Werner's reply did not equate with accepted industry wisdom so I went and looked for a reference. According to the first thing to hand - the first edition and therfore now ancient Solders and Soldering, silver is soluble in tin up to large amounts, but the actual amount depends on the temperature, thus at around 240C the solubility of silver in 63/37 is about 3%. So I guess there is a practical benefit here unless current editions or other learned tomes say different? Mike Fenner BSP ------------------------------ To my knowledge it is a myth, that SN62 alloy (with 2% silver) is effective in reducing silver metallization leaching during reflow. Solder has such high solubility in tin and silver/tin intermetallics rapidly disperse throughout the solder joint that a 2% silver content is not likely to any effect in the leaching--actually dissolution-- process of the silver into tin. That is really the reason why the nickel barriers came into widespread use. Werner Engelmaier *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ***************************************************************************