Copper die bonding using copper formate based pastes with α-terpineol, amino-2-propanol and hexylamine as binders

Copper sintering is gaining prominence as a prospective alternative to silver sintering in die-attach applications. However, process temperatures and sintering times are still high compared to silver sintering and a challenge for large scale industrialization. In this paper, rapid and low temperature die-attach bonding using copper formate based inks is investigated. While these inks are successfully used to form metal traces on substrates by inkjet and aerosol printing, they reveal a substantial challenge for die-attach bonding. Based on results using polyethylene glycol (PEG) as binder, different pastes were realized and investigated using binders which form metal complexes with copper formate. Beside the promising result using PEG, best bonding results were obtained using α- terpineol as binder while traditional conductive ink binders amino-2-propanol and hexylamine caused challenges during pre-drying, degassing and in establishing a reliable interconnect.