TY - JOUR
T1 - Drilling of micron-scale high aspect ratio holes with ultra-short pulsed lasers
T2 - critical effects of focusing lenses and fluence on the resulting holes’ morphology
AU - Nasrollahi, Vahid
AU - Penchev, Pavel
AU - Jwad, Tahseen
AU - Dimov, Stefan
AU - Kim, Kyunghan
AU - Im, Changmin
PY - 2018/11
Y1 - 2018/11
N2 - Micro drilling employing ultra-short pulsed lasers is a promising manufacturing technology for producing high aspect ratio holes, particularly on ceramic substrates due to the growing range of application in electronic industry. Controlling the morphology and quality of the holes is an important factor in fulfilling the requirements of such applications. In this research, the effects of a wide fluence spectrum associated with the use of femto-second lasers on achievable aspect ratios were investigated by employing lenses with different focal distances. The holes’ morphology and quality were analysed utilising a high resolution X-ray tomography (XCT). It was demonstrated that the achievable aspect ratio can be increased from 3 to 25 just by varying the lenses focal distances. In addition, the quality of produced holes in terms of taper angle and cylindricity was investigated and the results showed that the quality would be improved by increasing the fluence and/or decreasing the focal distance. At the same time, the limitations of drilling holes with low focal distance lenses were discussed, i.e. sensitivity to defocusing and increased risks of recast formations inside the holes and bending effects, that should be considered in designing processes for high aspect ratio percussion drilling.
AB - Micro drilling employing ultra-short pulsed lasers is a promising manufacturing technology for producing high aspect ratio holes, particularly on ceramic substrates due to the growing range of application in electronic industry. Controlling the morphology and quality of the holes is an important factor in fulfilling the requirements of such applications. In this research, the effects of a wide fluence spectrum associated with the use of femto-second lasers on achievable aspect ratios were investigated by employing lenses with different focal distances. The holes’ morphology and quality were analysed utilising a high resolution X-ray tomography (XCT). It was demonstrated that the achievable aspect ratio can be increased from 3 to 25 just by varying the lenses focal distances. In addition, the quality of produced holes in terms of taper angle and cylindricity was investigated and the results showed that the quality would be improved by increasing the fluence and/or decreasing the focal distance. At the same time, the limitations of drilling holes with low focal distance lenses were discussed, i.e. sensitivity to defocusing and increased risks of recast formations inside the holes and bending effects, that should be considered in designing processes for high aspect ratio percussion drilling.
KW - Laser microdrilling
KW - hole morphology
KW - high aspect ratio holes
KW - focusing lenses
U2 - 10.1016/j.optlaseng.2018.04.024
DO - 10.1016/j.optlaseng.2018.04.024
M3 - Article
SN - 0143-8166
VL - 110
SP - 315
EP - 322
JO - Optics and Lasers in Engineering
JF - Optics and Lasers in Engineering
ER -