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1 – 10 of 41
Article
Publication date: 1 August 2016

Thomas D.A. Jones, David Flynn, Marc P.Y. Desmulliez, Dennis Price, Matthew Beadel, Nadia Strusevich, Mayur Patel, Chris Bailey and Suzanne Costello

This study aims to understand the influence of megasonic (MS)-assisted agitation on printed circuit boards (PCBs) electroplated using copper (Cu) electrolyte solutions to improve…

Abstract

Purpose

This study aims to understand the influence of megasonic (MS)-assisted agitation on printed circuit boards (PCBs) electroplated using copper (Cu) electrolyte solutions to improve plating efficiencies through enhanced ion transportation.

Design/methodology/approach

The impact of MS-assisted agitation on topographical properties of the electroplated surfaces was studied through a design of experiments by measuring surface roughness, which is characterised by values of the parameter Ra as measured by white light phase shifting interferometry and high-resolution scanning electron microscopy.

Findings

An increase in Ra from 400 to 760 nm after plating was recorded for an increase in acoustic power from 45 to 450 W. Roughening increased because of micro-bubble cavitation energy and was supported through direct imaging of the cavitation. Current thieving effect by the MS transducer induced low currents, leading to large Cu grain frosting and reduction in the board quality. Current thieving was negated in plating trials through specific placement of transducer. Wavy electroplated surfaces, due to surface acoustic waves, were also observed to reduce the uniformity of the deposit.

Research limitations/implications

The formation of unstable transient cavitation and variation of the topology of the Cu surface are unwanted phenomena. Further plating studies using MS agitation are needed, along with fundamental simulations, to determine how the effects can be reduced or prevented.

Practical implications

This study can help identify manufacturing settings required for high-quality MS-assisted plating and promote areas for further investigation, leading to the development of an MS plating manufacturing technique.

Originality/value

This study quantifies the topographical changes to a PCB surface in response to MS agitation and evidence for deposited Cu artefacts due to acoustic effects.

Details

Circuit World, vol. 42 no. 3
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 14 March 2018

Alaaldeen Al-Halhouli, Hala Qitouqa, Abdallah Alashqar and Jumana Abu-Khalaf

This review paper aims to introduce the inkjet printing as a tool for fabrication of flexible/wearable sensors. It summarizes inkjet printing techniques including various modes of…

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Abstract

Purpose

This review paper aims to introduce the inkjet printing as a tool for fabrication of flexible/wearable sensors. It summarizes inkjet printing techniques including various modes of operation, commonly used substrates and inks, commercially available inkjet printers and variables affecting the printing process. More focus is on the drop-on-demand printing mode, a strongly considered printing technique for patterning conductive lines on flexible and stretchable substrates. As inkjet-printed patterns are influenced by various variables related to its conductivity, resistivity, durability and dimensions of printed patterns, the main printing parameters (e.g. printing multilayers, inks sintering, surface treatment, cartridge specifications and printing process parameters) are reported. The embedded approaches of adding electronic components (e.g. surface-mounted and optoelectronic devices) to the stretchable circuit are also included.

Design/methodology/approach

In this paper, inkjet printing techniques for fabrication of flexible/stretchable circuits will be reviewed. Specifically, the various modes of operation, commonly used substrates and inks and variables affecting the printing process will be presented. Next, examples of inkjet-printed electronic devices will be demonstrated. These devices will be compared to their rigid counterpart in terms of ease of implementation and electrical behavior for wearable sensor applications. Finally, a summary of key findings and future research opportunities will be presented.

Findings

In conclusion, it is evident that the technology of inkjet printing is becoming a competitor to traditional lithography fabrication techniques, as it has the advantage of being low cost and less complex. In particular, this technique has demonstrated great capabilities in the area of flexible/stretchable electronics and sensors. Various inkjet printing methods have been presented with emphasis on their principle of operation and their commercial availability. In addition, the components of a general inkjet printing process have been discussed in details. Several factors affect the resulting printed patterns in terms of conductivity, resistivity, durability and geometry.

Originality/value

The paper focuses on flexible/stretchable optoelectronic devices which could be implemented in stretchable circuits. Furthermore, the importance and challenges related to printing highly conductive and highly stretchable lines, as well as reliable electronic devices, and interfacing them with external circuitry for power transmission, data acquisition and signal conditioning have been highlighted and discussed. Although several fabrication techniques have been recently developed to allow patterning conductive lines on a rubber substrate, the fabrication of fully stretchable wearable sensors remains limited which needs future research in this area for the advancement of wearable sensors.

