Optimization of printed circuit board component placement using an efficient hybrid genetic algorithm

The hardware restrictions of surface mount placement machines, such as height, pick and place restrictions, and simultaneous pickup are often in printed circuit board (PCB)-related studies. This study proposes an efficient hybrid genetic algorithm (HGA) for solving the nozzle assignment problem and the component pick and place sequence problem. First, the proposed method obtains the sequence of the automatic nozzle changer (ANC) with the maximum number of simultaneous pickups and the minimum number of picks as the solution of the nozzle setup problem. Then, the proposed method uses the nearest neighbor search (NNS), 2-optimization, and a genetic algorithm (GA) with the known ANC sequences to obtain the PCB assembly time with the optimal component pick and place sequence. Experiments are conducted on the PCB of the EVEST EM-780 surface mount placement machine. Results show that the proposed HGA gives the lowest total number of picks, the shortest total head movement distance, and the minimum total PCB assembly time compared to those of other methods.     

基于多信号模型的电路板TPS开发方法研究

结合电路板测试程序集的开发现状和开发经验,提出了一种基于多信号模型的电路板TPS开发方法;首先给出了多信号模型方法的定义和表示,然后结合示例根据其有向图得到组成单元故障和测试之间的相关矩阵,最后通过相关矩阵的简化和测试的优选制定出被测电路板的故障诊断策略,完成电路板TPS开发;该方法通用性好,适用于不同类型的电路板和武器系统其他装备;实践证明,该方法提高了电路板TPS开发效率和质量,降低了对开发人员的要求。     

基于信息流模型的光驱电路板故障诊断

从故障诊断的角度对光驱电路板原理图进行分析,建立了光驱电路板的诊断信息流模型,模型以映了试验间及试验与故障之间的观察关系,基于该模型讨论了光 电路板的故障诊断问题。实例说明了 有效性。     

The development of a weighted evolving fuzzy neural network for PCB sales forecasting

This research develops a weighted evolving fuzzy neural network for PCB sales forecasting and it includes four major steps: first of all, collecting 15 factors among macroeconomic data, downstream production demand and total industrial production outputs and then using the Grey Relation Analysis (GRA) to select a combination of key factors which have the greatest influence on PCB sales. Secondly, taking the time serial factor into consideration, the Winter’s Exponential Smoothing method is applied to predict the tendency of PCB sales and the influences of seasonal effects. Thirdly, applying historical data to proceed the training of Weighted Evolving Fuzzy Neural Network (WEFuNN) and then forecasts the future PCB sales by the WEFuNN. Finally, compare three kinds of performance measurements for each model. The experimental results reveal that the MAPE for WEFuNN model is 2.11% which is the best compared to others. In summary, the WEFuNN model can be applied practically as a sales forecasting tool in the PCB industry.     

基于网络点集合分割算法的PCB故障测试研究

文章研究了印制电路板(PCB)网络点集合分割算法,提出了网络集加激励产生响应的测试算法,给出了基于该算法的测试逻辑电路和控制流程图。实践表明,该算法较好地解决了网络点数与测试速度的矛盾,是快速检测PCB短路故障的一种有效方法。     

A Study for the Effect of the PCB Motion on the Dynamics of MEMS Devices Under Mechanical Shock

We present a theoretical and experimental investigation into the effect of the motion of a printed circuit board (PCB) on the response of microelectromechanical systems (MEMS) devices to shock loading. For the theoretical part, a 2-DOF model is used, where the first degree of freedom accounts for the PCB. The second degree of freedom represents the motion of the MEMS microstructure. Low-g acceleration pulses are applied to the MEMS–PCB assembly base to simulate shock pulses generated from a drop-table test. Simulation data are presented to show the effects of the natural frequency of the PCB, the natural frequency of the microstructure, and the shock pulse duration. Universal 3-D spectra representing the effect of these parameters are presented. It is found that neglecting the PCB effect on the design of MEMS devices under shock loads can lead to undesirable motion of their microstructures. The effects of electrostatic force and squeeze film damping are investigated. It is found that the amplification of motion due to the PCB can cause early pull-in instability for MEMS devices implementing electrostatic forces. The effect of higher order modes of a microbeam is studied through a continuous beam model coupled with a lumped model of the PCB. The limitations of the 2-DOF model are discussed. An experimental investigation is conducted to verify the theoretical results using a capacitive accelerometer. Experimental data for the response of the accelerometer while it is mounted on two representative PCBs due to different low-g shock conditions are shown.$hfill$[2008-0026]      

