Klondike - 16 chip ASIC Open Source Board - Preliminary

[evilscoop]

Bkk, query regards pcb plz

How many layers is it ?
And since avalon chips pass heat underneath (docs state there is an air gap in the chip), do we need to user something like :-
http://www.dkthermal.co.uk/index.php?option=com_content&view=article&id=49&Itemid=63
for the pcb manufacture.....?

Also would it be worth adding some small heat fins on the underside, and mount vertically as avalon do their boards ?

cheers

Please read through the thread.

4 layer board with VIAS in the pcb to transfer heat to the heat sink.
Heat sinks to be determined he has a few sample heat sinks coming his way and will test them and report back.

yeah somehow I convinced myself it was 6 layer....this thread moves so fast I cant wade through all the posts after I go to sleep :/

thx for reply...

[Bicknellski]

Bkk, query regards pcb plz

How many layers is it ?
And since avalon chips pass heat underneath (docs state there is an air gap in the chip), do we need to user something like :-
http://www.dkthermal.co.uk/index.php?option=com_content&view=article&id=49&Itemid=63
for the pcb manufacture.....?

Also would it be worth adding some small heat fins on the underside, and mount vertically as avalon do their boards ?

cheers

Please read through the thread.

4 layer board with VIAS in the pcb to transfer heat to the heat sink.
Heat sinks to be determined he has a few sample heat sinks coming his way and will test them and report back.

yeah somehow I convinced myself it was 6 layer....this thread moves so fast I cant wade through all the posts after I go to sleep :/

thx for reply...

Just READ BKKcoins post. That way you can see only the important info and skim through everything pretty quick and get up to speed. Heat sinks have been discussed numerous times already and there are many different options for off the shelf fits. No one should order anything yet just get some ideas and keep looking for suppliers locally for heat sinks especially... I guarantee there will be several different heat sinks and water blocks that will probably be available depending on the configuration you are going for. For a single board maybe even an older CPU heat sink with fan would be ideal... all depends on some testing.

I'm expecting to have 1 or 2 heat sinks on the back of each board. Either one large one or 2x(6cmx10cm). I have a socket 478 CPU (AL) heatsink on hand and I think I'll initially test with that and see where it goes. These seem to be easy to find locally. I also may make some myself with sheet aluminum for trials. In the end I don't know what will be sufficient except by looking at the Avalon we should expect similar size and results - I won't be able to magically vanish any heat but there's no reason it should be worse. - BKKcoins

http://www.aliexpress.com/snapshot/233967692.html


Brand Name: SZOMK
Type: Heatsink
Heatsink Material: Aluminum
Model Number: HS9
Place of Origin: China (Mainland)
color: dark grey
size(mm): 90x90x15mm
size(inch):3.54"x3.54"x0.59"

Sent one of these to BKKCoins airmail... hoping it arrives when he needs it.

[emanymton]

Bkk, query regards pcb plz

How many layers is it ?
And since avalon chips pass heat underneath (docs state there is an air gap in the chip), do we need to user something like :-
http://www.dkthermal.co.uk/index.php?option=com_content&view=article&id=49&Itemid=63
for the pcb manufacture.....?

Also would it be worth adding some small heat fins on the underside, and mount vertically as avalon do their boards ?

cheers

Please read through the thread.

4 layer board with VIAS in the pcb to transfer heat to the heat sink.
Heat sinks to be determined he has a few sample heat sinks coming his way and will test them and report back.

yeah somehow I convinced myself it was 6 layer....this thread moves so fast I cant wade through all the posts after I go to sleep :/

thx for reply...

Just READ BKKcoins post. That way you can see only the important info and skim through everything pretty quick and get up to speed. Heat sinks have been discussed numerous times already and there are many different options for off the shelf fits. No one should order anything yet just get some ideas and keep looking for suppliers locally for heat sinks especially... I guarantee there will be several different heat sinks and water blocks that will probably be available depending on the configuration you are going for. For a single board maybe even an older CPU heat sink with fan would be ideal... all depends on some testing.

