1. AOC Performance Death rates – Channel distribution & FEA Decrease in optical power with time Summary

2. VCSEL Failures 20 AOC channels have failed. Failure rate << TL but still much higher than expected. AOC

3. AOC Failures (Steve McMahon) 3 infant mortality and 17 random failures Failures appear to peak at centre of array – Probability (More fails in one channel than observed) = 0.06% If this is not a fluctuation  problem is not inherent to array but must be a result of the packaging.

4. FEA Analysis (Stephanie Yang) Epoxy on top surface VCSEL causes stress because of mismatch in CTE epoxy and GaAs and change in T between epoxy cure and operation.

5. PCB 1.6 mm Silver Epoxy <10 um GaAs 120 um Epoxy 50 um MaterialCTE (ppm/ °C)Y (Gpa)Density g/cm3 FR4 PCB175 (z) or 13 (x)0.51.9 Epoxy 353-ND Tg ≥ 90 o C 54 (below Tg)/ 206 (above Tg) 3.56**1.06 GaAs6.8685.55.3 H20E3125 (guess)2.55 Cure temperature: 100°C, normal operating temperature 20°C 5 Diagram and parameters provided by Tony Weidberg **http://www.epotek.com/SSCDocs/datasheets/353ND.PDFhttp://www.epotek.com/SSCDocs/datasheets/353ND.PDF 08 Oct 2012

6. 6 GaAs stress: Max stress along its length on GaAs is 140MPa ; GaAs displacements: Max out-of-plane displacement is 0.022mm; and max in-plane displacement is 0.072mm. Max von-mises stress of GaAs is 173MPa 08 Oct 2012

7. Power Changes (Will Kalderon) Use on-detector p-i-n diode current Ipin to monitor power of VCSELs Look for long term trends Split samples into installation periods. Check for evidence of radiation damage to p- i-n diodes

8. Group results by 4 installation periods

10. Summary Death Rate for AOC VCSELs much higher than expected. Peaking in central channels  packaging issue – FEA stress larger in centre of array Decrease of power with time is ~ 5 times larger than expected. – Should expect the rate of decrease to get worse with time according to Bob Herrick.

11. Radiation Damage p-i-n diode? No