A case-based reasoning system for PCB principal process parameter identification

The Printed Circuit Board (PCB) manufacturing process usually consists of lengthy production activities. Each activity is controlled by a number of process parameters. Although numerous process parameters must be determined before fabrication, only a number of parameters called principal process parameters because they affect the quality of a PCB product. As long as the principal process parameters are identified efficiently and controlled well, the manufacturing lead-time can be shortened and the quality of the new PCB product can be assured. This research proposes a Case-Based Reasoning (CBR) system to infer the principal process parameters for a new PCB product. Each case in the case-base stores design specifications, process parameters, and the corresponding production quality specifications. A Significant Nearest Neighbor (SNN) search is developed to retrieve similar cases from a case-base. A Mutual Correlation Parameter Selection (MCPS) method and a correlation-based parameter setting method are developed to identify the principal parameters and infer their reasonable value range. A set of experiments and a practical implementation case are demonstrated to show the efficiency and accuracy of the proposed system.     

A case-based reasoning system for PCB defect prediction

The manufacturing process for a new Printed Circuit Board (PCB) design is often instable and might generate a number of defects during the complicated production process. Defects reduce the yield rate and increase the production costs. Although skilled engineers can predict the possible defect items for a new PCB product, this approach requires strong engineering experience and is time consuming. To conquer this problem, this research applies case-based reasoning (CBR) methodology to develop a defect prediction system for new PCB products. In the CBR system, each case is represented using the design specifications, defect items and corresponding costs. A vantage-based case indexing mechanism is developed to accelerate the case retrieval efficiency. In addition, a reasoning algorithm that considers the defect cost is proposed to infer the defect items that are interesting to PCB manufacturers. The system performance is analyzed to show the efficiency and accuracy of the proposed system. A practical implementation using a case-base provided by a PCB manufacturer is demonstrated.     

Simulation of the coupling of the external electromagnetic field to PCB traces in the SPICE simulator

In this article, a simple method of modeling and simulating electromagnetic field coupling to PCB in the SPICE simulator is presented. The method exploits two assumptions: quasi-TEM wave propagation along PCB traces and representation of an external electromagnetic noise by a plane wave. Under these assumptions, a model of electromagnetic field coupling to the PCB traces is created in the form of an active n-wire transmission line placed in an inhomogeneous (that is, three layers) medium. Next, using the method of successive approximations, an equivalent active n-port (described by means of scattering parameters) is found. This work results in formulas that express the external electromagnetic field in the form of current sources and the way they are simulated in SPICE. The method is illustrated with two examples. © 2004 Wiley Periodicals, Inc. Int J RF and Microwave CAE 14, 190–200, 2004.     

Production control policies for a flexible assembly system

Production control policies for an automated printed circuit board (PCB) assembly system are developed which fulfill a number of characteristics. First, they satisfy demand requirements for a realistic environment, i.e. an environment which allows machine failures and repairs as well as demand changes to occur. Second, they constitute solutions of intermediate generality, i.e. they are not specific to the system under study. Third, they are easily implementable in real time for a computerized system. Policies seek to satisfy both total production volume and balance among part types and to minimize work-in-process. The system's main controlling variables are the part entry decisions; that is, the time and type of part or parts to enter the system. Entry decisions are based on cumulative performance measures and current system capacity constraints like machine failures, bottleneck cell status, and maximum allowed work-in-process. Dispatching in front of production cells is done with the use of simple priority rules. Policies are tested on a simulation model of the PCB assembly implemented on an AI environment, the KEE-SIMKIT package on an Explorer Lisp machine.     

