From:
Marsh, Darren S. [marsh@SLAC.Stanford.EDU]
Pursuant
to the Tracker Production Readiness Review, an onsite visit to G&A
Engineering occurred on October 4, 2002.
The purpose of the visit was to perform a post-production review of 10
ladders manufactured with encapsulation materials that are NASA flight approved
and to review and assess quality processing documentation.
The
following individuals were participants in the meeting held at G&A
Engineering.
Alessandro
Brez - INFN-PISA Development Engineer, Production Supervisor
Tom
Borden, Tracker System Engineer
Darren
Marsh, LAT Mission Assurance
Francesco
Belli, INFN-Rome Physicist/Test Engineer
Luigi
Valentini, G&A Engineering, Technical Staff
Giorgia
Ponteri, G&A Engineering, Technical Staff
Antonio
Ponteri, G&A Engineering, Technical Staff
Gianfranco
Grifom, G&A Engineering, Quality Assurance
The
following information is provided regarding the meeting.
1. As previously reported by Robert Johnson in
the LAT Project Weekly Report Ending 10/3/02, shipping the NASA flight approved
encapsulation material to Italy has proved to be very difficult due to the
hazardous material classification of the Nusil CV-2500. The review of the 10 ladders which were to
be completed prior to the visit of the LAT review team was not possible. It was clear in discussions with G&A
Engineering personnel they have concerns regarding their ability to develop a
robust encapsulation process utilizing the new encapsulation material due to
the viscosity properties of materials.
Consequently, it would have been imprudent to be begin production
without a thorough encapsulation process development effort by G&A
Engineering. It now appears the new
encapsulation material will be delivered to G&A Engineering this week as
initial quantities have made it to Italy.
Once G&A Engineering receives the materials, they will begin a
process development effort utilizing
marginally
acceptable Silicone Strip Detector's (SSDs) and SSD cut-outs provided by
INFN. The process development will take
4 weeks and it is now planned to have a lot of 10 ladders complete and tested
utilizing the "new" material by the second week of November.
2. It was clearly evident by a detailed review
of the ladder processing documentation that G&A Engineering has a very good
handle on ensuring the ladder manufacturing process is carried out under
controlled conditions. Specifically,
the G&A Tracker Ladder Production Ladder Traveler along with internal
G&A Quality Procedures were reviewed and deemed to be suitable and adequate
to ensure process capability. Internal
Quality Procedures reviewed include, Personnel Training and Qualification,
Handling and Packaging, In-Process Inspection (including wire bonding equipment
verification) and Configuration Management.
Also, Tracker Ladder Assembly Procedure, LAT-PS-635 was discussed. The source inspection requirement was
negotiated to meet LAT requirements and G&A concerns over unexpected
inspections. SLAC personnel will be
provided the G&A internal traveler upon formal request (the equivalent of a
nondisclosure agreement).
3. A concern surfaced in the Ladder PRR
regarding the manufacture of a large quantity of ladders prior electrical
testing. It was previous proposed by
Robert Johnson that no more than 20 ladders may be wire bonded before
electrical testing begins on the lot. G&A
Engineering has concerns over this proposal as they would not be able to optimize
their ladder production flow. They
indicated a contract modification would be necessary to cover the added cost of
this requirement. It was agreed that no
more than 300 ladders would be wire bonded before electrical testing
begins. It should be noted that the way
the current contract is structured, G&A is allowed 5% defective
ladders. The cost of any ladder
rejections over the 5% has to be absorbed by G&A Engineering so they are
quite aware of the need to assure the ladders meet all requirements.
4. Based on the detailed review of ladder
production activities at G&A Engineering, Messrs. Brez, Borden and Marsh
approved the release of 246 flight ladders for production up through the
encapsulation process. Upon completion
of the encapsulation process development effort and the manufacture of 10
production ladders utilizing the NASA approved encapsulation material, a
post-production reviewed will take place to evaluate ladder conformance to
specification requirements. The 246
flight ladders will be released for encapsulation and final testing after
approval by the PRR Committee.
5. A new action was generated for INFN to
ensure all INFN personnel are adequately trained and qualified to perform the
ladder testing activity at G&A Engineering and at Mipot. In addition, it is necessary for INFN
personnel who are involved with handling and inspection and test activities to
meet NASA ESD requirements.