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Article
Publication date: 17 August 2012

Bilal Mkhlef, Andy Cobley, Larysa Paniwnyk and Tim Mason

The purpose of this paper is to develop an optimised sonochemical surface modification process which could be operated at low temperature and which uses non‐hazardous chemistry…

Abstract

Purpose

The purpose of this paper is to develop an optimised sonochemical surface modification process which could be operated at low temperature and which uses non‐hazardous chemistry with short treatment times. A range of sonochemical parameters such as ultrasonic intensity/power and process temperature were investigated.

Design/methodology/approach

A 20 kHz ultrasonic probe was used as the ultrasonic source. Ultrasound was applied through deionised water (DI) to sonochemically surface modify a high Tg epoxy laminate material (Isola 370 HR). The efficiency of the sonochemical surface modification process was determined by weight loss, roughness, adhesion and scanning electron microscopy (SEM).

Findings

This study has confirmed that ultrasound has the ability to surface modify a high Tg epoxy substrate material (Isola 370 HR). Weight loss and roughness values were increased by using an optimised ultrasonic process compared to control samples which were processed under “silent” conditions. Adhesion testing showed an improvement in the adhesion level between the surface and the subsequently electroless plated copper.

Originality/value

Surface modification of high Tg materials generally utilizes wet chemical methods. These processes involve using hazardous chemicals, high temperatures, require high volumes of water for rinsing and need relatively long immersion times. This research has shown that by optimising ultrasonic parameters, surface modification can be brought about in deionised water (DI) at low temperature.

Article
Publication date: 24 August 2010

A.J. Cobley, D.J. Comeskey, L. Paniwnyk and T.J. Mason

The purpose of this paper is to investigate if copper nanoparticles could be utilized for two types of through hole plating in printed circuit boards, namely: as a catalytic…

Abstract

Purpose

The purpose of this paper is to investigate if copper nanoparticles could be utilized for two types of through hole plating in printed circuit boards, namely: as a catalytic material to initiate the electroless copper deposition process; and as a “conductive” layer which is coherent and conductive enough to allow “direct” electroplating of the through hole. The employment of nanoparticles means that an effective method of dispersion is required and this paper studies the use of mechanical agitation and ultrasound for this purpose.

Design/methodology/approach

The paper utilized drilled, copper clad FR4 laminate. The through holes were functionalized using a commercially available “conditioner” before being immersed in a solution of copper nanoparticles which were dispersed using either a magnetic stirrer or ultrasound (40 kHz). When the copper nanoparticles were utilized as a catalytic material for electroless copper plating, the efficacy of the technique was assessed using a standard “backlight” test which allowed the plating coverage of the through holes to be determined. As a control, a standard palladium catalysed electroless copper process was employed. The morphology of the electroless copper deposits was also analysed using scanning electron microscopy. In the “direct plate” approach, after immersion in the copper nanoparticle dispersion, the through holes were electroplated at 3 Adm−2 for 15 min, sectioned and examined using an optical microscope. The distance that the copper electroplate had penetrated down the through hole was then determined.

Findings

The paper has shown that copper nanoparticles can be used as a catalytic material for electroless copper plating. The coverage of the electroless copper in the through hole improves as the copper nanoparticle concentration increases and, at the highest copper nanoparticle concentrations employed, good, but not complete, electroless copper coverage is obtained. Dispersion of the copper nanoparticles using ultrasound is critical to the process. Ultrasonically dispersed copper nanoparticles achieve some limited success as a conductive layer for “direct” electroplating with some penetration of the electroplated deposit into the through hole. However, if mechanical agitation is employed to mix the nanoparticles, no through hole plating obtaines.

Originality/value

The paper has demonstrated the “proof of concept” that copper nanoparticles can be utilized to catalyse the electroless copper process, as well as their potential to replace costly palladium‐based activators. The paper also illustrates the potential for copper nanoparticles to be used as a “direct plate process” and the necessity for using ultrasound for their dispersion in either process.

Details

Circuit World, vol. 36 no. 3
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 28 August 2007

Andy Cobley and Tim Mason

This paper sets out to give an introduction to sonochemistry and the effects brought about by the application of ultrasound that might be useful in surface modification; and to…

Abstract

Purpose

This paper sets out to give an introduction to sonochemistry and the effects brought about by the application of ultrasound that might be useful in surface modification; and to show the feasibility of sonochemical surface modification in water on a range of materials employed in electronic manufacturing.

Design/methodology/approach

Ultrasound was applied through DI water for the surface modification of four materials: a ceramic, a polyphenylene ester (polystyrene polymer (Noryl HM4025)), an acrylonitrile‐butadiene‐styrene/polycarbonate (ABS/PC‐Cycolac S705), and an FR4 laminate (Isola Duraver 104). The efficacy of the treatment was determined by weight loss, scanning electronic microscopy, contact angle and roughness.

