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Article
Publication date: 3 April 2017

József Hlinka, Miklós Berczeli, Gábor Buza and Zoltán Weltsch

This paper aims to discuss the effect of surface treatment on the wettability between copper and a lead-free solder paste. The industrial applications of laser

Abstract

Purpose

This paper aims to discuss the effect of surface treatment on the wettability between copper and a lead-free solder paste. The industrial applications of laser technologies are increasing constantly. A specific laser treatment can modify the surface energy of copper and affect the wetting properties.

Design/methodology/approach

The surfaces of copper plates were treated using an Nd:YAG laser with varying laser powers. After laser surface treatment, wetting experiments were performed between the copper plates and SAC305 lead-free solder paste. The effect of laser treatment on copper surface was analysed using optical microscopy and scanning electron microscopy (SEM).

Findings

The experimental results showed that the wetting contact angles changed with the variation in laser power. Furthermore, it means that the surface energy of copper plates was changed by the laser treatment. The results demonstrated that the contact angles also changed when a different soldering paste was used.

Originality/value

Previous laser surface treatment can be a possible way to optimize the wettability between solders and substrates and to increase the quality of the soldered joints.

Details

Soldering & Surface Mount Technology, vol. 29 no. 2
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 1 July 2006

Paulo Bartolo, Joel Vasco, Bruno Silva and Carlos Galo

Laser milling is a recent process in mould making, providing several advantages over traditional mould making technologies by reducing manufacturing time, shortening the…

Abstract

Purpose

Laser milling is a recent process in mould making, providing several advantages over traditional mould making technologies by reducing manufacturing time, shortening the number of machining operations and avoiding expensive electrodes. This paper investigates the influence of the operating conditions on both the surface quality and material removal for two types of materials commonly used in mould making.

Design/methodology/approach

Laser scanning strategies and operating parameters like scanning speed and laser frequency and power were tested, regarding surface quality and material removal rate. The most representative parameter of the real surface quality, Rk, the core roughness parameter, is used to characterise the surface finishing on all cavities.

Findings

The findings of this research work suggest that it is possible to significantly reduce processing time by increasing the hatch spacing up to a value close to the laser beam spot diameter, without compromising surface quality. Lower pulse frequencies and laser power are more appropriate whenever surface quality is an issue. Higher material removal rates are achieved by increasing both the pulse frequency till an optimum value and laser power. The increase of scanning speed reduces the material removal rate by decreasing the overlap degree between individual laser pulses.

Originality/value

The originality is to correlate the influence of the operating conditions of laser milling on both the surface quality and material removal for different types of materials.

Details

Assembly Automation, vol. 26 no. 3
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 1 April 1995

J.H. Choi

Photoresist imaging traditionally uses silver halide or diazo based phototools for contact exposure to an actinic UV light source. By contrast, laser direct imaging uses…

Abstract

Photoresist imaging traditionally uses silver halide or diazo based phototools for contact exposure to an actinic UV light source. By contrast, laser direct imaging uses digital imaging data to control a laser beam scanner to write directly on to the photoresist, therefore eliminating the need for phototools. In the past, even though the benefit of a UV system was recognised, laser direct imaging was mainly limited to the use of a visible laser as early UV lasers were low in power, unreliable and expensive. So far, no visible systems have gained commercial recognition because of the inherent deficiencies of the visible system. Recent advantages in UV laser equipment and UV sensitive photoresist have now made UV laser direct imaging a viable alternative to traditional contact imaging. As new UV laser imaging systems start to emerge, interest and attention are also growing among printed circuit board manufacturers. This paper discusses various attributes of a UV laser direct imaging system and fundamental differences in photophysics between laser direct imaging and conventional UV imaging.

Details

Circuit World, vol. 21 no. 4
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 1 June 1999

Franck Rigolet

Conventional processes for cleaning, stripping and surface preparation mainly use solvents or abrasives which can be harmful for the environment, and can also damage the…

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558

Abstract

Conventional processes for cleaning, stripping and surface preparation mainly use solvents or abrasives which can be harmful for the environment, and can also damage the surface of the material. Moreover, the use of these products generates a large quantity of waste that needs to be reprocessed or discarded. In many cases, laser is the solution to these problems. Its possibilities are still under‐exploited but they are growing with the improvement of the performances of the CO2, YAG and Excimer lasers. This paper describes the laser cleaning process and the benefits which can be obtained.

Details

Assembly Automation, vol. 19 no. 2
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 1 June 2002

Ian Jones

The latest developments in the use of lasers for welding plastics are reviewed. Lasers were demonstrated as being suitable for welding plastics in 1970. However, it is…

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1550

Abstract

The latest developments in the use of lasers for welding plastics are reviewed. Lasers were demonstrated as being suitable for welding plastics in 1970. However, it is only now that they are finding wide application following technical developments in transmission laser welding and ClearWeld™, and the availability of small, economic diode laser systems.

Details

Assembly Automation, vol. 22 no. 2
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 29 July 2014

Shouxu Wang, Li Feng, Yuanming Chen, Wei He, Zhihua Tao, Shijing Chen and Huan Xu

The purpose of this paper is to form good cutting qualities in glass-epoxy material for opening flexible areas of rigid-flex printed circuit boards (PCB) by ultraviolet…

Abstract

Purpose

The purpose of this paper is to form good cutting qualities in glass-epoxy material for opening flexible areas of rigid-flex printed circuit boards (PCB) by ultraviolet (UV) laser cutting.

Design/methodology/approach

The cut width and cut depth of glass-epoxy materials were both observed to evaluate their cutting qualities. The heat affected zone (HAZ) of the glass-epoxy material was also investigated after UV laser cutting. The relationships between the cut width and the parameters of various factors were analyzed using an orthogonal experimental design.

