-
PDMS是由交替连续的Si和O原子通过共价键连接在一起,侧链上两个甲基基团连接在Si原子上。本实验中采用型号为Sylgard 184预聚液所形成的固体板材,材料体厚度为2 mm,并切割成体积为20 mm× 20 mm×2 mm的实验备品。掩模材料选用PI薄膜,是指主链上含有酰亚胺环(—CO—N—CO—)的一类聚合物,选用美国杜邦(Kapton)公司生产的均苯型薄膜,厚度h分别为15 μm、25 μm、50 μm;该薄膜具有优异的热稳定性,常被用于耐高温电机电器的绝缘材料。PDMS和PI的主要性能参数如表 1所示。
表 1 PDMS和PI的热物理特性
Table 1. Thermal physical property of PDMS and PI
performance parameter density(25 ℃)/ (g·cm-3) heat capacity at constant pressure/(J·K-1·kg-1) thermal conductivity/ (W·m-1·K-1) glass transition temperature/℃ decomposing temperature/℃ Poisson’s ratio PDMS 0.97 1460 0.16 230 ≈350 0.46 PI 1.42 1090 0.12 385 ≈500 0.34 -
实验中所使用的紫外纳秒固体激光切割实验系统包括:一台Nd ∶YAG紫外固体激光器、激光控制及水冷系统、光学系统、脉冲能量计及3-D移动平台,如图 1所示。
实验前将PI薄膜贴附于PDMS上表面,并放在3-D移动平台上,且PDMS和PI表面皆较为光滑,无需任何粘结剂便可将PDMS和PI紧固粘贴。图 2a中透明材料为PDMS,图 2b中黄色材料为PI薄膜,图 2c中黑灰色条纹为被烧蚀的PI和PDMS喷溅物。实验中选用激光波长为266 nm,光束经过反射镜与透镜(焦距f=50 mm)聚焦到PI上表面;激光脉宽为7 ns,频率为50 Hz,光斑半径约为25 μm。整个实验过程在常温常压大气环境中进行。实验完成后将PDMS放入超声波清洗机中清洗15 min,清除表面大部分熔融喷溅物,并利用数字显微镜(OLYMPUS DSX1000)对PDMS表面的微槽形貌进行观测。
掩模辅助激光切割PDMS的工艺实验研究
Experimental investigation on mask assisted laser cutting of PDMS
-
摘要: 为了提高紫外纳秒固体激光切割聚二甲基硅氧烷(PDMS)的加工质量,提出了一种掩模辅助激光切割PDMS的方法。采用聚酰亚胺薄膜作为掩模材料,进行了无掩模及不同厚度掩模下紫外纳秒固体激光切割PDMS实验,分析了PDMS材料表面微裂纹的形成机理,获得了激光主要工艺参数对微槽的槽深、槽宽及加工质量的影响规律。结果表明,掩模条件下激光切割PDMS的表面加工质量较好,无微裂纹产生且玻璃态转化较少;槽深和槽宽均随激光脉冲能量、扫描速率的增加而增大;掩模厚度为15 μm和50 μm、扫描速率为40 μm/s和50 μm/s、脉冲能量高于0.40 mJ时,微槽表面热影响区较小。本研究为提高紫外纳秒固体激光切割PDMS的加工质量提供了一种方法。Abstract: In order to improve the processing quality of ultraviolet (UV) nanosecond solid-state laser cutting polydimethylsiloxane (PDMS), a new method of mask-assisted laser cutting PDMS was proposed in this paper. Using polyimide film as the mask material, the process experiments of cutting PDMS with UV nanosecond solid-state laser without mask and with different thickness masks were carried out. The formation mechanism of microcracks on the surface of PDMS material was analyzed, and the influence of main laser process parameters on the groove depth, groove width, and processing quality of microgrooves was obtained. The results show that the surface quality of laser cutting PDMS under mask condition is good, no microcrack is generated and the glass transition is less. The groove depth and width increase with the increase of laser pulse energy and scanning speed. When the mask thickness is 15 μm and 50 μm, the scanning speed is 40 μm/s and 50 μm/s, and the pulse energy is higher than 0.40 mJ, respectively, and the heat-affected zone of the microgroove surface is small. This study provides a new method for improving the processing quality of UV nanosecond solid-state laser cutting PDMS.
