A study to reduce the substrate warpage on flash light sintering for copper nanoparticles

A study to reduce the substrate warpage on flash light sintering for copper nanoparticles was investigated. In order to minimize the substrate warpage, two-step flash light sintering method was performed. The flash light sintering process was divided into a preheating step and a main sintering step. To find the optimum sintering conditions of copper nanoparticles, the flash light conditions (irradiation energy, pulse number, on-time and off-time) was varied. The microstructures and transformation crystal phase of the sintered copper nanofilms were analyzed by scanning electron microscopy. In addition, the sheet resistance was measured using a four-point probe method. Also, the thickness of copper nanofilms was measured by alpha-step. From these results, it is found that the flash light sintered copper nanofilms have a low resistivity without any damage to the thin polyimide substrate.This work was supported by a National Research Foundation of Korea (NRF), funded by the Ministry of Education (Nos. 2012R1A6A1029029). This workwas also supported by the Technology Innovation Program (or Industrial Strategic technology development program, 10048913, Development ofthe cheap nano-ink which is sintered in the air for smart devices) funded By the Ministry of Trade, industry & Energy(MI, Korea). Also, we would liketo acknowledge the financial support from the R&D Convergence Program of MSIP (Ministry of Science, ICT and Future Planning) and ISTK (Korea Research Council for Industrial Science and Technology) of Republic of Korea (Grant B551179-13-02-05)