Tracker Meeting
February 19, 2004
Action Items:
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Robert and Jim:
look at the sidewall need date in the Tower-A schedule
-
Mike Menning:
review the thermal-strap RTV decision with Jack and Jeff
-
Ben: send Jim
and email about where to ship the left-over prepreg
-
Robert: update
the bias circuit NCR
-
Jerry: update
the grounding tube in the tray assembly drawings
-
Sandro: get a
time estimate from G&A on when they will have results from wirebonding the
preproduction MCMs
-
Dave: ship 10
preproduction MCMs to Pisa
-
Jeff: prepare
and ship 2 burn-in cables for Pisa
-
Jeff: talk to
Gunther about how to ship items to Italy
-
Erik: complete
the static test procedure document by next week
-
Sandro: find a
person to be responsible for static testing
Agenda:
-
Sandro & Erik: feedback on the redlined titanium parts drawings
-
Jeff: information needed on sidewall thermal test coupons
-
Nanda/Ben: Sidewall test matrix
-
Mike: status of titanium parts drawings and procurement
-
Dave: MCM status
-
Jerry: bias circuit status (scrapping old circuits)
-
Sandro: G&A progress/status on MCM integration
-
Riccardo: Plyform status on mid tray production and bottom-tray assembly
tooling
-
Nicola or Jack: T/V test status
Last week's action items:
-
Nanda: Status of prepreg procurement
-
Jeff: Mid-tray assembly drawing status (grounding tubes)
-
Sandro: ownership of static testing
-
Tom V: bakeout specs
Nicola reported that work is in progress assembling
the tower with thermo-couples. They
plan to release procedures and plans tomorrow for the Feb 26 TRR. Sandro
reported that the resistance seen by each MCM is now well known. They will put the TEM on the tower when the
tower is still open and will power it up and probe at different points the
voltage. Sandro also reported that they
have all the pieces for the blanket structure and Al box.
Jeff and Jack need information on the thermal
coupons. Each group of 6 coupons, now
at SLAC, is identified by a part number and group number, but SLAC does not
know what those numbers mean. Riccardo
has the information but is at Plyform.
He should have the IDs of the coupons.
There should also be a drawing from Tom Borden.
Nanda reported that Plyform reviewed the
prepreg specs and test matrix. They had
questions on the test matrix. Specifically,
is it necessary to test coupons from every sidewall? This would require a lot of extra material. Plyform would like to do test matrix once
per purchase lot and keep coupons for all sidewalls from the border. Full thickness test coupons come from a
separate layup.
Ben's proposal: do the full test matrix for
every material purchase lot. Do in
addition the short-beam shear test on every cure. Those coupons are small, 20mm by 10mm, and can be cut off close
to the sidewall. Also, the fiber volume
and void content need to be measured on each layup. Each sidewall will also get a dimensional inspection.
Nanda said that Plyform is moving forward
with the spec toward purchasing prepreg.
Robert and Jim need to take a look at the schedule constraints. Sandro estimated for the manufacturing time 5
or 6 weeks total, after the prepreg is received. It was suggested that INFN should use SLAC to expedite response
from COI if necessary.
Erik said that he looked over the redlined
drawings from Mike and Martin’s meetings in Pisa and went over the analysis
with John Ku. Erik had discussed some
concerns with Mike Menning. Mike Foss
will have the drawings done this afternoon.
Mike made some comments to address Erik's
concerns on the flexure blade fit into the corner bracket. It is a transitional press fit in both
dimensions. He will send the drawings
to the vendors, then travel there and discuss details of tolerances. If a light press fit is thought by the
vendors to be possible, then they will negotiate that.
Mike sent Ron in purchasing an email asking
for a meeting tomorrow morning to adjust details of the titanium PO. He will add source inspection of the first
two articles before authorizing the remaining items. Jeff will help Mike make sure there are no administrative
hangups.
Tom Venator reported that the Goddard expert
(Chris) said that from a contamination standpoint there is no requirement for a
tray bakeout. Tom will talk to him more
in detail, but he suggested that if the bakeout is a workmanship test, then 24
hours is not necessary. Sandro asked if
there were bakeout requirements regarding the Hysol EA934 glue cure. Ben says it is commonly used with a 7-day
room temperature cure, so no bakeout is required for that reason. We will go ahead with the bakeout as a
pre-silicon workmanship test, but cutting the time down could help our
schedule.
