| Co-Investigator(Kenkyū-buntansha) |
TAKENO Shozui Mitsubishi Electric Co., Production Technology Center (researcher), 生産技術センター, 研究員
SANO Tomokazu Osaka University, Institute of Laser Engineering, Assistant Professor, 大学院・工学研究科, 助手 (30314371)
OHMURA Etsuji Osaka University, Graduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (90144435)
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| Research Abstract |
Purpose of this study is to develop an innovative system for precision micro-processing with short pulse laser or short wavelength laser for further development of IT devices. The investigated results are reported here on the following subjects; (1) molecular dynamics analysis of laser ablation, (2) analysis on resin removal in laser drilling of printed circuit board, and (3) analysis of conversion efficiency and beam profile in second harmonic generation. Main results obtained are summarized as follows: (1) Applying the modified molecular dynamics method that Ohmura who is one of the members has developed, ablation phenomena of aluminum with picosecond pulse laser irradiation whose intensity is Gaussian distribution was analyzed. As a result, it was revealed that there are two types in ablation process. One is explosive ablation, which occurs by ultrashort pulse irradiation. The other is calm ablation, which occurs by relatively long pulse irradiation. Scattering angle and scattering velocity of ablation particles, their size and number, energy per ablation atom and ablation energy depend on the ablation types deeply. (2) About laser drilling of printed circuit board, one-dimensional non-steady heat conduction problem of two-layers composed of resin and metal was analyzed with the finite element method (FEM), considering resinous evaporation. Validity of analysis method was verified by comparing with experimental results. (3) Temperature dependence of conversion efficiency and output-beam profile were examined theoretically by solving the coupling problem composed of heat conduction equation and complex amplitude equations. The latter equations were derived by Ohmura, considering laser absorption in the crystal. Effect of temperature control was also investigated quantitatively, supposing KH2PO4 (KDP) which is a negative uniaxial crystal.
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