Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, "electronut" <electronut@...> wrote:
>
> Recently, I started making electronic circuits as a hobby and now
> I want to do more complex stuff like FPGAs.
> For that I need to solder BGAs. I'm considering buying a hot air 
> rework station. 


Personally, I avoid BGA's like the plague, even for work. Unless I
need all of the IO pins, I stick to other packages. BGA's can be
difficult to solder well. The pads have to be perfect (very small
geometries), chip alignment right on, reflow done just right, and on
top of that, the balls on the BGA themselves need to be prepped
properly. We have a special rework person at work just for re-balling
BGA's.  Then after mounting, it's difficult to inspect your work and
impossible to do any touch up. (again at work, we have special
microscopes to peek under the chips and also x-ray machines). It can
be done but it's hard and reliability is a big problem. Also, if your
board flexes at all, that can crack the BGA joints as they have no give.

My suggestion, stick to the TQFP / PQFP packages. I like to stay with
TQFP for home pcb if I can. The 100 and 144 pin TQFP is actually
pretty easy to work with. You can get up to 240 pins and 20K LE's with
240K of RAM.  Only if I needed bigger than that, would I think about
doing BGA (and I can't afford a part bigger than that anyways ;-) ).

That's my personal suggestion.
Phil