Mike said that Riccardo owes a sketch of the shipping
container and lifting fixture and also a redlined drawing for the thermal
strap. Sandro replied that Emelio has
prepared sketches to send tomorrow for the container and fixture. Nothing has been done yet on thermal straps.
Jeff asked if there were Italian governmental
regulations on the lifting fixture.
None were known, but we decided that it would be safe to design it to
NASA requirements.
Mike asked about use of RTV on the thermal
strap where it gets sandwiched between Tracker sidewall and bottom tray. This is not presently in the drawings. We discussed what material to use and
settled on the electrically conductive Nusil that is already being used to glue
down ladders and to glue the grounding tube into trays.
Mike will review this decision with Jack and
Jeff.
Jim asked about disposition of COI excess
material from the sidewall build, which is about to expire unless we pay to
requalify it. SLAC has decided to scrap
it. There are 22 square feet of YS90
and several pounds of K13D. Ben will
send Jim email about where it could be sent at GSFC.
Sandro reminded us that 4 completed sidewalls
are already at Plyform (Robert pointed out that another 4 are at COI). We will keep in mind the option to use these
by post-bonding 25micron aluminum to the inside face and redrilling the
countersinks. Sandro estimates a month lead time for that. He will have to ask Plyform about the
post-bonding operation, whether we can expect any problems with that.
Jerry reported on the bias circuits. He needs to get modifed Gerber file from
Tung (this was changed to Thien later in the day). Robert and Sandro will review the resulting Gerber data. A 3D model is being made and will be checked
against the import Gerber files. We
will scrap all of the existing circuits.
New circuits will have the serial number, will not have extended traces
for plating, will have the circuit properly centered w.r.t. the alignment
holes, and will have grounding pads modified to give much better clearance from
the high-voltage SSDs. Darren pointed
out that the NCR needs to be completed.
Jerry reported that he has taken the action
for marking up the tray assembly drawings for the grounding tubes and getting
the drawings re-finalized.
Sandro reported that G&A has the tray mockup
drawings and 10 MCMs. They agreed with
him on a scheme of mechanical measurements.
Sandro will ask them for a time estimate to complete this work. He had discussions with them for a tool to
attach MCMs to trays. Next week he will
send a sketch. The tool includes a good
idea how to recover alignment of the pitch-adapter to the bias circuit and SSDs.
Dave reported on the MCM status.
Preproduction: 14 were completed a while ago
(10 of which are in Italy). Another 14 recently
completed burn-in and in final test and others are in progress at Teledyne. Teledyne started Tuesday the final 10 with V7
chips, using tall boards. We expect 2
weeks to complete this build cycle.
Flight production: SLAC screened 150 pitch
adapters so far and rejected about 12%.
Dave is adding temperature and humidity monitoring, because we observed
systematic differences in average length from one week to the next. Dave and Jeff are kitting flight materials
at SLAC. Tomorrow they will ship about
25% of the flight build for all parts available. The gating item is coupon-tested, machined PWBs. This has been held up partly by a need to
qualify a new machine shop, as Holt will no longer do this work for us. 25 are at a new vendor today. They will get CMM at SLAC when done. Our plan is to start flight production next
week. We still need to close on the PO,
and there is a meeting for that tomorrow.
Teledyne on their side has been reprogramming the wire bonding so that
all wires bond to one side of the ASIC pad, leaving undisturbed metal for
making a rework bond when necessary.
This will allow all rework wire bonding to be done to Mil Spec.
Sandro requested that SLAC send 10 preproduction
MCMs and 2 burn-in cables to Pisa, for software development. Jeff said there is a problem with getting
connectors to assemble more burn-in cables right now, but Robert and Jeff will
try to find enough parts for 2 cables.
Sandro reported a shipping problem. VME processors arrived in Italy FedEx. This causes a big delay and hassle in
customs. Jeff Tice will talk to Gunther
about this and request that all shipments to Italy go through him. Jeff knows how to ship items to the Pisa
airport, cargo-no-courrier.
The static test system left for Italy last
week. Erik will have his procedure document done in 1 week. Sandro will hold a meeting to decide on the
responsible person in Italy for this equipment and test. After these two items are taken care of we
can consider the need to send Erik to Italy for setup and training.
Honeycomb is being inspected today and
tomorrow in Plyform. Plyform is generating
a document which will be appended to the NCR.
Sidewall thermal cycles were done at Terni
and the results were good, with no effects seen on the walls. This has been documented in LAT-TD-03065.