Star-fst-l mailing list

[Zhenyu Ye <yezhenyu2003 AT gmail.com>]

Minutes:

Attendees: Elke, Han-Sheng, Jianing, Krishan, Mike, Prithwish, Zhenyu

*** Mechanical structure: We went through Yi’s slides w/o his presence. Some 
questions were already communicated to him by email. Other questions were 
asked: 

1. Elke: what causes bending of the structure and how the vendor is going to 
fix it?
Because Yi was not present to answer this question, ZY explained his 
understanding based on the brief discussion with Yi on Tuesday (Yi, please 
correct me if I am wrong). The bending was believed to be caused by unevenly 
distributed material during injection and formation. The vendor was going to 
add additional injection points and distribution tunnels. This is not 
mentioned in Yi’s slide, but instead they are going to add a rib to 
strengthen the structure. 

2. Elke: What caused the bubbles in the hybrids? Is baking hybrids at 120 
degree a standard procedure? Do we have documents from the vendors on the 
recommended procedure and/or requirements
ZY answer for Yi: The company in Taiwan to do the soldering thinks that the 
bubbles may be caused by water vapor intrusion during the transportation. 
They expected hybrids sealed in vacuum bags to prevent it from happening 
during transportation and storage, but this was not the practice done by the 
Chinese vendor, which made the hybrids. 
Jianing: after communicating the “bubble” issue with the Chinese vendor, they 
recommended baking hybrids at 120 degree C for 2 hours before soldering. 
JIaning will try to get the recommended handling and soldering procedure from 
the hybrid vendors. She will also ask the vendors to use vacuum bags. She has 
contacted two vendors (the old + a new ones) to make new outer hybrids with 
modified APV positions, and the new vendor to make new inner hybrids. The 
latter will need the confirmation from ZY that the 0.528mm shift is not a 
problem for wire-bonding at Fermilab.

*** hybrids 
Jianing: The delivery time for new hybrids from the old vendor is 2-3 weeks, 
and 3-4 weeks from the new vendor. 
ZY: unless the 0.528mm shift is found to be an issue, we should stick to the 
current inner hybrid design. 

*** Module assembly 
ZY met the Fermilab engineers and technicians on Wednesday. They confirmed 
that 0.011mm shift for sensor-APV bonding pads for the outer region won’t be 
a problem. The technician does not think the 0.528mm shift for the inner 
region is a problem either, but she will double check. Also started 
discussing fabrication of the assembly fixture, e.g., machine shop options, 
materials, etc. 

*** F2F meeting at BNL for forward upgrade 
The STAR management started discussing the need to hold a 2-3 day workshop on 
Spin/Forward upgrade in early 2020 (e.g. January) 





> On Oct 15, 2019, at 5:10 PM, Zhenyu Ye <yezhenyu2003 AT gmail.com> wrote:
> 
> Dear all,
> 
> We will have a meeting starting at 9am BNL time this Thursday Oct 17.  The 
> meeting agenda and bluejeans info can be found at 
> https://drupal.star.bnl.gov/STAR/blog/yezhenyu/forward-silicon-tracker-weekly-meeting
> 
> 1. News - All
> 2. Mechanical Structure - Yi Yang, Han-sheng Li
> 3. Hybrid - Jianing Dong
> 4. Module Assembly - Zhenyu Ye
> 
> If you have other updates and items for discussion, please add them to the 
> agenda.
> 
> Thanks and Best,
> Zhenyu
> 
>