Difference between revisions of "Minutes-8-16-2012"
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| − | - | + | - Microscope pictures from the damaged cathodes (package one) on which we have removed the rigid-flex assemblies (or daughter cards) are linked. On the card contacts one can see the silver balls, on the foil contacts the conductive tape is visible with some balls inside and also on the copper pads. |
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== Engineering == | == Engineering == | ||
Revision as of 12:25, 17 August 2012
August 16, 2012 FDC meeting
Contents
Agenda
- Cathode production Construction Tracking (Dave)
- Cathode corrosion
- Status [1]
- Possible procedure changes
- Conductive tape technology
- Test results [2], ball counting hist.#1, ball counting hist.#2, ball counting hist.#3, ball counting hist.#4, ball counting hist.#5, ball counting hist.#6
- Procedure changes
- Engineering (Bill)
- Cathode strong-back
- Other: epoxy tests
- Electronics (Chris, Nick)
- PCBs
- TDR, pages 132-145 (Lubomir)
- Other
Minutes
Participants: Eugene, Bill, Dave, Simon, Vlad, Beni, and Lubomir
Cathode production
- Dave: working on 8 new cathodes to be used in the second package. The bottleneck is the card gluing since we have not decided if we want to change the procedures.
Cathode corrosion
- Lubomir about the SEM results: On the wire samples some small crystals (~3um) are seen containing sulfur, Olga counted about 25 of these on 2cm wire length; too small quantity to account for the copper damage on the cathodes. On the EPDM surface - no conductivity and very low yield from the microscope - still one sees some sulfur on the used EPDM, and much less or nothing on the virgin EPDM and on the prototype EPDM. Dave will check if the virgin and used EPDMs are from the same batch.
- Results from the vacuum chamber (Vlad's) experiment: it was running from last Thursday (end of the day) till Monday morning, pictures linked above. One clearly sees damages on the EPDM sample, just a little on the Viton one and no damages are seen on the Viton+grease sample. The samples are now with Olga and will have SEM results next week. Bill proposed to make another sample with Viton+grease with curving shape to have more potentially damaged area and then measure if the resistance has changed. Vlad will check the resistance of the samples that we have now. On Tuesday we started the same test except there's no water inside the gas volume.
- As of now we see two solutions of the corrosion problem: using the technology that we used already for the third and fourth packages, i.e. Viton+grease, or in addition to that, covering big areas on the cathode including all the traces with Kapton glued with Hysol. Using Kapton foils doesn't seem to create leakage but we tested this on a flat Lexan sheet. We decided to use the standard technology for the second package, i.e. only Viton+grease. When we come to the first package (in about two-three month from now) we will discuss again the use of Kapton; there we may have to use it if we are going to re-use the cathodes from the former second package since some of the channels have to be fixed with conductive ink. Of course we will wait for the latest SEM results before continuing with this procedure.
