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Article
Publication date: 1 January 1977

M.L. Ackroyd and C.A. MacKay

In the production of printed circuit assemblies, the demand for higher reliability levels has increased over the years. In order to achieve a high level of soldering quality, it…

Abstract

In the production of printed circuit assemblies, the demand for higher reliability levels has increased over the years. In order to achieve a high level of soldering quality, it is essential that solderability is built into the system at all stages and various factors must be taken into account. In the first section of this paper some of these factors are discussed. The various solderable coalings that are available are reviewed, some of the problems that can be encountered are illustrated and the effects of impurities in solders discussed. In the second part of the paper, the use of circuit boards having fused tin/lead coatings is discussed from the solderability point of view.

Details

Circuit World, vol. 3 no. 2
Type: Research Article
ISSN: 0305-6120

Article
Publication date: 1 February 1995

K. Akinade, R. Burgess, M. Campbell, S. Carver, L. Sanderson, R. Wade and C. Melton

The increased interest in the electronics industry to search for alternatives to lead‐containing solders is evidenced by the number of recently published articles on lead‐free…

Abstract

The increased interest in the electronics industry to search for alternatives to lead‐containing solders is evidenced by the number of recently published articles on lead‐free solders in this journal and other journals. At the latest Surface Mount International conference, several papers were presented on lead‐free solder alloys, conductive adhesives and organic preservatives, all in search of replacements for lead‐containing finishes. The efforts to find a replacement for tin/lead are in response to possible legislation banning lead or possible taxation on the use of lead. In an attempt to reduce the use of lead in this company's assembly operation, five lead‐free solder pastes and four corresponding flux vehicles (for A, B, C and E pastes) were evaluated. All of the flux vehicles passed the standard industry tests except for two flux vehicles (pastes B and C) that failed the copper mirror test. An assembly trial of the lead‐free pastes was carried out by building liquid crystal display panels with minimal process modification. Printability, process compatibility and solder joint reliability were assessed. This paper describes the preliminary results of the authors' investigation.

Details

Soldering & Surface Mount Technology, vol. 7 no. 2
Type: Research Article
ISSN: 0954-0911

Article
Publication date: 1 June 1997

C. Melton and H. Fuerhaupter

The use of lead in electronics assembly operations has come under scrutiny due to health and environmentalconcerns associated with lead exposure. Lead is one of the most useful…

443

Abstract

The use of lead in electronics assembly operations has come under scrutiny due to health and environmental concerns associated with lead exposure. Lead is one of the most useful metals in modern industry; however, lead has the dubious distinction of being one of the most toxic of metals. Increasingly restrictive government regulations on the use of lead are hastening the search for feasible alternatives to tin‐lead solder alloys. From an electronics assembly standpoint, there is a desire to replace lead bearing HASL (hot air solder levelling) coatings with a metallic, lead‐free alternative. To answer these needs, Motorola have developed a lead‐free, immersion plating technology for the surface finish of PCB printed circuit board bond pads. The Motorola development work has focused on the metallurgical system of tin‐bismuth, which is a simple eutectic system similar to that of tin‐lead, featuring a minimal number of phases and a wide operating window.

Details

Circuit World, vol. 23 no. 2
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 1 March 1988

B. Bismuth

This study of the contemporary printed circuit market in France has been undertaken from a new standpoint, using a more appropriate methodology. It seeks to determine the factors…

Abstract

This study of the contemporary printed circuit market in France has been undertaken from a new standpoint, using a more appropriate methodology. It seeks to determine the factors influencing the present situation and assesses their likely impact on the future organisation and underlying technological approach of this industry.

Details

Circuit World, vol. 14 no. 4
Type: Research Article
ISSN: 0305-6120

Article
Publication date: 24 October 2008

Enver Baris Bingol, Hilal Colak, Hamparsun Hampikyan and Karlo Muratoglu

This study was performed to determine the microbial quality of stuffed mussels and to discuss the microbiological quality criteria of ready‐to‐eat (RTE) foods defined in the…

837

Abstract

Purpose

This study was performed to determine the microbial quality of stuffed mussels and to discuss the microbiological quality criteria of ready‐to‐eat (RTE) foods defined in the Turkish Food Codex (TFC).

