Plasma Diagnostics Using CO2 Laser Absorption and Interferometry

1972 ◽  
Vol 43 (2) ◽  
pp. 574-577 ◽  
Author(s):  
A. A. Offenberger ◽  
R. D. Kerr ◽  
P. R. Smy
Keyword(s):  
Co2 Laser ◽  
Plasma Diagnostics ◽  
Laser Absorption

Optoacoustic cross-section measurements for ir pulses: CO2 laser absorption by CF3I

1981 ◽  
Vol 24 (4) ◽  
pp. 363-368 ◽  
Author(s):  
J. M. Weulersse ◽  
R. Genier
Keyword(s):  
Cross Section ◽  
Co2 Laser ◽  
Laser Absorption

Cu-Direct Via-Hole Drilling of Aramid Fiber Reinforced Build-Up Layer by CO2 Laser Beam

2005 ◽  
Author(s):  
Eiichi Aoyama ◽  
Toshiki Hirogaki ◽  
Keiji Ogawa ◽  
Nobuyuki Doi ◽  
Ryu Minagi
Keyword(s):  
Co2 Laser ◽  
Copper Foil ◽  
Effective Means ◽  
Hole Diameter ◽  
Hole Drilling ◽  
Printed Wiring Boards ◽  
Laser Absorption ◽  
Direct Laser ◽  
Via Hole ◽  
The Difference

This report describes the features of Cu-direct laser drilled hole quality on multi-layer Printed Wiring Boards (PWBs). Cu-direct laser drilling drills the outer copper foil and build-up layer at the same time, which makes it difficult to form a blind via hole (BVH) with high quality because the copper foil has high reflection coefficient for a CO2 laser with wavelength 10.6 μm. Therefore, this study focused on improving drilled hole qualities such as diameter and overhang. First, the influence of laser irradiation conditions on forming BVH and the drilled hole diameter were investigated in detail. Second, a new method employing thermography was proposed in order to evaluate the absorption of copper foil after surface treatment. Third, the effect of mixing fillers into the build-up layer in order to reduce the amount of overhang was shown to be effective both experimentally and theoretically. As a result, it is clear that decreasing the difference in the laser absorption rate of the outer copper foil is an effective means to control the hole diameter and reducing the heat characteristic difference between the outer copper foil and the build-up layer can effectively decrease overhang.

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