Study on Micro-holes Processing of High Frequency Flexible Copper Clad Laminate Substrate via Femtosecond Laser
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摘要: 为解决目前激光加工挠性覆铜板(简称挠性板)微孔存在的加工精度差、孔型差及热损伤大等问题,探索了飞秒激光加工高频挠性板基材-改性聚酰亚胺(MPI)微孔的材料去除过程及其加工质量。采用飞秒激光进行了改性聚酰亚胺微孔加工实验,使用热重-红外联用系统分析了改性聚酰亚胺材料热解机理,并利用激光共聚焦显微镜、场发射扫描电镜对改性聚酰亚胺微孔形貌进行了三维测量、显微观察及物性分析。结果表明:改性聚酰亚胺在飞秒激光作用下发生光化学和光热反应,材料以宽而圆滑的弧形沟壑形式逐层被去除,并形成了波纹阶梯、颗粒物堆积等烧蚀显微结构;加工过程中材料烧蚀反应随加工圈数的增加而减弱;微孔深度的变化速率基本保持不变,材料去除量随加工圈数的增加而减小并在最后剧增;飞秒激光可实现改性聚酰亚胺基材表面高质量微孔加工。Abstract: In order to solve the poor processing accuracy, poor hole shape and large thermal damage in laser processing of micro-holes of flexible copper clad laminate (FCCL), the material removal process and processing quality of micro-holes in high frequency flexible copper clad laminate substrate modified polyimide (MPI) via femtosecond laser were explored. The experiment of MPI micro-holes processing via femtosecond laser was carried out. And the pyrolysis mechanism of MPI was analyzed by thermogravimetry infrared combined system. Then, laser confocal microscope and field emission scanning electron microscope are used to measure the micro-hole morphology. The results show that photochemical and photothermal reactions occur when the femtosecond laser act on the MPI substrate. And the MPI substrate was removed layer by layer in the form of wide and smooth arc gullies. Corrugated steps, particle accumulation, and other ablation microstructures were found in the material removal process. In the processing, the material ablation reaction decreased with the increasing of number of machining cycles. The change rate of micro-hole depth was basically unchanged. And the amount of material removal decreased with the increasing of processing turns but increased sharply in the end of processing. Femtosecond laser can realize high-quality micro-hole processing on the surface of modified polyimide substrate.
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图 3 微孔最小外接圆半径与同心内切圆半径[13]
表 1 飞秒激光加工系统规格参数
参数名称 数值及单位 波长 343 nm 峰值功率 30 W 光束质量M2 <1.3 光斑直径 20 μm -
[1] 谌凯, 任英杰, 张帆, 等. 基于专利分析的高频覆铜板发展态势研究[J]. 绝缘材料, 2021, 54(12): 101-106 https://www.cnki.com.cn/Article/CJFDTOTAL-JYCT202112016.htmSHEN K, REN Y J, ZHANG F, et al. Research on development status of high-frequency copper-clad laminate on basis of patent analysis[J]. Insulating Materials, 2021, 54(12): 101-106 (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-JYCT202112016.htm [2] 新思界网. 5G时代到来, 改性聚酰亚胺(MPI)应用需求持续增长[DB/OL]. (2021-08-10)[2022-01-10]. https://www.163.com/dy/article/GGVK0CP30514E30D.htmlXinsijie Network. The 5G era is coming, and the demand for modified polyimide MPI applications will continue to grow after 2021[EB/OL]. (2021-08-10)[2022-01-10]. https://www.163.com/dy/article/GGVK0CP30514E30D.html (in Chinese) [3] 杨宏强. PCB微孔成孔技术的现状[J]. 印制电路信息, 2020, 28(4): 31-38 https://www.cnki.com.cn/Article/CJFDTOTAL-YZDL202004009.htmYANG H Q. Current status of PCB micro-via processing technology[J]. Printed Circuit Information, 2020, 28(4): 31-38 (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YZDL202004009.htm [4] 刘雷文. 紫外激光在柔性线路板盲孔微加工中的应用[J]. 