Di Maio, D; Hunt, C P (2009) On the factors affecting the dissolution of copper in molten lead-free solders and development of a method to assess the soldering parameters. Solder. Surf. Mount Technol., 21 (4). pp. 24-31.

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Abstract

The transition from tin-lead to lead-free has increased the tendency for copper dissolu-tion in molten solders. PCB land and plated through holes can be eroded and dissolved away in the presence of molten solder rendering the PCB non-functional. Significant dissolution can po-tentially occur with certain tin-rich alloys due to increased solubility of copper. This is further exacerbated by the higher process temperatures, due to the higher melting points of these tin rich alloys. Clearly this phenomenon represents a serious risk to circuit reliability. To determine the dissolution rate of copper in lead-free solders, a well defined and simple technique has been developed to compare solder performance. This methodology provided repeatable measure-ments that allowed the various experimental parameters to be isolated. Particular attention was paid at the flow rate of the molten solder. In fact, different alloys at the same temperature can have considerably different flow rates, due to the different viscosity at that temperature. The performances of seven lead-free alloys and the Sn-Pb alloy were compared at three tempera-tures. It was observed that generally, the samples with a thicker intermetallic layer where those that showed better performance.

Item Type:	Article
Keywords:	lead-free soldering, copper dissolution
Subjects:	Advanced Materials Advanced Materials > Electronics Interconnection
Last Modified:	02 Feb 2018 13:15
URI:	http://eprintspublications.npl.co.uk/id/eprint/4503

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