Tin pest issues in lead-free electronic solders

Plumbridge, W. J.

doi:10.1007/s10854-006-9025-3

Cited by 43 publications

(51 citation statements)

References 22 publications

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“…However, with the recent global introduction of lead-free solders in the electronics industry to replace formerly used Sn-Pb alloys, the potential susceptibility to tin pest at low temperatures has attracted renewed vivid attention. The topic was re-investigated by several groups for typical tin-rich alloys used in electronic soldering applications with the goal of better understanding the factors influencing the start and spread of tin pest and its dependence on alloy components and impurities [5,8,[11][12][13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

“…It was found that minor impurities in the tin specimens can influence the transformation strongly. Minute concentrations of impurities like Sb, Bi and Pb, each element having an appreciable solid solubility in the tin matrix, can suppress or slow down the transition to gray tin significantly [1,8,[12][13][14][15][16][17], since they hinder lattice expansion by the pinning of dislocations.…”

Section: Introductionmentioning

confidence: 99%

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Induction of tin pest for cleaning tin-drop contaminated optics

Böwering

2017

Materials Chemistry and Physics

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Highlights Tin pest induction leads to embrittlement of tin drops after β → α Sn transformation.  The purity grade influences the transformation speed of tin very strongly.  Tin drops on multilayer-coated optics disintegrate after β → α Sn transformation.  Tin drop contamination of optics is cleaned via phase transformation at -24 °C.  Reflectance of multilayer-coated mirrors is restored after tin drop transformation. Graphical Abstract AbstractTin pest, the allotropic β → α phase transformation of tin, was examined for use in cleaning of tin-contaminated optics. Induction of change in material structure led to disintegration of tin samples into pieces and powder. The transition times were studied for tin drops of different purity grades, using inoculation with α-Sn seed particles, also after prior mechanical deformation and surface oxide removal. For tin of very high purity levels fast nucleation within hours and full transformation within a day could be achieved during cooling at -24 °C, resulting in strong embrittlement of the material. Tin dripped onto samples of multilayer-coated optics as used in extreme ultraviolet lithography machines was made cleanable by phase transition after inoculation and cooling. The reflectance of multilayer-coated mirrors was found to decrease by no more than 1% with this cleaning method.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Induction of tin pest for cleaning tin-drop contaminated optics

Böwering

2017

Materials Chemistry and Physics

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“…However there are some examples in the literature of tin transformation in alloys. [2][3][4][5][6][7] These studies have focused on determining whether there is any danger in using lead-free alloys in electronic devices kept at low temperatures. The studies of are particularly relevant, as a wide variety of Sn alloys was exposed for times up to 4 and 10 years.…”

Section: Introductionmentioning

confidence: 99%

Monitoring the Growth of the α Phase in Tin Alloys by Electrical Resistance Measurements

Maio

Hunt

2009

Journal of Elec Materi

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The b phase of tin is stable only down to 13°C. Below that temperature the thermodynamically stable phase is a tin, more commonly known as tin pest. This phase has gained notoriety because of the catastrophic consequences of the transforming metal. Interest in this subject increased after the transition from tin-lead to lead-free solder, driven by European restriction of the use of hazardous substances (RoHS) legislation. Lead-free alloys contain from 95% to 99% tin and could potentially be susceptible to the b/a transformation mentioned above. The nucleation of the a phase takes a long time to occur, months or even years, especially in alloys of tin. For this reason this phenomenon is particularly difficult to study. The growth, however, occurs faster, and this paper describes a procedure for observing and measuring growth based on electrical measurements. Furthermore, a sample preparation technique that considerably accelerates the nucleation in alloys is described. Seven binary alloys were tested with this procedure and ranked in terms of their propensity to transform. Experimental results demonstrated that the a crystal growth is not stopped by alloying, but just decelerated, and that lead and bismuth are the most effective at this. The same procedure was then demonstrated successfully on printed circuit boards and hence is shown to be a general method for monitoring a tin growth in critical field applications.

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“…It seems that the salient point is the kinetics of the b-to-a transformation and, as illustrated in Ref. 1, the controlling factors have yet to be elucidated. Three factors merit consideration when attempting to unravel the conditions affecting tin pest formation.…”

Section: Discussionmentioning

confidence: 99%

“…These should be regarded as general observations: the true complexity of the situation is described in greater detail in Ref. 1. The process itself involves nucleation and growth, and may take years or even decades to occur without the assistance of artificial nucleation by seeds of a tin.…”

Section: Introductionmentioning

confidence: 98%

Recent Observations on Tin Pest Formation in Solder Alloys

Plumbridge

2007

Journal of Elec Materi

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The most recent observations of the response of bulk samples of several leadfree solder alloys, exposed to temperatures below the allotropic transition for tin for extended periods, are reported. Tin pest has been observed in Sn-0.5Cu, Sn-3.5Ag, Sn-3.8Ag-0.7Cu, and Sn-3.0Ag-0.5Cu alloys at both -18°C and -40°C. The process is slow and inconsistent, usually requiring several years, but may eventually result in complete disintegration of the sample. No tin pest was detected in Sn-Zn-3Bi or in the traditional Sn-37Pb solder alloy after exposure for up to 4 and 10 years, respectively. It is suggested that nucleation is affected by local composition and that extremely small amounts of either intentional solute or impurity are influential. Growth of tin pest is accompanied by a large volume change, and it is likely that stress relaxation ahead of the expanding grey tin front is a controlling factor. A stronger matrix would be more resistant in this case, and at the temperatures of exposure Sn-37Pb is stronger than either Sn-3.5Ag or Sn-0.5Cu. The absence of tin pest, to date, on actual joints is attributed to their restricted free surface area and the greater strength associated with very small samples.

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Tin pest issues in lead-free electronic solders

Cited by 43 publications

References 22 publications

Induction of tin pest for cleaning tin-drop contaminated optics

Induction of tin pest for cleaning tin-drop contaminated optics

Monitoring the Growth of the α Phase in Tin Alloys by Electrical Resistance Measurements

Recent Observations on Tin Pest Formation in Solder Alloys

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