Electronics > Beginners
Hot air soldering, what am I doing wrong?
Jwillis:
Interesting discussion all around .I found this method but haven't tried it myself and was wondering if anyone here would have any input .
KL27x:
hermitengineer:
--- Quote ---Just a beginner with QFP myeslf, and reflecting on my many failures before giving up and getting TSSOP versions, but I wonder if one of the major problems when hand-soldering them is that you don't get an even amount of solder on each pad? Some will have plenty of solder and others... not so much. So when you heat the chip up and even get it to stick in place after the solder melts, you still might end up with unconnected pins. Or at least, I almost always did :-//
The other issue is when it has the middle pad, because it requires "just enough" solder. Not enough, and the pad can't act as a good heat sink. Too much, and the chip just floats on the middle pad.
--- End quote ---
Imo it sounds like hermitengineer is talking about hot air reflow.
hermitengineer:
--- Quote ---The tweezers probably do help in that area though, as they will squish some of the (hopefully not egregious) excess solder out and make sure that all pins get at least some solder bonding the chip to the pad when it cools. I wasn't trying the tweezers at the time other than to hold it in place, so that's just my speculation.
--- End quote ---
Yes. I like to err on too much solder than too little. The excess just squishes out and stays out. If this squeezeout is too ugly or causes a bridge, then I would have to go over it with a soldering iron. But if you start with too little, then the chip suctions to the center pad and doesn't align itself. It will take a hard nudge with tweezers to move it, and where it stops will be random.
If you don't have to solder the center pad and the part has "side pad," I personally find it to be faster/easier to use an iron to solder the outer pads vs hot air reflow.
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