Thermal stability at the anisotropic conductive films (ACFs)/ organic solderability preservatives (OSPs) Interface

Failure surface analysis by SEM and XPS showed that OSP layers disappeared after heat treatment above 240degC. Furthermore, FT-IR analyses of OSP layer showed that C=N bonding strength became stronger after heat treatment, and it was considered that Cu-N coordinate bonds that form the OSP layers were broken. Considering that the OSP layer remained after ACF bonding and OSP layer was weakness after heat treatment above 240degC, interface between the ACFs and OSP treated Cu has a weakness for high temperature environment above 240degC. Finally, in application to OSP finished rigid substrates-flexible substrates system, ACFs/OSP finished Cu electrodes interface was major failure site after heat treatment above 240degC.