ePIC pfRICH electronics mailing list

["Cacace, Daniel" <dcacace AT bnl.gov>]

Alexander,

I would recommend using a torque screwdriver to mitigate the concern of damaging the screw and still use a stainless screw and nut, but either way should work.

With the new layout of the PCB it seems to me that the ASICs are back under the mezzanine PCBs, which will reduce the efficiency of the heatsink. As opposed to the image to the left where the fins were directly over the ASICs. If I'm mistaken, then I agree, we should be able to take a similar approach as shown on the left. 

Cheers,

Dan Cacace
sPHENIX
Physics Department
Office: 631.344.2197
dcacace AT bnl.gov

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From: Kiselev, Alexander <ayk AT bnl.gov>
Sent: Friday, August 18, 2023 12:34 PM
To: Cacace, Daniel <dcacace AT bnl.gov>; Alexey Lyashenko <alyashenko AT incomusa.com>
Cc: eic-projdet-pfrich-electronics-l AT lists.bnl.gov <eic-projdet-pfrich-electronics-l AT lists.bnl.gov>
Subject: Re: HRPPD screws and nuts sizes

 

  Hi Daniel,

  I think the objective of using plastic nuts is to avoid even a remote possibility to damage the screw itself. But I'd agree with you in a sense that if one uses steel or titanium screws, an aluminum alloy nut would also work.

  I don't think we are going to use snaky pipes (or any water cooling) for this first iteration. So essentially we are talking about a single heat sink which sits on top of the exposed ASICs, and all what needs to be taken care of is to provide a pair of pockets for the FPGAs. I mean it is nothing more than the layout on the left hand side of the image below, which you proposed last time. Am I right?

  I think the mechanical and component / fixture placement part of the overall design is converging. As long as ASIC locations do not change any longer (and they are not shadowed by the FPGA boards), ERF5 height is chosen to not interfere with the screws, and FPGA location is roughly known, the interface to the heat sink is pretty much defined. I'd prefer to bolt it rather than to glue, but it's IMHO. What is then left are the cutaways for the connectors, and  a decision how do we power the fans up (presumably not off the ASIC boards, but separately?)

  Cheers,

    Alexander.

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From: Cacace, Daniel <dcacace AT bnl.gov>
Sent: Friday, August 18, 2023 11:37 AM
To: Alexey Lyashenko <alyashenko AT incomusa.com>; Kiselev, Alexander <ayk AT bnl.gov>
Cc: eic-projdet-pfrich-electronics-l AT lists.bnl.gov <eic-projdet-pfrich-electronics-l AT lists.bnl.gov>
Subject: Re: HRPPD screws and nuts sizes

 

Hi Alexander,

I would recommend using stainless hardware, especially for small hardware like 2-56s, unless there is a particular reason you need to use plastic.

I should be able to design the heat sink, though the PCBs seems to be changing every week. The latest iteration that you showed yesterday seems to make air cooling significantly more difficult. Maybe this should be part of next Monday's meeting to settle the approach we want to take with the PCB layout and cooling. As for mounting, we should be able to use coupling nuts on a few existing hole locations, or alternatively we could just use some thermal tape or epoxy.

Cheers,

Dan Cacace
sPHENIX
Physics Department
Office: 631.344.2197
dcacace AT bnl.gov

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From: Eic-projdet-pfrich-electronics-l <eic-projdet-pfrich-electronics-l-bounces AT lists.bnl.gov> on behalf of Kiselev, Alexander via Eic-projdet-pfrich-electronics-l <eic-projdet-pfrich-electronics-l AT lists.bnl.gov>
Sent: Friday, August 18, 2023 9:41 AM
To: Alexey Lyashenko <alyashenko AT incomusa.com>
Cc: eic-projdet-pfrich-electronics-l AT lists.bnl.gov <eic-projdet-pfrich-electronics-l AT lists.bnl.gov>
Subject: Re: [Eic-projdet-pfrich-electronics-l] HRPPD screws and nuts sizes

 

  Hi Alexey,

  look like low profile ones. As long as the screws are not too long, one can probably use ERF5's with a 5mm high profile. 

  Daniel, will you find time to come up with a heat sink design, which would match the anticipated layout (provide cooling for both ASICs and FPGAs, and whatever else needs to be cooled), and also provide options for mounting? I can imagine we just add four threaded fixtures at the corners of the ASIC PCB rather than relying on a separate support structure?

  Cheers,

    Alexander.

 

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From: Alexey Lyashenko <alyashenko AT incomusa.com>
Sent: Thursday, August 10, 2023 4:09 PM
To: Kiselev, Alexander <ayk AT bnl.gov>
Cc: eic-projdet-pfrich-electronics-l AT lists.bnl.gov <eic-projdet-pfrich-electronics-l AT lists.bnl.gov>
Subject: RE: HRPPD screws and nuts sizes

 

Tentatively it will be nylon nuts as shown below.

 

https://www.mcmaster.com/94812A100/

 

I ordered them for a test. I believe the geometrical dimensions for any other nut type (if nylon is not strong enough) will be similar.

 

Alexey

 

 

From: Kiselev, Alexander <ayk AT bnl.gov>
Sent: Wednesday, August 9, 2023 8:47 PM
To: Alexey Lyashenko <alyashenko AT incomusa.com>
Cc: eic-projdet-pfrich-electronics-l AT lists.bnl.gov
Subject: HRPPD screws and nuts sizes

 

  Hi Alexey,

 

  (Cc to the pfRICH electronics list)

 

  can you please share the models (or sizes) of screws and nuts we are presently planning to use to fix the ASIC boards to HRPPDs, with the colleagues developing these ASIC boards?

 

  We are particularly interested in screw height and nut dimensions, to see what should be the minimal clearance between the ASIC backplane and FPGA mezzanine board, but also how much space will the nuts take away from the ASIC board footprint. We also better agree on the diameter of the integrated nut washer and / or tool used to tighten them, in order to avoid surprises in the future (like a need to thin down stock tool diameter, which plagued us in one of the previous designs).

 

  Cheers,

    Alexander.

 

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