Zhang Xifang, Yao Zhenqiang, Hou Zhibao, Song Jiacheng
School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
College of Mechanical Engineering, Suzhou University of Science and Technology, Suzhou 215009, China.
Micromachines (Basel). 2022 Feb 21;13(2):340. doi: 10.3390/mi13020340.
Polydimethylsiloxane (PDMS) is hailed as one of the foundational materials that have been applied to different products in various fields because of its chemical resistance, low cost, excellent flexibility, and high molding capability. With the aim to achieve surface texture with high efficiency by means of electrochemical micromachining with PDMS mask, a femtosecond laser is utilized to process a precision array of micro-through-holes on PDMS films as the molds. The ablation process of PDMS with a femtosecond laser was investigated via numerical simulation verified with experiments indicating a laser energy density of 4.865 mJ/mm as the ablation threshold of PDMS with the melting temperature of 930 K. The spiral scanning path with optimized radial offset was developed to ablate materials from the PDMS film to form the laminated profiles, and a tapered through hole was then formed with multilayer scanning. The profile dimension and accuracy were examined as control targets in terms of laser pulse energy and scanning speed, showing that a 12 μJ femtosecond laser pulse energy and 1000 mm/s scanning speed could bring about a nearly circular laminating profile with expected smaller exit diameter than the entry diameter. All the cross-section diameters of the microcone decreased with the increase of laser scanning speed, while the taper increased gradually and then saturated around a laser scanning speed of 800 mm/s due to the energy absorption resulting in smaller ablation in diameter and depth.
聚二甲基硅氧烷（PDMS）因其耐化学性、低成本、出色的柔韧性和高成型能力，被誉为已应用于各个领域不同产品的基础材料之一。为了通过使用PDMS掩膜的电化学微加工高效实现表面纹理，利用飞秒激光在PDMS薄膜上加工出精密的微通孔阵列作为模具。通过数值模拟并经实验验证，研究了飞秒激光对PDMS的烧蚀过程，结果表明激光能量密度为4.865 mJ/mm为PDMS的烧蚀阈值，其熔化温度为930 K。开发了具有优化径向偏移的螺旋扫描路径，以从PDMS薄膜上烧蚀材料以形成层叠轮廓，然后通过多层扫描形成锥形通孔。将轮廓尺寸和精度作为激光脉冲能量和扫描速度方面的控制目标进行了检查，结果表明12 μJ的飞秒激光脉冲能量和1000 mm/s的扫描速度可产生接近圆形的层叠轮廓，其出口直径比入口直径小，符合预期。微锥的所有横截面直径均随着激光扫描速度的增加而减小，而锥度逐渐增大，然后在激光扫描速度约为800 mm/s时达到饱和，这是由于能量吸收导致直径和深度上的烧蚀变小。
