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Article
Publication date: 1 June 2004

Keith Whitlaw, André Egli and Mike Toben

A new pure tin process is described which produces a deposit with a crystal orientation combination that minimises whisker growth, particularly when used with a specific…

Abstract

A new pure tin process is described which produces a deposit with a crystal orientation combination that minimises whisker growth, particularly when used with a specific pre‐treatment process. A recommended etch depth of minimum 2.5 μm has been shown to reduce whisker growth, particularly with thin (3 μm) tin coatings. Crystal orientation is determined by X‐ray diffraction and the angles between adjacent crystal planes are calculated from the pattern produced. A minimum proportion of small angles is required for lowest whisker risk. Angles smaller than 22° have been shown to be critical. The predominant orientations of the deposits from new tin process are 101, 211, 112, and 312. This combination of orientations has 8 percent of angles in the critical range. A typical pure tin process with a high tendency for whiskering may have a texture of 431, 321, and 211 orientations, and this combination produces 65 percent of angles smaller than 22°.

Details

Circuit World, vol. 30 no. 2
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 1 January 2006

Keith Whitlaw, Jeff Crosby and Mike Toben

To present a new tin plating process which provides deposits having a fine‐grained structure and stable crystal orientation with a combination of properties which are well…

Abstract

Purpose

To present a new tin plating process which provides deposits having a fine‐grained structure and stable crystal orientation with a combination of properties which are well suited for use as a lead‐free finish on semiconductor lead‐frames.

Design/methodology/approach

The new process was designed to produce tin coatings with a deposit grain size ca 20 per cent that of a traditional matte pure tin finish to ensure that the deposit retains good solderability after steam ageing.

Findings

The enhanced solderability from the finer‐grained deposit has been demonstrated and other functionally important deposit properties have been confirmed. A stable single crystal orientation 〈220〉 indicates low whiskering propensity and measurements have confirmed the excellent whisker performance, even without specific whisker‐preventing countermeasures. The deposit has high ductility. Analytical methods are available for all key components to ensure optimum process control. The process has been tested in a continuous production environment for over 12 months with excellent results.

Originality/value

The novel process described in the paper provides tin deposits having a unique combination of properties and with production‐proven capability to be an ideal lead‐free solution as a solderable finish for electronic components.

Details

Circuit World, vol. 32 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

Content available
Article
Publication date: 1 April 2000

24

Abstract

Details

Soldering & Surface Mount Technology, vol. 12 no. 1
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 1 February 1986

LeaRonal (UK) plc of Buxton, Derbyshire, have announced management changes within their organisation.

Abstract

LeaRonal (UK) plc of Buxton, Derbyshire, have announced management changes within their organisation.

Details

Circuit World, vol. 12 no. 3
Type: Research Article
ISSN: 0305-6120

Content available
Article
Publication date: 1 December 2001

41

Abstract

Details

Soldering & Surface Mount Technology, vol. 13 no. 3
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 1 March 1985

The CCA is a non‐profit organisation composed of member companies within the state of California, aimed at providing an environment for information exchange between…

Abstract

The CCA is a non‐profit organisation composed of member companies within the state of California, aimed at providing an environment for information exchange between individuals involved in the printed circuit industry. Each branch holds monthly meetings on state‐of‐the‐art technology. Other benefits of CCA membership include: free admission to Nepcon technical sessions; educational and employment information; reduced fees for the annual fall symposium; and a monthly newsletter.

Details

Circuit World, vol. 11 no. 4
Type: Research Article
ISSN: 0305-6120

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