Findings

The cut width of the glass-epoxy material gradually increased with the increment of the laser power and Z-axis height, while cutting speed and laser frequency had less effect on the cut width. Optimal parameters of the UV laser process for cutting glass-epoxy material were obtained and included a laser power of 6W, a cutting speed of 170 mm/s, a laser frequency of 50 kHz and a Z-axis height of 0.6 mm, resulting in an average cut width of 25 μm and small HAZ.

Originality/value

Flexible areas of rigid-flex PCBs are in good agreement with the cutting qualities of the UV laser. The use of a UV laser process could have important potential for cutting glass-epoxy materials used in the PCB industry.

Details

Circuit World, vol. 40 no. 3
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 1 April 1984

M.N. Watson

Many small holes need to be drilled in printed circuit boards to achieve a high packing density of circuit components. Even with NC control, conventional mechanical…

Abstract

Many small holes need to be drilled in printed circuit boards to achieve a high packing density of circuit components. Even with NC control, conventional mechanical techniques are relatively slow and holes smaller than 035 mm diameter are difficult to achieve in production. Laser drilling has been suggested as a potentially fast technique capable of drilling small holes, so trials have been conducted on thin, flexible kapton board, and on 08 mm and 16 mm thick epoxide woven glass fabric board with 12 and 36 micron thick copper cladding. Using a 600 W CO2 laser, the proposed technique was to pre‐etch holes in the copper which would then act as a mask to the beam, so drilling only where etched holes existed. This technique was feasible on the flexible board, but not on the thicker boards because of damage to the copper. Using a pulsed Nd‐YAG laser to drill through both copper and laminate gave good results, but more work is necessary to eliminate occasional delamination of the copper around the hole. Through‐hole plating of the drilled holes appeared to present no special problems.

Details

Circuit World, vol. 11 no. 1
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 23 February 2010

Steffen Nowotny, Robert Muenster, Siegfried Scharek and Eckhard Beyer

Laser materials processing system technology has become indispensible to the tool and die manufacturing industries and for repairing engines and turbines. The laser

Abstract

Purpose

Laser materials processing system technology has become indispensible to the tool and die manufacturing industries and for repairing engines and turbines. The laser build‐up welding process especially is now a standard technology where cost efficient, precisely localized and near net shape repair welds are required. The concept of integrating the modular laser components into standard machine tools makes the technology easily accessible to the user and very efficiently combines build‐up welding and metal‐cutting processes.

Design/methodology/approach

Specially designed laser system technology is available as add‐on kits for different machine tools of the end‐users. They can choose from a large variety of laser sources, manufacturing heads, welding material supply as well as process control devices. User‐friendly software guides through the entire process chain. So, optimized laser systems for different cladding and build‐up applications can be installed easily and inexpensively in common turning and milling machines.

Findings

The laser integration into machine tools connects efficiently laser and mechanical finish operations. This way, repairs, rapid design changes, and direct manufacturing of parts are available with a high level of accuracy and in very short times. Additionally, exactly specified property profiles can be realized.

Originality/value

The laser application shown here represents a new technical solution of laser integration into machine tools, which offers an efficient complete machining. It allows to quickly switch between milling and laser processing, which simplifies the combination of both processes. The computer numerical controlled process control treats the laser head just like a milling tool. This shortens the machining time and expands the capability of the machine with respect to generating multiple shapes.

Details

Assembly Automation, vol. 30 no. 1
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 1 September 2005

K.M. Fan, W.L. Cheung and I. Gibson

The purpose of this paper is to report on a study of the movement of the powder bed material during selective laser sintering (SLS) of bisphenol‐A polycarbonate (PC…

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1720

Abstract

Purpose

The purpose of this paper is to report on a study of the movement of the powder bed material during selective laser sintering (SLS) of bisphenol‐A polycarbonate (PC) powder and its effect on the morphology of the sintered specimen.

Design/methodology/approach

Two sintering experiments, i.e. single‐spot laser sintering and raster‐scan laser sintering, were carried out and the material movement mechanisms were investigated in situ and subsequently by scanning electron microscopy.

Findings

During the raster‐scan laser sintering process, the movement of the powder was found to be primarily perpendicular to the scanning direction. When sintering at a high laser power, it significantly affected the surface morphology of the sintered specimens and parallel surface bands occurred along the scanning direction.

Research limitations/implications

Experiments were carried out on a modified laser engraving machine rather than a commercial SLS machine.

Practical implications

A schematic model of the material movement mechanism for each of the sintering strategies is presented.

Originality/value

The results further the understanding of the sintering behaviour of the powder bed.

Details

Rapid Prototyping Journal, vol. 11 no. 4
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 June 1994

Shu‐Hao Chuang and Zuu‐Chang Hong

Solutions of the twin plane jets HF chemical laser flow based on aturbulent kinetic theory, due to a modified Green’s function method, arepresented. The calculated results…

Abstract

Solutions of the twin plane jets HF chemical laser flow based on a turbulent kinetic theory, due to a modified Green’s function method, are presented. The calculated results of probability density function (PDF) of various chemical species in velocity space, and mass fraction concentration distributions of various reactants and products in the flow field, are revealed and discussed in this analysis. The transport phenomena of different pumping rate, collisional deactivation rate, and radiative deactivation rate in the interaction between the twin plane jets HF chemical laser show that the properties of species mass fraction concentrations, collisional reaction rate, and radiative incident intensity are the dominant factors. The present study provides the fundamentals for theoretical understanding of twin plane jets HF chemical laser and further application to multiple‐jet HF chemical laser analysis.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 4 no. 6
Type: Research Article
ISSN: 0961-5539

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