A eutectic alloy is a) one which behaves like a pure or single metal on heating. In other words it melts from solid to liquid with no transition through some pasty phase. b) It is the lowest melting point composition. If you have a non eutectic composition what happens on heating is the eutectic mixture will melt and the "surplus" constituent will still be solid. A liquid with solids mixed into it is a paste. So if you have say, a mixture of equal portions of tin and lead (50Sn/50Pb), on heating the eutectic (63/37) will melt into a liquid leaving the surplus lead floating around till it too melts / dissolves. This is what the phase diagrams you see in text books/supplier literature etc are describing. Mike ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################