Minutes of the Tracker Meeting
August 14, 2003
Luca Baldini: write a short document for the mini-tower end-item data package with references to the web links
Luca Baldini: bring the Pisa TEM to SLAC for initial tests
Jeff: help Luca with his travel to SLAC
Robert: have a Keithley source-meter sent to Building 33
All: review the draft plan for EM sidewalls
All: review the EM discrepancy list
Sandro and Riccardo were not available to review the tray closeout drawings LAT-DS-00092 and LAT-DS-00093. This will be done in the last week of August. The updates with respect to the already released versions came from Italy:
- change threaded holes to smooth holes on the MCM walls
- remove the MCM location tabs on the MCM walls
- changes to the structural walls to introduce an asymmetry for avoiding wrong assembly during flight production
Minitower data package: Luca Baldini reported that all of the necessary items are available. The plans for testing the tower upon arrival at SLAC are also on the web. Luca was asked to provide a short written document, which can refer to the web links.
Pre-ship review: all material for the pre-ship review is on the Pisa web site. It was decided to hold the review at the LAT engineering meeting next Tuesday.
Luca agreed to bring the Pisa TEM/PS with him to use for initial testing of the tower at SLAC. The TEM will return to Pisa with him at the end of 2 weeks.
Luca will arrive at SFO on August 20 in the afternoon. Jeff Tice agreed to meet him at the airport and also to provide some documentation in advance to help with customs.
Luca said that he needs a pico-ammeter in the SLAC cleanroom. Robert agreed to have a Keithley source-meter sent over from UCSC.
There was a discussion of sidewall issues and what to do with the existing left-over prepreg. Robert asked for review of his draft plan. Part of the plan is to make official drawings and specifications of the coupons for EM sidewall testing. Erik will send his notes to BJ, and BJ will make up a new drawing for Cyberdocs and send it out for review.
There was a discussion of prepreg orders. Sandro’s plan sent out on Monday called for Plyform to order prepreg from COI on August 13. We need verification of whether that actually occurred. An order from SLAC can be released immediately and give us prepreg at the end of the month. COI has already been procuring the fibers from Japan.
Robert summarized the MCM production status. Teledyne is working on a contract to test all of the production and tooling changed introduced since the last build, which include
a) improved PWB radius for flex attach
b) corrected alignment of tooling for flex attach
c) use of fumed silica in the epoxy for flex attach
d) staking of large capacitors; vibration testing
e) dam to limit encapsulation and keep clear from the region on the pitch adapter needed by G&A; application of encapsulation without need for a second layer
f) grounding screw and protective wire-bond cover during electrical testing
A problem was found when trying to machine the radius in the new boards. DDI did not use the correct adhesive for attachment of the raised strip. The 50 boards were rejected. DDI will provide 5 boards with acrylic adhesive to get started with by next Tuesday.
The proposal from Teledyne for the flight production is expected by the end of this week.
Darren provided an updated EM discrepancy list to be reviewed. Robert noted that the list does not mention the issue with the bowed closeout wall in bottom tray SN002. Erik said that when they used that tray in the static test the bowing was not noticeable and did not cause any problem.
Robert, Hartmut and BJ discussed the issues with the flex-circuit cables. Cables C0 and C1 have the lowest cactus arms, and their arms protrude through the bend region going through the grid. See the drawing from BJ. The arm was extended to move all vias away from the bend region (see drawing). In order to achieve the IPC required radius, either the grid or the bottom tray must be chamfered. The latter is not acceptable at this point, especially since it would cut into the titanium corner bracket.