Enhancing intense pulsed light sintering characteristic of Cu nanoparticle/microparticle-ink using ultraviolet surface modification on polyimide substrate

Abstract

The effect of ultraviolet (UV) surface modification on a polyimide (PI) substrate was investigated for the intense pulsed light (IPL) sintering of Cu nanoparticle (NP)/microparticle (MP)-ink. The UV surface-modification conditions, such as the wavelength range (UVA, UVB, and UVC) and irradiation intensity, were optimized to enhance the IPL sintering characteristic. To measure the surface roughness of the UV-modified PI substrate, atomic force microscopy was conducted. X-ray photoelectron spectroscopy and contact-angle analysis were performed for measuring the change in the surface functional groups of the PI substrate. The IPL irradiation conditions (pulse power and pulse duration) were optimized to obtain a high electrical conductivity and high adhesion strength. Scanning electron microscopy was performed to analyze the microstructure of the IPL-sintered Cu NP/MP-ink. Laser flash analysis was used to measure the thermal conductivity of the sintered Cu NP/MP-ink on the PI substrate. Additionally, in situ temperature monitoring was conducted to monitor the IPL sintering process in real time. According to the results, the optimal IPL-sintered Cu NP/MP-ink film with UVC modification exhibited a low resistivity of 5.94 μΩ cm and a high adhesion strength level of 5B.