Step 6: Go for it!

Picture of Go for it!
Once it all looks good, give it a try! With a microcontroller, the first thing to do is to try programming it and see if it responds. From there, you can test if it can interact with the things that it's connected to (LED's, sensors, actuators, etc). Happy soldering!
There is one huge problem with your method. You put solder on each pad, which has thickness. Then you melt only one pad, when you do this all the other pads will keep that one pad from properly seating. As a result the entire chip will not be seated properly. If you could heat all pads at the same time, then this would work.

What I do is put solder on only one pad, then solder down that one pad. Then I head each trace and have the trace melt the solder. This will cause the solder to wick-up onto the pad. This way all the pads are properly seated.

I like your ideas of using the Flux marker, I didn't know these existed.

Thanks for the good tips. I have never done anything before............I am starting out doing whatever I can do with electronic stuff, because I started with PCs...um, this is my project and after reading your post I may have a go at this 3rd generation ipod headphone to motherboard connecton repair job. Tricky because the wires on the "board" part are torn from the chip pins.
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g_c_c8 years ago
Another good tactic is to put a drop of solder on each of the pads, use a flux marker on them, then use a torch to heat a razor blade to red hot. I've only tried it once, and on larger parts than that, but- might be worth a try.
bfr9 years ago
Cool. I didn't believe this was possible when I first heard about it, but now I think it's just as easy, if not easier than soldering leaded packages since bridges are harder to make. I use paste rather than solder though which makes a big difference. I also remove the solder balls with wick first so the chip sits flat. A chisel tip also helps a lot, fine tips aren't that great unless you have a metcal :-)
bikeNomad9 years ago
And one possibility for the hotplate is to get an old electric skillet from the thrift shop.
I've heard of alternate methods of soldering the tiny, tiny MLF packages by putting a bit of solder/solder paste on the pads then placing the board with the micro held on onto a hotplate to reflow the solder. Whole thing ends up being flat, and it permits soldering to the large ground pad.
prank9 years ago
cool. How did you take the pictures?
davidmerrill (author)  prank9 years ago
I just used my Nikon Coolpix 5600 (5MP point-and-shoot camera) in macro (close-up) mode, and shot the pictures through the eyepiece of the microscope that I was using for soldering. It helps to make sure that it's very, very well-lit, and there's a lot of fine positioning needed before the image all of a sudden jumps into view, but once it does, as you can see the pictures are pretty nice!
klee27x9 years ago
That chip IS an SMD part. :)
you can do this with SMD parts too.
ian9 years ago
This is great. I'm going to try a 20 lead QFN package soon, this gives me confidence that it can be done.