The lead/tin oxides formed by corrosion have a much higher melting temperature than the purse lead/tin. If you get that sort of corrosion hot enough to melt it will be so hot that the pad will lift from the PCB. I use a fiberglass pen to scratch the surface oxides off, getting down to something closer to pure lead/tin. Then you can desolder. You can also use a small flat blade screwdriver to carefully scrape the surface.
Many metals have this refractory nature to their oxides. Aluminum and stainless steel are few that come to mind. You can’t flame cut either as by the time you get the oxide layer on the surface hot enough the pure metal under it is far too hot and you will just blow a big hole in the work piece. Jeff Birt From: M100 <m100-boun...@lists.bitchin100.com> On Behalf Of Daniel L Sent: Wednesday, February 15, 2023 2:44 PM To: m100@lists.bitchin100.com Subject: Re: [M100] stupid move = expected results I actually tried this having watched years of ben heck vids. The new solder beads rolled right off the old solder - almost bridging with another joint. Blew me away. On 2/15/23 05:23, Royce Taft wrote: I’m not sure if you’ve tried this or not, but I figured I’d mention it anyway. Try adding some new solder to the old solder to get it to melt, then extract the component leads and use your desoldering methods to clean up the pads. To do this, I keep my soldering iron tip against the old solder and press some new solder against the tip. The molten new solder with its flux always seems to get the old stuff flowing again. Best of luck, Royce
