What I don't get is why people hate QFN. I think QFN packages are much easier to work with compared to QFP if you have a decent pair of tweezers and a hot air station.
Really? I find TQFP miles easier.. for one if you have a solder bridge short you can simply just wick it off.. with QFP you have to remove it and solder it again, not to mention you can't visually inspect the solder joints since they are under the package, still much better than BGA.
The trick with QFN is to make sure the pads extend at least 0.5mm from the edge of the package. You can then see whether or not there are solder fillets, and you can easily deal with shorts and resolder individual pins ( need 0.3mm solder).
A big advantage, especially for production, is they don't suffer from bent pins like QFPs can - a lifted QFP pin can be very hard to spot.
The only downside is where the QFN requires the centre pad to be soldered, as this reduces available routing area.
With hot air, I find QFNs quicker to replace then QFPs as the pull onto the pads much more readily
Hmm.. interesting. I think my problem might be the fact that I don't order a stencil for my prototypes. I usually just dab some solder paste on the pads with a toothpick. This is why I sometimes get solder bridges. Should probably use stencils more often. Will give QFN another chance.
For QFN's what I do is put flux on the pads for the QFN footprint on the PCB, tin the pads with a chisel tip, not too much, especially for the center pad, reflux the tinned pads, flux the bottom of the IC, position the IC on the pads, and gently bring it up to solder melting temp with a hot air gun, push it back and forth to watch surface tension pull the IC into place, and then stop, clean it up, and look at it under the microscope. Never had to deal with stencils or solder paste. Anyone else go this way? It works for me.
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