxing capability towards the oxides layer removal. The study was focussed on wetting performance of the SAC305 interacting with different fluxes candidates on NiP substrate was on the impact to solder joint strength. Ball shear test and ball pull test were conducted to validate the strength of solder joint developed through the use of various fluxes. In summary, the selected water soluble HF flux provides good solder joint in general than the other HF flux candidates. Comparing IMC morphology among all flux candidates, it is concluded that high angle within IMC layers plays an essential role in ensuring good solder joint as well as the contribution of scallope shape IMC and the present of small Ag3Sn along IMC layer in solder joint strengthening.