From:
Marsh, Darren S. [marsh@SLAC.Stanford.EDU]
Sent:
Tuesday, April 22, 2003 3:11 PM
Subject:
Summary of Tracker Ladder Production Readiness Review
A
Tracker Ladder Production Readiness Review (PRR) was held on April 16, 2003, at
Mipot S.P.A. (http://www.mipot.com/). The purpose of the PRR was to show that the
ladder assembly will meet the final performance and design specifications.
The
following individuals were participants in the PRR.
Darren
Marsh - LAT Mission Assurance - Committee Chair
Tom
Borden, LAT Tracker System Engineer
Alessandro
Brez, INFN Development Engineer
Robert
Terpin, Mipot Technical R&D Director
Eva
Neiner, Mipot Quality Assurance
Pietro
Bresciani, Mipot Senior Engineer
Completion
of the PRR and resolution of all resulting action items constitutes readiness
for flight production.
The
subject Tracker Ladder Production Readiness Review (PRR) is for product
manufactured at Mipot S.P.A. in Cormons, Italy. A total of 800-1000 Tracker ladders will be manufactured at
Mipot. The total number of ladders
manufactured at Mipot will be determined upon execution of the follow-on
contract to the first order of 100 ladders.
Links
for all relevant ladder production documentation can be obtained at:
http://www-glast.slac.stanford.edu/Tracker-Hardware/latdocs.html
The
following issues were addressed as part of the ladder PRR and action items are
noted.
1. 10 flight quality ladders were manufactured
subsequent to completion of ladder process development activities. The test result summary for these 10 ladders
is attached. All 10 ladders produced
results that met specification requirements.
There was a brief discussion on the post-encapsulation leakage current
on ladder #3004 which was higher (but well within specification requirements)
than the balance of the production lot.
There was agreement this leakage current measurement was in all
liklehood, due to a variation in the amount of time after encapsulation the
ladder was tested. It was recommended
the leakage current be retested on this ladder.
It was
also suggested efforts to improve the dead channel attribute would be
beneficial to the Tracker program.
Specifically, it was identified improvement on the probe station
measurement activity be investigated.
The
Mipot production traveler for the first 10 flight quality ladders was reviewed
and found to be thorough and complete.
In addition, a visual inspection of ladder bonds on a sampling basis by
LAT personnel was performed with no adverse observations identified. It was noted a failed bond was identified on
ladder 3000 (acceptable per MIL-STD-883) but it was not noted on the production
traveler. The LAT representatives
requested all ladder abnormalities be documented for informational purposes.
2. The Mipot Ladder Assembly Quality Plan,
PQ02.03, was reviewed and discussed in detail.
The plan was determined to be complete and concise. It was recommended the plan incorporate a
reference to the LAT Tracker Ladder Assembly Procedure.
3. Mipot was reminded that no process changes
are allowed without the approval of the INFN Technical Lead.
4. A test correlation was performed by INFN on
4 ladders (G&A ladders) between test equipment located at INFN, Mipot and
G&A Engineering. The results of
this correlation study indicated there was no statistical measurement
difference between ladder equipment test set-ups at the various locations.
5. A database is planned to be implemented to
capture pertinent inspection and fabrication data for the ladders manufactured
at Mipot. The database will be
implemented by INFN personnel in conjunction with the production of the next 90
ladders. It is understood the database
will supplement the Mipot internal process traveler system and not replace
it. It should be noted the database is
web based and will be accessible to all LAT personnel.
6. Presently, leakage current is performed by
INFN personnel. The plan is for INFN to
transfer the responsibility for this test to Mipot prior to the follow-on
contract. INFN regongizes the
importance of providing adequate training to Mipot personnel to perform this
activity.
Authorization
to proceed with flight production of the Tracker Ladder production at Mipot is
granted based on the results of the PRR performed. Additionally, it was
determined the first 10 production ladders manufactured are flight quality
ladders and usable as such.
Darren
S. Marsh
GLAST
Large Area Telescope Project
Stanford
Linear Accelerator Center
2575
Sand Hill Road, M/S 43A
Menlo
Park, CA 94025
(650)
926-4577