中国高新科技, 2019(7): 110-112 https://www.cnki.com.cn/Article/CJFDTOTAL-GXKE201907040.htmLIU L W. Application of ultraviolet laser in blind via micromachining of flexible circuit board[J]. China High-Tech, 2019(7): 110-112 (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-GXKE201907040.htm [5] 聂世琳, 管迎春. 紫外激光器及其在微加工中的应用[J]. 光电工程, 2017, 44(12): 1169-1179 https://www.cnki.com.cn/Article/CJFDTOTAL-GDGC201712008.htmNIE S L, GUAN Y C. Review of UV laser and its applications in micromachining[J]. Opto-Electronic Engineering, 2017, 44(12): 1169-1179 (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-GDGC201712008.htm [6] GAUTAM G D, PANDEY A K. Pulsed Nd: YAG laser beam drilling: A review[J]. Optics and Laser Technology, 2018, 100: 183-215 doi: 10.1016/j.optlastec.2017.09.054 [7] 赵城, 田新博, 刘宏伟, 等. 5G高频LCP带胶材料UV激光盲孔品质改善研究[J]. 印制电路信息, 2021, 29(S1): 172-178 https://www.cnki.com.cn/Article/CJFDTOTAL-YZDL2021S1027.htmZHAO C, TIAN X B, LIU H W, et al. Research on the quality improvement of UV laser blind hole of 5G high frequency LCP adhesive material[J]. Printed Circuit Information, 2021, 29(S1): 172-178 (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YZDL2021S1027.htm [8] ZHAO W Q, WANG L Z. Microdrilling of through-holes in flexible printed circuits using picosecond ultrashort pulse laser[J]. Polymers, 2018, 10(12): 1390 doi: 10.3390/polym10121390 [9] 郭钊. 不同偏振光对FPC打孔加工技术研究[D]. 武汉: 湖北工业大学, 2017GUO Z. Study on drilling technology of FPC with different polarized light[D]. Wuhan: Hubei University of Technology, 2017 (in Chinese) [10] 刘凯. FPC覆铜板飞秒激光刻蚀及细微线路成形技术的研究[D]. 苏州: 苏州大学, 2019LIU K. Research on FPC CCL etching and fine line forming technology based on femtosecond laser[D]. Suzhou: Soochow University, 2019 (in Chinese) [11] 张云龙, 孙树峰, 王茜, 等. 激光加工微孔质量的研究[J]. 激光与光电子学进展, 2021, 58(19): 1900002 https://www.cnki.com.cn/Article/CJFDTOTAL-JGDJ202119004.htmZHANG Y L, SUN S F, WANG X, et al. Research on quality of micro-holes fabricated by laser drilling[J]. Laser & Optoelectronics Progress, 2021, 58(19): 1900002 (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-JGDJ202119004.htm [12] WU Q, WANG J, HUANG C Z. Analysis of the machining performance and surface integrity in laser milling of polycrystalline diamonds[J]. Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 2014, 228(6): 903-917 doi: 10.1177/0954405413510290 [13] 岳端木, 孙会来, 杨雪, 等. 飞秒激光环切加工不锈钢微孔工艺及其质量控制神经网络模型[J]. 红外与激光工程, 2021, 50(10): 20200446 https://www.cnki.com.cn/Article/CJFDTOTAL-HWYJ202110017.htmYUE D M, SUN H L, YANG X, et al. Annular drilling process and quality control neural network model of stainless steel micro-hole with femtosecond laser[J]. Infrared and Laser Engineering, 2021, 50(10): 20200446 (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-HWYJ202110017.htm [14] 付立凡, 王丹, 谢春萍, 等. 基于热重红外联用法的聚酰亚胺阻燃织物热解行为研究[J]. 化工新型材料, 2020, 48(2): 237-240 https://www.cnki.com.cn/Article/CJFDTOTAL-HGXC202002051.htmFU L F, WANG D, XIE C P, et al. Study on pyrolysis behavior of polyimide flame retardant fabric based on TG-FTIR method[J]. New Chemical Materials, 2020, 48(2): 237-240 (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-HGXC202002051.htm [15] 林恩旻. 超短脉冲激光制备精密微孔的技术研究[D]. 苏州: 苏州大学, 2019LIN E M. Research on fabrication of precision micropores by ultrashort pulsed laser[D]. Suzhou: Soochow University, 2019 (in Chinese)