Challenges in joining conductive adhesives in structural application – Effects of tolerances and temperature

Abstract

Our investigations evaluate the usage of an electrically conductive adhesive facing the challenges of structural application when at the same time antistatic electrical properties are important. Structural adhesive joints typically have the characteristic of an electrical insulation between the adherends. To overcome this issue we incorporated 20wt% electrically conductive graphene nano-platelets in an epoxy resin, to achieve an electrically conductive adhesive composite. Under unloaded condition the investigated composite joint provides shear strength of 11.4MPa and a volume resistivity of 8.5×104Ωcm.In summary following observations are identified: Electrically conductive adhesive composite joints are able to meet structural requirements at a temperature within the structural application range even if tolerances up to 1mm need to be compensate. The volume resistivity of the joints is sensitive to elongation. Suppression of the load-dependent elongation by thin adhesive layer benefits the conductive robustness of the joint. If a high displacement is important, a thick adhesive layer enhances the ability of an undamaged shift of the conductive particle network by an increased deformability.