Details

Sensor Review, vol. 38 no. 4
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 3 July 2007

David J. Clements, Marc P.Y. Desmulliez and Eitan Abraham

The objective of this investigation is the derivation of a mathematical model that describes the pressure characteristics of paste during the stencil printing process. This model…

Abstract

Purpose

The objective of this investigation is the derivation of a mathematical model that describes the pressure characteristics of paste during the stencil printing process. This model is intended to generalise a qualitative understanding of these effects using squeegees that can be curved but otherwise are standard in design.

Design/methodology/approach

This is an analytical treatment of the paste behaviour from the foundations of continuity of fluid flow and shear stresses that are imparted by the squeegee blade movement.

Findings

An equation is obtained that profiles the pressure generated by the squeegee movement which, for the case of a linear squeegee, shows very good agreement with predicted pressure profiles using experimental data.

Practical implications

This model provides a theoretical framework for a better understanding of how to overcome the failure modes inherent in stencil printing, such as over‐ or under‐filled stencil cavities.

Originality/value

This is a generalisation of a previously developed mesh printing model. It goes beyond flat squeegee designs to describe the printing process when the blade and stencil are in contact. In addition, it encompasses non‐Newtonian fluid behaviour.

Details

Soldering & Surface Mount Technology, vol. 19 no. 3
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 1 April 2014

Robert W. Kay, Gerard Cummins, Thomas Krebs, Richard Lathrop, Eitan Abraham and Marc Desmulliez

Wafer-level stencil printing of a type-6 Pb-free SAC solder paste was statistically evaluated at 200 and 150 μm pitch using three different stencil manufacturing technologies…

Abstract

Purpose

Wafer-level stencil printing of a type-6 Pb-free SAC solder paste was statistically evaluated at 200 and 150 μm pitch using three different stencil manufacturing technologies: laser cutting, DC electroforming and micro-engineered electroforming. This investigation looks at stencil differences in printability, pitch resolution, maximum achievable bump height, print co-planarity, paste release efficiency, and cleaning frequency. The paper aims to discuss these issues.

Design/methodology/approach

In this paper, the authors present a statistical evaluation of the impact of stencil technology on type-6 tin-silver-copper paste printing. The authors concentrate on performances at 200 and 150 μm pitch of full array patterns. Key evaluated criteria include achievable reflowed bump heights, deposit co-planarity, paste release efficiency, and frequency of stencil cleaning. Box plots were used to graphically view print performance over a range of aperture sizes for the three stencil types.

Findings

Fabrication technologies significantly affect print performance where the micro-engineered electroformed stencil produced the highest bump deposits and the lowest bump height deviation. Second in performance was the conventional electroformed, followed by the laser-cut stencil. Comparisons between the first and fifth consecutive print demonstrated no need for stencil cleaning in the case for the micro-engineered stencil for all but the smallest spacings between apertures. High paste transfer efficiencies, i.e. above 85 per cent, were achieved with the micro-engineered stencil using low aperture area ratios of 0.5.

Originality/value

Stencil technology influences the maximum reflowed solder bump heights achievable, and bump co-planarity. To date, no statistical analysis comparing the impact of stencil technology for wafer-level bumping has been carried out for pitches of 200 μm and below. This paper gives new insight into how stencil technology impacts the print performance for fine pitch stencil printing. The volume of data collected for this investigation enabled detailed insight into the limitations of the printing process and as a result for suitable design guidelines to be developed. The finding also shows that the accepted industry guidelines on stencil design developed by the surface mount industry can be broken if the correct stencil technology is selected, thereby increasing the potential application areas of stencil printing.

Details

Soldering & Surface Mount Technology, vol. 26 no. 2
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 15 May 2009

J.H.‐G. Ng, M.P.Y. Desmulliez, M. Lamponi, B.G. Moffat, A. McCarthy, H. Suyal, A.C. Walker, K.A. Prior and D.P. Hand

The purpose of this paper is to present a novel manufacturing process that aims to pattern metal tracks onto polyimide at atmospheric pressure and ambient environment. The process…

Abstract

Purpose

The purpose of this paper is to present a novel manufacturing process that aims to pattern metal tracks onto polyimide at atmospheric pressure and ambient environment. The process can be scaled up for industrial applications.