基于FPGA的RAID控制卡实现及仿真研究

首先介绍了基于FPGA的一种RAID控制卡的原理及系统设计、印刷电路板(PCB)的具体实现.由于板卡运行在66MHz总线时钟之上,必须考虑高频下电路的性能及电路的信号完整性等, 因而在PCB设计阶段对电路的仿真显得尤为重要.还将介绍基于IBIS模型的信号完整性仿真分析,并利用信号噪声分析软件(Hyperlynx)对高速电路设计中的PCB布局布线、匹配电阻设计和并行线串扰分析进行深入研究.根据仿真分析结果调整原设计,从而提高了信号质量,减少开发成本.     

3-Dimensional graphic image representation of holographic microscopical displacement pattern by using cubic spline function

For quantitative measurement of microscopical displacement of an object surface due to thermal stress, the holographic pattern measuring system (HPMS) has been developed by the authors, which is combined both the techniques of holographic interferometry and graphic image processing.

In this measuring sytem, a cubic spline function was applied to get the 3-dimensional graphic image patterns of the distribution of the displacement. The displacement is calculated from the interferometry fringe pattern, and the system was applied to deformation analysis of printed circuit board (PCB) due to thermal stress. The PCB deformation was expresed by 3-dimensional graphic image. A smooth curve could be obtained from rather less number of sampled data of interferometry fringe.     

Codence EDA中PCB分析工具Specctraquest的使用

电子设计自动化(EDA)技术是目前进行电子产品设计中所采用的主要技术,设计者利用它可以设计出更完美的产品,并且极大地缩短了设计周期。但是随着电子技术的不断发展,在设计中,特别是在高速PCB的设计中出现了一些新的问题。例如:延时、串扰、电磁干扰等物理设计问题,迫切需要提供一些仿真分析工具来解决这些问题。本文主要介绍了Cadence EDA软件中的信号完整性仿真设计工具SpecctraQuest的使用与建模方法。     

基于虚拟仪器的通用数字电路板测试系统设计

针对对数字电路板快速检测的需求,提出了一种基于虚拟仪器技术的通用数字电路板测试系统设计方案,以满足对数字电路板进行快速功能验证的需要;整个系统包括硬件总体结构模块和数字电路测试软件模块,系统通过硬件平台产生测试激励,然后利用LabVIEW软件开发的通用型数字电路板测试软件进行数字电路板功能验证测试,实现了对数字电路板快速功能验证测试;实际应用表明,该系统具有测试准确、运行稳定可靠、操作方便、维护简单的特点,为数字电路板的故障排除提供了依据。     

PCB数控钻床下钻机构多体动力学分析与研究

为了改善印制电路板数控钻床下钻时的动力学特性,针对印制电路板孔位成形的重要总成——下钻机构,构建了它的实体模型和动力学模型,并在动力学模型中采用基于三次曲线的平滑运动加速度控制方法。通过罗伯森一维腾堡方法对下钻机构进行多体动力学分析,发现采用预拉弹簧以平衡运动部件的重力可以改善其动力学特性,并可将电机的扭矩控制在一定振幅范围内。最后,采用机械多体动力学分析软件证实其可行性并提出确定弹簧的预拉长度参数的方法。     

基于区域填充算法的PCB网络提取

随着电子技术的迅速发展,用于PCB行业的设备与技术也突飞猛进。飞针测试机作为判定PCB板的电气连接是否良好的PcB检测设备,可以准确无误地检测出PCB板上各点之间的开短路情况,从而发现PCB板上出现开短路错误的位置。而要对PCB板的物理通断进行电气测量,首先必须知道PCB板正确的物理连接（即PCB的网络分布）情况。文章将主要讲述如何利用一种图形区域填充的算法,从用于绘制PCB板的GERBER文件中获取PCB板的正确网络分布。     

