Disassembling end-of-life printed circuit boards (PCBs) and reusing the high-value electronic components is an effective way of recycling. During the disassembly process, the quality of components is easily to reduce if the process is inappropriate. A common defect which usually arises in the disassembly process is interfacial delamination within plastic-encapsulated integrated circuits (ICs). The IC delamination is mainly caused by excessive high temperature. Therefore, research of the temperature field of the PCB and the heating strategy is necessary. A peak-temperature principle and a ramp-rate principle are proposed to meet the purpose of heating, i.e. melting the solder sufficiently and avoiding the IC delamination. The peak-temperature principle requires the peak temperature of the PCB should be as low as possible on the premise of melting the solder sufficiently;the ramp-rate principle requires that the ramp-up should be fast at first, and slow when the temperature is approaching the peak temperature. Then a thermal model of PCB heated in multiple temperature zones successively with hot air is built. Combined with this model, a heating strategy is proposed based on the temperature-field uniformity to achieve the temperature profile which conforms to the two heating principles. An experiment is conducted using an independently-developed disassembly machine for end-of-life PCBs to validate the heating strategy. The experimental results show:The PCB temperature field with the fast-then-slow (FTS) ramp from the heating strategy is more uniform than the temperature field with the ramp-to-spike (RTS) which is usually used in reflow process; their component disassembly rate is very close to each other; compared with the RTS ramp, the delamination fraction caused by the disassembly process is 80%lower with the FTS ramp;and thus the proposed heating strategy can effectively reduce IC delamination during the disassembly process.

Printed Circuit Board Assembly (PCBA), is an important basic part of Electric and Electronic Equipment, which has lots of high-value components and toxic substances. Normally, when Electric and Electronic Equipment (EEE) is scraped, some components on waste PCBA still keep good performances. Therefore, it is feasible and economical to environment-friendly reuse the high-value components on waste PCBA. In order to guarantee the quality of the disassembled components, the components reuse-oriented disassembly process is proposed, in which. the mechanical and physical characteristics of solder and the joint type of PCBA are considered comprehensively. In the process, through the analysis and measurement of the temperature distribution of PCBA, the optimized heating mode and heating temperature curve can be drawn up for the different joint type of PCBA. For getting the disassembly mode of PCBA, the disassembly force and separating displacement of components on PCBA are defined and the disassembly energy models for different kinds of components are set up. On the basis of the heating mode, heating temperature curve and disassembly energy, two kinds of disassembly apparatus and a performance testing procedure for certain kinds of old components are developed. In the end the components reuse-oriented disassembly process parameters are optimized to get a high separation ratio and reuse ration of components with orthogonal test.

Reuse of plastic IC packages disassembled from printed circuit boards ( PCBs) has significant environmental benefits and economic value. The interface delamination caused by moisture diffusion is the main failure mode of IC packages during the disassembling process, which greatly reduces the reusability and reliability of disassembled IC packages. Exploring moisture diffusion mechanism is a prerequisite to optimize prebaking processes before disassembling that is an effective way to avoid the interface delamination. To this end, a computational model with variable boundary conditions is developed based on the different combination state of water in IC packages. The distribution characteristics and mechanism of moisture diffusion behavior are analyzed including the humidity distribution field and the relation among baking temperature, water loss rate, and baking time during baking process, and then the results are validated by FEA simulation based on the improved definition of relative moisture concentration. Baking under variable temperature is proposed and compared with the baking process and baking efficiency under constant temperature to find out the optimized baking parameters. Finally, a set of curves which indicate the relation between baking energy consumption and temperature are determined under actual industrial baking experiments, which could be used as references to develop industrial standards for PCB disassembling process.

In some occasions, high accuracy and real-time 6-degree-of-freedom (6-DOF) displacements should be measured so that the control system can regulate the X-Y stages' attitude in real time. The accuracy and real-time property of measurement's result depend on not only the sensors itself, but also the accuracy and effort of the computational algorithm using the sensors' measured data. As the relation between sensors' measured data and displacements is immensely complex and usually described as strong nonlinear coupling equation when 6-DOF displacements are all considered, computational accuracy and effort are difficult to be ensured simultaneously. This paper designs a 6-DOF displacements' measurement setup for X-Y stages based on nine interferometers' additional information, and derives the corresponding computational algorithm. For rotation, its range is usually very small and high accuracy computational results can be obtained using two interferometers' differential computation; for translation, the closed form solutions without rotational displacement's computational error's transmission are derived by making full use of all additional interferometers' information, so that the computational accuracy can be ensured. In addition, the algorithm has simple form and doesn't involve iteration and transcendental function's computation, so that it helps real-time computation. This algorithm can acquire the computational accuracy of 10(-15) rad and 10(-13) mm for rotational and translational displacement separately, which can be seen in the simulation result for a lithography's wafer stage. (C) 2013 Elsevier Inc. All rights reserved.

For an X–Y stage’s six-degrees-of-freedom (6-DOF), displacement measurement system using multi-interferometers, this paper builds the geometric error’s transfer model first, and then analyses the sensitivity of the measurement error to the geometric error. On this basis, a method of a geometric error tolerance design for the accuracy of a measurement system is proposed using an improved genetic algorithm (GA) with minimal weighted and multi-source error bounds. For the high correlation of transfer coefficients in the propagation process of various errors, using GA’s global optimal searching capability in the entire motion range of each stage, this method overcomes the shortcoming that conservative results are usually produced when an equivalent effect method is used. Therefore, this method acquires a more objective result of the tolerance design of a geometric error for the X–Y stage measurement system accuracy.

