Minutes of the Tracker
Meeting
March 11, 2004
Action Items:
1.
Jerry:
submit an NCR on the extended traces for plating the 50 bias circuits
2.
Darren:
notify the software development team of the implications of the bias circuit
NCR
3.
Robert:
write a statement on the science impact of the heavier copper
4.
Sandro:
respond to Robert and Jerry on the options presented for avoiding trimming
through bias circuit traces
5.
Jim:
find a designer to revise the static test and vibe test tooling for the new
interface
6.
Riccardo:
give Robert a breakdown on the 20 trays expected March 29
7.
Riccardo:
send a sketch of the thermal strap concept to Mike Menning
8.
Martin:
send check prints on the bottom tray assembly and closeout assembly to Riccardo
9.
Riccardo:
send Martin information on the grounding tube diameter and tolerance and
adhesive to Martin
10.Riccardo: resolve the TBDs
(best guesses at least) in LAT-TD-01918 and send to Robert for release
11.Robert: send Mike Menning a
schedule need date for the revised static test fixture
12.Jim: contact Erik Swensen
regarding his possible availability for travel to Italy
The first 45 minutes covered
the MRB for bias circuits, in particular the copper weight non-conformance with
respect to the drawings.
Agenda for the MRB (Material
Review Board) meeting for Bias Circuits
Ref: NCR 00065
LAT-DS-00192/rev 6
Dispo: IS: First shipment of 50 circuits, are to be
delivered with 0.5 oz copper foil.
SHOULD BE: All
circuits should have 0.25 oz copper foil, per Note-4 of drawing.
This will be LAT QA's
standard MRB agenda, each nonconformance will address most of these questions,
however, there will be some deviation based upon type of NC.
MRB AGENDA:
1. Present documented evidence/facts of failure or non-conformance.
a. What, where, why,
when, how?
2. Overstress analysis or additional testing required?
3. Suspected root cause? (present evidence as to why).
4. Impact to inventory, WIP, supplier PO, already built product.
5. Corrective action to prevent recurrence.
a. Design, test,
procedure options, trades & recommendation.
b. Recommended Was/Is
change description.
c. Impacts to other
subsystems.
d. Affected
documentation. (dwg, ICD, existing analysis, supplier EIDP).
e. Verification plan to
validate effective corrective action.
f. Estimated costs
& impact to schedule.
6. Effectiveness of corrective action
a. Any modification to
performance capability.
b. Impact on FMEA,
reliability, risk assessment.
7. Recommended final disposition(s):
a. Rework
b. Repair
c. Return To Vendor
d. Reclassify
e. Scrap/Purge
f. Use As Is
8. Action items:
who-what-ECD.
Richard Gobin (LAT QA)
chaired the MRB and will send out detailed minutes.
He reported that today or
tomorrow there will be a source inspection at Parlex in San Jose, and then they
will hand carry to 50 circuits back to SLAC.
The plan has been for Robert
to hand carry them to Italy on Monday.
However, Riccardo reported that Plyform will not deliver the first trays
to Pisa for ESPI testing until March 29.
Only after that will they go back to Plyform for installation of
tungsten foils and bias circuits.
Therefore, we decided that they will be shipped to Pisa in the normal
manner.
In Italy they will ensure
that the bias-circuit serial number will be reported on the tray traveler. For those trays that receive bias circuits
with ½ oz copper, the NCR will be reported on the tray traveler. Richard will ensure that all bias circuits
have a serial number before they ship to Italy.
Robert said that a
difference in copper weight from one tower to the next results in some
complications for the software, in that the simulation and reconstruction
programs have to be flexible enough to have different geometries from one tower
to the next. We need to be sure that
this is clear to the software development team. Also, Robert was requested to write down a statement on the
science impact.
Jerry reported that Parlex
expects to receive the ¼ oz material this week, in which case conforming bias
circuits may be available for at least some trays of Tower A.
