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Laser soldering provides a useful tool for the electronics manufacturer and has found a number of successful industrial applications. The laser provides highly controllable localised heating in a manner similar to hand soldering and has distinct advantages over other soldering methods. However, the heating processes that occur in laser soldering are complex making it difficult to predict whether a particular operation will be successful. Numerical modelling provides a valuable tool in answering such questions but the modelling process and the assumptions upon which it is based must be understood if the results are to be reliable.This paper explains the assumptions made in deriving a suitable model and describes the use of a commercial finite element modelling package to aid the understanding of laser soldering processes, with a particular emphasis on single and multi‐pass scanned beam soldering operations.

The application of laser technology has recently become economically viable for microelectronics and surface mount technology. Semiconductor laser technology may prove to be the only technology capable of solving the assembly problems that will accompany further advances in microelectronics. Some characteristics of Nd‐YAG and CO2 lasers are compared with the performance of semiconductor diode lasers for soldering purposes. The early stages of evaluation of semiconductor diode lasers in an experimental soldering station at the University of Hull suggest that these lasers serve as an efficient selective, controllable and compact high power density heating source capable of meeting present and future microelectronics soldering requirements.

The use of lasers to selectively solder joints in electronic assemblies has a number of advantages over methods which involve heating of the whole assembly. However, the localised energy delivery means that the heating and melting behaviour of the solder is particularly dependent on external and process influences. This paper aims to propose a new approach to monitoring and feedback control of the melting process through image acquisition and processing.

In order to evaluate the proposed feedback strategy, a series of experiments have been performed using a semiconductor diode laser controlled by a PC, which also performs image acquisition and processing operations. Two main processing techniques, based on edge detection and Fourier analysis, have been evaluated.

It has been shown that the proposed technique is capable of controlling laser pulse duration to correct for variations in joint geometry, material parameters and laser energy delivery and results in more consistent solder joint formation than is achieved using fixed pulse durations.

The results demonstrate that image processing is a viable technique for the control of laser soldering processes. This could significantly increase the range of applications of laser soldering techniques where determination and control of pulse parameters have been one of the major challenges.

Although some work has been conducted on the use of pyrometer feedback to control laser processing, it appears that no work has been published on the use of image processing. While the processing algorithms themselves are not novel, this is a new application of these algorithms.

To design a flexible integrated robotic assembly and rework (remanufacturing) cell for assembly, selective assembly and rework of advanced surface mount components (SMCs) using the generic methodology developed in this paper.

Manual rework procedures are investigated for all advanced SMCs. General and specific component‐related rework considerations are obtained and necessary tooling candidates for automation are determined. This is followed by determination of the specific automated rework procedure and selection of suitable tooling for automated robotic rework and generation and evaluation of design concepts.

The developed methodology, which considers the reflow tool at the centre of the development process, has worked well in designing a flexible integrated robotic assembly and rework cell.

This study identified the rework requirements for advanced SMCs, the essential features for rework reflow tools, criteria for comparing reflow tools, and a generic procedure for design and concept selection.

It provides valuable knowledge for designers of flexible integrated robotic assembly and rework cells for assembly, selective assembly and rework of advanced SMCs.

In this paper a spline approximation of deficiency 3 and a step of length 3h method is proposed to approximate the solution of the problem and its derivatives. The Falkner‐ Skan equation has been solved through the use of the shooting technique for handling the problem when the conditions imposed are of boundary‐value rather than an initial‐value type for different values of its parameters. Comparisons are made between the data resulting from the proposed method and those obtained by others.

With the ever‐decreasing size of electronic components, examines the use of laser soldering, particularly of fine‐pitch, high value devices. Discusses the advantages and disadvantages of using lasers and the applications to which they are suited. Looks at the different types of lasers and how their different wavelength of operation affects the soldering process. Describes an experimental laser soldering station and its ability to solder circuit boards. Concludes that modern electronic component packaging technology is demanding new techniques for the interconnection of devices, and that the application of lasers to the traditional technique of soldering will enable this tested process to be applicable to the very fine pitch devices now being introduced.

This study aims to review the effect of copper percentage in Sn-based solder alloys (Sn-xCu, x = 0–5 Wt.%) on intermetallic compound (IMC) formation and growth after laser soldering.

This study reviews the interfacial reactions at the solder joint interface, solder joint morphology and the theory on characterizing the formation and growth of IMCs. In addition, the effects of alloying and strengthening mechanism, including wettability, melting and mechanical properties are discussed.

