Publication Date:
2016-07-15
Description:
Direct evidence of the relationship between the polymorphic phase transformation from monoclinic Cu 6 Sn 5 to hexagonal Cu 6 Sn 5 and stress accumulation/release in Cu 6 Sn 5 , formed at the interface between Sn-0.7Cu lead-free solder and their Cu substrates, has been obtained. To explore this challenging phenomenon, we developed an in situ heating/isothermal observation technique in ultrahigh-voltage transmission electron microscopy that enables the observation of thick samples (around 0.5 μ m) for solder joints, including Cu/Cu 3 Sn/Cu 6 Sn 5 /Sn-0.7Cu solder interfaces prepared by a focused ion beam milling technique. The results show evidence of stress creation and release events by imaging bend contours that may arise due to the polymorphic transformations of the Cu 6 Sn 5 phase and the associated volumetric change.
Print ISSN:
1047-4838
Electronic ISSN:
1543-1851
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