Design/methodology/approach

Stuffed mussel (Midye Dolma), which can be classified as RTE foods, made from mussel and rice, cooked separately then put together in the shell, is commonly consumed in Turkey. This special food might be an important source of microorganisms especially pathogen bacteria because of preparation and serving process. During the period of March‐October 2006, a total of 168 stuffed mussel samples were collected randomly from restaurants, buffets and street sellers located in Istanbul and analysed some microbiological parameters.

Findings

Coliforms were detected in 130 (77.38 per cent), Escherichia coli in 37 (22.02 per cent), Staphylococcus aureus in 40 (23.80 per cent), Bacillus cereus in 65 (38.69 per cent), yeast and moulds in 147 (87.50 per cent) and sulphite‐reducing anaerob bacteria in 61 (36.30 per cent) stuffed mussel samples, respectively. Total aerobic bacteria count (TAB) was between 1.0 × 102 and 3.2 × 107 CFU/g. No Salmonella spp. was detected in analysed samples.

Originality/value

This is the first comprehensive study to provide information on the microbiological quality of stuffed mussels sold in Istanbul, Turkey. This information is important in the determination of measures that can be taken to control the safety of these cooked or prepared foods.

Details

British Food Journal, vol. 110 no. 11
Type: Research Article
ISSN: 0007-070X

Keywords

Article
Publication date: 1 April 1988

The LA/Ventura Annual Workshop was held on 22 June on the theme ‘Fine Line and Military Requirements’. Four workshops were conducted simultaneously on the following aspects…

Abstract

The LA/Ventura Annual Workshop was held on 22 June on the theme ‘Fine Line and Military Requirements’. Four workshops were conducted simultaneously on the following aspects: Mechanical, Imaging, Wet Process, Quality.

Details

Circuit World, vol. 15 no. 1
Type: Research Article
ISSN: 0305-6120

Article
Publication date: 5 March 2024

Fateme Asadi Touranlou, Ahmad Raeesi and Mitra Rezaei

This study aims to systematically review the health risk assessment of the concentration of heavy metals in Pistacia species globally.

Abstract

Purpose

This study aims to systematically review the health risk assessment of the concentration of heavy metals in Pistacia species globally.

Design/methodology/approach

The authors systematically searched PubMed, Science Direct, Scopus and Google Scholar to identify all articles published between 1 January 2002 and 20 August 2022. A total of 33 studies met the authors’ inclusion criteria, and their data were extracted. Additionally, the potential risk to human health was assessed by calculating the target hazard quotient and hazard index for both child and adult consumers.

Findings

The estimated daily intake for heavy metals in the included studies ranged from 9.72 × 10–9 to 7.35 (mg/day) in the following order: zinc (Zn) > mercury (Hg) > iron (Fe) > lead (Pb) > copper (Cu) > aluminum (Al) > nickel (Ni) > chromium (Cr) > manganese (Mn) > cadmium (Cd) > arsenic (As) > selenium (Se) > cobalt (Co). Among the studies that investigated heavy metals in Pistacia species around the world, the non-carcinogenic risk for all species of Pistacia was determined to be less than 1, except for Pb and Hg in Pistacia lentiscus.

Originality/value

The soil near the industrial area contained excessive amounts of heavy metals, which led to the transfer of heavy metals to plants. Owing to the insufficiency of the number of studies that examined heavy metals in Pistacia species, further monitoring and investigations were recommended.

Details

Nutrition & Food Science , vol. 54 no. 3
Type: Research Article
ISSN: 0034-6659

Keywords

Article
Publication date: 22 June 2010

Jian Fang, Yubin Sun, Yanqiu Xia and Weimin Liu

The purpose of this paper is to understand the effect of base media on the tribological performance and tribochemistry of bismuth thiophosphate additive.

