Journal of SMT Article
Influence of Microalloying Elements on Reliability of SnAgCu Solder Joints
Company: Universal Instruments Corporation, Binghamton University, and Alcatel-Lucent
Date Published: 4/1/2016 Volume: 29-2
Thus various commercial solders alloys with microalloying elements, such as SN100C, SACM and Innolot, were examined and compared to observations for SAC105, SAC 305 and eutectic SnPb alloys. Both mechanical and thermal cycling tests were performed on solder joints assembled on Cu-OSP or ENIG. The thermal history of each individual solder joint was carefully controlled and monitored by differential scanning calorimeter. Thus the effects of varying reflow parameters on the mechanical behavior in shear and shear fatigue test were analyzed. ATC reliability test was conducted on BGA components using a -40/125°C profile.
Careful microstructural analysis was performed on as reflowed and failed samples. Polarized light microscopy and electron backscatter diffraction techniques were used to assess the effect of Sn grain morphology on life time of solder joints, particularly on early and late failures. The effect of variation in solder volume, composition, Sn grain morphology and PCB surface finish on solder joint microstructure and lifetime was carefully evaluated.
Sn Grain Morphology, ATC, PCB Surface Finish, LGA, Thermal Fatigue, Pb-free, Microalloying
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