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Article
Publication date: 1 March 2002

John Rigelsford

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Sensor Review, vol. 22 no. 1
Type: Research Article
ISSN: 0260-2288

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Article
Publication date: 1 December 2005

Peng Sun, Cristina Andersson, Xicheng Wei, Liqiang Cao, Zhaonian Cheng and Johan Liu

Sn‐Zn based lead free solders with a melting temperature around 199°C are an attractive alternative to the conventional Sn‐Pb solder and the addition of bismuth improves…

Abstract

Purpose

Sn‐Zn based lead free solders with a melting temperature around 199°C are an attractive alternative to the conventional Sn‐Pb solder and the addition of bismuth improves its wetability. Whilst lead‐free soldering with Sn‐8Zn‐3Bi has already been used in the electronics assembly industry, it is necessary to study its low cycle fatigue properties since such data have not been reported up to now.

Design/methodology/approach

In this study, displacement‐controlled low cycle fatigue testing of Sn‐8Zn‐3Bi and Sn‐37Pb solder joints was done on lap shear samples. The test amplitude was varied whilst the frequency was kept constant at 0.2 Hz and failure was defined as a 50 per cent load reduction. Finite element (FE) modelling was used for analysis and the results were compared to the experimental data.

Findings

The microstructure of the Sn‐8Zn‐3Bi solder showed a mixed phase of small cellular‐shaped and coarser needle‐shaped areas. Au‐Zn intermetallic compounds were observed near the interface from the SEM‐EDS observation. The average lifetime for the Sn‐8Zn‐3Bi solder joints was 17 per cent longer compared to the Sn‐37Pb solder joints. The cross section observation indicated that the fatigue cracks propagated along the interface between the solder bulk and the Au/Ni layer. The locations of maximum equivalent stress from the FE simulation were found to be at the two opposite corners of the solder joints, coinciding with the experimental observations of crack initiation.

Originality/value

This is believed to be the first time, the low cycle fatigue properties of Sn‐8Zn‐3Bi solder have been reported.

Details

Soldering & Surface Mount Technology, vol. 17 no. 4
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 8 May 2009

Björn Carlberg, Teng Wang, Johan Liu and Dongkai Shangguan

The purpose of this paper is to present a novel nanostructured polymer‐metal composite film providing continuous all‐metal thermally conductive pathways, intended to meet…

Abstract

Purpose

The purpose of this paper is to present a novel nanostructured polymer‐metal composite film providing continuous all‐metal thermally conductive pathways, intended to meet future performance requirements on thermal interface materials (TIMs) in microelectronics packaging applications.

Design/methodology/approach

Porous polymer structures with a thickness of approximately 100 μm were manufactured using electrospinning technology. Pressure‐assisted infiltration of low‐melting temperature alloy into the porous polymeric carrier resulted in the final composite film. Thermal performance was evaluated using an accurate and improved implementation of the ASTM D5470 standard in combination with an Instron 5548 MicroTester. Finally, a brief comparative study using three current state‐of‐the‐art commercial TIMs were carried out for reference purposes.

Findings

Composite films with continuous all‐metal thermally conductive pathways from surface to surface were successfully fabricated. Thermal resistances down to 8.5 K mm2 W−1 at 70 μm bond‐line thickness were observed, corresponding to an effective thermal conductivity of 8 W m−1 K−1, at moderate assembly pressures (200‐800 kPa), more than twice the effective thermal conductivity of the commercial reference materials evaluated.

Originality/value

A unique high‐performance nanostructured polymer‐metal composite film for TIM applications with the potential to meet the microelectronics industry's future demands on thermal performance and cost efficiency is presented.