Abstract

Purpose

The purpose of this paper is to understand the effect of base media on the tribological performance and tribochemistry of bismuth thiophosphate additive.

Design/methodology/approach

The oil‐water double soluble additive bismuth dithiophosphate was prepared and identified. The contributions of the two base media on the additive tribological behavior and the tribofilm components were comparatively studied.

Findings

The extreme pressure (EP) and friction‐reducing properties are remarkably improved with water substituted for paraffin as the base medium. The EP performance of the lubricating media containing this additive mainly results from the tribochemical reaction film on the rubbing surface, not from the viscosity of the base media. In water or paraffin medium, the adsorption process of this additive from the lubricant bulk onto the rubbing surface and the components and the properties of the tribochemical reaction films formed are different, which have important effect on the tribological performance.

Research limitations/implications

The paper mainly focuses on how the water medium with polarity and the liquid paraffin base medium with non‐polarity affect on the tribological performance of the bismuth thiophosphate additive.

Practical implications

The research has found a water‐oil double soluble lubrication additive with outstanding EP and friction‐reducing performance.

Originality/value

The designed experiment provides a new approach to further learn the action mechanism of thiophosphate additive.

Details

Industrial Lubrication and Tribology, vol. 62 no. 4
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 1 January 1992

A. Nicholson and D. Bloomfield

In view of the increasing interest in low temperature and lead‐free solder alloys, a review was made of existing information on the physical properties of bismuth alloys suitable…

Abstract

In view of the increasing interest in low temperature and lead‐free solder alloys, a review was made of existing information on the physical properties of bismuth alloys suitable for electronic bonding applications, by reflow and wave soldering. A comparison was made, where possible, with existing tin‐lead alloys already in widespread use, with new information experimentally derived where none was currently available.

Details

Soldering & Surface Mount Technology, vol. 4 no. 1
Type: Research Article
ISSN: 0954-0911

Article
Publication date: 28 September 2010

Jian Fang, Yanqiu Xia and Weimin Liu

The purpose of this paper is to study the tribological behavior and mechanism of water‐soluble bismuth dithiophosphate as the additive of water‐based cutting fluid in aluminum…

Abstract

Purpose

The purpose of this paper is to study the tribological behavior and mechanism of water‐soluble bismuth dithiophosphate as the additive of water‐based cutting fluid in aluminum alloy tapping.

Design/methodology/approach

Comparable investigation has been made on the lubrication performance of bismuth dithiophosphate and sodium dithiophosphate in aluminum alloy tapping. The aluminum alloy‐machined surface finish was observed on scanning electron microscope. The films on the work‐piece‐machined surface and the tap tool working surface were analyzed by X‐ray photoelectron spectroscopy.

Findings

The results indicated that the water medium containing 1 wt% the prepared water‐soluble bismuth dithiophosphate exhibited better tapping efficiency than the liquid paraffin containing 2.5 wt% chlorinated paraffin and 2.5 wt% sulfurized olefin. The bismuth sulfide component in the reaction film on the tap working surface plays a leading role in elevating the tapping efficiency and improving the machined surface finish.

Research limitations/implications

The paper is restricted to the lubrication performance of bismuth dithiophosphate as the water‐based cutting fluid additive in 2024 aluminum alloy tapping.

Practical implications

The test method adopted is very close to the machined method applied in industry. The test results show that the bismuth dithiophosphate can obviously improve the tapping efficiency and the machined surface finish. Thus, it can be applied to the aluminum alloy cutting in automotive and aviation.

Originality/value

An attempt has been made to identify the chemical reaction film sourced from bismuth element and dithiophosphate group on the work‐piece‐machined surface and the tool working surface and their contribution to enhancing the tapping efficiency and improving the machining surface finish. This is helpful to the designers and the practitioners of the additives of metalworking fluid.

Details

Industrial Lubrication and Tribology, vol. 62 no. 6
Type: Research Article
ISSN: 0036-8792

Keywords

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