foft's dfb1 build

[foft]

I just ordered all the parts and boards for a DFB1 build. Excited! Going to be several weeks before I get everything so this thread is just a placeholder for now.

[foft]

I received all the parts from Digikey + elsewhere.

PCBs just arrived today, here they are. In the background you can see the Eagle Sonic which may have to donate its CPU!

So here goes, wish me luck.

DFB1.png

[viking272]

Good luck!
Can you share the individual cost of the board and parts? I presume there is much better economies of scale doing the 5?

[foft]

I bought only one set of parts for now.

I did get 5 pcbs made though, those cost about 9CHF each. I guess I should sell the extras rather than them lying in my cupboard for ever, but not sure its worth it :D

Anyway costs were:
45USD for the boards
15.5USD for the RAM (64MB) (ebay)
18.5USD for the CPLD (ebay)
27USD for the other parts (digikey) + shipping (I ordered a bunch of other stuff...)

So 106USD total

[coonsgm]

So are you thinking about building any to sell onwards?

Just curious...

[foft]

Just started on this this afternoon. I'm feeling pleased that I ordered 5 boards, because this one is a complete mess :( ! I think some days I don't have the state of mind to do a good job at surface mount!

I put as thin a strip of paste on the 4 sides of the CPLD footprint with the syringe as I could. I guess it was too much since after soldering I had lots of bridges. Anyway I completely messed up the clean up, over about 3 hours using the microscope, paste, braid, soldering iron with a multitude of heads. i.e. I have plenty of tools but not enough skill.

Anyway after putting on the 18 caps I found I had a short over C17. So I removed them all, and still had a short over it. I guess related to the CPLD mess. So in putting them back on I managed to fire one across the room.

Think I'd better start again on another day on a fresh board!

Any tips for applying the right amount of paste without a stencil? Or is it better to drag solder this CPLD? I don't have experience with such fine pitch, particularly without a stencil.

CPLD_FAIL.JPG

CPLD_FAIL2.JPG

[foft]

So are you thinking about building any to sell onwards?

Just curious...

If you look at my post, you'll probably realize you are better off with one made by someone else :lol:

[DoG]

As you said. Start with a new one.

As you have noticed, small amount of paste goes a long way. Use a lot of flux when you need to touch up pins or remove solder. Sticky flux is better when using hot air. To much solder creates hard to find bridges of solder behind pins. If the flux evaporates or the solder not melts together, small solder balls will be formed and that can cause bridges as well. Clean with IPA to get rid of those, or a small pick to get them loose. They can stick to the solder mask.

Don't use to much downforce when using braid. Lots of flux helps with braid too.

I don't use paste when doing the big chip. I use iron. I prefer knife edge (since I drag solder a lot). Put sticky flux on footprint on PCB. Drop the chip in place and get it in place as perfect as you can. Tack a leg or two in with a soldering iron on one side. Check position. Remove or reheat the leg you just solder in if it is not perfect. Then Solder a leg or two on the opposite side. Then start soldering in the rest. Lots of flux. Very little solder is needed when doing this.

[frank.lukas]

... watch the full video !

Use leaded solder with flux. 1mm or smaller

[foft]

That video makes it look so easy. One day I'll get there!

Many thanks for all the tips.