Homebrew PCBs

Mumin:  

The problem you are having is common with "solid copper" tips.  When solder 
is liquid (hot!), it acts upon the copper as does hot water on sugar or salt!  

This is why "better" soldering-iron tips are "iron plated".  That is, the 
copper is heavily electroplated with elemental IRON (Eisen).  Iron can be 
"tinned" with solder with some difficulty, but if NEVER chipped nor filed nor sanded 
(abraded), the iron will not DISSOLVE as does copper.  Thus, it acts as a 
SHIELD, to prevent the copper from coming into contact with the solder.

This iron is relatively thin (less than 0.3 mm?), as it is a POOR conductor 
of heat.  Copper is an excellent conductor of heat.  Also, you must NEVER wipe 
the iron-plated tips on any flux (Lotmittel) other than that in "electronics 
solder" (also called "rosin core" or "rosin flux").  The "soldering stands" 
with yellow sponges on them are for cleaning off that "black stuff" you 
mentioned.  Keep the tip "wetted" with fresh solder, and "fling it off" (onto an 
ash-tray, etc, NOT the floor!) ever time you pick it up to use.  If "dirty looking", 
apply some fresh solder to the tip, and "fling it off" again.  When really 
nasty, use the sponge to wipe off the dirty solder, and apply some fresh right 
away, but do NOT "carry" solder on the tip to the joint!  Always fling or wipe 
off the excess, place the iron on the joing, and the solder immediately to the 
joint and the iron (that is, across the line where the two meet).  

Older-style copper-only tips were expected to "dissolve away", so we "old 
boys" became skilled in maintaining tip-shape with files or emery-cloth (good 
sandpaper).  This might "keep the tip-shape", but the LENGTH of the tip gets 
shorter, so it must be replaced when there isn't enough left to hold it on the 
soldering iron!

OK?  Jan Rowland, OLD [deleted]


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