Quantitative metallography of β-Sn dendrites in Sn-3.8Ag-0.7Cu ball grid array solder balls via electron backscatter diffraction and polarized light microscopy

Document Type

Conference Proceeding

Publication Date



Electron backscatter diffraction and polarized light microscopy have been used to quantify the number of crystallographically independent β-Sn dendrites present in near-eutectic, ball grid array Sn-Ag-Cu (SAC) solder balls as a function of cooling rate (0.35-3.0°C/s). Based on these data, it is estimated that a single 900-μm-diameter solder ball contains on average eight individual β-Sn dendrites, independent of cooling rate. Specific orientation relationships were also found to be prevalent between neighboring β-Sn dendrites. These results confirm and expand upon recent research, and further emphasize the probable anisotropic nature of SAC solder joints.

Publication Title

Journal of Electronic Materials