結像光学系の回折を考慮したプリント基板レーザ穴あけの樹脂除去解析

概要

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Two-dimensional axisymmetric non-steady heat conduction was analyzed considering the laser diffraction in the image formation optical system and resinous evaporation. The validity of analysis was confirmed comparing with the experimental results. Main results obtained are as follows : (1) When the resin is relatively thick, the shape of via hole reflects the laser intensity distribution because the thermal conductivity of resin is not so large. (2) As the thickness of remained resin becomes thinner than the absorption length of resin by repetitive irradiation, the removal quantity rapidly decreases and the smear remains on the substrate. (3) Less the removal quantity, less the reflection of the laser intensity distribution to the bottom shape of via hole although the side angle of via hole hardly changes. (4) Two- or three-dimensional non-steady heat conduction analysis considering the diffraction of the optical system is necessary for estimating the shape of via hole. (5) The one-dimensional analysis proposed in the previous paper is useful enough to estimate the removal depth although the removal depth by the second shot would be a little deeper than expected because heat is transferred in the radial direction.
社団法人精密工学会の論文
2005-10-05