Details

Microelectronics International, vol. 26 no. 2
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 13 February 2007

Yu Wang, Michael Olorunyomi, Martin Dahlberg, Zoran Djurovic, Johan Anderson and Johan Liu

The ever present need for the miniaturization of electronic assemblies has driven the size of passive components to as small as the 01005 package size. However, the…

Abstract

Purpose

The ever present need for the miniaturization of electronic assemblies has driven the size of passive components to as small as the 01005 package size. However, the packaging standards for these components are still under development. The purpose of this work is to report results from experiments designed to establish optimum process parameters, pad sizes and component clearances for the surface mounting of 01005 passive components.

Design/methodology/approach

The experiments were designed using MODDE, an experimental design software tool, and were carried out with both 01005 capacitors and resistors. All the assembled components were examined under microscope and judged according to industrial workmanship standards.

Findings

It was found that a viable solder paste printing process for the assembly of 01005 components can be achieved with a 75 μm thick stencil. Type 5 solder paste achieved a similar printing performance to type 4. Under the experimental conditions used, the optimum pad dimensions for the 01005 capacitors were 210 μm length, 220 μm width, 160 μm separation and for the resistors were 190 μm length, 220 μm width, 160 μm separation. The smallest component clearance to reliably avoid bridging was found to be 100 μm. A high placement force of 3.5 N was found to cause cracking of 01005 resistors.

Originality/value

From this work, a surface mount process for 01005 passive components is established and it is concluded that electronics packaging density can be increased through the assembly of these small components. In the near future, the widespread use of them will definitely facilitate a further reduction in the size of electronic assemblies, especially in handheld and portable devices.

Details

Soldering & Surface Mount Technology, vol. 19 no. 1
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 6 February 2009

Xia Zhang, Johan Liu, Camilla Kärnfelt, Shiwei Ma, Xu Wang, Linqin Meng and Herbert Zirath

Liquid Crystal Polymer (LCP) materials are considered to be promising substrates for wireless applications because of their excellent properties. The purpose of this paper…

Abstract

Purpose

Liquid Crystal Polymer (LCP) materials are considered to be promising substrates for wireless applications because of their excellent properties. The purpose of this paper is to describe now a novel and compact microstrip ultra‐wideband bandpass filter (UWB BPF) with ultra‐fine conductor traces working over 22 to 29 GHz is fabricated on LCP substrates.

Design/methodology/approach

Using standard processing technology, such as photolithography, plasma pretreatment, sputter deposition and wet etching, a microstrip UWB BPF is fabricated on LCP substrates. In order to obtain better adhesion between LCP substrate and copper, the oxygen plasma pretreatment of the LCP substrate surface and a thin titanium adhesion layer are introduced before a copper layer is sputter‐deposited onto the substrate.

Findings

The measured and the simulated results agree well. The measured insertion loss is about 8 dB in the passband of the bandpass filter, which is a little high compared to the simulated result (∼5 dB). The out of band performance at both the high frequency and low frequency is very good, almost higher than 35 dB.

Originality/value

This paper presents the realization of (UWB BPF) working over 22 to 29 GHz based on an LCP substrate, which demonstrates the feasibility of the application of the LCP substrate in RF wireless systems and also gives some useful information for later research.

Details

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

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Article
Publication date: 1 April 2006

Peng Sun, Cristina Andersson, Xicheng Wei, Zhaonian Cheng, Dongkai Shangguan and Johan Liu

To determine the Coffin‐Manson (CM) equation constants for fatigue life estimation of Sn‐8Zn‐3Bi solder joints, since Sn‐8Zn‐3Bi solder has a melting temperature of around…

Abstract

Purpose

To determine the Coffin‐Manson (CM) equation constants for fatigue life estimation of Sn‐8Zn‐3Bi solder joints, since Sn‐8Zn‐3Bi solder has a melting temperature of around 199°C which is close to that of the conventional Sn‐Pb solder which has previously been used in the electronics assembly industry.

Design/methodology/approach

Three dimensional finite element (FE) simulation analysis was used for comparison with the experimentally measured data and to determine the CM constants. Low cycle fatigue tests and FE simulations were carried out for these lead‐free solder joints, and eutectic Sn‐37Pb solder was used as a reference.

