Chinese Journal of Lasers, Volume. 47, Issue 12, 1202008(2020)
Techniques for Femtosecond Laser Processing of Micro-Holes in FR-4 Copper Clad Laminate
Figures & Tables(19)
Fig. 1. Basic processes and time scales of interaction between femtosecond laser and metal materials
Fig. 3. Effect of single pulse energy on inlet diameter, outlet diameter and taper of micro-hole
Fig. 4. Inlet and outlet SEM images under different single pulse energies. (a) 5μJ; (b) 30μJ
Fig. 5. Effect of repetition rate on inlet diameter, outlet diameter and taper of micro-hole
Fig. 6. Local inlet SEM images under different repetition rates. (a) 80kHz; (b) 160kHz
Fig. 7. Effect of number of pulses on inlet diameter, outlet diameter and taper of micro-hole
Fig. 9. Locally enlarged inlet images under different numbers of pulses. (a) 1000; (b) 3000
Fig. 10. Effect of defocusing amount on inlet diameter, outlet diameter and taper of micro-hole
Fig. 11. Roundness of micro-hole under different defocusing amounts. (a) -0.05mm; (b) 0.05mm
Fig. 12. Schematic of traditional PCB board circuit. (a) Overall circuit; (b) local circuit
Fig. 13. Processing pictures. (a) Processing window; (b) micro-hole inlet morphology; (c) micro-hole outlet morphology
Table 1. Main performance parameters of femtosecond laser
View tableTable 1. Main performance parameters of femtosecond laser
Parameter Power Wavelength Pulse duration Frequency Single pulse energy Focus spot diameter Content 6W 1030nm /532nm 255fs-20ps 1MHz 2mJ 18μm
Table 2. Element arrangement and results of single factor test
View tableTable 2. Element arrangement and results of single factor test
Serial No. Single pulse energy /μJ Repetition rate /kHz Number of pulses Defocusing amount /mm Inlet diameter/μm Outlet diameter /μm Taper/ (°) 1 5 40 2000 0 10.56 9.23 0.25 2 10 40 2000 0 11.74 10.92 0.23 3 20 40 2000 0 17.39 16.21 0.21 4 30 40 2000 0 18.16 17.53 0.12 5 40 40 2000 0 22.30 21.94 0.07 Serial
No.Single pulse
energy /μJRepetition
rate /kHzNumber of
pulsesDefocusing
amount /mmInlet
diameter /μmOutlet
diameter /μmTaper/
(°)6 20 10 2000 0 16.33 15.15 0.23 7 20 80 2000 0 17.95 16.89 0.20 8 20 120 2000 0 18.23 17.37 0.16 9 20 160 2000 0 18.89 17.65 0.14 10 20 40 1000 0 16.03 15.01 0.19 11 20 40 1500 0 17.32 16.24 0.20 12 20 40 2500 0 17.45 16.27 0.23 13 20 40 3000 0 17.76 16.42 0.26 14 20 40 2000 -0.050 16.22 14.62 0.31 15 20 40 2000 -0.025 14.98 13.58 0.26 16 20 40 2000 0.025 19.46 18.16 0.24 17 20 40 2000 0.050 20.22 18.72 0.29
Table 3. Factor levels
View tableTable 3. Factor levels
Level Single pulse energy /μJ Repetition rate /kHz Number of pulses Defocusing amount /mm 1 15 40 1200 0 2 22 66 1646 0.01 3 29 92 2112 0.02 4 35 120 2200 0.04
Table 4. Element arrangement and results of orthogonal test
View tableTable 4. Element arrangement and results of orthogonal test
Serial No. Level Inlet diameter/ μm Outlet diameter/ μm Taper/ (°) A B C D 1 1 1 1 1 12.83 -- -- 2 1 2 2 2 17.87 6.37 2.19 3 1 3 3 3 18.21 11.59 1.26 4 1 4 4 4 12.38 11.24 0.22 5 2 1 2 3 16.81 12.03 0.91 6 2 2 1 4 17.56 15.49 0.40 7 2 3 4 1 17.74 15.57 0.42 8 2 4 3 2 18.87 18.23 0.12 9 3 1 3 4 17.17 13.36 0.73 10 3 2 4 3 18.42 17.88 0.10 11 3 3 1 2 19.16 17.68 0.24 12 3 4 2 1 16.16 14.03 0.41 13 4 1 4 2 16.17 14.51 0.32 14 4 2 3 1 18.57 16.23 0.45 15 4 3 2 4 20.08 18.92 0.22 16 4 4 1 3 15.36 13.97 0.27
Table 5. Range analysis
View tableTable 5. Range analysis
Item Average Single pulse energy /mW Repetition rate/kHz Number of pulses Defocusing amount /mm Inlet diameter k1 15.323 15.745 16.228 16.325 k2 17.745 18.105 17.730 18.018 k3 17.728 18.798 18.205 17.200 k4 17.545 15.693 16.178 16.798 Range 2.422 3.105 2.027 1.693 Item Average Single pulse
energy /mWRepetition
rate/kHzNumber of
pulsesDefocusing
amount /mmOutlet diameter k1 7.300 9.975 11.835 11.458 k2 15.330 13.993 12.834 14.248 k3 15.788 15.990 14.852 13.868 k4 15.908 14.368 14.800 14.753 Range 8.608 6.015 3.017 3.173 Taper k1 0.918 0.490 0.223 0.228 k2 0.463 0.785 0.933 0.718 k3 0.370 0.535 0.640 0.635 k4 0.315 0.255 0.265 0.393 Range 0.603 0.530 0.710 0.490
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Guo Minchao, Wang Mingdi, Zhang Shengjiang, Lin Yao, Wang Xinyue, Yin Zihang, Wang Xianbao. Techniques for Femtosecond Laser Processing of Micro-Holes in FR-4 Copper Clad Laminate[J]. Chinese Journal of Lasers, 2020, 47(12): 1202008
Paper Information
Category: laser manufacturing
Received: Aug. 12, 2020
Accepted: --
Published Online: Dec. 3, 2020
The Author Email: Wang Mingdi (wangmingdi@suda.edu.cn)
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