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Article
Publication date: 1 February 1993

A.F.J. Baggerman and F.J.H. Kessels

Tape automated bonding (TAB) is an interconnection technique for integrated circuits (ICs) with a small lead pitch and a thin assembly thickness. During inner lead bonding the…

Abstract

Tape automated bonding (TAB) is an interconnection technique for integrated circuits (ICs) with a small lead pitch and a thin assembly thickness. During inner lead bonding the flying (Au plated Cu) leads of the TAB foil are connected to the Au bumps on the bondpads of an IC. The Au bumps are deposited in the openings of a thick Novolac based resist layer by electroplating. The resist is coated on a sputtered TiW‐Au metallisation; TiW is the barrier layer between Au bump and Al bondpad. Bonding of the leads to the Au bumps requires substantial plastic deformation of the bump and lead. As a result of this deformation, the TiW barrier layer underneath the bump may crack easily. A theoretical model has been used to describe the occurrence of these cracks. This theoretical model is compared with experimental results of deformation and cracking behaviour by visual inspection of the TiW barrier and the etched cross‐sections. Separate (single point) and simultaneous (gang) bonding techniques, different gold plating baths and TAB tapes are used to study the cracking behaviour.

Details

Microelectronics International, vol. 10 no. 2
Type: Research Article
ISSN: 1356-5362

Article
Publication date: 1 March 1992

E. Zakel, J. Simon, G. Azdasht and H. Reichl

Tape automated bonding (TAB) is a suitable technology for assembling ICs with a high number of l/Os. The gang bonding process usually applied requires increasing thermode forces…

Abstract

Tape automated bonding (TAB) is a suitable technology for assembling ICs with a high number of l/Os. The gang bonding process usually applied requires increasing thermode forces for chips with high lead counts and narrow tolerances regarding thermode parallelism and planarity. Due to the high bonding pressure, TC bonding of Au bumps to Au‐plated tapes becomes critical for these applications. In order to avoid damage to the pad structure an inner lead bonding (ILB) process with reduced pressure is required. A tape metallisation of 0.5–1.0 µm Sn is not sufficient for a significant reduction of thermode pressure. As an alternative, the application of an eutectic Au‐Sn cushion which is deposited on top of the bumps is presented. A modified bumping process was developed for the deposition of the solder bumps. Soldering of the Au‐Sn bumps to a Au‐plated tape was performed successfully by two techniques: thermode gang bonding and laser soldering. Bond parameters and tin layer thickness were optimised. Reliability investigations by thermal ageing were performed. The special metallurgical aspects of the system were investigated with a microprobe.

Details

Soldering & Surface Mount Technology, vol. 4 no. 3
Type: Research Article
ISSN: 0954-0911

Article
Publication date: 1 January 1992

B. Waterfield and Geoff Griffiths

At the Annual General Meeting of ISHM‐France, held on 12 June 1991, the following were elected:

Abstract

At the Annual General Meeting of ISHM‐France, held on 12 June 1991, the following were elected:

Details

Microelectronics International, vol. 9 no. 1
Type: Research Article
ISSN: 1356-5362

Article
Publication date: 20 February 2023

Soufyane Belhenini, Imad El Fatmi, Caroline Richard and Abdellah Tougui

This study aims to contribute to the numerical modelling of drop impact on a flip-chip component assembled on printed circuit boards using solder micro-bumps. This contribution is…

Abstract

Purpose

This study aims to contribute to the numerical modelling of drop impact on a flip-chip component assembled on printed circuit boards using solder micro-bumps. This contribution is based on the introduction of non-linear fracture mechanics in the numerical approach.

Design/methodology/approach

The integration of non-linear fracture mechanics into the numerical approach requires the proposal and validation of several simplifying assumptions. Initially, a dynamic 3D model was simplified to a dynamic 2D model. Subsequently, the dynamic 2D model is replaced with an equivalent static 2D model. The equivalent static 2D model was used to perform calculations considering the non-linear fracture mechanics. A crack was modelled in the critical bump. The J-integral was used as a comparative parameter to study the effects of crack length, crack position and chip thickness on the fracture toughness of the solder bump.

