面向元器件重用的废弃线路板拆解加热均匀性研究

发布时间：2018-05-17 13:39

  本文选题：废弃线路板 + 拆解　； 参考：《清华大学》2015年硕士论文

【摘要】：废弃线路板(Printed Circuit Board,PCB)是废弃电器电子产品(Waste Electrical and Electronic Equipment,WEEE)的常见部件。废旧塑封芯片是废弃线路板上的重要元器件,具有较高的可重用价值。在废弃线路板拆解加热过程中,线路板加热不均匀很容易引起板面局部高温,导致塑封芯片分层损伤,不利于重用。因此,本文进行废旧塑封芯片分层热影响分析和线路板拆解加热均匀性分析与优化,这对实现废旧塑封芯片的高价值重用具有重要意义。首先提出废旧塑封芯片的热力学仿真分析方法,利用该方法分析了不同拆解温度对芯片翘曲变形、内部结构最大应力分布和内部结合面应力分布的影响规律,并给出了旧芯片内部的易分层区域。进行塑封芯片界面剪切强度实验,对比分析了拆解温度的高低对新旧芯片界面强度的影响规律,得到了废旧塑封芯片分层的热影响关系,为线路板加热均匀性分析与优化提供理论依据。根据线路板拆解加热均匀性分析结果,指出影响线路板加热均匀性的关键因素。基于冲击射流模型计算出热风与线路板之间的对流换热系数,建立了线路板表面传热模型,利用传热模型分析了出流高度、整流板结构参数对线路板换热的影响规律,利用流场仿真的方法分析了风机转速对线路板加热均匀性的影响,最终确定了出流高度、整流板结构参数、风机转速等温区参数对线路板加热均匀性的影响水平,为加热温区结构的优化设计提供决策支持。基于线路板加热影响特性分析的结果,重点对整流板结构参数进行优化设计。提出了将多孔整流板等效为多孔介质阻抗模型的方法,利用该方法建立了整流板两侧热风的压力、速度等物性参数与多孔介质阻抗的数学关系,基于多孔介质模型进行了整流板阻抗的优化设计,获得优化后的板面阻抗分布。最后根据阻抗特性优化结果提出了几何拓扑调整方案,将优化后的板面阻抗转化为具体的整流板几何结构,实现了面向线路板加热均匀性的温区结构优化设计。利用自主研制的废弃线路板拆解设备及辅助测量仪器进行了整流板出口风速检测实验和线路板拆解升温监测实验。结果表明,整流板出口风速的不均匀度由优化前的31.8%降低至优化后的8.3%,线路板加热过程中,板面最大温差由优化前的50℃降低至优化后的20℃,验证了整流板结构优化方法的合理性和优化结果的可行性,为面向元器件重用的废弃线路板加热拆解提供技术支持。
[Abstract]:Waste Circuit printed Circuit (PCB) is a common component of waste Electrical and Electronic equipment (WEEE). The waste plastic seal chip is an important component of the waste circuit board, and has high reusable value. In the process of disassembling and heating the waste circuit board, the uneven heating of the circuit board can easily lead to the local high temperature of the board, resulting in the lamination damage of the plastic seal chip, which is not conducive to reuse. Therefore, it is of great significance to analyze and optimize the lamination thermal effect of waste plastic seal chip and the uniformity of circuit board disassembly and heating, which is of great significance to realize the high value reuse of waste plastic seal chip. Firstly, a thermodynamic simulation analysis method of waste plastic seal chip is put forward. By using this method, the influence of different dismantling temperatures on the warpage deformation, the maximum stress distribution of internal structure and the stress distribution of internal bonding surface are analyzed. The easily stratified region inside the old chip is also given. Experiments on the interfacial shear strength of plastic seal chip were carried out, and the effect of dismantling temperature on the interface strength of new and old chips was compared and analyzed, and the thermal effect relationship of lamination of waste plastic seal chip was obtained. It provides theoretical basis for the analysis and optimization of circuit board heating uniformity. According to the analysis results of the heating uniformity of circuit board disassembly, the key factors affecting the heating uniformity of circuit board are pointed out. Based on the impinging jet model, the convection heat transfer coefficient between the hot air and the circuit board is calculated, and the heat transfer model on the surface of the circuit board is established. By using the heat transfer model, the influence of the outlet height and the structure parameters of the rectifier board on the heat transfer of the circuit board is analyzed. By using the method of flow field simulation, the influence of fan speed on the heating uniformity of circuit board is analyzed. Finally, the influence level of outlet height, structure parameter of rectifier board, isothermal zone parameter of fan speed on the uniformity of circuit board heating is determined. It provides decision support for optimal design of heating temperature region structure. Based on the analysis of heating characteristics of circuit board, the structural parameters of rectifier board are optimized. A method of equating porous rectifier plate to porous dielectric impedance model is proposed. The mathematical relationship between the physical parameters such as pressure and velocity of hot air on both sides of the rectifier plate and the impedance of porous medium is established by using this method. Based on the porous media model, the impedance of rectifier plate is optimized and the optimized impedance distribution is obtained. Finally, according to the results of impedance characteristics optimization, a geometric topology adjustment scheme is proposed. The optimized plate surface impedance is transformed into a specific rectifier board geometry structure, and the optimal design of the temperature region structure oriented to the uniformity of circuit board heating is realized. The test of wind speed at the outlet of rectifier board and the temperature monitoring experiment of circuit board disassembly were carried out by using the disassembly equipment and the auxiliary measuring instrument of the waste circuit board developed by ourselves. The results show that the unevenness of wind velocity at the outlet of the rectifier board is reduced from 31.8% before optimization to 8.3% after optimization. During the heating process of the circuit board, the maximum temperature difference of the plate surface decreases from 50 鈩，

本文编号：1901593