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Proceedings Paper

Analysis on resin removal in laser drilling of printed circuit board
Author(s): Satoru Noguchi; Etsuji Ohmura; Isamu Miyamoto
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Paper Abstract

On 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. The main conclusions are as follows: (1) Proportionality between latent heat of evaporation and absorptivity can be obtained using the experimental results of removal quantity when resin is thick enough. These values can be estimated simultaneously by comparing analytical results by FEM and experimental results. (2) An equation for rough estimate of maximum removal velocity was derived. (3) Removal quantity is proportional to the number of shots, but its proportionality is lost after layer thickness reaches to absorption length, yielding smear in practical use. Residual smear is caused by heat conduction to substrate during pulse. (4) Removal quantity depends on fluence most, but hardly depends on repetition rate. When resin thickness is larger than absorption length, removal quantity per pulse is proportional to fluence. (5) Removal velocity becomes larger with shorter pulse width. When resin thickness is smaller than absorption length, residual thickness increases as pulse width becomes long.

Paper Details

Date Published: 19 February 2003
PDF: 6 pages
Proc. SPIE 4830, Third International Symposium on Laser Precision Microfabrication, (19 February 2003); doi: 10.1117/12.499621
Show Author Affiliations
Satoru Noguchi, Osaka Univ. (Japan)
Etsuji Ohmura, Osaka Univ. (Japan)
Isamu Miyamoto, Osaka Univ. (Japan)

Published in SPIE Proceedings Vol. 4830:
Third International Symposium on Laser Precision Microfabrication
Isamu Miyamoto; Kojiro F. Kobayashi; Koji Sugioka; Reinhart Poprawe; Henry Helvajian, Editor(s)

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