Design/methodology/approach

From a thorough literature survey, different approaches were carried out for processing polyimide. Following a design of experiments for the processing and various characterisation techniques, a micro‐coil was manufactured as a test demonstrator.

Findings

The characteristics of some main formaldehyde‐based electroless copper baths were compared. The quality of the sidewalls was characterised and the performance of the process was assessed.

Originality/value

This paper demonstrates a high‐value manufacturing technique that is mass manufacturable, low cost and suitable for use on 3D surfaces. Criteria required for the development of a direct‐writing process have been described. The issues surrounding electroless plating on polyimide have been explained.

Details

Circuit World, vol. 35 no. 2
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 6 February 2009

Stoyan Stoyanov, Chris Bailey and Marc Desmulliez

This paper aims to present an integrated optimisation‐modelling computational approach for virtual prototyping that helps design engineers to improve the reliability and…

Abstract

Purpose

This paper aims to present an integrated optimisation‐modelling computational approach for virtual prototyping that helps design engineers to improve the reliability and performance of electronic components and systems through design optimisation at the early product development stage. The design methodology is used to identify the optimal design of lead‐free (Sn3.9Ag0.6Cu) solder joints in fine‐pitch copper column bumped flip‐chip electronic packages.

Design/methodology/approach

The design methodology is generic and comprises numerical techniques for computational modelling (finite element analysis) coupled with numerical methods for statistical analysis and optimisation. In this study, the integrated optimisation‐modelling design strategy is adopted to prototype virtually a fine‐pitch flip‐chip package at the solder interconnect level, so that the thermal fatigue reliability of the lead‐free solder joints is improved and important design rules to minimise the creep in the solder material, exposed to thermal cycling regimes, are formulated. The whole prototyping process is executed in an automated way once the initial design task is formulated and the conditions and the settings for the numerical analysis used to evaluate the flip‐chip package behaviour are specified. Different software modules that incorporate the required numerical techniques are used to identify the solution of the design optimisation problem related to solder joints reliability optimisation.

Findings

For fine‐pitch flip‐chip packages with copper column bumped die, it is found that higher solder joint volume and height of the copper column combined with lower copper column radius and solder wetting around copper column have a positive effect on the thermo‐mechanical reliability.

Originality/value

The findings of this research provide design rules for more reliable lead‐free solder joints for copper column bumped flip‐chip packages and help to establish further the technology as one of the viable routes for flip‐chip packaging.

Details

Soldering & Surface Mount Technology, vol. 21 no. 1
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 16 November 2012

Gerard Cummins and Marc P.Y. Desmulliez

The purpose of this paper is to present an exhaustive review of research studies and activities in the inkjet printing of conductive materials.

9051

Abstract

Purpose

The purpose of this paper is to present an exhaustive review of research studies and activities in the inkjet printing of conductive materials.

Design/methodology/approach

This paper gives a detailed literature survey of research carried out in inkjet printing of conductive materials.

Findings

This article explains the inkjet printing process and the various types of conductive inks. It then examines the various factors that affect the quality of inkjet printed interconnects such as printing parameters, materials and substrate treatments. Methods of characterising both the inkjet printing process and the electrical properties of printed conductive materials are also presented. Finally relevant applications of this technology are described.

Originality/value

Inkjet printing is currently one of the cheapest direct write techniques for manufacturing. The use of this technique in electronic manufacturing, where interconnects and other conductive features are required is an area of increasing relevance to the fields of electronics manufacturing, packaging and assembly. This review paper would therefore be of great value and interest to this community.

Article
Publication date: 3 February 2012

Robert Kay and Marc Desmulliez

The purpose of this paper is to present a detailed overview of the current stencil printing process for microelectronic packaging.

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Abstract

Purpose

The purpose of this paper is to present a detailed overview of the current stencil printing process for microelectronic packaging.

Design/methodology/approach

This paper gives a thorough review of stencil printing for electronic packaging including the current state of the art.

Findings

This article explains the different stencil technologies and printing materials. It then examines the various factors that determine the outcome of a successful printing process, including printing parameters, materials, apparatus and squeegees. Relevant technical innovations in the art of stencil printing for microelectronics packaging are examined as each part of the printing process is explained.

