Experiments with routing on printed circuit boards

Several ways of utilizing Lee's wave algorithm for routing on printed circuit boards were compared. It was proved that the order of net processing influenced the quality of the solution of a given interconnection problem. Moreover, it was found that the choice of ‘source’ and ‘target’ formations influenced both the computational time and the quality of the solution. The results obtained allowed the performance of the SYSDEB77 system for routing on two-layer boards to be improved.     

Prerouting analysis of printed circuit boards

Several methods used for the prerouting analysis of printed circuit boards are compared. The quality of a method is expressed as the correlation between predicted and actual values of objective measures of an interconnection problem complexity. The experimental data confirm that some indicators of a board complexity which are often used in practice, such as component density, are highly unreliable. The PAP program is based on the modelling of the actual routing process. It has been experimentally proved that the PAP program provides reliable results which can be used for the detailed analysis of an interconnection problem.     

Automatic inspection system for printed circuit boards

The purpose of this correspondence is to present problems and methods in automating visual inspection of printed circuit boards (PCB's). Vertical and diagonal illumination are useful in detecting PCB patterns correctly. An algorithm comparing local features of the patterns to be inspected with those of the pattern to be referenced is proposed. An inspection system using developed technologies is also described.     

Inspection of printed circuit boards by connectivity preservingshrinking

Two algorithms for visual inspection of printed-circuit boards are presented that perform width checking of conductors and insulators. The first detects the difference between the results of shrinking and connectivity-preserving shrinking (CPS). The second algorithm produces a difference between the original and the shrunk picture. This result is subject to a number of CPS-operations after which errors are easily detected. Both algorithms can be adapted to a suitable level of sensitivity to sharp corners and edge irregularities. A sequential version of CPS is also described which is well suited for hardware implementation in a pipelined structure     

Artwork production for multi-layer printed circuit boards by computer

This paper describes a computer system which integrates three types of numerical control machines in the production of artwork drawings and drill tapes for multi-layer printed circuit boards.     

Design of meander line inductors on printed circuit boards

A partial‐element circuit model for meander line inductors printed on circuit boards is proposed and its relation with the physical layout is derived. A procedure for the design is presented allowing to obtain inductances between 8 and 50 nH in the range from 30 to 1000 MHz with a 5% mean error. © 2001 John Wiley & Sons, Inc. Int J RF and Microwave CAE 11: 219–230, 2001.     

An evolutionary design methodology of printed circuit boards for high-speed VLSIs

As operation frequencies of the printed circuit boards (PCBs) increase in keeping with VLSI frequencies in the GHz domain, two independent serious problems occur in the PCB design. One is waveform distortion problem, or signal integrity (SI) degradation problem, in PCB traces. And the other is power-supply drop problem, or power integrity (PI) degradation problem, in PCB power planes. Those problems are barely able to be overcome on case-by-case empirical designs conventionally. In this paper we newly propose a design approach for each problem, both of which are based on the genetic algorithm. And we obtained improvement ratios of more than double compared with the both conventional designs for SI and PI degradations, respectively.     

Modeling double‐side printed meander‐line inductors on printed circuit boards

A lumped element model for a double‐side printed meander‐line inductor with closed‐ form expressions for the electrical model parameters L, C, R_l, and R_c is presented. These structures are cheaper than coils and need less area per unit of inductance than single‐side printed meander‐line inductors. The model has been validated with measurements from 30 to 1000 MHz, finding a mean error in the inductance parameter of about 1%. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 13: 105–112, 2003.     

The application of interactive graphics to computer aided circuit design

When a computer is used in electric circuit design it forms part of an iterative loop and so the ergonomics of its input and output become of major importance. A circuit analysis program is described, which uses interactive graphics, and which was designed with particular attention given to ergonomics.     

Gear-tooth generation with interactive graphics

The contact surfaces of most practical gearing systems are of involute form. This satisfies the fundamental geometrical requirements imposed by the need for continuous contact and a constant velocity ratio. The parts of the tooth form which do not mesh are determined by other considerations such as tooth strength and wear characteristics. The overall geometry of a generated tooth is a complex shape that may be analysed most readily by numerical techniques, particularly when the generating rack is nonstandard. This paper describes computer programs which enable the user to define the rack geometry by interactive graphics, to examine the shape of teeth generated by such a rack and to compute such quantities as the area enclosed by meshing teeth for applications in the field of gear-pump design.     

A solution technique for placing digital integrated circuitry on printed circuit boards

A mathematical formulation of the problem is presented using the concepts and terminology of graph theory. This formulation includes both stages of the placement problem wherein the vertices of the circuit graph are partitioned into several subsets (representing integrated circuit packages) which are, in turn, assigned to geometric positions corresponding to the printed circuit board specifications. Utilizing the manhattan metric, a heuristic procedure is described which provides minimum length placements on two-sided printed circuit boards consistent with the requirements of PC board designers. Computational results from problems arising in actual design efforts are discussed.     

