Topic: Block Erupter: Dedicated Mining ASIC Project (Open for Discussion) (Read 58619 times)

Submerge it in mineral oil, and circulate it directly onto the chip faces that have an epoxy-heat-sink on top, and a through-hole to a sunk-ground on the bottom.

Beyond that, you can still cool them from the top, with epoxy-heat-sink that is either segregated and vacuum-bonded to the surface, or a standard thermal setup with "spring-tension", that will not damage the package with massive torque-pressure. Yet, still allow the heat-expanding aluminum and board to slide as needed.

The spring tensions can be simple push-through "V" tabs, attached to the heat-sinks directly, pushed through slots in the pcb, between the actual chips along the center-line of the board. (Not at the edges of the heat-sink... You want a center-line so the least movement is centralized and pressure around the whole surface uses the other chips as "supporting" feet to rest-on.)

Instead of cutting the PCB, place large exposed solder pads on both sides of the board, connected by lots of vias.  Then just mount the heatsink to the exposed pads on the underside, while the thermal interface on the bottoms of the QFN packages get soldered to the connected pads on the top side.

Obviously the biggest constraint is time-to-market or time-to-mine.

Wouldn't it be practical to keep all PCB layers clean under the ground paddles; use a hole punch to cut out the PCB epoxy under the chips and mount the real heatsink on the bottoms with copper washers/thermal spreaders? The tops would then just need a mechanical clamp.

I'm just brainstorming. I made a suggestion about 5 months ago about using power IC packages in this thread: https://bitcointalksearch.org/topic/m.1062969 . friedcat responded then immediately deleted his response because it probably disclosed something NDA-embargoed.

They do, but I think you'll be fighting a difficult battle cooling them through the thermal pad depending on the board design. Given the massive number of chips, the density is probably going to be quite high to keep board size reasonable. Cooling through the ground plane only works well if there aren't 8 chips all around the one is question all dumping heat in as well. If they can manage to keep the bottom clean they could definitely use a back plate to help cool the board.

Most QFNs have epoxy from the top of the die to the top of the package. It might not be a great thermal interface, but given the very low power per chip it will still be able to help.

But are they going to help? BGA cases are flip-chip; with chip substrate connected to the top of the case.

QFN packages don't flip the chip and actually have air between the top of the package and the chip, because they need to accommodate the bonding wires. They really want to be cooled through the bottom of the PCB because this is where they have the least thermal resistance and a biggest piece of metal: ground connection for the substrate.

I assume so. I'm just going off the publicly available information, so your guess is as good as mine.

Diablo, the small adhesive attached BGA heatsinks weigh almost nothing. They're not going to stress the chips.

Actually i see no reason to reinvent the wheel here..
Either use the chips within a spec that requires no heatsink or use thermal epoxy to bond small commodity BGA RAM sinks to the chips and mount the PCBs in 5 1/4" 4-in-3 HDD cages that comes with standard 120mm fan.

Mount the cages in standard HDD or ATX tower cases(12 bays) and you could have 16 PCBs per case x 16 chips(at least) per PCB for a total of 256 chips per case. 256 x 1.3W = ~333Watt per case, perfect for a standard PC ATX style PSU.

Final throughput would conservatively be around 85Ghash per system. Servicing shouldn't be too much trouble either, it's all stock PC components.
If using a PC to control the PCBs, using 1 USB connector per PCB, it's within reach of most standard motherboards too. Can scale it up/down easily to get the best balance as needed.

BOM for each system:

HDD Tower case incl. 400W ATX PSU = ~$70-80
4 x HDD cages w/120mm fan= ~$60-75
256 x BGA heatsinks and Thermal epoxy = ~$30-40
ATX mobo + cpu + ram = $80-120 (Optionally customer installable, could be replaced with a USB hub to have single PC control multiple cases)
16 x usb cables = ~$15-20

So ~$300 in parts per COMPLETE system, which can be sourced MUCH cheaper in China, above prices are what they could be found for here in Euroland.

Examples:
HDD cage(can be found much cheaper, just an example)
HDD Tower case (12 & 13 bay versions available too)

That's what the images Josh posted today suggest.

That heatsink is a waste of money. Its clearly a high performance one, but you never waste copper on the fins on a heatpipe assembly, it doesn't improve the performance. Plus, the base isn't nickel plated. Even if I needed a low profile heatsink like that, thats not the one I'd be buying.

Plus, friedcat couldn't easily tile those closely due to the overlap of the heatpipe assembly, and the airflow is down facing on those thus also hard to use in small assemblies. Its easier to blow air across the board than straight into it. BFL keeps making this design mistake.

So they're using Aluminum for the Little Single, but Copper for the SC Single? https://forums.butterflylabs.com/dbtgallery.php?do=view_image&id=2&gal=gallery

According to the pics posted on their website, BFL is using Al for their Little Single heatsink.

https://forums.butterflylabs.com/dbtgallery.php?do=view_image&id=1&gal=gallery

95 chips = 30GH/s @ ~125W?

Yeah, but if the chips remain stable at high clock rates while driving the voltage up, it'll need much better cooling. Also, its cheaper and saner to just use one large heatsink thats mounted on the board instead of placing the entire load on the chip itself.

If their 4.2J/GH number is correct, each chip is dissipating 1.3W. They aren't going to require anything special at all for cooling, likely small BGA heatsinks with pressure sensitive thermal adhesive would be fine.

Thermal pads aren't magically bad here, though. They have high end ones that conduct as much heat as shitty paste and only slightly less than high end paste (that no OEM ever uses, they always use the shitty paste on GPUs, or shitty pads on CPU HSFs).

These chips are probably sane at higher core voltages than what friedcat has announced (1.2v), but the problem is heat output. High end thermal pads would still work well here because the chips simply don't get hot enough to warrant paste (and like I said, OEMs don't even use high end paste, even ASUS's ultra expensive premium GPUs with the triple wide coolers use generic paste, which is kind of a shame).

AlCu alloy heatsinks (light like Al, heat conductive like Cu, half as expensive as pure Cu) they use in low profile rackmount servers would probably work well here.

This discussion is off topic. Kindly take it to the ASICMINER thread.

And yet you bought shares without knowing the answers to those questions...

Your definition of "free" is strange.

As a shareholder, and ostensibly one of the people who funded their operation, they are potentially destroying the value of my shares, depending on 1) how much they're actually going to pay real shareholders, 2) whether any devices will be for sale to the general public, 3) whether shareholders can buy devices above their shareholdings, 4) whether they're going to use customer money to expand their mining operation in contravention of their original business plan, 5) whether shareholders are going to see any money from the sale of mining devices.

I haven't seen any hard numbers or descriptions of anything yet.

Hope those things aren't ESD sensitive.

0.01BTC says they are

Twat..... learn to handle semiconductor packages correctly.