Tracker Status
Tray Assembly
-
Tile etching and priming was successfully accomplished
at GSFC, as well as in
- The tray test articles were tested up to 75C. The etched and primed tiles performed well.
- Installation of tungsten and Kapton onto flight trays restarted at the beginning of this week. The recommended process and facility improvements were completed at Plyform.
- A meeting was held this week to settle on the resolution of the connector/sidewall interference problem. Most of the problem was process related, and G&A/Pisa submitted a corrective action plan. The rest of the problem will be corrected by making thinner spacers for the MCM glue joint.
- A decision was made to eliminate encapsulation of all wire bonds between MCM pitch adapters and SSDs.
MCMs
- An inspection plan was finalized for the conformal coating issues, and inspection is in progress, including visual inspection of the pitch-adapter traces.
-
39 MCMs ready for Tower-A were shipped to
- The parts for an electrical test fixture for pitch adapters are partially done, but this effort was delayed by urgent accelerator work in the SLAC shops.
- Production is at 363 units delivered to SLAC, of 576 needed for 16 towers, plus 38 needed for the electronics group and 72 more needed for the two spare towers.
- The production is still halted at Teledyne pending various process improvements, including a bakeout of boards before soldering.
- A new pitch-adapter prototype was received to try to eliminate the trace cracking.
- Four MCMs completed 200 thermal cycles from -30C to +85C to investigate the effects on pitch adapters and conformal coating. The cycles did not cause any nonconductive cracks in traces and did not change the conformal coating in any way.
- Progress was made on understanding issues with high-voltage failures on some MCMs. Two MCMs were send to GSFC for DPA. 4 bare boards were tested at 120V AC for several days, and 4 fully populated boards are now being tested (this is to verify that corona discharge in tiny bubbles is not causing the failures). Evidence has increased that the failures are clustered in one small set of panels made at about the same time.
- Good progress was made in understanding the timing margin issues. We found that the margins can be greatly increased by lowering the termination resistance on the flex-circuit cable clock bus. This was verified both on burn-in cables and on flight cables (with no connector savers attached).
Flex Circuit Cables
- A two day meeting was held at Parlex. They have provided cause and corrective action for both NCR types, and they believe that they have their process back online now and can meet our needs.
- A backup plan involving splicing together two shorter cables is in the works at SLAC, just in case Parlex cannot deliver.
- A present we do not yet have a full set of cables for Tower-A with good coupon tests.
Tower Assembly
- The trial tower assembly (Tower-0) completed. A list of issues is being worked to ensure that the Tower-A assembly will be smooth. By the end of this week the comprehensive performance test was executing on this tower. The alignment work went very well. The cable installation, including bending at the top, was successful. The one open issue is to understand now why 1 of the 8 cables does not read out, a problem that was found immediately after its installation. The problem appears to be in the data line from the bottom MCM to the TEM. On that tower side all channels are being read from the redundant cable.
Misc.
- Progress was made on production of various pieces of GSE, including the shipping containers.
- Progress was made on drawing improvements, including the mid-tray panels.