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Article
Publication date: 1 March 1993

J.H. Lau

An exact analysis is presented for the creep deformation of solder interconnects subjected to the actions of bending moment, twisting moment and axial force. Dimensionless…

Abstract

An exact analysis is presented for the creep deformation of solder interconnects subjected to the actions of bending moment, twisting moment and axial force. Dimensionless interaction curves and charts which relate the variables, interconnect geometry, solder material properties, axial force, bending moment, twisting moment, bending stress, shearing stress, curvature rate and twist rate are also provided for engineering practice convenience. The constitutive relationship of the 96.5Sn3.5Ag solder interconnects is described by the Garofalo‐Arrhenius steady‐state creep equation.

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Soldering & Surface Mount Technology, vol. 5 no. 3
Type: Research Article
ISSN: 0954-0911

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Book part
Publication date: 30 June 2000

Abstract

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The Theory of Monetary Aggregation
Type: Book
ISBN: 978-0-44450-119-6

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Article
Publication date: 1 January 1992

J. Lau, G. Dody, W. Chen, M. McShane, D. Rice, S. Erasmus and W. Adamjee

The reliability of 0·5 mm pitch, 208‐pin FQFP solder joints has been studied by experimental temperature cycling and 3‐D nonlinear finite element analysis. Temperature…

Abstract

The reliability of 0·5 mm pitch, 208‐pin FQFP solder joints has been studied by experimental temperature cycling and 3‐D nonlinear finite element analysis. Temperature cycling results have been presented as a Weibull distribution. Thermal fatigue life of the solder joints has been estimated based on the calculated plastic strain and isothermal fatigue data on solders. A correlation between the experimental and analytical results has also been made.

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Circuit World, vol. 18 no. 2
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 1 April 1993

J. Lau, S. Golwalkar, P. Boysan, R. Surratt, R. Forhringer and S. Erasmus

The reliability of 0.5 mm pitch, 32‐pin thin small outline package (TSOP) solder joints has been studied by experimental temperature cycling and a cost‐effective 3‐D…

Abstract

The reliability of 0.5 mm pitch, 32‐pin thin small outline package (TSOP) solder joints has been studied by experimental temperature cycling and a cost‐effective 3‐D non‐linear finite element analysis. Temperature cycling results have been presented as a Weibull distribution, and an acceleration factor has been established for predicting the failure rate at operating conditions. Thermal fatigue life of the corner solder joints has been estimated based on the calculated plastic strain, Coffin‐Manson law and isothermal fatigue data on solders. A correlation between the experimental and analytical results has also been made. Furthermore, failure analysis of the solder joints has been performed using scanning electron microscopy (SEM) and an optical method. Finally, a quantitative comparison between the Type‐I and Type‐II TSOP solder joints has been presented.

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Circuit World, vol. 20 no. 1
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 1 January 1990

J.H. Lau, S.J. Erasmus and D.W. Rice

A review of state‐of‐the‐art technology pertinent to tape automated bonding (for fine pitch, high I/O, high performance, high yield, high volume and high reliability) is…

Abstract

A review of state‐of‐the‐art technology pertinent to tape automated bonding (for fine pitch, high I/O, high performance, high yield, high volume and high reliability) is presented. Emphasis is placed on a new understanding of the key elements (for example, tapes, bumps, inner lead bonding, testing and burn‐in on tape‐with‐chip, encapsulation, outer lead bonding, thermal management, reliability and rework) of this rapidly moving technology.

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Circuit World, vol. 16 no. 2
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 1 January 1998

T. Chou and J. Lau

Presents a new wire bondable land grid array (LGA) chip scale package called NuCSP. NuCSP is a minimized body size wire bondable package with rigid substrate interposer…

Abstract

Presents a new wire bondable land grid array (LGA) chip scale package called NuCSP. NuCSP is a minimized body size wire bondable package with rigid substrate interposer. The design concept is to utilize the plating bars on the edges of the package substrate as the wire bond fingers. Bond fingers are redistributed inward to an array of plated through hole vias underneath the chip, then are connected to copper pads on the bottom of the package. NuCSP package size is about equal to die size + 3 mm. Using conventional PCB substrate manufacturing with 4/4 mils routing width/space and wire bonding process, NuCSP offers a very low cost package suitable for memory chips and low pin count application specific IC (ASIC) applications. The other advantages are that the use of wirebonding allow NuCSP be applicable for die size, pad count and pitch variations. Because it is wire bondable, NuCSP may be as generic as plastic quad flat pack (PQFP), yet providing smaller body size, lower cost and smaller package electrical parasitic parameters.

