Soldering (hopefully lead-free) help/advice needed

Discussion in 'The Projects Forum' started by GreenPenInc, Jun 9, 2007.

  1. GreenPenInc

    Thread Starter Member

    May 13, 2007
    12
    0
    I just started learning how to solder, and I figured that it'd be easier to start using lead-free from the beginning, than to get spoiled by using the 60/40 and having to switch. I am willing to use leaded solder, but only as a very last resort.

    I have a 30W pencil which I'm using. Everything I've read about soldering tells me it shouldn't take more than a few seconds. However, when doing practice joints (resistor onto solder strip, for example), I have to heat it for quite a long time before the solder melts. It often takes a minute or more, and if that trend continues it seems like it'd be murder once I get to solid-state components!

    I bought some bare alligator clips to use as heatsinks, and tried them out soldering a 1N4001 diode (since I have plenty). They seemed to work well, since the diode itself wasn't hot when I finished, but it still took a long time.

    My thinking is that the pencil might not have enough power to heat the joint quickly, since lead-free has a higher melting temperature. Should I try with a higher-wattage pencil? Radio Shack has a 40W for 8 bucks -- would that be sufficient?

    By the way, the joints I have made are mechanically strong and electrically good, as far as I've been able to test them.

    I'd appreciate anyone who has experience with lead-free soldering for hobbyists giving me some pointers. Thanks in advance!
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    It does sound like your iron is not hot enough for the (horrible) tin-silver solder. Is it flux cored, or are you using liquid or paste flux? Do you have a film of sloder on the soldering iron tip to help heat transfer? If so, the 40 watt iron may be the way out.

    I never use the stuff. The gold standard is Ersin 63/37 eutectic. I am not convinced that going to lead-free solder is going to affect the environment significantly. And, if you're only doing personal projects, it is not as if the quantity is significant. I'm more concerned with damage to pcb foil and components from excessive heat.
     
  3. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
    10
    With lead-free solder you won't have much choice, since you always take the risk of damaging components. By using a higher wattage iron, you melt the solder more quicky, but you can exceed the temperature. But using a less wattage iron won't solve the problem, since you will need more time to heat up the solder/component but the heat will have time to transfer to the component itself. Perhaps, the risk taken by the use of a higher wattage iron could be minimized by applying heat quickly so the heat won't have time to transfer to the component through the leads.
    I think also the use of alligator clips increased the thermal mass, thus being more heat required to heat all at that temperature, and also acted as an heatsink. That could be the reason why the soldering took too long.
    I think you should try the 40W iron, or you should not use the alligator clips and try to solder for 5 seconds maximum. I normally use these precautions (by wrapping thin copper wire around) when soldering ICs.
     
  4. GreenPenInc

    Thread Starter Member

    May 13, 2007
    12
    0
    I understand why the lead-free stuff is so hated, particularly after obtaining a little first-hand experience with it. Perhaps I should explain why I'm so determined to give it a good try.

    While I do care about the environment, it's not my primary reason for eschewing lead. When I read about lead, it seems that it can be poisonous even in very small amounts, and generally the first thing I read is that it can be highly toxic to children. My wife and I are planning to have kids, and the room which is currently my lab will be converted into the baby's room. When I further consider that I am planning to get my kids interested in electronics when they're old enough, including soldering, it seems obvious that lead-free would be much better for them.

    Another reason has to do with bad experiences with lead. Before we were married, my wife hired a sandblaster who turned out to be incompetent. He didn't check for lead before blasting her paint, and she was sued by her neighbours since it turned out that the paint did contain lead. As you might imagine, the whole experience left rather a bad taste in our mouths.

    So -- I'm going to give lead-free a real try, even though it melts 50 degrees higher, is about 8x more expensive, and makes me fret about tin whiskers and such. The stuff I'm using is here:
    http://www.radioshack.com/product/i...D/Product+Type/Solder&fbc=1&parentPage=family

    It doesn't look like it has a flux core, which suggests that I'd have to get some external flux and apply it each time -- even more of a pain.

    Is there anybody on these forums who actually uses lead-free for hobbyist work?
     
  5. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
    10
    Gee, you can be sued for that? Let me see...you live in the US.
     
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