Findings

Ceramic and Noryl materials can be surface modified sonochemically in DI water. Weight loss results suggested that, this was also the case for the Duraver laminate but the ABS/PC substrate was least affected by treatment in an ultrasonic field under these benign processing conditions.

Originality/value

Traditional “wet” surface modification techniques often use hazardous chemistry, high‐process temperatures, copious rinsing and long dwell times. This research programme addresses these issues by evaluating sonochemical surface modification techniques with the objective of producing a one‐step process using benign chemistry at lower temperature with less rinsing.

Details

Circuit World, vol. 33 no. 3
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 8 February 2011

Andrew J. Cobley, Lindsay Edgar, Martin Goosey, Rod Kellner and Timothy J. Mason

Previous studies have proven that, under optimised ultrasonic conditions, a range of materials used in electronic manufacturing can be sonochemically surface modified using benign…

Abstract

Purpose

Previous studies have proven that, under optimised ultrasonic conditions, a range of materials used in electronic manufacturing can be sonochemically surface modified using benign solutions at low temperature. The purpose of this paper is to focus on a specific process, namely, the desmearing of through holes in printed circuit boards (PCB). The objective was to determine whether the introduction of low frequency ultrasound (20 kHz) to the “etch” stage of a standard “swell and etch” desmear system could enable reduced temperature processing and the use of less chemistry in the permanganate solution.

Design/methodology/approach

The study was divided into three main stages. In the first “screening” phase, the effect of ultrasound in the etch solution was studied by measuring the weight loss after desmear on a PCB laminate material (Isola 370HR). Factors such as etch temperature and concentration of permanganate (including permanganate‐free) were varied. In stage 2, confirmatory runs were carried out on the most promising conditions from the screening work and through holes in a four‐layer multi‐layer board (MLB) were assessed for smear removal using a scanning electron microscope (SEM). Finally, a four‐layer MLB was desmeared through the most promising ultrasonic process and then metallized at a PCB manufacturer. Thermal shock testing was subsequently carried out and sections from the board assessed for inter‐connection defects (ICDs).

Findings

The initial screening study indicated that, whenever ultrasound was used in the etch stage of the desmear process, significantly higher weight loss was achieved compared to a standard “silent” process. This effect was most pronounced when permanganate was removed from the etch solution and, in this situation, weight loss could be an order of magnitude higher than the silent equivalent. Further testing on through holes suggested that smear‐free inner‐layers could only be guaranteed if permanganate was present in the etch solution but that ultrasound again improved smear removal. Final testing under semi‐production conditions confirmed that, if ultrasound was employed in the etch part of the desmear process, then a reduction in processing temperature from 85°C to 60°C could be achieved and the permanganate concentration halved (65 to 33 g/L) whilst still achieving ICD‐free boards.

Originality/value

The paper indicates the feasibility of using ultrasound to reduce temperatures and chemical concentrations used in the permanganate etch solution, whilst still producing through holes with no ICDs.

Details

Circuit World, vol. 37 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 3 February 2012

Andrew J. Cobley and Veronica Saez

Electroless plating is an important process in printed circuit board and electronics manufacturing but typically requires temperatures of 70‐95°C to give a suitable deposition…

Abstract

Purpose

Electroless plating is an important process in printed circuit board and electronics manufacturing but typically requires temperatures of 70‐95°C to give a suitable deposition rate. This is becoming problematic in industry due to the rising price of energy and is a major contribution to production costs. Previous studies have noted beneficial effects of ultrasonic irradiation upon electroless plating processes and it has been reported that sonication can increase the plating rate and produce changes to the chemical and physical properties of the deposited coating. The purpose of this paper is to reduce the operating temperature of an electroless nickel bath by introducing ultrasound to the process.

Design/methodology/approach

The deposition rate of an electroless nickel solution was determined by two techniques. In the first method, test coupons were plated in an electroless nickel solution at temperatures ranging from 50‐90°C and the plating rate was calculated by weight gain. In the second approach the mixed potential (and hence the current density at the mixed potential) was determined by electrochemical analysis of the anodic and cathodic reactions. In both cases the plating rate was found with and without the application of an ultrasonic field (20 kHz). The electroless nickel deposits obtained in the plating tests were also analysed to determine the phosphorus content, microhardness and brightness.

Findings

The plating rates under ultrasonic agitation were always higher than under “silent” conditions. Most importantly, considering the objectives of this study, the deposition rate under sonication at 70°C was significantly higher than that found with mechanical agitation at 90°C. In addition, the results indicated that the deposits produced in an ultrasonic field had consistently lower phosphorus content, higher microhardness and were brighter than those prepared in an electroless nickel bath that was not sonicated.

Originality/value

Although previous work has been performed on the effect of ultrasound on electroless plating, all these studies have been carried out at the normal operating temperature of the electroless process. In this paper, ultrasound has been applied at temperatures well below those normally used in electroless nickel deposition to determine whether sonication can enable low temperature electroless plating.