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Circuit World, vol. 24 no. 1
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 1 April 1992

J. Lau, R. Govila, C. Larner, Y.‐H. Pao, S. Erasmus, S. Dolot, M. Jalilian and M. Lancaster

Solvent‐clean and no‐clean mass reflow processes of 0.4 mm pitch, 28 mm body size, 256‐pin fine pitch quad flat packs (QFPs) are presented. Emphasis is placed on fine…

Abstract

Solvent‐clean and no‐clean mass reflow processes of 0.4 mm pitch, 28 mm body size, 256‐pin fine pitch quad flat packs (QFPs) are presented. Emphasis is placed on fine pitch parameters such as printed circuit board (PCB) design, solder paste selection, stencil design, printing technology, component placement, mass reflow, cleaning and inspection. Furthermore, cross‐sections of component/PCB assemblies from both processes have been thoroughly studied using scanning electron microscopy (SEM).

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Circuit World, vol. 19 no. 1
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 1 January 1994

J. Lau, Y.‐H. Pao, C. Larner, R. Govila, S. Twerefour, D. Gilbert, S. Erasmus and S. Dolot

The reliability of 0.4 mm pitch, 28 mm body size, 256‐pin plastic quad flat pack (QFP) no‐clean and water‐clean solder joints has been studied by temperature cycling and…

Abstract

The reliability of 0.4 mm pitch, 28 mm body size, 256‐pin plastic quad flat pack (QFP) no‐clean and water‐clean solder joints has been studied by temperature cycling and analytical analysis. The temperature cycling test was run non‐stop for more than 6 months, and the results have been presented as a Weibull distribution. A unique temperature cycling profile has been developed based on the calculated lead stiffness, elastic and creep strains in the solder joint, and solder data. Also, the thermal fatigue life of the solder joints has been estimated and correlated with experimental results. Furthermore, a failure analysis of the solder joints has been performed using scanning electron microscopy (SEM). Finally, a quantitative comparison between the no‐clean and water‐clean QFP solder joints has been presented.

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Soldering & Surface Mount Technology, vol. 6 no. 1
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 1 February 1994

J. Lau, J. Miremadi, J. Gleason, R. Haven, S. Ottoboni and S. Mimura

A no‐clean mass reflow process for 396‐pin, 324‐pin and 225‐pin over moulded plastic pad array carriers (OMPACs) or plastic ball grid array (BGA) is presented. Emphasis is…

Abstract

A no‐clean mass reflow process for 396‐pin, 324‐pin and 225‐pin over moulded plastic pad array carriers (OMPACs) or plastic ball grid array (BGA) is presented. Emphasis is placed on the OMPAC assembly parameters such as the design, material and process of the packages and printed circuit board (PCB), solder paste, stencil design, printing technology, pick and place, mass re‐flow and inspection. Furthermore, cross‐sections and the ‘popcorn’ effect of the OMPAC assembly are provided and discussed.

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Circuit World, vol. 20 no. 3
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 1 March 1991

J. Lau, S. Leung, R. Subrahmanyan, D. Rice, S. Erasmus and C.Y. Li

In this study, the reliability of solder joints and plated‐through hole copper pads/barrels of pin grid array assemblies under rework condition has been determined by…

Abstract

In this study, the reliability of solder joints and plated‐through hole copper pads/barrels of pin grid array assemblies under rework condition has been determined by fatigue experiments. The cross‐sections of the re‐worked PGA assemblies (before and after fatigue tests) are also provided for a better understanding of the failure mechanisms of the composite structure. Furthermore, the load‐drop curves of the PGA interconnects for up to three reworks are provided for a better estimate of their fatigue life.

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Circuit World, vol. 17 no. 4
Type: Research Article
ISSN: 0305-6120

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