期刊
MATERIALS
卷 15, 期 11, 页码 -出版社
MDPI
DOI: 10.3390/ma15113932
关键词
laser drilling; ultrashort pulse (USP) laser; printed circuit board (PCB); heat accumulation; pulse to pulse interactions; microvia; ablation threshold; materialography
类别
资金
- Free State of Bavaria thru project LEZ@THAB [H.2-F1116.AS/34/2]
- DFG project ultrashort pulsed lasers [671/39-1]
In this study, a comprehensive investigation on laser percussion microvia drilling of FR-4 printed circuit board material using ultrashort pulse lasers is carried out. The effects of different laser parameters on the quality of microvias are analyzed, and the optimal conditions are identified.
We report on a comprehensive study of laser percussion microvia drilling of FR-4 printed circuit board material using ultrashort pulse lasers with emission in the green spectral region. Laser pulse durations in the pico- and femtosecond regime, laser pulse repetition rates up to 400 kHz and laser fluences up to 11.5 J/cm(2) are applied to optimize the quality of microvias, as being evaluated by the generated taper, the extension of glass fiber protrusions and damage of inner lying copper layers using materialography. The results are discussed in terms of the ablation threshold for FR-4 and copper, heat accumulation and pulse shielding effects as a result of pulse to pulse interactions. As a specific result, using a laser pulse duration of 2 ps appears beneficial, resulting in small glass fiber protrusions and high precision in the stopping process at inner copper layer. If laser pulse repetition rates larger than 100 kHz are applied, we find that the processing quality can be increased by heat accumulation effects.
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