IN-SITU RESISTANCE CHARACTERIZATION DURING CURE PROGRESSION OF A CONDUCTIVE ADHESIVE

摘要

Methodology and equipment have been developed for in-situ characterization of electrical resistance of thermosetting conductive adhesives during the cure process. It has long been known that conductive adhesives have poor conductivity while in their uncured state, and develop conductivity as the polymer cures and allows the establishment of a conductive filler network. In this paper, we will present a novel method for obtaining sheet resistance measurements of a conductive thermosetting composite under controlled heating conditions, during the crosslinking process. In-situ resistance measurements are compared with calorimetry performed under the same heating conditions, allowing direct correlation. As a result, unexpected and previously unreported behavior during the final stages of cure has been identified: a significant and temporary increase in electrical resistance mid-cure, after the resistance has begun decreasing, contrary to the power-law reduction as cure progresses. The dynamics of this process, and the final adhesive properties, are not yet understood. As such, this new in-situ technique will be instrumental for ongoing work to improve the conductivity of adhesives at lower filler contents and costs.