It was noted that these 50
bias circuits have a second nonconformance (deviation from the drawings), which
is identical to one issue with the previous set that was scrapped for other
reasons. Parlex extended traces from
the wire bond pads to allow electroplating, which means that those traces have
to be cut while trimming the circuit following installation. This will require a careful electrical test
after trimming to be sure that no shorting of the bias results. Jerry had thought that Parlex solved this
issue, but recently found that their solution was not really a solution. Since then two real solutions have been
found and have been presented to Sandro by email. We are waiting for a response from him as to which he prefers. Both solutions avoid trimming through the
metal but do require slight modifications of the trace layout.
Tracker Meeting Agenda:
1. Questions from Tom Borden:
Fifth tray for mini tower
Clips for assembling mini tower
Parts for bottom tray drill fixture
Prototype trays for Tracker Mock-up
2. Static Test of the Bottom Tray (see below)
3. Thermal strap design and interface to the bottom tray (see
below)
4. Status of bottom tray assembly drawings and assembly tooling
drawings
- Also: Bottom-tray PRR, Bottom-tray procedure,
Bottom-tray inserts
5. MCM production status
6. Cables for stacked tray testing. C0 versus C0/C1.
7. G&A MCM pitch-adapter bonding fixture.
8. Document status for trays (ESPI, vibration, bakeout,
transportation)
9. A.O.B.
Static test discussion: Riccardo
reported that the static test fixture is still in customs. Documents are ready
for tomorrow to get the thing out and into the lab.
Andrea Tenze will return
next week to start work on the static test tool. He is the designated point person. The plan is to test it out with the EM bottom tray. Mike Menning said that Mike Opie will be the
responsible person on the SLAC side. He
would like to send Mike and John Ku there for the practice tests, among other
reasons. We also need a designer at
SLAC to work the drawings for the new interface. Jim is working this issue.
Mike and John also need to work the dynamic test issues, with an eye
toward simplifying the vibe test for towers B through 16. Robert asked that they consider taking the
EM bottom tray to destruction with the static test, since that was originally
the plan.
Mike Menning presented prior
to the meeting the following questions to consider regarding the Static Test
preparation:
1. INFN's status in evaluating the static test
hardware........Have they unpacked the hardware? Have they studied HYTEK's
instructions ? Have they identified a responsible test engineer?
2. Are HYTEK's instructions adequate or does Erik Swensen need
to travel to Pisa ?
3. What is INFN's schedule for performing " practice
" tests with the test fixture using the old interface design?
4. I assume that HYTEK provided INFN with the fixture itself
but not the test instrumentation. I also assume the instrumentation for the
acceptance tests will be a reduced subset of the qual instrumentation and that
the load cases will be a reduced subset of the qual load cases. INFN may not
have the same type of instrumentation that HYTEK had or there may be mods
needed to accommodate INFN's instrumentation and it's placement. The SLAC
structures group needs to define the needed instrumentation, detailed placement
of the instrumentation, the load cases, the success criteria, and provide a
redlined test procedure to INFN. I believe it's necessary for John Ku and Mike
Opie to travel to INFN in the very near future to have these discussions with
the INFN test engineer. We also need to come to agreement with Sandro on the
level of responsibility and involvemen that SLAC will have in the acceptance
tests. For example, I can see the SLAC test owner ( Mike Opie ) being present
for acceptance tests on the first two towers and then dropping down to being a
" remote participant " for
tests on the remaining towers. On the first two towers, I would expect Mike to
have the authority approve the test readiness and to stop the test if he deems
it necessary.
5. John and Mike also need to have similar set of discussions
for the acceptace vibration tests at the tower level.
6. It would be very desirable for Mike and John to make their
trip during the time that INFN is doing or preparing for practice tests with
the static test fixture.
Input from Robert and Erik
on the Static Test preparation:
- In Italy they will need a
granite table with holes at 4" centers to mount the fixture on. If they don't have 4" centers, then it
may be necessary to build an adapter plate.
