Comparison of Tensile and Fatigue Properties of Copper Thin Film Depending on Process Method

Abstract

In this study, tensile and fatigue tests were performed and analyzed to evaluate an influence of fabrication method on mechanical characteristics of copper thin film which widely used in flexible printed circuit board (FPCB). In general, manufacturing methods are known to affect the mechanical properties of materials, especially for thin films. The copper thin film is manufactured by a rolling process or an electrodeposition process. Therefore, specimen for tensile and fatigue tests were fabricated using by etching process with the rolled and electrodeposited thin films. First, the tensile tests were performed to obtain the elastic modulus, 0.2% offset yield stress, and tensile strength of the rolled copper and the electrodeposited copper thin film. Second, the copper thin films in FPCB is most often subjected to mechanical or/and thermal cyclic loading. The fatigue tests were performed to compare the fatigue characteristics and to evaluate an influence of fabrication method. Tensile test results showed that the elastic modulus was similar for each process, but the 0.2% yield strength and ultimate tensile strength were greater in the rolling process. In addition, the fatigue test results show that the copper thin films by the rolling process are better than by the electrodeposition process in fatigue life in all region.

Real-time dynamic behavior analysis of thin film during in-situ SEM tensile testing

“…In a previous study [ 29 ], we used a capacitance displacement sensor, one of the non-contact sensors, to measure the strain of thin film specimens. It can be obtained accurate data by the capacitance sensor which has high precision and resolution.…”

Finite Element Simulation of Solid–Liquid Interdiffusion Bonding Process: Understanding Process-Dependent Thermomechanical Stress

“…The yield stress values of electroplated Cu are reported to be in the range of 233±15 MPa [26]. It has also been found to depend on the processing conditions [27], structure, texture, grain size and temperature [28][29]. The yield stress for electroplated Cu has been found to decrease from ≈ 250 MPa at room temperature to < 100 MPa at 250 °C [29].…”

Numerical simulation of fatigue behavior of flexible metal films in multiphysics fields

“…The fatigue life of thin metal films with different thicknesses under cyclic mechanical loading has been studied. Min et al 16 investigated the effects of different process methods on tensile and fatigue properties of the copper thin film. Sim et al 17 carried out fatigue experiments on polymer‐supported Ag films and studied the effect of pre‐stretch, length scale, and strain range on the fatigue life of these films.…”