Homebrew PCBs

In a message dated 1/13/2005 8:04:44 A.M. Central Standard Time,  
naveedguy2@... writes:

Can  anyone please tell me about different types of solder bits based on the  
material used? Which one is the best one? How can I clean dirty bits? I am a  
newbie, please help me.<<
Forty or more years back, "all" soldering-iron tips were made of  copper.  
This conducted heat very well and assuming you didn't try to  solder 
black-painted cast-iron, it'd remain "tinned" easily.  However, at  "soldering heat", 
copper DISSOLVES in liquid solder, so the tip would develop a  nasty shape quite 
quickly, requiring filing, which require re-tinning, which was  difficult for 
cerebrally challenged impatient folks.
 
THEN someone discovered IRON did not dissolve nearly as rapidly (if at all)  
in hot solder, but iron is a poor conductor of heat.  SO, some  
chemical/metallurgical wizards came up with the obvious idea to IRON-PLATE  copper tips.  
The 0.1 mm thick iron was too thin to be a detriment to the  heating from the 
copper inside, yet enough to preclude dissolving the copper tip  (bit).  Sadly, 
those cerebrally challenged folks would FILE these tips if  the tinning got 
spoiled (it is MUCH more difficult to re-tin iron than copper),  and the tip 
would immediately begin to dissolve UNDER whatever was left of the  iron, and, 
well, you had "tooth decay" in a bad way. 
 
A NEW iron tip is pre-tinned.  Proper (aka SENSIBLE) handling will  keep it 
tinned.  That kind of tip will last a very long time.  Don't  MASH it onto 
connections.  Don't use ANY abrasives on it.  Keep  it clean by "shaking" the 
solder off it every couple of connections, apply some  fresh solder, and if REALLY 
nasty, swipe it on a slit-sponge slightly moistened,  the kinda thing MADE 
for this purpose.  A scrap of terry-cloth with a  couple ml. water can do nearly 
as well.   I find I can keep a tip  bright and fresh simply by applying some 
fresh rosin-flux solder and "tap the  iron body" against the rim of a 
porcelain or glass saucer, tray, old caster,  etc, to "shake off" the excess solder.  
NEVER try to "carry" solder on the  tip to the joint!  ALWAYS apply the 
solder-wire so that its end touches the  soldering iron's tip AND the joint at the 
same time.  Then, shake-off the  excess drop or two clinging on the iron.  If 
you DON'T, and let it  "collect", it will "turn nasty" and subsequent soldering 
joints will look like  they were done in East Europe by patients.
 
Takes a day or so of practice.  Works better if some OLD guy who has  BEEN 
there, DONE that, stands over you with a small bat, making threats if you  don't 
do it WELL, and quickly!  Oh, and he must also explain what you need  to 
change, etc.





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