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Article
Publication date: 1 June 2004

67

Abstract

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Circuit World, vol. 30 no. 2
Type: Research Article
ISSN: 0305-6120

Keywords

Content available
Article
Publication date: 1 April 2004

88

Abstract

Details

Microelectronics International, vol. 21 no. 1
Type: Research Article
ISSN: 1356-5362

Keywords

Content available
Article
Publication date: 1 April 2001

45

Abstract

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Microelectronics International, vol. 18 no. 1
Type: Research Article
ISSN: 1356-5362

Keywords

Content available
Article
Publication date: 1 April 2002

45

Abstract

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Microelectronics International, vol. 19 no. 1
Type: Research Article
ISSN: 1356-5362

Content available
Article
Publication date: 1 August 2004

76

Abstract

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Microelectronics International, vol. 21 no. 2
Type: Research Article
ISSN: 1356-5362

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75

Abstract

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Microelectronics International, vol. 20 no. 3
Type: Research Article
ISSN: 1356-5362

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Content available
Article
Publication date: 1 December 2003

25

Abstract

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Microelectronics International, vol. 20 no. 3
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 16 November 2012

Jan Vanfleteren, Thomas Loeher, Mario Gonzalez, Frederick Bossuyt, Thomas Vervust, Ingrid De Wolf and Michal Jablonski

In the past 15 years stretchable electronic circuits have emerged as a new technology in the domain of assembly, interconnections and sensor circuits and assembly…

1717

Abstract

Purpose

In the past 15 years stretchable electronic circuits have emerged as a new technology in the domain of assembly, interconnections and sensor circuits and assembly technologies. In the meantime a wide variety of processes with the use of many different materials have been explored in this new field. The purpose of the current contribution is for the authors to present an approach for stretchable circuits which is inspired by conventional rigid and flexible printed circuit board (PCB) technology. Two variants of this technology are presented: stretchable circuit board (SCB) and stretchable mould interconnect (SMI).

Design/methodology/approach

Similarly as in PCB 17 or 35 μm thick sheets of electrodeposited or rolled‐annealed Cu are structured to form the conductive tracks, and off‐the‐shelf, standard packaged, rigid components are assembled on the Cu contact pads using lead‐free solder materials and reflow processes. Stretchability is obtained by shaping the Cu tracks not as straight lines, like in normal PCB design, but as horseshoe shaped meanders. Instead of rigid or flexible board materials, elastic materials, predominantly PDMS (polydimethylsiloxane), are used to embed the conductors and the components, thus serving as circuit carrier. The authors include some mechanical modeling and design considerations, aimed at the optimization of the build‐up and combination of elastic, flexible and rigid materials towards minimal stress and maximum mechanical reliability in the structures. Furthermore, details on the two production processes are given, reliability findings are summarised, and a number of functional demonstrators, realized with the technologies, are described.

Findings

Key conclusions of the work are that: supporting the metal meanders with a flexible carrier prior to embedding in an elastic substrate substantially increases the reliability under mechanical stress (cyclic uniaxial stretching) of the stretchable interconnect and the transition areas between rigid components and stretchable interconnects are the zones which are most sensitive to failure under mechanical stress. Careful design and technology implementation is necessary, providing a gradual transition from rigid to flexible to stretchable parts of the circuit.

Originality/value

Technologies for stretchable circuits, with the same level of similarity to standard PCB manufacturing and assembly, and thus with the same high potential for transfer to an industrial environment and for mass production, have not been shown before.

Details

Circuit World, vol. 38 no. 4
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 1 April 2000

David A. Hutt, Daniel G. Rhodes, Paul P. Conway, Samjid H. Mannan, David C. Whalley and Andrew S. Holmes

As the demand for flip‐chip products increases, the need for low cost high volume manufacturing processes also increases. Currently solder paste printing is the wafer…

Abstract

As the demand for flip‐chip products increases, the need for low cost high volume manufacturing processes also increases. Currently solder paste printing is the wafer bumping method of choice for device pitches down to 150‐200μm. However, limitations in print quality and stencil manufacture mean that this technology is not likely to move significantly below this pitch and new methods will be required to meet the demands predicted by the technology roadmaps. This paper describes experiments conducted on carriers made from silicon for bumping of die using solder paste. An anisotropic etching process was used to generate pockets in the silicon surface into which solder paste was printed. Die were then placed against the carrier and reflowed to transfer the solder directly to the bondpads. An assessment was carried out of the potential application and limitations of this technique for device pitches at 225 and 127μm.

Details

Soldering & Surface Mount Technology, vol. 12 no. 1
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 6 February 2009

Mario Gonzalez, Fabrice Axisa, Frederick Bossuyt, Yung‐Yu Hsu, Bart Vandevelde and Jan Vanfleteren

The purpose of this paper is to present an update on the progress of the design and reliability of stretchable interconnections for electronic circuits.

2016

Abstract

Purpose

The purpose of this paper is to present an update on the progress of the design and reliability of stretchable interconnections for electronic circuits.

Design/methodology/approach

Finite element modelling (FEM) is used to analyse the physical behaviour of stretchable interconnects under different loading conditions. The fatigue life of a copper interconnect embedded into a silicone matrix has been evaluated using the Coffin‐Manson relation and FEM.

Findings

The mechanical properties of the substrate and the design of the metal interconnection play an important role on the fatigue lifetime of circuit. In the case of copper embedded into a PDMS Sylgard 186, more than 2,500 tensile cycles have been observed for a periodic deformation of 10 per cent.

Research limitations/implications

Reliability results are limited and need further work to create a more accurate empirical model to estimate the lifetime of stretchable interconnections.

Originality/value

The combined use of FEM and experimental analysis enable a more reliable design of the stretchable metal interconnections. The proposed horseshoe design offers the benefit of reduced permanent damage during elongation.

Details

Circuit World, vol. 35 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

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