Findings

The different simplifying assumptions were validated by comparing the results obtained by the various models. Numerical results showed a high risk of failure at the critical solder bump in a zone close to the intermetallic layer. The obtained results were in agreement with the post-test observations using the “Dye and Pry” methods.

Originality/value

The originality of this study lies in the introduction of non-linear fracture mechanics to model the mechanical response of solder bumps during drop impact. This study led to some interesting conclusions, highlighting the advantage of introducing non-linear fracture mechanics into the numerical simulations of microelectronic components during a drop impact.

Details

Soldering & Surface Mount Technology, vol. 35 no. 4
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 29 June 2010

Fang Liu, Guang Meng and Mei Zhao

The purpose of this paper is to investigate the mechanism of ball grid array (BGA) lead‐free solder joint failure under board‐level drop impact.

Abstract

Purpose

The purpose of this paper is to investigate the mechanism of ball grid array (BGA) lead‐free solder joint failure under board‐level drop impact.

Design/methodology/approach

A round shaped test board was used. First, drop tests at three different heights were carried out. Then, dye stain testing and metallurgical analysis were performed in order to study the failure mechanism of lead‐free solder joints under drop impact.

Findings

The test results indicate that the combined effect of mechanical shock and printed circuit board bending vibration is the root cause of solder joint failure under drop impact. On the other hand, the fracture of BGA lead‐free solder joints occurs at the intermetallic compound interface near the package side, and the failure mode is brittle fracture.

Originality/value

These results are the same as those for JEDEC standard test boards. The round test board could take the place of the JEDEC standard test board when conducting drop testing.

Details

Soldering & Surface Mount Technology, vol. 22 no. 3
Type: Research Article
ISSN: 0954-0911

Keywords

Book part
Publication date: 30 December 2013

Guido Erreygers and Roselinde Kessels

In this chapter we explore different ways to obtain decompositions of rank-dependent indices of socioeconomic inequality of health, such as the Concentration Index. Our focus is…

Abstract

In this chapter we explore different ways to obtain decompositions of rank-dependent indices of socioeconomic inequality of health, such as the Concentration Index. Our focus is on the regression-based type of decomposition. Depending on whether the regression explains the health variable, or the socioeconomic variable, or both, a different decomposition formula is generated. We illustrate the differences using data from the Ethiopia 2011 Demographic and Health Survey (DHS).

Details

Health and Inequality
Type: Book
ISBN: 978-1-78190-553-1

Keywords

Book part
Publication date: 19 September 2022

Abstract

Details

COVID-19 and the Media in Sub-Saharan Africa: Media Viability, Framing and Health Communication
Type: Book
ISBN: 978-1-80382-272-3

Article
Publication date: 1 February 1982

J. Colin Dodds

In financial markets investors and borrowers are faced with a whole structure of prices and interest rates on financial instruments. The determination of equilibria in these…

Abstract

In financial markets investors and borrowers are faced with a whole structure of prices and interest rates on financial instruments. The determination of equilibria in these markets is a complex process and presents a challenge to researchers and practitioners alike. In this article we are concerned with a single section of these markets where we study the relationships between the interest rates or yields on financial securities which can be distinguished from each other (as far as possible) only by their term to maturity. We only cover the structure of money or nominal yields, as an examination of the real returns would require another arti‐cle in itself.

Details

Managerial Finance, vol. 8 no. 2
Type: Research Article
ISSN: 0307-4358

Abstract

Details

Pedestrian Behavior
Type: Book
ISBN: 978-1-848-55750-5

Article
Publication date: 1 April 1949

It has often been said that a great part of the strength of Aslib lies in the fact that it brings together those whose experience has been gained in many widely differing fields…

Abstract

It has often been said that a great part of the strength of Aslib lies in the fact that it brings together those whose experience has been gained in many widely differing fields but who have a common interest in the means by which information may be collected and disseminated to the greatest advantage. Lists of its members have, therefore, a more than ordinary value since they present, in miniature, a cross‐section of institutions and individuals who share this special interest.

Details

Aslib Proceedings, vol. 1 no. 4
Type: Research Article
ISSN: 0001-253X

1 – 10 of 511