Home computer construction with SMT parts and PLCCs

ElEctric_EyE · Post by **ElEctric_EyE** » Fri Mar 12, 2010 11:05 pm

Yesterday I received 2 XC3S400-208PQFP's. .5mm 208 pin PQFP. There is no way to solder this thing! Today I received the 208 pin PQFP to PGA adapter, and in the pic you can see the WW headers, and my intentions...

I did notice the IC is just a bit "springy" when put onto a flat surface. And the pads on the adapter seem to have just the slightest bit of solder. So I guess the idea would be to clamp the IC onto the pads and heat it all up until the solder flows? I do have a mini-torch...

If anyone has experience in this type of intricate work, I'd like to know the details. The socket was $78, the IC was $25. I'm thinking of using a C-clamp and a minitorch without adding solder....

8BIT · Post by **8BIT** » Fri Mar 12, 2010 11:23 pm

You might get some ideas or help from these:

http://www.youtube.com/results?search_q ... +soldering

Good luck!

Daryl

GARTHWILSON · Post by **GARTHWILSON** » Sat Mar 13, 2010 12:14 am

Instead of trying mechanical means, I might skip the clamp, put the board on a pan or thick piece of sheet metal on hot plate and bring it up to a little below the melting point of the solder, and use a heat lamp to finish it up. Do not use a torch! If you need more solder, get a solder paste syringe from Chip Quick (I think Digi-key carries it) and first apply it to the pads before adding the IC and heating it up. With the right amount of solder paste, it should pull into the pads and not leave any solder where it shouldn't be.

OwenS · Post by **OwenS** » Sat Mar 13, 2010 12:26 pm

Position the chip, then heat up your iron, and apply solder (and flux) liberally. Don't worry about bridging pins. Then, once all the pins are soldered down, take your solder wick and it will suck the excess and bridges away (Without removing the actual bonding solder - solder binds more tightly to tin legs & PCB than solder wick)

In general, tack down one corner in place then start at the oposite

ElEctric_EyE · Post by **ElEctric_EyE** » Sun Mar 14, 2010 8:22 pm

Daryl, the youtube video was very informative. I watched it a couple of times, and headed out this morning to get paste flux, and solder wick (braid as radio shack calls it). It was a sinch. Much, much easier than I thought. I didn't have to add solder, there was enough on the adapter. I had to use the wick once when the solder built up on the tip and bridged 2 pins. Took me less than 5 min's total. The hardest part is precisely lining up the pins, on all four sides, to the adapter.

I was intimidated because I had tried a couple weeks ago to solder a 44 pin QFP (no where near the fine pitch of this 208 pin QFP) without using flux, just rosin core solder, and it was bridging pins like mad, and looked sloppy. I was using a solder sucker to unbridge the solder. I went back over it today after adding some flux, and it cleaned it right up...

Owen, you said it, a liberal amount of flux is mandatory for success... I wish I could take better close up pictures.

Garth, I can't believe I was thinking about using a torch, (it was a small mini butane torch though, still...)

edit:
Thanks for the pointers all. (No pun intended with the last pic

BigDumbDinosaur · Post by **BigDumbDinosaur** » Mon Mar 15, 2010 2:23 am

ElEctric_EyE wrote:

I wish I could take better close up pictures.

Smaller ones would help.

As for the slobbering job, it almost looks like it came from the factory.

ElEctric_EyE · Post by **ElEctric_EyE** » Mon Mar 15, 2010 11:14 pm

Thanks! Probably my last post on this thread... Hope it helps those so inclined for home brew.

ElEctric_EyE · Post by **ElEctric_EyE** » Fri Jul 16, 2010 11:38 pm

Sorry to dig up this old thread yet once again, but...

There's another company which deserves mention here. I forgot to do so in regards to my last pic, with the 208-pin QFP version of the Spartan 3...

My current project uses a Spartan 2 100-pin VQFP PGA adapter and also a 54-pin TSOP II PGA adapter, made by EPBoard, which you can see here: (1st and 3rd sockets down), viewtopic.php?t=1370&postdays=0&postorder=asc&start=172

They have excellent timely service, I usually receive the order 3-5 days after placing it online. Not sure about a minimum order, maybe $50US?

Don't confuse PGA with BGA. These are "through-hole" QFP adapters that can fit wire-wrap headers, check out the pre-mount 208-pin QFP pics: viewtopic.php?t=1492&start=32

Visit the site and check out the diag's:

http://epboard.com/eproducts/protoadapt ... PGAAdapter

-EyE

ElEctric_EyE · Post by **ElEctric_EyE** » Wed Aug 29, 2012 3:47 pm

Recently, I found it very frustrating to be limited to 144-pin QFP's. So, I've been looking at some IR "welders" to solder BGA's. Found one today for about $150US. I figure I could practice on QFP's or old motherboards and work my way up to designing with 1mm BGAs. I imagine the tough part would be accurately placing the part.
Here's a link to the one I found. There's an annoying little video there too. Anyone tried using one before?

EDIT: A related thread on BGA soldering in the Programmable Logic section. BTW, I

@myself on the Virtex 6 comment in there. Those IC's cost more than a new car!!! There are more capable IC's though, even just a larger 484-pin Spartan 6 in 1mm BGA, that are reasonable prices, i.e. <$50. Scratch that

. The Virtex-6 IC is the XC6VLX75T-1FFG484C @ $530ea. Mucho deneiro, but still in range for a most powerful 484-pin FPGA!
Re-EDIT: The most powerful Spartan 6 in 484-pin package is the XC6VLX130T, although that weighs in @$767!

Home computer construction with SMT parts and PLCCs

Re: Home computer construction with SMT parts and PLCCs