GLAST Large Area Telescope: Tracker Subsystem WBS 4.1.4 7C: Electronics Module Testing

1. Gamma-ray Large Area Space Telescope 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@scipp.ucsc.edu

2. 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

3. 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 Interface Card (with cover removed) VME with COM Card and ADC Frequency Counter PC MCM DUT Adjustable Clock

4. 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 85°C for 336 hours for burn-in. During this time the electronics are continually exercised and tested.

5. 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).