Tray Assembly
- Plyform is producing tray panels at the full production rate.
- An MRB was held concerning bubbles in the Kapton bonding. Strong evidence was presented from the Tower-0 experience showing that a small puncture made to allow gas to escape will not present any significant risk of short circuits. We will proceed with these trays for Tower-A.
- Etching and priming of tungsten tiles is proceeding well at GSFC.
- Tray assembly at G&A resumed following shipment of MCMs from SLAC with 100% inspection of the connection from pitch-adapter to amplifiers and bias. There is a new issue with one MCM having about a 5mm length of the pitch-adapter flex circuit (22 channels) delaminated in the wire-bonding region. This should not pass inspections done after the pitch-adapter bonding at Teledyne, but it may also have occurred during soldering or thermal cycles. SLAC will prepare for an inspection of this following burn-in, and the Teledyne inspections will be reviewed by SLAC QA when Teledyne restarts. G&A will rework the affected region to try to recover those channels.
Sidewalls
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Plyform received the first prepreg shipment from COI,
and the second and final is ready to ship to
- Sidewalls for two towers have been completed.
- The Tower-A sidewalls had an error in paint masking. The regions for thermocouple attachment were not masked. This is not an issue if the tower is located in the center of the Grid.
MCMs
- About 36 more MCMs are being prepared this week to be shipped out today. The failure rate on the pitch-adapter connections is almost 14% this week, much worse than in the set shipped last week (<3%). The root cause of this is still under investigation, but it is believed to be a problem of control of wire bonding to the pitch adapter at Teledyne.
- The work flow at SLAC includes now the thermal cycles, burn-in, visual inspection, rework to remove conformal coating from the connectors, measurement of the MCM thickness (at the connectors), and full electrical test, including 100% testing of the pitch-adapter channel input and bias connections.
- Next week SLAC will start reworking conformal coating on MCMs, in addition to cleaning the connectors.
- Quite a few MCMs have connectors not fully pulled flush to the board. This caused conformal coating to flow underneath and even up onto the mating surface. This nonconformance is being worked with Teledyne. It is a problem for tower assembly because it can cause an interference with the sidewalls. The MCMs are being screened by measuring the thickness, and those exceeding 0.1mm beyond nominal will have to have the connector attachment reworked.
- 38 nonflight MCMs and 8 cables were delivered to the electronics group. 36 are now set up in a tower configuration for software testing. Most of the MCMs were rejected for flight because of broken pitch-adapter traces, which is of no consequence for this testing.
-
Teledyne is not yet back online, but the contractual
issues were resolved, and the revised
Flex Circuit Cables
- Daily contact is being made with Parlex to resolve the QA and workmanship issues.
- Titan is making a set of first-article cable circuits, due the first of December. SLAC QA will survey their facilities next week.
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A
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Cables have been tested and inspected for Tower-A, but
work is in progress now to get a
Parts and GSE for Tower A and beyond:
-
Bias Circuits: 725 out of 850
delivered by Parlex. A shipment
of 272 is ready to go to
- Grid interface studs are at Nyloc where the locking mechanism is being reworked and tested under SLAC supervision. A good fraction of the studs have to be returned to the machine shop to get the threads corrected.
- New cable bending tools have arrived. More alignment tools and custom wrenches (for the studs) are in work.
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The new tower shipping container is ready to go to
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Flight heat straps and mounting bars are in hand and nearly
ready to ship to