- Instrumentation is needed
for the load cell. Here is info from
Erik:
We use a strain gage
indicator here to monitor the output from all Omega
loadcells. The P/N is DP-41-S and can be found at: http://www.omega.com/toc_asp/subsectionSC.asp?subsection=D01&book=Pressure.
It will need to be wired up and can be wired for RS 232 output to a computer is
they so desire. There are other ways to
make these measurements, which they might have already.
- Hytec also used some
digital displacement probes. We don't
think that is needed for the workmanship test.
They used it for model correlations.
- Erik will send the whole
drawing package to Mike, to be passed on to Italy in case they need it for
reference. The solid model is in Solid
Works, which Erik did not think was really usable at SLAC.
Riccardo reported that they
expect to receive mid-tray panels for 20 trays on March 29. Part of the delay was due to work required
to repair the honeycomb. He thought
that the crushed cells probably resulted from the shipping, because the spacer
between cores was smaller than the core size.
All honeycombs are repaired, and he will send a complete report. Robert asked to receive a breakdown of the
20 trays. How many are heavy, for
example? If 5 are used for non-flight
purposes, then that leaves only 15 for Tower A, whereas 17 are required.
Nanda reported that at
Alenia they are on the 2nd to last balance. Jack said that they started the -15C test
this morning, at 12W power. By meeting
time it was reasonably stable. The top
half of the tower was very stable and the bottom half was catching up. He expects to finish during the night and
then go down to the next power level. They
would like to complete 2 power levels at –15C, but they do have to recover the
chamber Friday morning to be out Friday night.
They completed 12W, 10W, and 8W at 0C.
They still have trouble with tower power stability, but are managing it.
Jack said that in the EM the
thermal straps are dry on both sides.
He has not looked carefully at the data yet, but his impression was that
the temperature drop from tower to Grid was roughly what was predicted.
Riccardo said that for the flight
thermal straps they plan to bond the two straps together and to the bar. Then they will fix it to the bottom tray,
referenced to two protruding inserts. They
will make bigger holes on Grid side, to give better clearance. He will send a sketch to Mike Menning.
We need to look at the T/V
data better to determine if adhesive is necessary. Riccardo would like to bond it to the bottom tray in any case at
the tower assembly level.
Sandro's note on thermal
strap design, sent prior to the meeting:
I had a short discussion
with Jack Goodman and we have an idea that can solve the problem of the thermal
straps without big changes. On the tray side we can glue the thermal strap with
an epoxy adhesive. The Al inserts stick out from the tray surface allowing a
good alignment of the strap to the closeout. The adhesive will prevent the
movements of the thermal strap during sidewall mounting and shake test, which
can generate the edge damages. Same thing can be made on the other side,
attaching the thermal straps to the small Al bars.
Bottom tray assembly tooling:
Riccardo said that he discussed the machining with G&A. However, he needs the assembly drawings to
check all the stay clears and inserts. Martin
said that at SLAC they are about 1 week away.
He can send check prints next Tuesday. Riccardo estimated 3 weeks to
machine the tooling. He needs 2-3 days
to finish the drawings after getting assembly drawings.
Martin said that check
prints of the closeout assembly will be available tomorrow. Riccardo estimated 2 weeks to make the
inserts. Plyform has material certs for
inserts. Midtrays should conform to the
drawings, but he will verify with Plyform that they really used 7075-T76
aluminum. Bottom and top tray inserts will
be to the same spec.
Riccardo will send
information needed on the grounding tube drawing to show the as-built info: diameter
and tolerance, and adhesive.
Titanium flexures: the
vendor agreed to 100% inspection on the first two articles, with SLAC QA
present (Joe Cullinan). The vendor will
not stop work for this. Are parts are
to be done by April 9.
Riccardo will fill in the
TBDs in 1918 with his best estimates and send it to Robert for release. It will be revised after the first tests.
INFN is preparing a document
on sidewall specifications. They need
to discuss it with Plyform before the prepreg order goes out.
Mike said that he wants a
schedule need date for the static test fixture upgrade.