Process for restricted lead content soldering of copper fins to copper alloy tubing with controlled copper contamination of the molten solder reservoir

Abstract From the Canadian patent

14 52,842, ABSTRACT OF THE DISCLOSURE, This is an article and process which provide the first essentially continuous high tin flow soldering method for attaching copper based fins to copper based tubing. This invention avoids sludge buildup in the reservoir and generally avoids lead carbonate formation when the heat exchanger is in service. In addition, a novel structure is produced having a braze like joint with eta phase layers adjacent to the copper based surfaces. The invention utilizes an essentially lead free, high tin solder cascade onto a preferably cool tube, generally with a limited time of contact between the liquid solder and the tube and with, a combination air quench and wipe …