Optimal component-insertion sequenceplanning methodology for the semiautomatic assembly of printed circuit boards

One of the primary concerns in the manufacturing of printed circuit boards (PCBs) is the definition of optimum component-insertion sequences for manual and automated operations. The problem is dynamic and multiple feasible solutions can be found. The research work described in this paper has developed a component-insertion sequencing methodology and a proof-of-concept expert system for printed circuit boards. This system solves the component-insertion sequencing problem for semi-automated work cells which utilize a light guiding system to identify for the operator where to assemble the next component. The innovation of the methodology is the application of Artificial Intelligence and Expert Systems techniques to represent the human reasoning involved in semi-automated PCB assembly planning. Based on established assembly criteria, sequencing decision rules and data available from a CAD system, the methodology leads to optimum component-insertion sequences.     

PCAAD—an object-oriented expert system for assembly of printed circuit boards

Abstract: Electronics manufacturing is the fastest growing segment of the manufacturing domain today. The rapid change in printed circuit board manufacturing has been possible with the induction of surface-mounted components and robotic assembly. The high density packaging capability of surface-mounted technology has contributed enormously to the development of new trends in printed circuit board manufacturing.
PCAAD—Printed Circuit Board Assembly Advisor—is an expert system developed to capture this new technology and its interaction with the existing through-hole-mounting technology. In building the system, rules and guidelines pertaining to assembly are formulated and incorporated into the knowledge-base. The system is built on an object-oriented paradigm. The object-oriented approach, Smalltalk-80, the object-oriented language and the hierarchical rule structure paradigm are briefly discussed. A rating system is also introduced to rank various assembly designs. PCAAD can advise whether or not to proceed with assembly with a particular assembly design, and suggests assembly modification at the early stage of design to eliminate the assembly problems in the later phase of board production.     

Knowledge-based linguistic equations for defect detection through functional testing of printed circuit boards

Increasing globalization of the economy is imposing tough challenges to manufacturing companies. The ability to produce highly customized products, in order to satisfy market niches, requires the introduction of new features in automation systems. Flexible manufacturing processes must be able to handle unforeseen events, but their complexity makes the supervision and maintenance task difficult to perform by human operators.This paper describes how linguistic equations (LE), an intelligent method derived from Fuzzy Algorithms, has been used in a decision-helping tool for electronic manufacturing. In our case the company involved in the project is mainly producing control cards for the automotive industry. In their business, nearly 70% of the cost of a product is material cost. Detecting defects and repairing the printed circuit boards is therefore a necessity. With an ever increasing complexity of the products, defects are very likely to occur, no matter how much attention is put into their prevention. Therefore, the system described in this paper comes into use only during the final testing of the product and is purely oriented towards the detection and localization of defects. Final control is based on functional testing. Using linguistic equations and expert knowledge, the system is able to analyze that data and successfully detect and trace a defect in a small area of the printed circuit board. If sufficient amount of data is provided, self-tuning and self-learning methods can be used. Diagnosis effectiveness can therefore be improved from detection of a functional area towards component level analysis.     

Analytical characteristic impedance determination method for microstrip lines fabricated on printed circuit boards

An analytical method for determining the characteristic impedance of microstrip lines fabricated on printed circuit board technology is presented. The method is based on a rigorous analysis of the equations involved with the coplanar‐waveguide to microstrip transitions composing an actual radio‐frequency test fixture, and allows the simultaneous determination of the characteristic impedance and the dominant pad parasitics. The extracted data agree well with the values expected from time domain data, verifying the validity of the method. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

Design and process considerations for fabricating RF MEMS switches on printed circuit boards

Design considerations and process development for fabricating radio frequency microelectromechanical systems (RF MEMS) switches on microwave laminate printed circuit boards (PCBs) are presented in details in this work. Two key processes, high-density inductively coupled plasma chemical vapor deposition (HDICP CVD) for low-temperature silicon nitride deposition, and compressive molding planarization (COMP) have been developed for fabricating RF MEMS switches on PCB. The effects of process conditions of HDICP CVD on low-temperature nitride film are fully characterized for its use in RF MEMS switches on PCB. Not only can COMP planarize the surface of the photoresist for lithographic patterning over topologically complex surfaces, but also simultaneously create a membrane relief pattern on the surface of a MEMS structure. Several membrane-type capacitive switches have been fabricated showing excellent RF performance and dynamic responses similar to those on semiconductor substrates. This technology promises the potential of enabling further monolithic integration of switches with other RF components, such as antennas, microwave monolithic integrated circuits (MMICs), phase shifters, tunable filters, and transmission lines on the same PCBs reducing the losses due to impedance mismatching from components/system assembly and simplifies the design of the whole RF system. [1416].     

A particle swarm optimization approach for components placement inspection on printed circuit boards

The importance of the inspection has been magnified by the requirements of the modern manufacturing environment. In electronics mass-production manufacturing facilities, especially in the printed circuit board (PCB) industry, 100% quality assurance of all work-in-process and finished goods is required in order to reduce the scrap costs and re-work rate. One of the challenges for PCB inspection is in the use of a surface mount device (SMD) placement check. Missing, misaligned or wrongly rotated components are the critical causes of defects. To prevent the PCB from having these defects, inspection must be done before the solder reflow process commences, otherwise, everything will be too late. The research reported in this paper concentrates on automatic object searching techniques, in a grey-scale captured image, for locating multiple components on a PCB. The presented approach includes the normalized cross correlation (NCC) based multi-template matching (MTM) method. The searching process has been carried out by using the proposed accelerated species based particle swarm optimization (ASPSO) method and the genetic algorithm (GA) approach as a reference. The experimental results of the ASPSO-based MTM approaches are reported.