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[Gerard Visser <gvisser AT indiana.edu>]

hi Yi,
	Thanks for reply, yes hopefully there is a way to ensure completely solid glue 
coverage under all bod pad (and thermal) areas, which is the crucial thing. Is 
there really no prospect to use a vacuum bag? I thought the overall strategy for 
the FST to was (at least originally) to try to follow the methods and materials 
that worked for IST. But, admittedly, this may be infeasible for good reasons, I 
cannot say other than that. And for actual details about what was done for 
hybrid bonding for IST, I do not know them anyway, it would have to be asked of 
Eric Anderssen.
        Anyway I am confident we'll get everything done well for FST. 
Sincerely,

                Gerard


On 7/9/2020 5:56 PM, Yi Yang wrote:
> Hi Gerard,
>
> Thanks a lot for your comments.
>
> Yes, we are also suspicious that the glue is not enough underneath the bonding 
> pad, so we are modifying the gluing pattern (as shown in Monday's 
> presentation) and we hope this will solve the issue.
>
> And you are right, we didn't use a vacuum bag during the assembly due to the 
> limitation from the equipment we are using.
> We understand your concern and we are thinking about it.
>
> 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!V3KqKiFZ9TbeITV8h6KXlCFpeCVFcG0APok9OYMU-BiOiY6wKpCmNaJ5tIvLnjivF8pyFKQ$ 
> +++++++++++++++++++++++++++++++++++++++++++++++++++
>
>
> On Fri, Jul 10, 2020 at 4:07 AM Gerard Visser <gvisser AT indiana.edu 
> <mailto:gvisser AT indiana.edu>> wrote:
>
>     hi Zhenyu,
>              I am wondering whether this (and your prior comment also from the
>     tech(?)
>     "adhesion under some pads was not so good and created some issue but she 
> got
>     all
>     in adjusting the powers") might be related to regions betweeen the 
> structure
>     and
>     the hybrid which are not filled with epoxy but rather are air pockets? 
> Recall,
>     the IST hybrid and structed were bonded I believe in a vacuum bag. As 
> near as I
>     can tell, the procedures for the FST are _quite_ different.
>              There may be some reliability concerns, if the assembly locally 
> on
>     some bond
>     pads is not rigid enough to wire bond consistently optimally. I do not 
> know but
>     there may also be some risks of damage to sensor if it deflects too much 
> under
>     the wirebonding force. The latter may be a small risk, the former I am 
> not sure
>     is allowable.
>              Sincerely,
>
>                      Gerard
>
>
>     On 7/9/2020 3:54 PM, Zhenyu Ye wrote:
>      > The inner and outer sensors were mounted and wire-bonded on FST03. A
>     comment from the technicians "bias bonds went in but noticed some 
> deflection
>     of the sensor”, which I think is related to the flatness of the hybrid 
> surface.
>      >
>      > We have been taking cosmic data with FST Inner sensor and IST staves
>     since Tuesday afternoon at UIC. Xu is taking STAR shifts but has managed 
> to
>     find time to analyze the data but so far so good. Will send out results 
> later.
>      >
>      > Zhenyu
>      >
>      >> On Jul 2, 2020, at 7:45 PM, Yi Yang <yiyang AT ncku.edu.tw
>     <mailto:yiyang AT ncku.edu.tw>> wrote:
>      >>
>      >> Hi Zhenyu,
>      >>
>      >> Thanks a lot for the feedback, we will discuss the possible reason for
>     this shifting.
>      >> My first guess is the mismatch of the CAD files. We will get it back 
> to
>     you later.
>      >>
