Phil Hobbs wrote in news: snipped-for-privacy@electrooptical.net:
soldering classes at TEK taught us to keep the irons at 600degF,but I usually had mine at 700degF. Most of the Weller tips TEK stocked were 600degF,a couple of the bigger ones were 900degF.They were those magnetic-switching tips,no " 50's" increments. The big fears the classes mentioned were about too high a heat causing pad lifting or via expansion and cracking at an inner layer on multilayer PCBs.
TEK switched to 63/37 solder a long time ago,after using 60/40 or the 3% AG stuff.