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Publication date: 1 December 2005

Janne J. Sundelin, Sami T. Nurmi, Toivo K. Lepistö and Eero O. Ristolainen

To provide further knowledge of the effect of solder composition and PCB surface finish on the creep properties of lead‐free SnAgCu solder joints.

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Abstract

Purpose

To provide further knowledge of the effect of solder composition and PCB surface finish on the creep properties of lead‐free SnAgCu solder joints.

Design/methodology/approach

Single‐overlap shear specimens were prepared for the creep testing. The test matrix included three different SnAgCu pastes with hypoeutectic, eutectic, and hypereutectic compositions. An Sn63Pb37 solder paste was used as a reference. The PCB finishes used were NiAu, organic solderability preservative (OSP) and immersion tin. The creep tests were performed at 85 and 105°C using a dead‐weight system.

Findings

According to the results, the SnAgCu solder with eutectic or near‐eutectic composition is the safest choice when the creep behaviour of solder joints is considered. Of the three different PCB surface finishes, immersion tin is the most favourable choice for use with SnAgCu joints when creep is the predominant deformation mechanism in the joints. On the NiAu finish the creep properties of SnAgCu solder joints were significantly weaker in eutectic and hypereutectic SnAgCu joints than on Sn and OSP.

Originality/value

The results can be used to enhance the reliability of SnAgCu joints in demanding conditions, when special attention is paid to the choice of PCB surface finish and SnAgCu solder composition.

Details

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

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Article
Publication date: 1 March 2005

Sami T. Nurmi, Janne J. Sundelin, Eero O. Ristolainen and Toivo K. Lepistö

To study the behaviour of voids in PBGA solder joints and their influence on the lifetime of lead‐free solder joints.

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Abstract

Purpose

To study the behaviour of voids in PBGA solder joints and their influence on the lifetime of lead‐free solder joints.

Design/methodology/approach

The behaviour of voids was studied using micro via and land pad PWBs, PBGA components, and by measuring voids in the solder joints. The lifetimes of solder joints were tested using accelerated temperature tests.

Findings

Number of factors affecting the solder joint lifetimes were found. The voids were discovered to have a significantly large influence on the solder joints.

Practical implications

The findings can be used to achieve better soldering results, methods, and designs.

Originality/value

In this paper, the effect and the behaviour of voids were studied profoundly. The findings can be valuable to researchers and process personnel.

Details

Soldering & Surface Mount Technology, vol. 17 no. 1
Type: Research Article
ISSN: 0954-0911

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