This study presents a systematic approach to modeling the position-dependent model variations of an ultra-precision positioning stage with minimal structured uncertainty in linear fraction transformation (LFT) representation. The position dependent dynamics characterizing by varying resonances, are introduced by the structural flexibility together with the measurement transformations, and should be accurately and non-conservatively modeled to maximize the achievable performance in subsequent controller design. The dynamics of the stage are first estimated by a group of nonparametric frequency response functions (FRF) through close-loop identification. And an iterative global rational fraction polynomial method is applied to fit the FRFs into transfer functions with common denominator. Then the differences in the coefficients of the fitted transfer functions are described by parametric uncertainty, and further converted to structured uncertainty in LFT form. Finally the dimension of the uncertain structure is reduced by principal components analysis (PCA). The reduced model captures the variations of identified FRFs very well, and it is demonstrated that the proposed method could be effectively used to develop the minimal structured uncertain model for position-dependent dynamics with the same characteristic equation.

Discusses the combination optimization problem of several grinding machines' plate clearance to realize lean production,and establishes the problem's mathematical model.The relationship of particle size distribution and productivity with the plate clearance is experimentally obtained.Design the genetic algorithm to minimize the target function within the integer domain and compare the result with the interior-point method.The results show that this GA has better effect and efficiency.

The quality of the coating of the photoresist impacts the quality of lithography directly.The spin coating and spray coating method and their development process were presented,as well as the electrodeposition（ED）,vapor deposition methods.Advantage and disadvantages of the spin coating,spray coating and ED were outlined,and the applications of the different coating methods were summarized.

A pan mill was introduced to pulverize waste tire tread rubber particles at ambient temperature,and the characteristics of rubber powder and its effect on the mechanical properties of SBR vulcanizate were investigated and compared with those of waste tire tread rubber particle.The results showed that,the size of rubber powder after pulverization process was reduced by one order of magnitude,and the shape was more irregular and the surface roughness was higher compared with original particles.The diameter and its distribution of rubber powder were not strongly affected by relative rotate speed between kinetic mill plane and static mill plane of the pan mill,but greatly affected by clearance between them.Thermal stability of rubber powder was decreased and the crosslink density was reduced by more than half.Compared with tire tread rubber particle,the elongation at break of SBR vulcanizate filled by rubber powder was enhanced evidently,but the Shore A hardness,100% and 300% modulus and tensile strength were reduced to some extent.

Tangential point tracing grinding machines grind the connecting rod by the way that follow the crankshaft which rotates around the crank journal with the grinding wheel mounting which is driven by a linear motion actuator.Researching,based on dimensional accuracy of connecting rod,obtains the mathematical expression of grinding wheel mounting velocity and acceleration,analyzes effect of changing of linear motion actuator interpolation cycle and crankshaft rotation speed on grinding wheel mounting velocity,acceleration,and effect of the smallest degree angle on connecting rod roundness.It provided a reference for the selection of the numerical control system parameters

In order to solve the problem of the design of the ultrasonic atomizing nozzle’s vibration system composed of certain elements of thin rod without simple analytic solutions,a piecewise approximate simulation method is proposed,and based on the method,an ultrasonic atomizing nozzle’s vibration system is designed.Using mechanic-electric analogy method,based on the four terminal network of the common longitudinal vibration of thin rod with variable cross-section,the thin rod without simple analytic solutions is divided into many parts to simulate the whole rod,then the overall transmission matrix of the vibration system is built up,and as a result,the design and analysis of the vibration system is achieved.Using different simulation accuracy values,calculates three kinds of half wavelength solid and hollow single horns with the shape like exponent,cone and catenary are calculated,then the simulation calculation results and the theoretical results are compared and analyzed.At the same time,three kinds of half wavelength solid and hollow compound horns with the shape like exponent-cylinder,cone-cylinder and catenary-cylinder are calculated and the simulation calculation results and the theoretical results are compared and analyzed.Compared with the simulation results and the theoretical value,it can conclude that simulation results are very close to the theoretical calculation value and piecewise approximation simulation calculation method can solve the problem of the thin rod’s longitudinal vibration’ design which variable cross section without simple analytic solutions.Based on the four terminal network transmission matrixes piecewise approximate simulation method,the nozzle’s vibration system is designed and analyzed,and the manufactured nozzle can work well.

Parallel manipulators for the machine tool industry have been studied extensively for various industrial applications. However, limited useful workspace areas, the poor mobility, and design difficulties of more complex parallel manipulators have led to more interest in parallel manipulators with less than six degrees of freedom (DoFs). Several parallel mechanisms with various numbers and types of degrees of freedom are described in this paper, which can be used in parallel kinematics machines, motion simulators, and industrial robots.

A new space subdivision algorithm for the application object like linear motor whose magnetic flux density of magnetic field is sinusoidal was proposed. Space sinusoidal and cosine signals can be obtained by two sensors whose distance equals a quarter of magnetic polar pitch. By continuously doubling the measured signals’ frequency by sinusoidal and cosine operation, a set of orthogonal signals were produced whose equivalent pole pitch equals half of previous signals’. Using an electronic comparator to detect zero crossings, quadrature binary pulses may in turn be obtained from the frequency doubled signals and high-speed, high-precision displacement measurement can be achieved. By analyzing the signal’s signal to noise ratio, subdivision multiples’ constraints when zero crossings detection is available can be obtained. Experimental results showed the effectiveness of this subdivision method.

According to actual situation of domestic enterprises,it introduces the disassembling strategy and relevant disassembly sequence planning methods.Based on the analysis of disassembly process of household appliances,it establishes the functional model and information model of disassembly information management system and develops the disassembly information management system.Taking disassembly of TV sets as an example,it proves the system effectiveness,generates disassembly process plan sheets.The generated disassembly process plan sheets are used in a color TV disassembly line of Chang Hong to guide the actual disassembling operation.