Klondike - 16 chip ASIC Open Source Board - Preliminary

[sensei]

The K1 stencil will work fine - I've done similar things with a laser cutter many times when I didn't have time to wait for a stainless foil.

Do yourself a huge favor though - run some 1000 grit sandpaper over both sides to clean up the burrs.  They don't look like much, but they end up holding the stencil off the board just enough that the paste oozes under 'everything'.  Experience speaking here

Enigma

You not only don't want the paste oozing underneath, but you also don't want is coming up with the stencil, getting caught in the cutouts. Cleaning it up as suggested with the sandpaper will help with that also.

[BkkCoins]

What's the heatsink mounting hole spacing? In fact, is there a drawing of the PCB anywhere? I tried to convert the SVG to DXF, but the mounting holes don't translate over. Trying to mess with it, but no success. Is the overall board about 111mm square?

90 x 90 mm

The gerber files are best guide right now. I use the gerbv program to view them and know that it works. It has an export function and I've used it to export PDF, SVG, or PNG - though the PNGs are pretty crappy - it doesn't have any output controls. I think exporting a PDF works well. This is also how the conversion is done for cutting the stencil.

The k16.drl file has very accurate drill hole sizes and positions but requires a bit of interpretation as it's meant for machine use not human. But the info is there and not hard to decipher.

The k16-B_Mask.gbs has the imagery for bottom mask and holes. The holes aren't as big as that shows since it allows a wide mask for the hole but the centers should be correct.

[marto74]

We'll see..
Here is the sample panel We are making

Looks good. One thing I know now - the K1 pcb isn't thick enough alone to make good contact in a USB socket. It will need some kind of plastic or metal tab to be incorporated into the case/heat sink for the board. I'd seen some USB-on-PCB designs online and presumed that 1.6mm would be close enough, but it isn't. I slipped a piece of thin 0.4mm aluminium in and that makes it snug. That leads me to think that 2mm is the right total thickness.

That's the main reason I need K1 pcb made.
I'm planing to make a sandwich:
1. Simple plastic enclosure on the bottom that is holding screw holes and K1 board clicks in ( I can produce sample injection mold for 1000 pcs in ALU for 3-4 days)
2. K1 nano board
3. On the top (bottom of the board) small Alu heat sink with a few threads to be attached to features on the plastic part

[Dunkelheit667]

We'll see..
Here is the sample panel We are making

Looks good. One thing I know now - the K1 pcb isn't thick enough alone to make good contact in a USB socket. It will need some kind of plastic or metal tab to be incorporated into the case/heat sink for the board. I'd seen some USB-on-PCB designs online and presumed that 1.6mm would be close enough, but it isn't. I slipped a piece of thin 0.4mm aluminium in and that makes it snug. That leads me to think that 2mm is the right total thickness.

Yes, should be 1.95 +/- 0.05mm. Source: http://www.usb.org/developers/devclass_docs/CCWG__A__Plug_Form_Factor_Guideline__Revision_1.0_.pdf - Appendix A.

[BkkCoins]

What's the heatsink mounting hole spacing? In fact, is there a drawing of the PCB anywhere? I tried to convert the SVG to DXF, but the mounting holes don't translate over. Trying to mess with it, but no success. Is the overall board about 111mm square?

The board is 100mm x 100mm. The corner holes are 90mm x 90mm. The heat sink holes between ASICs are 62mm x 55mm (unless I've made a mistake in reading that off - the gerbers are gospel right now).

[BkkCoins]

Yes, should be 1.95 +/- 0.05mm. Source: http://www.usb.org/developers/devclass_docs/CCWG__A__Plug_Form_Factor_Guideline__Revision_1.0_.pdf - Appendix A.

Saved for future reference. Thx.
I knew there was an official doc out there but for some reason when I googled for it a month ago I couldn't locate it. Not that I would have gone to a 2mm PCB anyway just for that. I think marto74 has the right idea by incorporating it into some casing.

[TomKeddie]

I have a US bank account but not Citibank. I don't want to put my email address here but anyone who gets an inkling to send PP can always PM me for that.

Perhaps take a look at coinbase, works well for me.

[bitcoiner49er]

What's the heatsink mounting hole spacing? In fact, is there a drawing of the PCB anywhere? I tried to convert the SVG to DXF, but the mounting holes don't translate over. Trying to mess with it, but no success. Is the overall board about 111mm square?

90 x 90 mm

The gerber files are best guide right now. I use the gerbv program to view them and know that it works. It has an export function and I've used it to export PDF, SVG, or PNG - though the PNGs are pretty crappy - it doesn't have any output controls. I think exporting a PDF works well. This is also how the conversion is done for cutting the stencil.

The k16.drl file has very accurate drill hole sizes and positions but requires a bit of interpretation as it's meant for machine use not human. But the info is there and not hard to decipher.

The k16-B_Mask.gbs has the imagery for bottom mask and holes. The holes aren't as big as that shows since it allows a wide mask for the hole but the centers should be correct.

The Mask gerber was the one I needed. Tried using Kicad first, but it didn't have any export options. Got it now. 100 x 100mm board, 90 x 90mm mounting holes spaced 5mm off board edge and 55 x 62mm heat sink mounting. Perfect!
I am toying with the idea of a quad mounting bracket.

