Preface

With the proposal of"Industrial Internet"in the United States and "Industry 4.0" in Germany, the intelligent manufacturing becomes national strategy of many countries. Based on the new generation of digital information technology, combined with new manufacturing processes and materials, intelligent manufacturing runs through all links of product design, production, management, and service. As an important part of intelligent manufacturing industry upgrade, electronic manufacturing has developed rapidly with the support of policies in recent years in China. Although the output value of domestic electronics industry has reached a relatively large scale, the profit margin is still relatively low. To occupy the upstream position of the industrial chain and achieve technological independence, it is urgent to improve electronic manufacturing process since the process is one of the most important factors determining the electronic product quality. Our project, its name is "Integration technologies of high-speed and high-precision intelligent manufacturing production line for large quantities of electronic products based on multi-field modeling and simulation of process", aims at the major needs of electronic manufacturing industry, overcomes the bottleneck of manufacturing technology, develops the integration technology and application demonstration of mass product manufacturing intelligent production line, forms an industry-class solution, which will promote the leapfrog development of electronic manufacturing technology.

The production of automotive micro-electromechanical systems (MEMS) pressure sensor, including the mounting, wire bonding, potting, shell injection, and other multi-step processes, involves a variety of complex manufacturing environments, and occurs various defects as the stress and strain concentration, warping, delamination, desoldering, crack, and so on. The formation mechanism of these defects is complex, involving macro-scale and micro-scale material constitutive relationships, which makes it difficult to control production quality. Currently, the automation level of automobile pressure sensor production is generally low due to the complex production process of automobile pressure sensor. Manufacturing processes need to be investigated to improve the production efficiency and product yield.

As the display panel field is developing towards ultrahigh resolution and ultra-high refresh rate, the demand for ultra-high resolution display panel is increasing rapidly and the market prospect is broad. Panel industry is facing a strong demand for high-end development. The manufacturing of flexible printed circuit board (FPCB) electrical components with the high performance and reliability is an important step in the manufacturing process of display panel. The FPCB manufacturing line involves exposure, development, etching, and other processes as well as complex manufacturing environment, and there are various problems such as the stress and strain concentration, warpage, crack, short circuit, and so on. However, the current research on the key processes of FPCB manufacturing is limited by high experimental cost,long cycle, over-simplified simulation model, and low accuracy. The influence mechanism of environment, material, structure, and process parameters on the yield and productivity of electronic products in the manufacturing process is not clear, and the intelligent control of manufacturing process still needs work.

Therefore, aiming at the defects such as the stress and strain concentration, warping, delamination, crack, short circuit caused by multi-step processes in the complex manufacturing environment of electronic product intelligent production line, this book studies the manufacturing processes and defect formation mechanisms by the multi-field and multi-scale modeling and simulation. In this book, the molecular dynamics theory and finite element analysis method with the multi-field coupling such as electric, thermal, optical, chemical, and fluid are used to study the manufacturing processes. By simulating the microstructures of materials and changes of physical and chemical properties in several electronic product manufacturing processes, the formation mechanisms, and evolution rules of product deformation, stress, defects are revealed, which are beneficial to the process optimization and greatly improve the yield of electronic products.

Chapters 1-5 study the manufacturing processes of MEMS automotive pressure sensor, and Chapters 6-9 study the manufacturing processes of FPCB. Chapter 1investigates the change of bonding force, atomic displacement, and von Mises stress distribution during the bonding process. Chapter 2 studies the behavior of six typical material pairs in wire bonding by analyzing the change of bonding force, energy, atomic displacement and von Mises stress distribution during the bonding process and material squeezing, and the key parameters of six pairs are analyzed to explain the difficulty of bonding. Chapter 3 investigates the residual stress on chip of automobile pressure sensor in the potting process by the experiment and finite element method (FEM) simulation, which analyzes the effect of stress on the pressure sensor by different thicknesses of potting adhesive. Chapter 4 investigates the thermal cycle failure of wire bonding weld by the experiment and FEM simulation, which analyzes the effects of creep and plasticity on the fatigue failure of solder joints and points out the most fatigue location. Chapter 5 investigates the acoustic injection on automobile MEMS accelerometer by the multi-physics field simulation and failure mechanisms of acoustic injection on the microprocessor unit 6050 (MPU6050) accelerometer are investigated by both the experiment and simulation. Chapter 6 studies the wetting behavior of Sn droplet on FPCB substrate surfaces using molecular dynamics simulation, which analyses the influence of different substrate surfaces on the wetting behavior of Cu/Sn wetting systems. Chapter 7 studies the etchant spraying characteristics in the FPCB etching process by numerical method based on the Euler multiphase flow model, and a 3D full model of multi-nozzle array is established to study the velocity distribution of etchant in the spraying domain. Chapter 8 studies the etchant concentration distribution and fluid characteristics in the FPCB etching cavity, which further studies the time evolution of etching cavity, concentration field and velocity field of CuCl ₂ solution, and effects of initial concentration and inlet velocity on the contour of etching cavity. Chapter 9 studies the etching cavity evolution in FPCB etching process, and the FPCB sample with 18 μm line pitch is manufactured based on the process parameters obtained by simulations, which validates the numerical simulation method by comparing with the micro-scopic analysis of actual structures and cavity profiles of simulation result.

Mr. Beikang Gu writes Chapter 1 and Chapter 2, Mr. Yunfan Zhang is responsible for Chapter 3 and Chapter 5,Mr. Kangkang Wu for Chapter 4,Mr. Jiazheng Sheng for Chapter 6 and Chapter 8, Mr. Ruijian Ming for Chapter 7 and Chapter 9,Professor Hui Li and Shengnan Shen are responsible for the organization and verification of the book, and contribute to the method of FEM simulation and molecular dynamics simulation.