Originality/value

Stencil printing is currently the cheapest and highest throughput technique to create the mechanical and electrically conductive connections between substrates, bare die, packaged chips and discrete components. As a result, this process is used extensively in the electronic packaging industry and therefore such a review paper should be of interest to a large selection of the electronics interconnect and assembly community.

Details

Soldering & Surface Mount Technology, vol. 24 no. 1
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 3 July 2007

T. Tilford, K.I. Sinclair, C. Bailey, M.P.Y. Desmulliez, G. Goussettis, A.K. Parrott and A.J. Sangster

This paper aims to present an open‐ended microwave curing system for microelectronics components and a numerical analysis framework for virtual testing and prototyping of the…

Abstract

Purpose

This paper aims to present an open‐ended microwave curing system for microelectronics components and a numerical analysis framework for virtual testing and prototyping of the system, enabling design of physical prototypes to be optimized, expediting the development process.

Design/methodology/approach

An open‐ended microwave oven system able to enhance the cure process for thermosetting polymer materials utilised in microelectronics applications is presented. The system is designed to be mounted on a precision placement machine enabling curing of individual components on a circuit board. The design of the system allows the heating pattern and heating rate to be carefully controlled optimising cure rate and cure quality. A multi‐physics analysis approach has been adopted to form a numerical model capable of capturing the complex coupling that exists between physical processes. Electromagnetic analysis has been performed using a Yee finite‐difference time‐domain scheme, while an unstructured finite volume method has been utilized to perform thermophysical analysis. The two solvers are coupled using a sampling‐based cross‐mapping algorithm.

Findings

The numerical results obtained demonstrate that the numerical model is able to obtain solutions for distribution of temperature, rate of cure, degree of cure and thermally induced stresses within an idealised polymer load heated by the proposed microwave system.

Research limitations/implications

The work is limited by the absence of experimentally derived material property data and comparative experimental results. However, the model demonstrates that the proposed microwave system would seem to be a feasible method of expediting the cure rate of polymer materials.

Originality/value

The findings of this paper will help to provide an understanding of the behaviour of thermosetting polymer materials during microwave cure processing.

Details

Soldering & Surface Mount Technology, vol. 19 no. 3
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 4 January 2011

Stoyan Stoyanov, Tim Tilford, Farid Amalou, Scott Cargill, Chris Bailey and Marc Desmulliez

Nano‐imprint forming (NIF) is a manufacturing technology capable of achieving high resolution, low‐cost and high‐throughput fabrication of fine nano‐scale structures and patterns…

Abstract

Purpose

Nano‐imprint forming (NIF) is a manufacturing technology capable of achieving high resolution, low‐cost and high‐throughput fabrication of fine nano‐scale structures and patterns. The purpose of this paper is to use modelling technologies to simulate key process steps associated with the formation of patterns with sub‐micrometer dimensions and use the results to define design rules for optimal imprint forming process.

Design/methodology/approach

The effect of a number of process and pattern‐related parameters on the quality of the fabricated nano‐structures is studied using non‐linear finite element analysis. The deformation process of the formable material during the mould pressing step is modelled using contact analysis with large deformations and temperature dependent hyperelastic material behaviour. Finite element analysis with contact interfaces between the mould and the formable material is utilised to study the formation of mechanical, thermal and friction stresses in the pattern.

Findings

The imprint pressure, temperature and the aspect ratio of grooves which define the pattern have significant effect on the quality of the formed structures. The optimal imprint pressure for the studied PMMA is identified. It is found that the degree of the mould pattern fulfilment as function of the imprint pressure is non‐linear. Critical values for thermal mismatch difference in the CTE between the mould and the substrate causing thermally induced stresses during cooling stage are evaluated. Regions of high stresses in the pattern are also identified.

Originality/value

Design rules for minimising the risk of defects such as cracks and shape imperfections commonly observed in NIF‐fabricated nano‐structures are presented. The modelling approach can be used to provide insights into the optimal imprint process control. This can help to establish further the technology as a viable route for fabrication of nano‐scale structures and patterns.

Details

Engineering Computations, vol. 28 no. 1
Type: Research Article
ISSN: 0264-4401

Keywords

1 – 10 of 41