プリント基板におけるCuダイレクトバイアホールレーザ加工に関する研究 : シリカフィラー添加基板のオーバーハング抑制効果(機械要素,潤滑,設計,生産加工,生産システムなど)

概要

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In recent years, electric devices have rapidly advanced in high performance and miniaturization. As a result, electric circuits on Printed Wiring Boards (PWBs) are becoming high-density and its layers are increasing more and more. Therefore, micro-via drilling technology using a laser has become the dominant method for drilling blind via-holes (BVHs). Cu-direct laser drilling has attracted attention as a new method. However, there are few reports dealing with Cu-direct laser drilling of PWBs. Especially, when the copper and the resin with a different processing threshold are drilled at the same time, a defect of the overhang occurs on the drilled hole. However, the overhang generation mechanism has not been clear. Therefore, we investigated the overhang generation mechanism by observation of drilled hole section in detail. Moreover, we estimated the influence of thermal conductivity of the build-up layer on the overhang length using finite element method (FEM). As a result, it was shown that the overhang length becomes smaller with thermal conductivity of the build-up layer increasing. Therefore, we carried out an experiment with prototype PWBs silica filler mixed in the build-up layer. Using the prototype PWBs, it was shown that overhang could be reduced as shown in FEM analysis results.
社団法人日本機械学会の論文
2009-11-25