Revision as of 12:40, 31 August 2012

August 30, 2012 FDC meeting

Agenda

1. Production Construction Tracking (Dave)
2. Cathode corrosion
   • Recent test results: [1]
3. Conductive tape studies: [2], [3], [4],[5], [6] (Vlad)
4. Engineering (Bill)
   • Cathode strong-backs
5. Electronics (Chris, Nick)
   • PCBs
6. Third package tests FDC E-log (Beni)
7. TDR, pages 132-145 (Lubomir)
8. Other

Minutes

Participants: Fernando, Bill, Dave, Elton, Simon, Chris, Vlad, Beni, and Lubomir

Production

- Dave: working on all the cathodes for package #1. Using the new tool to hold the cathodes flat, two cathodes moved to tables and the cards are being glued there. Will have cathodes for the first, second, and third cells by next Tuesday, next Thursday, and next next Tuesday respectively. This is assuming one cathode per day, which is limited by the tools that we use now.

- Wire frames: Chris will put the resistors on the first PCB set next week. Then we will start laminating the wire plane #29, we have a frame for it. The other three G10 wire frames will come from the machine shop in ~2 weeks. Fernando and Bill confirmed that the new PCBs can be used.

- Roger got quotations from Allflex and Flexible Circuits, the two Minnesota companies that made the cathode foils and the rigid-flex assemblies. According to Allflex they have material for 18-19 foils and we asked for 20. We will need the foils for some of the cathodes on package #2. Based on Dave's estimations for the refurbishment of the first package and then completion of the fourth one, we will need the foils sometime in November-December. In any case it's better to submit the PRs now and contact Eugene to use funds (~$26K) from FY12, if possible?

Cathode corrosion

- The last test with the vacuum chamber: we had a sample with Viton+Apiezon, three O-ring pieces across a strip using the strong (red) clamp and keeping it for one week at high temperature and humidity, the longest time so far. The picture of the sample is linked above: copper changed color everywhere except at the place where the Apiezon was applied. Several dark lines are visible at the O-ring positions. Two on the sides are darker, probably they took the main pressure from the clamp. Only in the middle we see some very small holes through the copper, visible only with good a back-light. Olga will do SEM analyes.

- This is the first time we had dark traces under the Vition+Apiezon O-rings, though the conditions of the above test were extreme and we see corrosion/oxidation everywhere on the sample. To make sure we have the right pressure on the Viton we started a new test with a real spacer ring "inserted" through the vacuum chamber and applying pressure on it with a lead brick.

Conductive tape studies

- Vlad did the same ball counting studies as before, but with another cathode (#4, one of the worst: top of former package #1) this time using improved technique in removing the conductive tape and measuring the resistances. The correlation between the resistances and the ball numbers is much more evident now (profile plot above). Again we have about 0.5-2 Ohms per ball and all the resistances above several Ohms (~10-15%) can be explained by loose contacts between the balls and the cathode traces. The highest resistance on this cathode was 50 Ohms.

Engineering

- The cathode strong-back tool needs more suction cups. The six that we have now are enough for type-1 but not for type-2/3. Will have them on Tuesday and then can continue with the cathode production. Bill suggested installing a guage meter to make sure

Electronics

- Fernando did some organization of the files for all the electronics components

- Main discussion was what to do the with these four PCB sets. Mechanically, compared to the original PCBs, there is a small difference in the gas connector positions (about a mm); according to Tim it will work and mechanically the wire planes will be interchangeable. Fernando: some of the signal traces are at different positions and the gold-plated ground area is bigger; the traces going through that area have to be covered with conformal coating. There should be no differences in the HV PCBs, but Fernando will check all the boards and on Monday we will decide if these can be used. Eugene: if you spend more than two weeks on these boards we better purchase new ones, which however will be tricky (at the end of the fiscal year) and will delay the production. Lubomir and Dave: we will need the boards in two weeks, if not we have to re-work the schedule.

TDR

- Lubomir received corrections from Bill and Simon, still some work remains to be done here.

Other

- Eugene urges us to do all the purchases for the FDC as soon as possible at least by the beginning of September; after that most likely there will be no money till the end of FY12.

-->