I'm expecting to have 1 or 2 heat sinks on the back of each board. Either one large one or 2x(6cmx10cm). I have a socket 478 CPU (AL) heatsink on hand and I think I'll initially test with that and see where it goes. These seem to be easy to find locally. I also may make some myself with sheet aluminum for trials. In the end I don't know what will be sufficient except by looking at the Avalon we should expect similar size and results - I won't be able to magically vanish any heat but there's no reason it should be worse. - BKKcoins

http://www.aliexpress.com/snapshot/233967692.html


Brand Name: SZOMK
Type: Heatsink
Heatsink Material: Aluminum
Model Number: HS9
Place of Origin: China (Mainland)
color: dark grey
size(mm): 90x90x15mm
size(inch):3.54"x3.54"x0.59"

Sent one of these to BKKCoins airmail... hoping it arrives when he needs it.

On behalf of all the klondike moochers, thankyou Bicknellski 

[Bicknellski]

One of the biggest moochers around ... a heat sink ain't much. Thanks though.

[mike2kt]

http://www.aliexpress.com/snapshot/233967692.html

Someone get out the drill bits!!!

[Knecke]

if you need one with special holes or something else, i would be honoured to send you one 100mm x 100mm.

[daemondazz]

What's the thermal resistance on that heatsink? The only place Google turns up that model for me is AliExpress and they don't have it listed.

[FTWbitcoinFTW]

In 4 glory

[emanymton]

if you need one with special holes or something else, i would be honoured to send you one 100mm x 100mm.

I think it needs to be slightly smaller to accommodate for the holes in the corners for stacking...

[Bicknellski]

if you need one with special holes or something else, i would be honoured to send you one 100mm x 100mm.

I think it needs to be slightly smaller to accommodate for the holes in the corners for stacking...

Won't be stacking prototypes right? Ask him via PM Knecke... probably save him time in the long run if you get him a sample different fins etc so can check different profiles.

[Bicknellski]

What's the thermal resistance on that heatsink? The only place Google turns up that model for me is AliExpress and they don't have it listed.

Hard to know so many variables. That is why he will test it. I think someone with the right skills could give us an idea of the best profile based on the type of Aluminum used and what the Thermal Resistance could be given a set of parameters.

Not sure it will be that big a deal given you get a fan on top of it and blow hard on the fins right? Move air across those fins you will get the desired effect. It be nice if someone with basic knowledge of Thermal resistance and knows the pcb design and chips etc could do a set of calculations for different profiles. I think that would help everyone out a lot.

[eroxors]

I know Avalon says not to mount on the chips, but I'm seriously considering ramsinks w/AS epoxy or TIM pads... they are light, cheap, and transfer heat very well...

[BkkCoins]

if you need one with special holes or something else, i would be honoured to send you one 100mm x 100mm.

Didn't you have long stock 100mm wide? I really like the idea of a long bar heat sink, say 400mm long x 100mm. And then the K16s mount on them in a row so that the heat sink becomes the structural frame holding the boards. For those with tiled arrays of K16 I could see that being a good plan.

Then, to go vertical you would put the spacers between heat sinks not boards.

I found a local heat sink bar like that - 60cm long but only 30mm wide. It was very cheap, like about $1 or so, but not quite right.

I know Avalon says not to mount on the chips, but I'm seriously considering ramsinks w/AS epoxy or TIM pads... they are light, cheap, and transfer heat very well...

You would need to mount those on the back side, not the plastic top. Seriously, the QFN package has a big metal pad on the bottom and the die is connected to the bottom expressly to send heat out the bottom.

[wrenchmonkey]

I know Avalon says not to mount on the chips, but I'm seriously considering ramsinks w/AS epoxy or TIM pads... they are light, cheap, and transfer heat very well...

Good luck with that... 

[KS]

Would a heatsink like this one do the trick?

http://www.befr.ebay.be/itm/10CM-100x76x21mm-Aluminum-Heat-Sink-for-4-6pcs-3W-LED-Power-Transistor-Cooling-/390557019421?pt=LH_DefaultDomain_0&hash=item5aef032d1d#shId

3 USD + 1 or 2 USD shipping for EU.

[mike2kt]

I know Avalon says not to mount on the chips, but I'm seriously considering ramsinks w/AS epoxy or TIM pads... they are light, cheap, and transfer heat very well...

You would need to mount those on the back side, not the plastic top. Seriously, the QFN package has a big metal pad on the bottom and the die is connected to the bottom expressly to send heat out the bottom.

^^^ this

https://en.bitcoin.it/wiki/Avalon#Others

"About install extra heat-sinks on each avalon chip: please do not do that. there is a air gap between the die and package top, install a heatsink on chip is useless. and will cause overheating. because the top PCB copper act as a heatsink too. do not cover them."

Please feel free to shoot yourself in the foot though...

