In-situ electron backscatter diffraction of thermal cycling in a single grain Cu/Sn-3Ag-0.5Cu/Cu solder joint

TL;DR

This study uses in-situ electron backscatter diffraction to analyze microstructural evolution and deformation mechanisms in a single Cu/Sn-3Ag-0.5Cu/Cu solder joint during thermal cycling, revealing localized lattice rotations and slip system activation.

Contribution

It introduces in-situ EBSD to observe microstructural changes and deformation mechanisms in a solder joint under thermal cycling, highlighting heterogeneity and slip system activity.

Findings

Heterogeneous lattice rotation localized at joint corners.

Formation of subgrains with increasing misorientation.

Activation of specific slip systems during deformation.

Abstract

The heterogeneous evolution of microstructure in a single Cu/SAC305/Cu solder joint is investigated using in-situ thermal cycling combined with electron backscatter diffraction (EBSD). Local deformation due to thermal expansion mismatch results in heterogeneous lattice rotation, localised towards the corners of the joint and decreases towards the centre of the joint. This deformation is induced by the constraint from the CTE between the \b{eta}-Sn, Cu6Sn5 and Cu at interfaces. The formation of subgrains with continuous increase in misorientation is revealed during deformation, implying the accumulation of plastic slip at the strain-localised regions and the activation of slip systems (1-10)[111]/2 and (11-0)[111]/2.