3D electronic packaging development Investigation of low temperature hybrid bonding Au passivation layer Fine grain Cu bonding Analysis the microstructure and phase composition by SEM, EDS and TEM Void morphology evolution ▲ Thermal compression bonding by heating press Analyzing the voids along the Cu-to-Cu bonding interface and confirm the effects of temperature and pressure Investigation of low temperature hybrid bonding : Fine grain Cu bonding ▲ Analysis of grain orienta