[BkkCoins]

Would a heatsink like this one do the trick?

http://www.befr.ebay.be/itm/10CM-100x76x21mm-Aluminum-Heat-Sink-for-4-6pcs-3W-LED-Power-Transistor-Cooling-/390557019421?pt=LH_DefaultDomain_0&hash=item5aef032d1d#shId

3 USD + 1 or 2 USD shipping for EU.

This is pretty close, and may work well enough. The dimensions between outer edges of the ASIC exposed copper pad under the board is 90mm x 80mm. So ideally you would cover that completely.

That one being 76mm would be just a bit shy but probably still work. It looks to have nice tall fins, which is good for the price.

[Knecke]

if you need one with special holes or something else, i would be honoured to send you one 100mm x 100mm.

Didn't you have long stock 100mm wide? I really like the idea of a long bar heat sink, say 400mm long x 100mm. And then the K16s mount on them in a row so that the heat sink becomes the structural frame holding the boards. For those with tiled arrays of K16 I could see that being a good plan.

Then, to go vertical you would put the spacers between heat sinks not boards.

I found a local heat sink bar like that - 60cm long but only 30mm wide. It was very cheap, like about $1 or so, but not quite right.

I know Avalon says not to mount on the chips, but I'm seriously considering ramsinks w/AS epoxy or TIM pads... they are light, cheap, and transfer heat very well...

You would need to mount those on the back side, not the plastic top. Seriously, the QFN package has a big metal pad on the bottom and the die is connected to the bottom expressly to send heat out the bottom.

yes i can get 500mm x 100mm heatsinks as well.
Up to 1.000mm length.

Heatsink



Tell me prefered size and send me the hole patterns and i will manufacture you a sample.

[eroxors]

I know Avalon says not to mount on the chips, but I'm seriously considering ramsinks w/AS epoxy or TIM pads... they are light, cheap, and transfer heat very well...

You would need to mount those on the back side, not the plastic top. Seriously, the QFN package has a big metal pad on the bottom and the die is connected to the bottom expressly to send heat out the bottom.

^^^ this

https://en.bitcoin.it/wiki/Avalon#Others

"About install extra heat-sinks on each avalon chip: please do not do that. there is a air gap between the die and package top, install a heatsink on chip is useless. and will cause overheating. because the top PCB copper act as a heatsink too. do not cover them."

Please feel free to shoot yourself in the foot though...

Thanks. This helps.... Plan B: let the smart people figure out how to do it.

edit: I do think there is value in self-sourced solutions, which can be cheaper/faster. I have dozens of slot 1/s370 HSFs that might fit the size/thermal envelope.

[marto74]

I think what we need is a 90 x 80 mm maybe 1.5 inches height and fins in one direction. Drilled in 4 places to accommodate 4-40 screws.

Also if the fins are narrow then drill the fins to accept a spring and long bolt on that side, a bit wider than bolt. The heat sink should probably not be tightened directly to the board but have springs for pressure, much like CPU heat sinks usually have. I think wider fin spacing is likely better anyway as it will allow better air flow. I'm not an expert on thermals but I suspect that narrow fin spacing are better suited to convection (passive) use.

Ideally there would be a group of holes or non-thru hole dents made at the PCIe power connector location to allow for pin protrusion. I've allowed for an alternate Phoneix SMD power connector but that is not as standard and easy to use a solution as a PCIe connector. So if custom heat sink machining is done it makes sense to include this.

So in batches of 200 pcs
Price will be 3.62 EUR , including profile 35 mm x 165 mm, machining of holes and release for spring clamping and power connector nest, surface machining on the back.
As soon I get some info I asked BKK, I'll provide CAD of the heat sink.
Price is based on available profile here on stock.

So 35 x 165 is the standard profile.
The heat sink dimension machined are 80 x 90 mm 35 mm high.
The price is including machining and raw material . Machining : drilled holes, countersinks for clamping springs, surface machining on mating area and power connector release .
To provide cad (parasolid and dwg/dxf) i need PCB cad transferred to dxf or any machining cad

If I'm reading that correctly...35mm width x 35mm length x 165mm height ~(1.4 x 1.4 x 6.5 inches)? Made of aluminum? Where do I sign up for 200 of them?!? (I have 800 chips on order.)

Or is that 35x165mm to cover one side of the board (8 ASICs)

Side note...would that be one full extruded aluminum piece and NOT two-part (base with fins mechanically attached)?