激光移动刻蚀树脂基复合材料仿真分析
发布时间：2018-10-21 18:40
【摘要】：激光技术的产生无疑推动了材料加工领域的发展,尤其是短脉冲激光具有能量高,方向性好,无需接触等优点,适合用于进行精细加工。对于某些卫星天线反射器表面的加工,纳秒脉冲激光具有不可替代的优势。这类天线反射器用到一种以聚合物为基底表面涂覆金属薄膜的复合材料,根据功能需要,需要将金属薄膜加工成按照一定规律图案分布的高精度功能薄膜。由于加工尺寸很小,金属薄膜也只有几微米的厚度,加工过程还不能损伤聚合物基底,所以传统的加工方法难以达到加工要求。但是,由于影响激光刻蚀结果的因素很多,确定合适的激光刻蚀参数的过程需要耗费时间和材料,具有一定的盲目性。因此本工作利用有限元模拟软件COMSOL Multiphysics对激光刻蚀金属-聚酰亚胺复合材料过程进行模拟实验,希望能加快实验进度,降低实验成本。工作主要有以下几个方面:(1)对激光刻蚀金属材料的过程进行分析和模型化,从激光与物质发生的相互作用机理着手,讨论了热传递过程及刻蚀过程中涉及到的重要的热物理参数,介绍了有限元软件的特点和计算过程。(2)建立了激光刻蚀单层和多层金属-聚酰亚胺复合材料的几何模型,选择“固体传热”接口,对模拟过程用到的物理参数进行了定义,将激光作为一个高能量热源,对热传导、热对流、热辐射的边界条件以及传热方程进行说明,对金属薄膜的网格做了加密处理。(3)考虑到脉冲激光加热方式和连续激光的不同,模拟中将刻蚀分为加热和冷却阶段,通过对加热阶段计算任一时刻的温度场,并对结果进行分别处理。假设温度达到气化点以上即成为金属蒸汽而被刻蚀,得到加热结束后刻蚀轮廓和温度场,并作为冷却阶段的初始输入值,如此得到一定移动速度下连续几个脉冲过后刻蚀深度和刻蚀轮廓。通过比较不同速度的刻蚀结果,随激光扫描脉冲的增加,刻蚀深度增加并逐渐达到最大值,之后刻蚀深度不变,刻蚀形貌呈盆状。移动速度越大的激光,越早达到其最大刻蚀深度,且刻蚀深度也越小。金属薄膜与聚酰亚胺基底界面处温度变化相对于金属薄膜表面在时间上有一定的滞后。(4)为了研究金属夹层对刻蚀结果的影响,对激光刻蚀双层金属薄膜过程进行了模拟,比较了涂覆纯铝和不同厚度铝-铜金属层,以及铝-铜和铝-金金属层时激光刻蚀效果。结果显示,每一次脉冲过后,铝铜双层膜与聚酰亚胺界面处峰值温度比单层铝薄膜低,且铜薄膜越厚,界面处温度越低,因此选用热导率大的金属做夹层可以起到保护聚合物基底的作用。
[Abstract]:The production of laser technology has undoubtedly promoted the development of material processing, especially the short pulse laser has the advantages of high energy, good directivity, no contact and so on, so it is suitable for fine processing. Nanosecond pulse laser has irreplaceable advantages for the surface processing of some satellite antenna reflectors. This kind of antenna reflector uses a composite material coated with metal film on the polymer substrate. According to the functional requirements, the metal film needs to be processed into a high-precision functional film distributed according to a certain pattern. Because the machining size is very small and the thickness of the metal film is only a few microns, the processing process can not damage the polymer substrate, so the traditional processing method is difficult to meet the processing requirements. However, because there are many factors that affect the laser etching results, it takes time and material to determine the appropriate laser etching parameters, so it is blind to a certain extent. In this work, the finite element simulation software COMSOL Multiphysics is used to simulate the process of laser etching of metal-polyimide composites, in the hope of speeding up the experimental progress and reducing the cost of the experiment. The main works are as follows: (1) the process of laser etching of metal materials is analyzed and modeled, and the interaction mechanism between laser and matter is discussed. The important thermophysical parameters involved in the process of heat transfer and etching are discussed, and the characteristics and calculation process of the finite element software are introduced. (2) the geometric models of laser etched monolayer and multilayer metal-polyimide composites are established. The "solid heat transfer" interface is selected to define the physical parameters used in the simulation process. The laser is used as a high energy heat source to explain the boundary conditions and heat transfer equations of heat conduction, heat convection, thermal radiation. The mesh of metal film is encrypted. (3) considering the difference between pulsed laser heating and continuous laser, the etching is divided into heating and cooling stages, and the temperature field at any time is calculated by heating phase. The results were treated separately. Assuming that the temperature above the gasification point becomes metal vapor and is etched, the etching profile and temperature field are obtained after heating, and as the initial input value of the cooling stage, The etching depth and profile are obtained after several pulses at a certain moving speed. By comparing the etching results with different velocities, the etching depth increases and reaches the maximum value with the increase of laser scanning pulse, and then the etching depth remains the same, and the etching morphology is basin shape. The larger the moving speed, the earlier the maximum etching depth is reached, and the smaller the etching depth is. The temperature change at the interface between metal film and polyimide substrate has some time lag relative to the surface of metal film. (4) in order to study the effect of metal interlayer on the etching results, the laser etching process of bilayer metal film is simulated. The effect of laser etching on pure aluminum and aluminum-copper coatings with different thickness and aluminum-copper and aluminum-gold coatings was compared. The results show that the peak temperature at the interface between aluminum and copper bilayer film and polyimide is lower than that of single layer aluminum film after each pulse, and the thicker the copper film, the lower the temperature at the interface. Therefore, the use of high thermal conductivity metal as interlayer can play a role in protecting the polymer substrate.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB332