This paper presents a comprehensive overview of the composition of tin-copper (Sn-Cu) solders with a potential to enhance their microstructure, mechanical characteristics and wettability by varying the Cu percentage. The study found that the best Cu content in the Sn-xCu solder alloy was 0.6–0.7 Wt.%; this composition provided high shear strength, vibration fracture life value and ideal IMC thickness. A method of solder alloy preparation was also found through powder metallurgy and laser soldering to improve the solder joint reliability.

This study focuses on interfacial reactions at the solder joint interface, solder joint morphology, modelling simulation of joint strength and the theory on characterising the formation and growth of IMC.

The paper comprehensively summarises the useful findings of the Sn-Cu series. This information will be important for future trends in laser soldering on solder joint formation.

The purpose of this paper is to apply the developed systematic mechanical design methodologies, that are obtained in part I, to investigate their success in designing mechanics of a flexible printed circuit board assembly (PCBA) rework cell.

The decision of soldering and desoldering tool, which is the most critical function of a PCBA rework or remanufacturing cell, significantly influences overall design concept. Therefore, the paper starts by applying the design methodology to the soldering and desoldering function. The same study is repeated for the rest of the sub‐functions but only the results are provided.

An application of rework machine design methodology for the design of a PCBA rework cell has been made available. In addition to this, the embedded knowledge, such as the requirements list, the function structure, the function/means tree, the weighted objective tree and evaluation chart for the soldering and desoldering function are provided.

The paper is the first work providing both embedded knowledge and the application of the systematic design methodology for the design of a fully automated flexible PCBA rework cell. The methodology leads rework machine designers in a well‐controlled and structured design environment.

The design methodology can be applied to all functions or targeted on key weighted areas to ensure that the designed rework machine meets the key areas of concerns. Furthermore, the methodology is generic and may be used to develop other complex manufacturing sytems.

The purpose of this paper is to investigate the laser soldering of fine pitch quad flat package (QFP) devices using lead‐free solders and solder joint reliability during thermal cycling.

QFP devices were selected as the test vehicles and were soldered with four alloy types, Sn37Pb, Sn3.5Ag, Sn3.8Ag0.7Cu and Sn3.8Ag0.7Cu0.03Ce. The experimental samples were QFP‐256 devices with lead‐free solder paste on the printed circuit boards. The packages were dried for 24 h at 125°C prior to reflow soldering. Soldering experiments on the QFP devices were carried out with an infrared (IR) reflow soldering oven and a diode laser (DL) soldering system. Reflow soldering was performed at peak temperatures of 210°C (SnPb), 240°C (SnAgCu and SnAgCuCe) and 250°C (SnAg), as determined on the boards. Pull testing was adopted to evaluate the tensile strength of the four solders using an STR–1000 micro‐joint strength tester.

The tensile force of the QFP micro‐joints increased as laser intensity increased when it was less than an “optimal” value. The maximum tensile force of the QFP micro‐joints was gained when the laser intensity had increased to 2,165, 2,127, 2,165 and 2,064 W/cm², depending on the alloy used. The thermal fatigue performance of three lead‐free solder joints, SnAgCuCe, SnAgCu and SnAg, was determined to be superior to that of the eutectic SnPb alloy. After soldering without thermal cycling tests, the fracture morphology of soldered joints exhibited characteristic toughness fracture with both of the soldering methods. After 700 thermal cycles, the fracture mechanism was also toughness fracture, nevertheless, the dimples became large. The fracture morphology of the soldered joints subjected to 1,500 thermal cycles indicated brittle intergranular fracture on the fracture surface and no intense plastic deformation appeared before fracture with IR soldering. For DL soldering, the pull fracture model of the SnAgCuCe was completely ductile in the soldered joint with 1,500 thermal cycles.

The paper usefully investigates the influence of laser intensity on the tensile strength of different soldered joints and the solder joint reliability during thermal cycling.

Accurate alignment is vital to acquire high‐quality joints with less negative effects on the rest parts of the chip or other components on a board. The purpose of this paper is to develop an integrated laser soldering system, which is accurate, compact, and flexible.

The system combines an X‐Y stage, a computer vision module and a laser module. It would automatically sense the soldering pads with computer vision, fulfill the alignment of laser beam and soldering pads together with the motion system, and finish the soldering work with laser power.

Based on the analysis of experimental data, it is found that lens distortion and assembly angular errors of the X‐Y stage play a distinct role on the alignment errors.

The paper proposes an algorithm based on straight line method to reduce image distortion, and a compensation algorithm on the angular errors of the X‐Y positioning stage. Experimental results show that the overall precision is satisfied for fine pitch applications and the system performs well.