Minutes of the Tracker
Meeting
August 19, 2004
Action Items:
-
Ronaldo:
talk to Plyform about scheduling a visit of the anomaly review team
-
Sandro:
respond to Neil’s question list
-
Arthur:
submit a proposal for a bonding test to be done at SLAC next week
-
Sandro:
review the status of the top tray and what can be done in the near term to make
it usable for Tower-A assembly
-
Dave:
check with Martin on the status of the alignment plan
-
Jeff:
get all the hardware shipped to Pisa before the end of the week
-
Hiro:
test the C0 cables with MCMs, including the bias leakage current
1) Bias-circuit bonding
anomaly review team
-
Schedule:
The “Tiger Team” will be ready for work on Monday morning, August 30, in
Pisa. They will be departing Friday
morning of the same week. 1 day will be spent at Plyform, probably Tuesday or
Wednesday (Ronaldo will talk to Plyform).
Ronaldo said that the prospective Italian consultant is on holidays, so no
contact had been made yet.
-
NDAs
and access to the detailed Plyform procedures: Ronaldo suggests not to open
this issue unless needed. Sandro thinks there is not much to know that we don’t
already know. Sandro will respond to Neil’s question list.
-
Sandro’s
question: is there any quantitative method to evaluate the cleanliness of the
tiles, so they could study it next week? Ben suggested simply a traditional
water break test: deionized water is dropped onto the surface to see if it
spreads smoothly; if it beads up like on a waxed car, then it is not a good
surface for bonding.
-
Bonding
test using etch (Mil recipe): Arthur will make a proposal for a test at
SLAC. Robert noted that Plyform has an
etch procedure that they use for Agile trays.
-
Neil
asked about the typical bond thickness.
Sandro said that it is close to 50 microns (2 mils).
-
Neil
said that he is trying to identify a time for a telecon on the analysis. John
Ku said that he will have some results summarized soon, hopefully today. Ben
recommended a strain based criteria, rather than stress, because of
nonlinearities of the adhesive, especially with temperature. He
stressed that we don’t have enough information on stress/strain curves versus
temperature for this adhesive to do the analysis in this way.
2) Tower A tray status
-
Completion
of the work at G&A: G&A has stopped work and gone on vacation.
-
Status:
16 trays in Pisa; 4 are shorted on one side; 2 have no ladders but have MCMs.
-
The
3 missing trays are set aside for investigation. 1 tray is 200 microns small in
both directions.
-
We
discussed the possibility of assembling working MCMs on the 3 trays. Sandro
will look at the status of the top tray in particular and see what is possible. The tracker team would like to maintain the
old schedule for Tower A assembly (starting August 26) with the trays as is, as
long as all have MCMs mounted. SLAC and
NASA management have yet to approve, however.
-
Stacked
tray testing plans, schedule, procedure release status PS-03361. Luca Baldini said that it should be done
already and ready for release. Robert
will ask Luca on Monday.
3) Tower Assembly PRR
readiness
-
Assembly
procedure PS-01854: still in work; to be released next week
-
Alignment
plan/procedure PS-03566: Dave will check the status with Martin
-
Arthur:
interface assembly procedure
-
Electrical
test procedure TD-00191: check with Luca
-
Cosmic-ray
test procedure PS-01855: apparently this number is not being used
-
Packaging,
handling, transportation PS-04525: in work, with the first draft to come out
next week
-
PRR
presentations: Emilio will prepare charts; Luca should also have some charts
4) Status of SLAC
deliverables for Tower A
-
A
large number of items need to be shipped from SLAC this week
-
lifting
fixture: ready to ship
-
inner
container: proof loading complete
-
cable
holding plate: ready to ship
-
vibe
fixture: ready to ship
-
screws
and pins: ready to ship
-
I/F
hardware: all ready, except the flight studs, which are still getting coated. Arthur will carry the studs to Pisa.
-
cable
bending tool and cable installation testing: Arthur will carry a mockup to Pisa
for testing the installation.
-
corner
brackets and clips and nests: corner brackets are coming out of plating today
-
C0
cables: Robert said that at least 3 new ones are in the clean room, and Robert
will hand carry them to Pisa. Luca
wants SLAC to include connector savers with them. Robert asked Hiro to check whether he can test them with MCMs
before Monday.
5) MCM issues
-
pitch
adapter cracking: SLAC is inspecting MCMs post-burn-in to try to avoid the
situation with one MCM on a tray that has 25 broken traces. So far, some MCMs have been found with many
apparent cracks, but almost all of the traces still conducted. Further study is in progress. Work is still going on to make an improved
pitch adapter. The first attempt
failed. The second attempt will have
the solder mask extend all the way around the bend region, in which case
Teledyne must improve the alignment (some improvement already made) to insure
that the wire bond pads don’t get lost.
-
HV
shorts: 6 MCMs have been found in the post-burn-in test to have HV shorts
internal to the PWB between the HV and AVDDA planes. Further investigation is in progress.
-
HV
capacitors: the Tracker data on MCMs do not show any problem with leakage
current, except that there is nearly always some decrease in current from the
burn-in. No MCMs have shorted so far
due to capacitor failure. The PCB
apparently approved flight use of the existing MCMs with the questionable
capacitors. Novacap is producing a
replacement lot that we will use at Teledyne when available.