I'm looking for a cheap source of broken/outdated TQFP-44 and SO-28 ICs or packages which I can test my soldering skills with. The chips I'm using are £3 each and this is money I'd rather not throw away if I damage them.
Any suggestions will be appreciated! Thanks!
Unless you're soldering with a blow torch I highly doubt you will damage a SO-28 as long as you have some soldering experience. Just tag 2 corners, use plenty of no-clean flux both on the board before you place and on the rest of the pins after you tag and you really can't go wrong.
The TQFP is pretty much the same process. Don't try to solder a pin at a time. Tag opposing corners (takes a bit more care to get all the pins lined up). Apply plenty of flux, again to the board before you place and then to the pins after its tagged and soldering the sides only takes a couple seconds.
In both cases don't try to be cheeky and solder 1 pin at a time, if you've fluxed properly you can use a chisel tip the size of the entire side of the IC and solder without bridging while only heating the IC for a few seconds, although i'd recommend starting with a smaller chisel. The only special thing you need is thin solder to avoid getting way too much on there, 0.4mm is what i use.
I really doubt you'll kill many, if any, ICs learning unless you try to solder with no flux and go 1 pin at a time.
You'll save way more IC's by using decent soldering equipment than anything else.
Sparkfun had a reel of fake ATmega328s which would have been perfect for this. Sadly, they're now seem to be sold out.
http://www.sparkfun.com/commerce/product_info.php?products_id=9831
It might be worth contacting them to see if they have any more...
Rework and soldering equipment vendors (Pace, etc) have little kits with a PCB, fake ICs, chip components, etc that they use as sales tools. You may want to contact some of these vendors to see if they'll sample you one. In my experience they are pretty free with them, in a professional environment at least.
Note that since these are sales tools, the PCB is designed for soldering success (no ground planes, big spacings between parts, etc).
If you can do it, you might find suitable chips in an old switch or motherboard or some other junk, desolder (hot air/gas/oven) them and use those for practice. Recycle and save the planet. :)
