Minutes of the Tracker Meeting
March 11, 2004
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
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.
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):
c. Return To Vendor
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)
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.