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[Gerard Visser <gvisser AT indiana.edu>]

hi Zhenyu,
    I think that the connectors we have purchased are the correct connectors, 
there is *no mistake* this is only a confusion. I looked at the drawings Yi sent 
(thanks!) and I am sure that A22-2-T-34-V22 for T-board and A22-1-T-34-V16 for 
hybrids has been our plan all along and is a good plan.
    (Also note that for the hybrids, in the absence of a stiffener it probably 
makes really no sense anyway to fix the connector to the hybrid with screws.)
    Whether or not to use an underfill epoxy, I am not really sure about. If we 
use it we must be sure that the soldering is good before the epoxy is applied. 
Also, we must be sure that everything is clean (of flux, particularly) before 
the epoxy is applied. But we should in general be sure that everything is clean 
(of flux, particularly) no matter what. So that last is not a particular extra 
concern, but I would say it is still a concern, as I saw flux residue on the 
FST01 hybrid in your lab. I don't know if the soldering and cleaning procedures 
are same for production new. BTW, if one can be absolutely sure that it stays 
very dry, then maybe some types of flux residue may be OK to allow, but better 
still to avoid it.

    - Gerard


p.s. As I now look again at pictures of the hybrid from my visit, I see that the 
screws were removed from the connectors. I don't know why that would be. I 
seriously hope it is not due to any incompatibility!? The screws should not be 
touching electrically connected metal on the hybrids! Actually the best design 
probably would have been clear holes in the hybrids for the connector screw 
heads to completely pass through. I think that is what is intended by Nicomatic 
for the V16 screws. It is what was done in the SSD case.
If the screws touch metal, then we will have to remove the screws (I didn't know 
it was possible but you guys have proved that it is) and replace them with PEEK 
screws. I hope we can find M1.6 PEEK screws if this is the way it has to be. It 
could be ugly, and expensive.
The screws are supposed to be used, to ensure the connectors are fully mated and 
stay that way. In the worst case I guess it is OK to not use the screws but it 
somewhat defeats the purpose of having bought these expensive and somewhat 
troublesome connectors for the project, so I hope we realy can use the screws.


On 11/15/2020 2:42 PM, Zhenyu Ye wrote:
> Hi Gerard,
>
> I am not sure if I interpret your emails correctly.
>
> Do I understand correctly that you agree with the approach to use the 
> connectors we have already purchased, but use epoxy to enhance the mechanical 
> bonding between connector and hybrid?
>
> Thanks
> Zhenyu
>
>
> > On Nov 10, 2020, at 11:04 AM, Gerard Visser <gvisser AT indiana.edu> wrote:
> >
> > Dear Yi,
> >         I think this is probably reasonable. But can you please document here 
> > in reply the exact and complete partnumbers for the connector we'll use on 
> > the hybrids, and the connector we'll use on the T-boards?
> >         The intention has always been that the connectors are fixed to each other by 
> > fixing screws. It is *not clear* to me that this would even have been possible with the 
> > "Male and female straight SMT on PCB" style (in attached picture here too). I 
> > think that was *not* the plan, and the 'mistake' is no mistake.
> >         But let's please reconfirm here with the exact full partnumbers, and 
> > if you have drawings for those two exact partnumbers too that will be helpful 
> > since the Nicomatic website doesn't seem to always have drawings available on 
> > all the parts. I'm not sure.
> >         Thanks, sincerely,
> >
> >                 Gerard
> >
> >
> > p.s. Filling under the connector around the solder joints with a suitable 
> > epoxy is perhaps good. We have to be sure that the solder joints are good, 
> > and are completely clean of flux, before doing that. I think so anyway. What 
> > sort of solder and flux are to be used?
> >
> >
> > On 11/10/2020 11:19 AM, Yi Yang wrote:
> > > (I have some issues sending email to the STAR mailing list, so I also added 
> > > the individual emails.)
> > > Hi Gerard,
> > > The short summary of what we discussed about the connector issue is that we purchased the WRONG 
> > > connectors. Please see the drawings in the bottom on page 3 of the first attachment, Felix 
> > > pointed out that we should use the middle one "Male and female straight SMT on PCB" 
> > > instead of the right one "Male SMT and female on cable".
> > > The perfect solution will be to replace the screw parts to "V22 Straight 
> > > jackpost" (the first item in the table), but it will take too much time. So we 
> > > proposed to use epoxy to enhance the strength between the connector and hybrid, and 
> > > this can be done later. What do you think?
> > > Cheers,
> > > Yi
> > > +++++++++++++++++++++++++++++++++++++++++++++++++++
> > > Yi Yang, Associate Professor
> > > Department of Physics
> > > National Cheng Kung University
> > > Tainan, 701 Taiwan
> > > E-Mail: yiyang AT ncku.edu.tw <mailto:yiyang AT ncku.edu.tw>
> > > Tel: +886-6-2757575 ext.65237
> > > Fax: +886-6-2747995
> > > Group Web: 
> > > https://urldefense.com/v3/__http://phys.ncku.edu.tw/*yiyang__;fg!!P4SdNyxKAPE!UM5dajKUnkd1FiTaFN7D0De3gzmIVhYFnBvfglNjVuR6ySU0t3QuKxkApvsmt8d0TTU9jUU$+++++++++++++++++++++++++++++++++++++++++++++++++++
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