Star-fst-l mailing list

[Gerard Visser <gvisser AT indiana.edu>]

hi Jianing,
	The outer hybrid layout looks pretty good, but I have a few comments for your 
consideration:

- I have some concerns about impedance of power routing on the hybrid, please 
see attached picture. Unless I am misunderstanding something, it is not too good 
and it could I think be very much improved with small changes in your layout. It 
is very hard to say how important this is. However I think the APV chip is not 
the best in the world for insensitivity to power supply voltage and noise; 
statement based on my recollections of prototyping for the STAR FGT. I think we 
should take care to make it as good as we reasonably can.

- It would be better if the temperature sensor was closer to one of the middle 
APV chips. Those will of course be the hot spots. But this is not critical, we 
don't really need an absolute temperature measurement from these, really we just 
need to monitor if temperatures are changing from whatever the normal reading 
turns out to be.

- I think it would be better if there was a lot more clearance around the APV 
die attach pad to other nets. You have 0.212 mm. This is surely plenty for 
building the hybrid, but I am worried about the die attach epoxy spilling out 
and risking a short. Have the Fermilab people reviewed the hybrid gerbers, any 
comment from them about it? I guess if they are not worried, I am not worried 
about it then either, as long as they saw this detail.

- Do we really want that long skinny bit of top coverlayer between the two 
sensors? (I am assuming the .GTS gerber is negative of the coverlayer.) Note I 
do not see this in the old (7/12/2019) hybrid in the picture that Yi recently 
sent. Maybe it was there in design and your vendor deleted it for you?

