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Article
Publication date: 16 October 2018

Wenxiong Lin, Huagang Liu, Haizhou Huang, Jianhong Huang, Kaiming Ruan, Zixiong Lin, Hongchun Wu, Zhi Zhang, Jinming Chen, Jinhui Li, Yan Ge, Jie Zhong, Lixin Wu and Jie Liu

The purpose of this paper is to explore the possibility of an enhanced continuous liquid interface production (CLIP) with a porous track-etched membrane as the…

Abstract

Purpose

The purpose of this paper is to explore the possibility of an enhanced continuous liquid interface production (CLIP) with a porous track-etched membrane as the oxygen-permeable window, which is prepared by irradiating polyethylene terephthalate membranes with accelerated heavy ions.

Design/methodology/approach

Experimental approaches are carried out to characterize printing parameters of resins with different photo-initiator concentrations by a photo-polymerization matrix, to experimentally observe and theoretically fit the oxygen inhibition layer thickness during printing under conditions of pure oxygen and air, respectively, and to demonstrate the enhanced CLIP processes by using pure oxygen and air, respectively.

Findings

Owing to the high permeability of track-etched membrane, CLIP process is demonstrated with printing speed up to 800 mm/h in the condition of pure oxygen, which matches well with the theoretically predicted maximum printing speed at difference light expose. Making a trade-off between printing speed and surface quality, maximum printing speed of 470 mm/h is also obtained even using air. As the oxygen inhibition layer created by air is thinner than that by pure oxygen, maximum speed cannot be simply increased by intensifying the light exposure as the case with pure oxygen.

Originality/value

CLIP process is capable of building objects continuously instead of the traditional layer-by-layer manner, which enables tens of times improvement in printing speed. This work presents an enhanced CLIP process by first using a porous track-etched membrane to serve as the oxygen permeable window, in which a record printing speed up to 800 mm/h using pure oxygen is demonstrated. Owing to the high permeability of track-etched membrane, continuous process at a speed of 470 mm/h is also achieved even using air instead of pure oxygen, which is of significance for a compact robust high-speed 3D printer.

Details

Rapid Prototyping Journal, vol. 25 no. 1
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 20 November 2009

Mikael Lindeberg and Klas Hjort

The purpose of this paper is to present an update and the latest results from work on high aspect ratio “multiple wire” microvias in porous flexible Kapton foils for…

Abstract

Purpose

The purpose of this paper is to present an update and the latest results from work on high aspect ratio “multiple wire” microvias in porous flexible Kapton foils for printed circuit boards (PCBs).

Design/methodology/approach

Kapton foils are made porous by ion track technology and dry resist patterning. In combination with thin film deposition and electroplating the technology is used to define circuits and sensors with microvias made of many individual high aspect ratio wires. The processes are within the reach of many production environments and are suitable for flexible PCB fabrication.

Findings

The use of these novel processes enables new types of microvias and multiple wire structures in the foils for millimeter wave circuitry of substrate integrated waveguides and shielding, as well as for sensors with high thermal resistance.

Research limitations/implications

Today, through foil electroplating is fairly slow and more work should be made with copper electroplating. Ion track technology works well on polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyimide (PI) but should also be studied for novel polymer foils such as liquid crystal polymers (LCPs).

Originality/value

The paper details how ion track and PCB technology can be combined to enable a new type of through the foil via interconnect that consists of a multitude of wires. With these porous substrates, double‐sided circuits with high aspect ratio microvias and other multiple wire structures can be created using only lithography, thin film deposition, and electroplating. A new type of electrothermal sensorfoil is presented with several advantages over its competing micro electro mechanical systems (MEMS) based Si sensors.

Details

Circuit World, vol. 35 no. 4
Type: Research Article
ISSN: 0305-6120

Keywords

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Article
Publication date: 5 February 2018

Simona Di Fraia, Nicola Massarotti and P. Nithiarasu

This paper aims to provide a comprehensive literature review on modelling electro-osmotic flow in porous media.

Abstract

Purpose

This paper aims to provide a comprehensive literature review on modelling electro-osmotic flow in porous media.

Design/methodology/approach

Modelling electro-osmosis in fluid systems without solid particles has been first introduced. Then, after a brief description of the existing approaches for porous media modelling, electro-osmotic flow in porous media has been considered by analysing the main contributions to the development of this topic.

Findings

The analysis of literature has highlighted the absence of a universal model to analyse electro-osmosis in porous media, whereas many different methods and assumptions are used.

Originality/value

For the first time, the existing approaches for modelling electro-osmotic flow in porous have been collected and analysed to provide detailed indications for future works concerning this topic.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 28 no. 2
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 December 2001

Maria M. Johnstone, Paul S. Phillips and Antony R. Denman

An extensive radon remediation programme in National Health Service properties in Northamptonshire has been conducted since 1992 and has resulted in many buildings with…

Abstract

An extensive radon remediation programme in National Health Service properties in Northamptonshire has been conducted since 1992 and has resulted in many buildings with raised levels being identified and remediated. In the autumn of 1997, several of the remediated properties were surveyed in order to determine the viability of the remedial measures and the dose reduction to staff. The initial assumption that reduction factors in radon levels would be greater than reduction factors in radiation dose per person was partially confirmed. This was due to the part‐time working patterns of staff and their mobility during working hours.

Details

Environmental Management and Health, vol. 12 no. 5
Type: Research Article
ISSN: 0956-6163

Keywords

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