Potential-assisted assembly of thiol-based materials for reliable copper-epoxy interface

Despite the fact that copper has continuously being used as leadframe materials in electronic packaging, adhesion strength between copper-epoxy joint is prone to be weaken during reliability test. In order to solve this problem, thiol-based self-assembled material (SAM) is applied as coupling agent between copper and epoxy system. A remarkable interfacial adhesion improvement was reported by different groups [1-2]. This work reports on adhesion enhancement effects of self-assembled organothiol treatment on copper/epoxy interface, as well as a significant reduction in treatment time under the influence of electric potential. The interfacial adhesion has a maximum enhancement of 20-fold through the treatment due to improved linkage between copper substrate and epoxy layer by chemisorbed organothiol molecules. The treatment time was greatly reduced by 32 times to 1800s with the proposed preparation method and maximum adhesion strength up to 97.2±6.1 Jm^-2 was demonstrated. The use of potential enhances preparation efficiency with adhesion improvement comparable to passive adsorption method make up in 16hrs.