[evilscoop]

that looks nice m8..

Little poke to bkk can we get Fiducials marks please

[BkkCoins]

The Mask gerber was the one I needed. Tried using Kicad first, but it didn't have any export options. Got it now. 100 x 100mm board, 90 x 90mm mounting holes spaced 5mm off board edge and 55 x 62mm heat sink mounting. Perfect!
I am toying with the idea of a quad mounting bracket.

That looks pretty cool. Don't close off the outside of the boards completely as they do need at least some convection and preferably a bit of air flow. I've put thermal vias under the buck regs but I don't know if that will be enough as their pads are quite small.

that looks nice m8..

Little poke to bkk can we get Fiducials marks please

They're already on the board. 8 of them, a pair for each ASIC quadrant. I put them on long ago but then found out that each board place likes to have them done "their way", so was going to remove them again but never got around to it. I tried to follow some generic guidelines for what most PnP like to "see". I don't if they're of much use the way I did them and no one has reported back. The place I know of that does assembly in Bkk was just going to add tabs around the board for their own so they've even become redundant for me.

[evilscoop]

that looks nice m8..

Little poke to bkk can we get Fiducials marks please

They're already on the board. 8 of them, a pair for each ASIC quadrant. I put them on long ago but then found out that each board place likes to have them done "their way", so was going to remove them again but never got around to it. I tried to follow some generic guidelines for what most PnP like to "see". I don't if they're of much use the way I did them and no one has reported back. The place I know of that does assembly in Bkk was just going to add tabs around the board for their own so they've even become redundant for me.

mm I must have got a quote from an old board version then...

2 fiducials diagonally opposite each other close to the edge of the board

 

[bitcoiner49er]

The Mask gerber was the one I needed. Tried using Kicad first, but it didn't have any export options. Got it now. 100 x 100mm board, 90 x 90mm mounting holes spaced 5mm off board edge and 55 x 62mm heat sink mounting. Perfect!
I am toying with the idea of a quad mounting bracket.

That looks pretty cool. Don't close off the outside of the boards completely as they do need at least some convection and preferably a bit of air flow. I've put thermal vias under the buck regs but I don't know if that will be enough as their pads are quite small.

Yeah. Need room for cables as well.

[BkkCoins]

Yeah. Need room for cables as well.

You may want to look at FPC or ribbon cable w/headers to tie the klego connectors on each side to the next side. Usually side-side would use a 2x5 pin header wired correctly, but since you have a corner to wrap maybe a short 3 lead FPC type connector could be fitted. Or possibly if the spacing is right a right angle header on one side matched with a vertical on the next would line up.

[itod]

Some good recent add on links for the reference thread.

Southerngentuk finds a perfect pick and place DIY for BKKcoins.
Southerngentuk finds video for recycled DIY home-made SMT metal stencil.
Southerngentuk wants you to read about the DIY home-made SMT metal stencil.

Very interesting method for making metal stencils from soda cans. I have only one question for more experienced people here: would not the soda can wall be to thin for a stencil? Average soda can wall thickness is about 0.1mm, I was under the impression that regular steel stencils are much, much thicker so you can get enough paste on the board.

[Enigma81]

Some good recent add on links for the reference thread.

Southerngentuk finds a perfect pick and place DIY for BKKcoins.
Southerngentuk finds video for recycled DIY home-made SMT metal stencil.
Southerngentuk wants you to read about the DIY home-made SMT metal stencil.

Very interesting method for making metal stencils from soda cans. I have only one question for more experienced people here: would not the soda can wall be to thin for a stencil? Average soda can wall thickness is about 0.1mm, I was under the impression that regular steel stencils are much, much thicker so you can get enough paste on the board.

The vast majority of solder stencils are .005" (5 Mils) thick.  This is .127mm, so the soda can isn't that much thinner.  It would work acceptably well.

Enigma

[Syke]

Beautiful.

[erk]

Some good recent add on links for the reference thread.

Southerngentuk finds a perfect pick and place DIY for BKKcoins.
Southerngentuk finds video for recycled DIY home-made SMT metal stencil.
Southerngentuk wants you to read about the DIY home-made SMT metal stencil.

Very interesting method for making metal stencils from soda cans. I have only one question for more experienced people here: would not the soda can wall be to thin for a stencil? Average soda can wall thickness is about 0.1mm, I was under the impression that regular steel stencils are much, much thicker so you can get enough paste on the board.

I prefer stencils you can see though so you can easily tell alignment and if you have missed something.

[Rakessh]

Can anyone say how many K16's could you run on a single rail of a ATX PSU? Is it correct you will need to manage max amps per rail as well? so you might have a very large wattage power supply but hit the amp ceiling first perhaps.

42.



But no seriously it depends on the 12v rail of the PSU and nothing else. Do some basic maths and you should be able to work it out....

The basic maths being Ohm's law. Anyway, you need to pay attention to wiring and plug amperage capacities if you use a lot of splitters to feed your boards from a high amp/watt rail. You may have to modify the psu.

[Tornate]

BkkCoins, where can I find a list of all components needed?

[Beastlymac]

BkkCoins, where can I find a list of all components needed?

https://raw.github.com/bkkcoins/klondike/master/docs/K16%20Parts%20List.pdf