>      >> 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!XXw41843jdZ_SJh6LgtKNd0CB3nnMZGPftwC4s_ENf3ONF01oRNicwlP_SSCVZ8dXgIM-AA$
>      >> +++++++++++++++++++++++++++++++++++++++++++++++++++
>      >>
>      >>
>      >> On Thu, Jul 2, 2020 at 11:50 PM Zhenyu Ye <yezhenyu2003 AT gmail.com
>     <mailto:yezhenyu2003 AT gmail.com>> wrote:
>      >>
>      >>> On Jul 2, 2020, at 2:40 AM, Yi Yang <yiyang AT ncku.edu.tw
>     <mailto:yiyang AT ncku.edu.tw>> wrote:
>      >>>
>      >>> Hi Zhenyu,
>      >>>
>      >>> It is good news. Thanks for the update.
>      >>>
>      >>> Could you please provide more details on the comments from the
>     technician, like the placement is off in which direction, what are the
>     reference points for these 500 and 200 microns (they are very different 
> from
>     our measurements).
>      >>> "The inner chip placement was off .500mm so I needed to reposition. 
> The
>     outer placement was off .200mm”.
>      >>
>      >> "They were inboard toward the sensor area . I needed to slide the 
> chips
>     back  or outward. Michelle mention adhesion under some pads was not so 
> good
>     and created some issue but she got all in adjusting the powers.”
>      >>
>      >>> Yi, Han-Sheng, Pu-Kai, do you have the measurement results on the
>     relative x and y positions of the hybrids w.r.t. mounting holes, and 
> compare
>     them with design?
>      >>>
>      >>> ==> We actually discussed this in our internal meeting, but so far we
>     don't know how to measure the relative x and y positions. Pu-Kai and
>     Han-Sheng are still working on this. But we didn't measure this for FST003. 
>     (Pu-Kai and Han-Sheng, please correct me if I said something stupid...)
>      >>>
>      >>> 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!XXw41843jdZ_SJh6LgtKNd0CB3nnMZGPftwC4s_ENf3ONF01oRNicwlP_SSCVZ8dXgIM-AA$
>      >>> +++++++++++++++++++++++++++++++++++++++++++++++++++
>      >>>
>      >>>
>      >>> On Thu, Jul 2, 2020 at 7:53 AM Zhenyu Ye <yezhenyu2003 AT gmail.com
>     <mailto:yezhenyu2003 AT gmail.com>> wrote:
>      >>> All the 8 APV chips were mounted and showed normal behavior in 
> readout.
>     I have instructed the Fermilab technicians to mount the Silicon sensors.
>      >>>
>      >>> One comment from the technician "The inner chip placement was off
>     .500mm so I needed to reposition. The outer placement was off .200mm”.
>      >>>
>      >>> Yi, Han-Sheng, Pu-Kai, do you have the measurement results on the
>     relative x and y positions of the hybrids w.r.t. mounting holes, and 
> compare
>     them with design?
>      >>>
>      >>> Best,
>      >>> Zhenyu
>      >>>
>      >>>> On Jun 19, 2020, at 7:18 AM, Yi Yang <yiyang AT ncku.edu.tw
>     <mailto:yiyang AT ncku.edu.tw>> wrote:
>      >>>>
>      >>>> Dear all,
>      >>>>
>      >>>> We've finished the second prototype and shipped it to Fermilab
>     directly per Zhenyu's request today. The DHL tracking number is: 
> 4658055916
>      >>>>
>     
> (https://urldefense.com/v3/__https://www.dhl.com/en/express/tracking.html?AWB=4658055916&brand=DHL__;!!P4SdNyxKAPE!XXw41843jdZ_SJh6LgtKNd0CB3nnMZGPftwC4s_ENf3ONF01oRNicwlP_SSCVZ8dh6CO4qA$
>     )
>      >>>>
>      >>>> Please find some details/pictures of this prototype here:
>      >>>> 20200619_FST_Second_Prototype_YiYang.pdf
>      >>>>
>      >>>> Overall it looks pretty good (much better than the first batch).
>      >>>> Thank you very much for being patient with us.
>      >>>>
>      >>>> Cheers,
>      >>>> Yi
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