High Adhesive Force between Laminated Sheets of Copper and Polyurethane Improved by Homogeneous Low Energy Electron Beam Irradiation (HLEBI) Prior to Hot-Press

抄録

2-layer copper/polyurethane (Cu/PU) laminated sheets were prepared by a new adhesion method, a double-step treatment consisting of applying low dose (≦0.43 MGy) homogeneous low energy electron beam irradiation (HLEBI) prior to hot-press under 5 MPa and 413 K. Although the weak hot-press adhesion of the Cu/PU was observed without HLEBI, the new adhesion raised the bonding forces as evidenced by the mean adhesive forces of peeling resistance (^oF_p). Based on the 3-parameter Weibull equation, the lowest ^oF_p value at peeling probability (P_p) of zero (F_s) could be estimated. An increasing trend in F_s occurred by the double-step treatment applying HLEBI up to 0.13 MGy reaching a maximum at 27.1 Nm⁻¹, improving the safety level without radiation damage. When HLEBI cut the chemical bonds in PU polymer and generated terminated atoms with dangling bonds, they probably induced the chemical bonding and intermolecular coulomb attractive forces. Therefore, increasing adhesion force between the laminated sheets could be explained.