        Sincerely,

                Gerard


On 11/7/2019 9:48 AM, Gerard Visser wrote:
> hi Jianing,
>      I checked the schematics
>
> outer hybrid
> https://drupal.star.bnl.gov/STAR/system/files/hybrid_outer_v2_3-schematic_0.pdf
>
> inner hybrid
> https://drupal.star.bnl.gov/STAR/system/files/hybrid_inner_v2_1-schematic.pdf
>
> T-board
> https://drupal.star.bnl.gov/STAR/system/files/T-Board_v3-schematic.pdf
>
>      I think everything looks correct in these. One minor point is that we 
> probably have to change the resistor values (on T-board and on hybrids) to have 
> less reflection on the CLK and TRG lines. The cable has a characteristic 
> impedance (differential) of around 100 to 110 Ohms. (It isn't very precisely 
> controlled, we should measure it when we have the cable, but it will be around 
> that value. So we should make the input impedance of T-board and hybrids 
> assembly around 100-110 Ohms. I suggest changing the resistors R1, R2 on outer 
> hybrid and on inner hybrid from 49.9 to 78.7 Ohm, and the leaving the resistors 
> R9, R10, R11, R12 on the T-board at 33.2 Ohm. Final values have to be confirmed 
> after all the boards and cable are available for a scope measurement. At that 
> time we _might_ decide to change the value on T-board; the 78.7 Ohm on hybrids 
> is very likely to be fine (and is of course a lot more trouble to modify on 
> existing boards, so we won't want to do that).
>      [FYI in IST from the documents at 
> https://drupal.star.bnl.gov/STAR/blog/yezhenyu/forward-silicon-tracker-ist the 
> naively calculated input impedance 166 Ohms which is not right. I am not sure 
> why, perhaps the documents are not really all correct. I think Ben did look at 
> CLK & TRG waveforms with a scope and optimize these, although I don't have any 
> record of it.]
>      I will have a look at new outer hybrid layout for electrical / layout 
> issues only -- not for mechanical interface issues -- but I expect no problems, 
> it will look nice as the prior version did.
>      Thanks,
>
>          Gerard
>
>
> On 10/31/2019 10:22 PM, 董家宁 wrote:
> > Hi Gerard,
> >    Thanks for your help.
> >    There are no changes on the connector part.
> >    Please let me know if you need any other files.
> >    Thanks!
> >
> > Best,
> > Jianing
> >
> >
> > > -----原始邮件-----
> > > 发件人: "Gerard Visser" <gvisser AT indiana.edu>
> > > 发送时间: 2019-11-01 10:14:39 (星期五)
> > > 收件人: star-fst-l AT lists.bnl.gov
> > > 抄送:
> > > 主题: Re: [Star-fst-l] Weekly FST meeting - 10/31/2019
> > >
> > > hi Jianing, Zhenyu,
> > >     Somebody was going to document (simply with a picture or two) how that the
> > > connector tab of outer (particularly) hybrid fits well to the T-board on
> > > mechanical structure. I think we should see this before the new outer hybrid 
> > > is
> > > ordered. (Is there any change in this aspect of the new outer hybrid? I
> > > understood no change.)
> > >     Meanwhile, yes it is in my inbox to check the electrical aspects, I will 
> > > try to
> > > have that done by early next week.
> > >     Thanks,
> > >
> > >         Gerard
> > >
> > >
> > > On 10/31/2019 10:04 PM, 董家宁 wrote:
> > > > Dear All,
> > > >
> > > >     2.Hybrid, T-board:
> > > >
> > > >     With the help of Mike and Gerard,  the address connection for the 
> > > > temperature
> > > > sensor chip on outer hybrid is modified and updated.
> > > >
> > > >     And the schematic for T-board v3.0 is also updated (keep one set of
> > > > temperature sensor and reset circuit).
> > > >
> > > >     I think they are all waiting for the double check.
> > > >
> > > >     If there are no other mistakes for outer hybrid layout, it will take 
> > > > about 3
> > > > weeks for the production.
> > > >
> > > >     All the detailed status are listed on the WIKI
> > > > (https://wiki.bnl.gov/star/index.php/Hybrid_and_T-board).
> > > >
> > > >
> > > > Best,
> > > >
> > > > Jianing
> > > >
> > > >
> > > >      -----原始邮件-----
> > > >      *发件人:*"Capotosto, Michael" <capotosto AT bnl.gov>
> > > >      *发送时间:*2019-11-01 05:43:15 (星期五)
> > > >      *收件人:* "Ye, Zhenyu" <yezhenyu AT uic.edu>, "star-fst-l AT lists.bnl.gov"
> > > >      <star-fst-l AT lists.bnl.gov>
> > > >      *抄送:*
> > > >      *主题:* Re: [Star-fst-l] Weekly FST meeting - 10/31/2019
> > > >
> > > >      All,
> > > >
> > > >      As discussed last meeting, I’ve compiled the documentation and posted 
> > > > it to
> > > >      the wiki: https://wiki.bnl.gov/star/index.php/Cables
> > > >
> > > >      T-Board/Inner Signal Cable:
> > > >
> > > >      Last meeting we agreed we would use the IST-type of cables, due to 
> > > > cost. It
> > > >      turns out I misinterpreted the quote – we were quoted for 400ft of 
> > > > cable but
> > > >      they had a minimum 1,000ft order. It is cheaper as Gerard expected to use
> > > >      the Polypropylene/PVC/PVC cable. I’m waiting to hear back from Gerard 
> > > > on how
> > > >      he’d like to proceed. The updated quotes binder mentioned can be found 
> > > > here:
> > > >      
> > > > https://drupal.star.bnl.gov/STAR/system/files/Cable%20Quotes%20Binder%2010-28-2019.pdf 
> > > >
> > > >      
> > > > <https://drupal.star.bnl.gov/STAR/system/files/Cable%20Quotes%20Binder%2010-28-2019.pdf> 
> > > >
> > > >      The quotes binder also includes new updated (non-expired) quotes, so 
> > > > once we
> > > >      have a decision we can order the cables. (Elke/Gerard/Zhenyu, will this 
> > > > be
> > > >      on one of the BNL accounts, or will I be sending this to someone else? 
> > > > If it
> > > >      will be on a BNL account I can start drafting the PO so it will be 
> > > > ready to
> > > >      send when we make a final decision).
> > > >
> > > >      Regarding the V2.1 T-Board modifications, I believe we just need to 
> > > > remove a
> > > >      handful of parts to in order to make it work, I’ve discussed this in an
> > > >      email with Jianing and Gerard, and am waiting to hear back from Gerard. I
> > > >      will have the cables re-labeled tonight before I leave (to match the 
> > > > VIA REF
> > > >      DES used in V2.1 T-Boards we are assembling). Once Gerard gives me the 
> > > > O.K.
> > > >      I’ll pull the parts off the boards, and we should be able to give them to
> > > >      the assembler within a working day or two. If there are no objections, I
> > > >      will extend the due date for the vendor to November 29.
> > > >
> > > >      If I’ve missed any points please let me know.
> > > >
> > > >      Best,
> > > >
> > > >            Mike Capotosto
> > > _______________________________________________
> > > Star-fst-l mailing list
> > > Star-fst-l AT lists.bnl.gov
> > > https://lists.bnl.gov/mailman/listinfo/star-fst-l

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