1. GLAST LAT ProjectMarch 24, 2003 6C Tracker Peer Review, WBS 4.1.4 1 GLAST Large Area Telescope: Tracker Subsystem WBS 4.1.4 6C: Ladder Fabrication A. Brez I.N.F.N. Pisa Brez@pi.infn.it Gamma-ray Large Area Space Telescope

2. GLAST LAT ProjectMarch 24, 2003 6C Tracker Peer Review, WBS 4.1.4 2 Ladder construction flow down LAT ladder construction follows the block diagram (see LAT-PS- 00635 and LAT-PS-00831 for details) Assembly in G&A Engineering (251 flight ladder produced) Assembly in Mipot staring up (PRR in April)

3. GLAST LAT ProjectMarch 24, 2003 6C Tracker Peer Review, WBS 4.1.4 3 SSD edge bonding Manual fast AND precise method 24 ladder assembly tools used in parallel Very good ladder alignment obtained Ladder assembly tool

4. GLAST LAT ProjectMarch 24, 2003 6C Tracker Peer Review, WBS 4.1.4 4 Encapsulation Dam & Fill encapsulation Dam Nusil 1142 Fill Nusil 15-2500 Requirements: 1.Height <0.5mm 2.Lateral overflow <0.05mm 3.Coverage of all the bondings and pads Fast system to check encapsulation height

5. GLAST LAT ProjectMarch 24, 2003 6C Tracker Peer Review, WBS 4.1.4 5 Ladder electrical test: methods 2 PA200 probe stations with modified chucks to accept ladders are in activity (G&A and Mipot) Tests: IV curve (ladder leakage current from 0V to 200V) CV curve (ladder total capacity and depletion voltage) Single channel AC test: 100 V voltage step to measure AC insulation and AC capacity  o Connected strips  o Interrupted strips I(5  )>10nA AC short IV,CV test scheme AC strips test scheme

6. GLAST LAT ProjectMarch 24, 2003 6C Tracker Peer Review, WBS 4.1.4 6 Electrical Tests: Results Electrical test results: 1.Ladder tested251 2.Accepted243 (97%) 3.Broken edge 4 4.Probe accident 1 5.Not understood 3 The causes of problems 3 and 4 have been corrected, foreseen rejection rate ∼ 1% Bad channels caused by bonding (coupling shorts)=0.016% (accepted limit 1%) No broken or bad bondings

7. GLAST LAT ProjectMarch 24, 2003 6C Tracker Peer Review, WBS 4.1.4 7 Database A Access database system installed in the two assembly centers, collects all the relevant data of the ladders: SSDs alignment IV curve CV curve Bad channels (AC insulation test) Not bonded channels The database allows a fast and accurate monitoring of the ladder production. This database adds to the traveler systems installed in the assembly company (ISO9001) which ensure the whole traceability of materials, instruments, procedures.

8. GLAST LAT ProjectMarch 24, 2003 6C Tracker Peer Review, WBS 4.1.4 8 Conclusions The ladder construction successfully started (9% of the ladders have been produced with a 97% yield, possible increase of the yield to 99%). Electrical and dimensional ladders characteristics well within specifications Production rate > 10 ladders/day in both assembly centers that will work in parallel (G&A Engineering and Mipot), so there are no schedule problems with this item