多头拱架型贴片机贴装顺序优化

针对全视觉贴片机的贴装顺序优化问题,首先通过建立贴装时间的数学模型,提出最大化同时取料次数和合理安排取贴循环顺序这一策略;随后,通过对数学模型的分析,提出了分别运用启发式搜索算法和单亲进化的遗传算法来解决同时取料次数的优化问题及取贴循环的优化安排问题;实验结果证明,所提算法能有效提升贴片机的贴装效率,减少贴装时间。     

基于GIS技术的双层PCB布线的空间剖分算法

双层印制电路板(PCB)通常空间结构及布线线形复杂、约束规则众多,而常用PCB空间结构简单、布线线形单一,不能有效利用PCB的空间关系及拓扑信息引导布线规划。为弥补以前工作的不足,提出一种基于GIS(geographic information system)技术的空间剖分算法,首先利用空间距离与几何要素拓扑关系进行分组预处理,然后引入矢栅一体化模型构建复杂空间及属性约束下的网络模型,基于该网络模型提取区域基准线并利用空间缓冲区技术得到空间剖分结果,从而引导布线规划。实验结果表明,该算法能够在满足所有设计规则的情况下实现100%的布线连通率,同时有效利用布线空间资源;提出的算法布线线形接近人工布线,对于实现复杂场景与多约束下的双层PCB自动化布线具有实际意义。     

A novel porous anodic alumina based capacitive sensor towards trace detection of PCBs

To detect polychlorinated biphenyls (PCBs), a novel porous anodic alumina (PAA) based capacitive sensor working at room temperature has been developed. The parallel nanopores of PAA not only provide large surface area for PCB adsorption, but also benefit for the enhancement of capacitive response. By dropping the PCB methanol solution on the surface of PAA, it is convenient to load PCB into the nanopores by solvent evaporation. 3,3′,4,4′-tetrachlorobiphenyl (PCB77) was chosen as a typical sample of PCBs to investigate the sensing properties of the capacitive sensor. The capacitance of the PAA membrane shows remarkable enhancement after PCB77 solution was loaded while no significant change can be seen after the pure solvent was loaded. The capacitive sensor also shows good response to PCB77 even in the presence of the interferent of benzene. The sensing mechanism has been qualitatively discussed based on a parallel plate capacitor model. The detection limit is down to 8 × 10⁻⁸ M towards PCB77. The novel PAA based capacitive sensor exhibits great potential for practical application in trace detection of PCBs.     

An adaptive clustering-based genetic algorithm for the dual-gantry pick-and-place machine optimization

This research proposes an adaptive clustering-based genetic algorithm (ACGA) to optimize the pick-and-place operation of a dual-gantry component placement machine, which has two independent gantries that alternately place components onto a printed circuit board (PCB). The proposed optimization problem consists of several highly interrelated sub-problems, such as component allocation, nozzle and feeder setups, pick-and-place sequences, etc. In the proposed ACGA, the nozzle and component allocation decisions are made before the evolutionary search of a genetic algorithm to improve the algorithm efficiency. First, the nozzle allocation problem is modeled as a nonlinear integer programming problem and solved by a search-based heuristic that minimizes the total number of the dual-gantry cycles. Then, an adaptive clustering approach is developed to allocate components to each gantry cycle by evaluating the gantry traveling distances over the PCB and the component feeders. Numerical experiments compare the proposed ACGA to another clustering-based genetic algorithm LCO and a heuristic algorithm mPhase in the literature using 30 industrial PCB samples. The experiment results show that the proposed ACGA algorithm reduces the total gantry moving distance by 5.71% and 4.07% on average compared to the LCO and mPhase algorithms, respectively.