On 03/31/2017 06:15 PM, Jon Elson via cctech wrote: > I have a project I do from time to time using 128-lead 14mm TQFPs > with 0.4mm lead spacing. I use a stereo zoom microscope with a > home-made LED ring light. First, I rub the pads with a pencil eraser > to remove oxidation caused by reflow temps on the rest of the board. > I put a tiny dab of solder on two pads at opposite corners. I then > place the chip in place and reflow those pads. If the alignment is > not good enough, I can "walk" the chip a bit by reflowing one, then > the other pad. Then, I apply liquid flux to the rows of leads with > a wire dipped in the flux. And, then solder down the rows with a > fine-tip soldering iron. If a bridge develops, solder wick fixes > it.
There are plenty of good Youtube videos describing this. I use pretty much the same method, but start off with just a binocular loupe and then finish with a stereo microscope for final inspection. The soldering iron tip that works best for me is a rather broad chisel tip. I leave the fine tips for other work. --Chuck