[Abstract]:The production of laser technology has undoubtedly promoted the development of material processing, especially the short pulse laser has the advantages of high energy, good directivity, no contact and so on, so it is suitable for fine processing. Nanosecond pulse laser has irreplaceable advantages for the surface processing of some satellite antenna reflectors. This kind of antenna reflector uses a composite material coated with metal film on the polymer substrate. According to the functional requirements, the metal film needs to be processed into a high-precision functional film distributed according to a certain pattern. Because the machining size is very small and the thickness of the metal film is only a few microns, the processing process can not damage the polymer substrate, so the traditional processing method is difficult to meet the processing requirements. However, because there are many factors that affect the laser etching results, it takes time and material to determine the appropriate laser etching parameters, so it is blind to a certain extent. In this work, the finite element simulation software COMSOL Multiphysics is used to simulate the process of laser etching of metal-polyimide composites, in the hope of speeding up the experimental progress and reducing the cost of the experiment. The main works are as follows: (1) the process of laser etching of metal materials is analyzed and modeled, and the interaction mechanism between laser and matter is discussed. The important thermophysical parameters involved in the process of heat transfer and etching are discussed, and the characteristics and calculation process of the finite element software are introduced. (2) the geometric models of laser etched monolayer and multilayer metal-polyimide composites are established. The "solid heat transfer" interface is selected to define the physical parameters used in the simulation process. The laser is used as a high energy heat source to explain the boundary conditions and heat transfer equations of heat conduction, heat convection, thermal radiation. The mesh of metal film is encrypted. (3) considering the difference between pulsed laser heating and continuous laser, the etching is divided into heating and cooling stages, and the temperature field at any time is calculated by heating phase. The results were treated separately. Assuming that the temperature above the gasification point becomes metal vapor and is etched, the etching profile and temperature field are obtained after heating, and as the initial input value of the cooling stage, The etching depth and profile are obtained after several pulses at a certain moving speed. By comparing the etching results with different velocities, the etching depth increases and reaches the maximum value with the increase of laser scanning pulse, and then the etching depth remains the same, and the etching morphology is basin shape. The larger the moving speed, the earlier the maximum etching depth is reached, and the smaller the etching depth is. The temperature change at the interface between metal film and polyimide substrate has some time lag relative to the surface of metal film. (4) in order to study the effect of metal interlayer on the etching results, the laser etching process of bilayer metal film is simulated. The effect of laser etching on pure aluminum and aluminum-copper coatings with different thickness and aluminum-copper and aluminum-gold coatings was compared. The results show that the peak temperature at the interface between aluminum and copper bilayer film and polyimide is lower than that of single layer aluminum film after each pulse, and the thicker the copper film, the lower the temperature at the interface. Therefore, the use of high thermal conductivity metal as interlayer can play a role in protecting the polymer substrate.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB332
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