Findings

The CM equation for Sn‐8Zn‐3Bi solder joints was fitted to the lifetimes measured and the shear strains simulated. The constants were determined to be 0.0294 for C, the proportional constant, and for the fatigue exponent, β, −2.833.

Originality/value

The CM equation can now be used to predict the reliability of Sn‐8Zn‐3Bi solder joints in electronics assembly and the knowledge base for the properties of the Sn‐Zn solder system has been increased.

Details

Soldering & Surface Mount Technology, vol. 18 no. 2
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 22 September 2020

Yan Zhang, Shaosheng Jin, Yu Yvette Zhang and Xiaohua Yu

The purpose of this study is to decompose the effects of country-of-origin labeling (COOL) into multiple dimensions—macrolevel image, related to the country image, and…

Abstract

Purpose

The purpose of this study is to decompose the effects of country-of-origin labeling (COOL) into multiple dimensions—macrolevel image, related to the country image, and microlevel image, related to dairy industry/product attributes—and investigate how each dimension affects Chinese consumers' evaluation of imported milk.

Design/methodology/approach

This study adopted the Becker–DeGroot–Marschak (BDM) auction mechanism to elicit consumers' willingness to pay (WTP) for milk from different countries (New Zealand, Australia, Germany, France and China). The experiment was conducted with 348 shoppers at supermarkets in three major cities of China (Hangzhou, Wuhan and Shijiazhuang). The study subject was ultrahigh-temperature processing (UHT) milk (200 mL Tetra Pak aseptic brick package).

Findings

The results show that Chinese consumers are willing to pay a premium for UHT milk from New Zealand, Australia, Germany and France compared to domestic milk, and the premiums are 59.4, 58.9, 57.9, and 52.9% respectively. Both microlevel and macrolevel images exert a substantial influence on consumers' WTP, and the microlevel image has a greater impact on consumers' evaluation of milk than the macrolevel image. Particularly, the macropolitical, microtechnology/quality and microdesign/package dimensions have a positive influence on WTP for milk.

Originality/value

This study contributes to the existing literature in introducing the country-of-origin image (COI) construct with different dimensions to get in-depth knowledge about the country-of-origin (COO) effect in food or agricultural economics.

Details

China Agricultural Economic Review, vol. 13 no. 1
Type: Research Article
ISSN: 1756-137X

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Article
Publication date: 11 September 2009

Robert Bogue

The purpose of this paper is to provide a technical review of recent nanosensor research.

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Abstract

Purpose

The purpose of this paper is to provide a technical review of recent nanosensor research.

Design/methodology/approach

This paper describes a number of nanosensor research themes and recent development activities, with an emphasis on work conducted or reported since 2006. It considers a range of emerging nanosensing technologies and two specific areas of application.

Findings

This paper shows that nanosensor technology is developing rapidly and is the subject of a global research effort. Technologies such as nano‐electromechanical system, nano‐opto‐electromechanical system, nanophotonics and the combination of nanotechnology with microtechnology offer prospects to yield sensors for a wide range of chemical, biochemical and physical variables in applications which include healthcare, defence and homeland security, environmental monitoring and light sensing and imaging.

Originality/value

This paper provides a technically detailed, up‐to‐date account of recent nanosensor research.

Details

Sensor Review, vol. 29 no. 4
Type: Research Article
ISSN: 0260-2288

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Article
Publication date: 10 April 2009

C. Andersson, B. Vandevelde, C. Noritake, P. Sun, P.E. Tegehall, D.R. Andersson, G. Wetter and J. Liu

The purpose of this paper is to assess the effect of different temperature cycling profiles on the reliability of lead‐free 388 plastic ball grid array (PBGA) packages and…

Abstract

Purpose

The purpose of this paper is to assess the effect of different temperature cycling profiles on the reliability of lead‐free 388 plastic ball grid array (PBGA) packages and to deeply understand crack initiation and propagation.

