GLAST Large Area Telescope:

1
GLAST Large Area Telescope Tracker
Subsystem WBS 4.1.4 7C Electronics Module
Testing Robert Johnson Santa Cruz Institute for
Particle Physics University of California at
Santa Cruz Tracker Subsystem Manager johnson_at_scip
p.ucsc.edu
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Overview

• Draft test plan LAT-TD-00249
• High yield and good quality of MCMs requires
  testing at several levels during the production
• Printed Wiring Board full test against the
  netlist by flying probe
• Parts screening specified in several
  procurements
• Polyswitches (LAT-SS-01116)
• Nano Connectors (LAT-DS-01807)
• HV Capacitors (LAT-PS-01194)
• Standard QML SMT parts
• Wafer probing of the GTFE and GTRC ASICs
  (Presentation 5D)
• MCM testing after SMT parts and connector
  soldering
• MCM functional tests after die attach
• MCM thermal cycle and burn-in
• Final acceptance test

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MCM Testing at Teledyne

• Test system and software supplied by UCSC/SLAC.
• Initial power-on test after soldering but before
  die attach.
• Check for shorts in the power bussing.
• Check for leakage on the SSD bias-voltage line.
• Complete electrical test after die attach and
  wire bonding but before die encapsulation (see
  also Presentation 6E).
• Functional test
• Power consumption
• Basic amplifier-discriminator performance

VME with COM Card and ADC
Interface Card (with cover removed)
Frequency Counter
PC
MCM DUT
Adjustable Clock
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Test and Burn-In

• This work will be done in the SLAC clean room in
  Building 33.
• The MCMs remain in their closed storage boxes
  throughout this procedure.
• A functionality test is done to check that no
  damage occurred during encapsulation.
• 9 MCMs are connected to a pair of special
  flex-circuit cables (1 is shown at right, with a
  repeater board).
• 4 such cables pairs are installed in a climatic
  chamber.
• 8 long cables attach to the repeater boards and
  exit the chamber, to connect with a TEM.
• The 36 MCMs are thermal cycled through the
  required acceptance cycles.
• The temperature is raised to 85C for 336 hours
  for burn-in. During this time the electronics
  are continually exercised and tested.

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Further MCM Testing

• Final Acceptance Test performed in Italy prior
  to bonding of the MCM to the edge of a tray
  panel.
• Test after wire bonding to the bias circuit but
  prior to mounting of SSD ladders.
• Checks for shorts or leakage in the SSD bias
  path.
• Final check of the tray before committing
  expensive SSD ladders.
• Test after completion of tray assembly.
• First test with input load on the amplifiers.
• Preliminary catalog of dead or noisy channels.
• Cosmic-ray testing of stacked trays (still in
  their service boxes).
• Tower electrical testing (test plan
  LAT-TD-00191).