Minutes of the Tracker Technical Meeting
July 10, 2002
Pisa started to run strain/strength measurements on the MCM transfer adhesive with 22mm by 22mm samples. The strength is factor of 5 less at +40C and okay at –40C. They are now starting thermal cycling tests with the MCM attached to a closeout. The will test whether the MCM will shift on the order of 100um in reference to the closeout. Next week the test with the full MCM will be done, with results possibly on Wednesday.
Tomorrow Sandro will be at Plyform to check the production line. There is an issue with the location of the inserts in the closeouts, with 70-80um shifts of the inserts in a tray observed. The tool for bonding inserts is within specifications, so possibly something is wrong with the assembly tool. This is the reason Sandro is making the visit.
Three trays, one thick tungsten and two thin tungsten, have been completed (as noted already two weeks ago), and two other trays, facesheet-core sandwich only, are done at Plyform. Tomorrow they will assemble the other two trays with closeouts. They will keep the 9 extra carbon-carbon pieces, unmachined, for backup in case they need more closeouts. Sandro asked about using trays that were not within dimensional tolerance for the functional trays. Tom agreed that is OK, but one functional tray will undergo vibration testing. Sandro said there was enough play in the tray vibration tool to use the trays that did not meet dimensional tolerance.
Mechanical wafers have been measured at Pisa and found to have a mean value of 20um gap for the glue, min of 5-6um, max is 45um. These wafers are not as good as the HPK wafers, and Sandro feels that there will be a smaller deviation with the Flight SSD’s.
Tom is to find out the status of the shipping of the trays back to Pisa. He needs a monetary value from Sandro, but if he cannot find his paperwork he will use $100.
Tom gave an update of the ART status and plans for analysis.
Real production of ladders will start on July 22 with the EM. On the last week of July they will start flight models. G&A is sending the last tooling information to Sandro, and he will finish the procedure documentation, taking into account the comments included from Robert. He expects it to be ready to release next week.
Sandro will send Tom approval for release of the update to LAT-DS-00527, “LAT Tracker SSD Dimensional and Electrical Inspection Requirements”.
We discussed the 4 month slip in the SSD delivery from May 03 to September 03. Sandro checked his schedule. The current May delivery has very little overlap of ladder assembly with tray assembly, but with a four month slip a lot of parallel effort will be required, including SSD test, ladder assembly, tray assembly/test, and tower assembly (Qualification Towers). This is much higher risk and should be avoided.