In-Situ Resistance Characterization During Cure Progression For Electrically Conductive Adhesives
Authors: Geoff Rivers, Pearl Lee-Sullivan, Boxin Zhao, Alex Chen, John Persic and Robert Lyn Company: University of Waterloo, Celestica Inc., and Microbonds Inc. Date Published: 7/1/2017
Abstract: Alternatives A new approach has 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 forms an increasingly connected network of conductive fillers. 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, a distinct behavior during the final stages of cure has been observed for the first time: 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.