Copper filled polyurethane based electrically conductive adhesive with improved mechanical strength

Generally, epoxy based silver (Ag) filled electrically conductive adhesive (ECA) is the most commonly found commercial ECA products in the market, but the main drawbacks for Ag is being relatively expensive. Thermosetting polyurethane material is a very promising candidate for practical applications in the field of electro-optics and photonics as the cross-linked films have normally good adhesion and proper mechanical performance. In this study, electrical and mechanical properties of a copper (Cu) filled polyurethane resin based ECA was investigated. Mechanical property of the ECA was evaluated through shear strength joint of the ECA with Cu specimens, whereas electrical property of the ECA was evaluated by using a standard four-point probe method. The effects of diethyl carbitol and tripropylamine on the electrical and mechanical properties of the ECA were investigated. Significant difference could be observed in electrical resistivity and shear strength joint of ECA with different amount of diethyl carbitol. However, only slight difference in electrical resistivity could be observed for ECAs prepared with tripropylamine. A considerably low electrical resistivity at a magnitude order of 10^-3 Ω.cm with relatively high shear strength joint (above 17 MPa) of the ECA was achieved.