Characterization and failure mode analyses of air plasma oxidized PDMS–PDMS bonding by peel testing

Abstract

Bonding of air plasma oxidized polydimethylsiloxane (PDMS) strips is evaluated in this paper by peel testing. Two PDMS–PDMS strips, after being treated with air plasma, were brought together for bonding into a specimen, which was subsequently subjected to peeling until breaking apart. The maximum load applied in each peel test was used to indicate the bonding strength. Among the 68 specimens tested, 40 experienced a maximum load in the range of 0.1–0.2 N mm⁻¹. Seventy-six percent of the specimens under peel testing failed at the cohesive mode, meaning that the air plasma-based bonding can be strong enough to retain its integrity after peeling. Correlation between the maximum load and failure modes suggests that strong bonding can be achieved with a higher plasma power for 50–60 seconds of treatment in air plasma. Based on the Kendall energy balance equation, we suggest that the higher the maximum load per unit width applied in the peel test, the larger the adhesion energy in the bonding interface.