Details

Circuit World, vol. 38 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 22 August 2008

Andy Cobley and Tim Mason

To build on the results detailed in the previous paper where it was shown that sonochemical surface modification could be achieved in water. This paper aims to look at one of the…

Abstract

Purpose

To build on the results detailed in the previous paper where it was shown that sonochemical surface modification could be achieved in water. This paper aims to look at one of the factors affecting sonochemical surface modification, namely the ultrasonic source to sample distance.

Design/methodology/approach

Ultrasound was applied through deionized water for the surface modification of three materials: a high Tg PCB laminate (Isola 370HR), a polyphenylene ether – polystyrene polymer (Noryl HM4025) and an acrylonitrile‐butadiene‐styrene/polycarbonate (Cycolac S705). The efficacy of the treatment was determined by weight loss, scanning electron microscopy, contact angle, roughness and tape testing after electroless copper plating.

Findings

The study confirmed, and extended the previous findings, that a range of substrates could be sonochemically surface modified in water, even though in this work the ultrasonic horn had a larger tip size and produced a different ultrasonic intensity. Although the results were material dependent, the ultrasonic source to sample distance was found to be critical. Employing a spacing of 5 mm produced samples which generally exhibited higher weight loss, roughness and significant changes in surface morphology than when a distance of 25 mm was utilized.

Originality/value

The paper demonstrates that sonochemical surface modification has the potential to be a much more sustainable surface modification process than those currently employed in the electronics industry. However, to achieve this outcome acoustic cavitation and factors affecting it (such as source to sample distance) must be understood so that suitable equipment can be built.

Details

Circuit World, vol. 34 no. 3
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 1 May 2010

M.M. Kamel, F.A. Nassar, H.M. Helmy and H.H. Kafafy

The dyeing of acrylic fabrics using C.I. Astrazon Basic Golden Yellow GLE is studied with both conventional (CH) and ultrasonic (US) techniques. The factors that affect…

Abstract

The dyeing of acrylic fabrics using C.I. Astrazon Basic Golden Yellow GLE is studied with both conventional (CH) and ultrasonic (US) techniques. The factors that affect dyeability, such as dye bath pH, US power, dyeing time and temperature, are studied. The colour strength values obtained are found to be higher with US than CH heating. Also, the fastness properties of the dyed fabrics are determined with. A comparative study using x-ray and scanning electron microscope (SEM) that is implemented on samples to explain for the better dyeability of acrylic fabrics with the US method. Dyeing kinetics and the time/dye-uptake isotherms reveal enhanced dye-uptake in the second phase of dyeing. The values of the dyeing rate constant, half-time of dyeing and standard affinity, and US efficiency are calculated and discussed.

Details

Research Journal of Textile and Apparel, vol. 14 no. 2
Type: Research Article
ISSN: 1560-6074

Keywords

Content available
Article
Publication date: 17 May 2011

John Ling

82

Abstract

Details

Circuit World, vol. 37 no. 2
Type: Research Article
ISSN: 0305-6120

Content available
Article
Publication date: 27 November 2007

J.H. Ling

251

Abstract

Details

Circuit World, vol. 33 no. 4
Type: Research Article
ISSN: 0305-6120

Article
Publication date: 3 November 2014

X.R. Zhang, L.Z. Liu, J.F. Li, W.W. Cui and L. Weng

The key purpose of this study was to investigate the effects of different ultrasonic irradiation times on the wettability and other properties of the resulting water-based…

Abstract

Purpose

The key purpose of this study was to investigate the effects of different ultrasonic irradiation times on the wettability and other properties of the resulting water-based coating. The subject water-based coating was prepared using water-soluble polyester and amino resins by ultrasonic oscillation.

Design/methodology/approach

The coating was prepared by polymerising polyester and amino resins in water using ultrasonic oscillation. The coating was baked for 40 seconds at 350°C to coalesce and solidify the film. The contact angle, thermal stability and mechanical properties of the film, as well as the molecular weight (MW) and structure of the polyester resin, were determined.

Findings

The contact angle of the coating was found to decrease with ultrasonic irradiation; the mechanical properties and thermal stability were not altered when the irradiation time was longer than 5 hours. The MW of the polyester initially decreased then increased and stabilized with ultrasonic irradiation. The structure of polyester molecule and aggregated state of the solidified coating were not changed by ultrasonic irradiation.

Research limitations/implications

In the study reported here, the effects of different ultrasonic irradiation times were investigated. Results of this research could benefit in-depth understanding of the influence of ultrasonic treatment on polyester resins and polyester coatings and could further promote the development of water-based coatings.

Originality/value

The contact angle of the water-based coating decreased by mechanical means. The effects of ultrasound on microstructure and properties of the coating and resin were discussed in detail.

Details

Pigment & Resin Technology, vol. 43 no. 6
Type: Research Article
ISSN: 0369-9420

Keywords

1 – 10 of 123