Star-fst-l mailing list

[Gerard Visser <gvisser AT indiana.edu>]

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> 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
> > 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> wrote:
> >
> > > On Jul 2, 2020, at 2:40 AM, Yi Yang <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
> > > 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> 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> 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