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Scientifically proven: Secondary tin has the same quality as primary tin

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SEM image of secondary tin at 1,000x magnification: the crystals and grain boundaries could be visualised well in the scanning electron microscope (SEM).

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Stannol GmbH & Co. KG has successfully completed an EU-funded project on tin recycling. As part of the project, the company commissioned an external examination at the University of Rostock under the direction of Prof. Dr.-Ing. habil. Mathias Nowottnick, in which solder samples made of primary and secondary tin were comparatively examined. The aim was to scientifically prove that primary and secondary tin do not differ in purity and quality.

Light microscopic examination

The result of the analysis: the crystallographic examination on the prepared microsections of the samples did not reveal any visible differences between the two variants. A chemical etching process made the individual crystals and grain boundaries in the tin samples clearly visible – no impurities could be detected along the grain boundaries in either the primary or secondary tin.

Scanning electron microscope and EDX

The purity of the tin samples was also analysed qualitatively by scanning electron microscope and by energy dispersive X-ray spectroscopy (EDX) using a mapping scan and quantitatively by point analysis with stoichiometric evaluation. The results of these analytical methods also show a high purity of the samples of both tin variants.

Thermal analysis

In the thermal analysis, only minor differences in the order of <0.5 K were found between secondary and primary tin. The slightly higher melting point of the secondary tin is somewhat closer to the theoretical literature value of the melting temperature for the pure tin. Together with a lower standard deviation of the measured melting temperature values for the secondary tin compared to the primary tin, it can therefore be concluded that the secondary tin is of high quality and purity. "With these results, we can clearly prove that secondary tin does not differ in quality from primary tin. We hope that we can thus finally dispel prejudices that prevail in the electronics industry against this valuable recycling raw material," emphasises Ingo Lomp, Head of Innovation at Stannol.

More information on the project is available at https://metallpasten-recycling.de/.

About Stannol GmbH & Co KG

Stannol looks back on a long tradition in the production of solder: the company has been combining experience and progress in its products for over 140 years. To this day, Stannol is considered a pioneer of modern soldering technology and is firmly established as a brand on the market. The company specialises in the production of solder wires, solder pastes, fluxes as well as solder bars. The product range also includes measuring and testing equipment, conformal coatings and other accessories. In addition to its high quality standard, Stannol focuses on sustainable and ecological manufacturing: Under the name greenconnect, the company offers a complete product range that focuses on sustainability and fairness.


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