-
表 1 PDMS和PI的热物理特性
Table 1. Thermal physical property of PDMS and PI
performance parameter density(25 ℃)/ (g·cm-3) heat capacity at constant pressure/(J·K-1·kg-1) thermal conductivity/ (W·m-1·K-1) glass transition temperature/℃ decomposing temperature/℃ Poisson’s ratio PDMS 0.97 1460 0.16 230 ≈350 0.46 PI 1.42 1090 0.12 385 ≈500 0.34 -
[1] ABBASI F, MIRZADEH H, KATBAB A. Modification of polysiloxane polymers for biomedical applications: A review[J]. Polymer International, 2001, 50(12): 1279-1287. doi: 10.1002/pi.783 [2] KANT M B, SHINDE S D, BODAS D, et al. Surface studies on benzophenone doped PDMS microstructures fabricated using KrF excimer laser direct write lithography[J]. Applied Surface Science, 2014, 314(30): 292-300. [3] AMID S, SHADMAN K, TOHID F D. Conventional and emerging strategies for the fabrication and functionalization of PDMS-based microfluidic devices[J]. Lab on a Chip, 2021, 21(16): 3053-3075. doi: 10.1039/D1LC00288K [4] 陈锐, 王锦成, 章文卓, 等. 微结构传感器的激光制造技术研究进展[J]. 光电工程, 2023, 50(3): 220041. CHEN R, WANG J Ch, ZHANG W Zh, et al. Research progress of laser manufacturing technology for microstructure sensor[J]. Opto-Electronic Engineering, 2023, 50(3): 220041(in Chinese). [5] GAO K P, LI G, LIAO L N, et al. Fabrication of flexible microelectrode arrays integrated with microfluidic channels for stable neural interfaces[J]. Sensors and Actuators, 2013, A197(1): 9-14. [6] ABDULHUSSEIN A T, KANNARPDDY G K, WRIGHT A B, et al. Current trend in fabrication of complex morphologically tunable superhydrophobic nano scale surfaces[J]. Applied Surface Science, 2016, 384(30): 311-332. [7] LIU Y Sh, ZHANG P, DENG Y B, et al. Polymeric microlens array fabricated with PDMS mold-based hot embossing[J]. Journal of Micromechanics and Microengineering, 2014, 24(9): 095028. doi: 10.1088/0960-1317/24/9/095028 [8] DENG Y, HONG W Sh, HE J F, et al. Micro-cracks on crosslinked poly (dimethylsiloxane) (PDMS) surface treated by nanosecond laser irradiation[J]. Applied Surface Science, 2018, 445(1): 488-495. [9] 顾江, 叶霞, 范振敏, 等. 激光刻蚀法制备仿生超疏水表面的研究进展[J]. 激光技术, 2019, 43(4): 493-499. GU J, YE X, FAN Zh M, et al. Progress in fabrication of biomimetic superhydrophobic surfaces by laser etching[J]. Laser Technology, 2019, 43(4): 493-499(in Chinese). [10] YAN Zh B, HUANG X Y, YANG Ch. Rapid prototyping of single-layer microfluidic PDMS devices with abrupt depth variations under non-clean-room conditions by using laser ablation and UV-curable polymer[J]. Microfluidics and Nanofluidics, 2017, 21(6): 108. doi: 10.1007/s10404-017-1943-2 [11] HOHNHOLZ A, OBATA K, NAKAJIMA Y, et al. Hybrid UV laser direct writing of UV-curable PDMS thin film using aerosol jet printing[J]. Applied Physics, 2019, A125(2): 120-125. [12] 谢凯武, 李泽斌, 邓宇, 等. 聚二甲基硅氧烷柔性基材上应力-激光复合制备直角微沟槽[J]. 高分子材料科学与工程, 2022, 38(3): 106-112. XIE K W, LI Z B, DENG Y, et al. Stress-laser composite fabrication of right-angle microgrooves on polydimethylsiloxane flexible substrate[J]. Polymer Materials Science and Engineering, 2022, 38(3): 106-112(in Chinese). [13] CHEUNG K C. Implantable microscale neural interfaces[J]. Biomedical Microdevices, 2007, 9(6): 923-938. doi: 10.1007/s10544-006-9045-z [14] 齐立涛, 刘亚升, 樊爱春, 等. 盖板辅助紫外固体激光打孔的实验研究[J]. 黑龙江科技大学学报, 2020, 30(1): 100-104. QI L T, LIU Y Sh, FAN A Ch, et al. Experimental study on ultraviolet solid laser drilling assisted by cover plate[J]. Journal of Heilongjiang University of Science & Technology, 2020, 30(1): 100-104(in Chinese). [15] HA K H, LEE S W, KIM J G, et al. Fabrication of a micro-hole array on metal foil by nanosecond pulsed laser beam machining using a cover plate[J]. Journal of Micromechanics and Microengineering, 2015, 25(2): 027001. doi: 10.1088/0960-1317/25/2/027001 [16] 张全利, 储成龙, 翟健超, 等. 紫外纳秒脉冲激光烧蚀单晶硅表面特征创成机制[J]. 航空学报, 2022, 43(4): 515-527. ZHANG Q L, CHU Ch L, ZHAI J Ch, et al. Surface characteristics formation mechanism of ablated monocrystalline silicon by UV nanosecond pulsed laser[J]. Acta Aeronautica et Astronantica Sinica, 2022, 43(4): 515-527(in Chinese). [17] WANG M J, ZHANG Y, BIN J X, et al. Cold laser micro-machining of PDMS as an encapsulation layer for soft implantable neural interface[J]. Micromachines, 2022, 13(9): 1484. doi: 10.3390/mi13091484 [18] GRAUBNER V M, NUYKEN O, LIPPERT T, et al. Local chemical transformations in poly (dimethylsiloxane) by irradiation with 248 and 266 nm[J]. Applied Surface Science, 2006, 252(13): 4781-4785. doi: 10.1016/j.apsusc.2005.07.123 [19] LI X X, GUAN Y Ch. Theoretical fundamentals of short pulse laser-metal interaction: A review[J]. Nanotechnology and Precision Engineering, 2020, 3(3): 105-125. [20] ZHANG X F, YAO Zh Q, HOU Zh B, et al. Processing and profile control of microhole array for PDMS mask with femtosecond laser[J]. Micromachines, 2022, 13(2): 340.