Design/methodology/approach

Temperature cycling of Sn‐3.8Ag‐0.7Cu PBGA packages was carried out at two temperature profiles, the first ranging between −55°C and 100°C (TC1) and the second between 0°C and 100°C (TC2). Crack initiation and propagation was analyzed periodically and totally 7,000 cycles were run for TC1 and 14,500 for TC2. Finite element modeling (FEM), for the analysis of strain and stress, was used to corroborate the experimental results.

Findings

The paper finds that TC1 had a characteristic life of 5,415 cycles and TC2 of 14,094 cycles, resulting in an acceleration factor of 2.6 between both profiles. Cracks were first visible for TC1, after 2,500 cycles, and only after 4,000 cycles for TC2. The crack propagation rate was faster for TC1 compared to TC2, and faster at the package side compared to the substrate side. The difference in crack propagation rate between the package side and substrate side was much larger for TC1 compared to TC2. Cracks developed first at the package side, and were also larger compared to the substrate side. The Cu tracks on the substrate side affected the crack propagation sites and behaved as SMD. All cracks propagated through the solder and crack propagation was mainly intergranular. Crack propagation was very random and did not follow the distance to neutral point (DNP) theory. FEM corroborated the experimental results, showing both the same critical location of highest creep strain and the independence of DNP.

Originality/value

Such extensive work on the reliability assessment of Pb‐free 388 PBGA packages has never been performed. This work also corroborates the results from other studies showing the difference in behavior between Pb‐free and Pb‐containing alloys.

Details

Soldering & Surface Mount Technology, vol. 21 no. 2
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 9 May 2019

Qiaoran Zhang, Abdelhafid Zehri, Jiawen Liu, Wei Ke, Shirong Huang, Martí Gutierrez Latorre, Nan Wang, Xiuzhen Lu, Cheng Zhou, Weijuan Xia, Yanpei Wu, Lilei Ye and Johan Liu

This study aims to develop a bimodal nano-silver paste with improved mechanical property and reliability. Silicon carbide (SiC) particles coated with Ag were introduced in…

Abstract

Purpose

This study aims to develop a bimodal nano-silver paste with improved mechanical property and reliability. Silicon carbide (SiC) particles coated with Ag were introduced in nano-silver paste to improve bonding strength between SiC and Ag particles and enhance high-temperature stability of bimodal nano-silver paste. The effect of sintering parameters such as sintering temperature, sintering time and the proportion of SiC particles on mechanical property and reliability of sintered bimodal nano-silver structure were investigated.

Design/methodology/approach

Sandwich structures consist of dummy chips and copper substrates with nickel and silver coating bonded by nano-silver paste were designed for shear testing. Shear strength testing was conducted to study the influence of SiC particles proportions on the mechanical property of sintered nano-silver joints. The reliability of the bimodal nano-silver paste was evaluated experimentally by means of shear test for samples subjected to thermal aging test at 150°C and humidity and temperature testing at 85°C and 85 per cent RH, respectively.

Findings

Shear strength was enhanced obviously with the increase of sintering temperature and sintering time. The maximum shear strength was achieved for nano-silver paste sintered at 260°C for 10 min. There was a negative correlation between the proportion of SiC particles and shear strength. After thermal aging testing and humidity and temperature testing for 240 h, the shear strength decreased a little. High-temperature stability and high-hydrothermal stability were improved by the addition of SiC particles.

Originality/value

Submicron-scale SiC particles coated with Ag were used as alternative materials to replace part of nano-silver particles to prepare bimodal nano-silver paste due to its high thermal conductivity and excellent mechanical property.

Details

Soldering & Surface Mount Technology, vol. 31 no. 4
Type: Research Article
ISSN: 0954-0911

Keywords

1 – 10 of 175