Packaging opto components: how much can we do ourselves? • Historical summary from ATLAS & CMS trackers • New developments for ATLAS tracker off-detector optoelectronics • Discussion Tony Weidberg Opto WG TWEPP 2012 1
Feb 22, 2016
Opto WG TWEPP 2012 1
Packaging opto components: how much can we do ourselves?
• Historical summary from ATLAS & CMS trackers
• New developments for ATLAS tracker off-detector optoelectronics
• Discussion
Tony Weidberg
Opto WG TWEPP 2012 2
On-detector Optoelectronics
• Constraints are:– Radiation tolerance– No magnetic material– Small– Low power– Low radiation length contribution low Z materials.– Last but not least: Extremely good reliability
• Not obvious that all these requirements will be met by commercial components, e.g. non-magnetic.
Tony Weidberg
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ATLAS SCT
• SCT: custom package designed by AS Taiwan.– Old and slow (obsolete) p
implant VCSEL– Wire bonding to the VCSEL– 45 degree angle polished
fibre above VCSEL, eliminates need for epoxy on VCSEL surface.
– Same technique for Si p-i-n diode (slow).
Tony Weidberg
ATLAS Tracker Upgrade Liverpool December '06
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CMS Tracker• CMS Analogue Opto Hybrid (AOH)• 3 channels laser drivers, lasers and fibres• Minor tweak of commercial OSA
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CMS Laser Sub-Mount• Compact: 4.5 * 4 * 1.3 mm3
• Fibre ends gold plated• Active alignment: resistor pads used to solder fibre in
location. Glue only for strain relief of fibre• Radiation hard by design
Removed for CMS (save $)
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Off-detector optoelectronics
• No constraints on radiation hardness, non-magnetic material, radiation length.
• Space constraints in crates favour arrays over single channel devices.
Tony Weidberg
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ATLAS SCT/Pixel arrays
• Same package for SCT & Pixel off-detector BOC.
• Same package also used for ATLAS pixel on-detector.
Tony Weidberg
ATLAS Tracker Upgrade Liverpool December '06
8Tony Weidberg
12 way array with MT guide pins for coupling to 12 way ribbon fibre
Epoxy over surface of VCSEL CTE mismatch problem with thermal cycling?
Used for Pixel on-detector and SCT/Pixel off-detector BOC
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CMS Analog Receiever• 12 channel receiver: minimal mods to
commercial components:– Same 12 channel PD array– Replace the receiver ASIC
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Ceramic package (can be hermetically sealed).
PD array and ASIC
MPO adaptor
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CMS Transceiver• 4 channel transceiver for control links• COTs
Tony Weidberg
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Reliability History (1)• CMS: excellent, no reported laser/pin diode deaths during
operation.• ATLAS on-detector
– ~ 1.3% non-functional data links, mostly but not all due to VCSEL failures.
– “delayed infant mortalities”. VCSEL channels died during commissioning and early operation
– death rate appears to have decreased, 5 deaths during 2011 run (5 fb-1) and 2 deaths so far in 2012 run (15 fb-1) Operational time scales with integrated luminosity because of NRZ data.
– Long term “harness test”. 41 channels operated for 271 days (longer on-time than 10 year LHC) showed no failures don’t expect catastrophic end of life failures. No change in OSA.
Tony Weidberg
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Reliability History (2)• ATLAS off-detector arrays.
– Very short lifetime observed. ESD problems identified and fixed.
– Small improvement in lifetime observed. VCSEL sensitivity to humidity identified. This could explain why no confirmed VCSEL deaths seen in pixel on-detector which uses same VCSELs and packaging.
– However long term tests in SR1 not consistent with death rate in ATLAS, so humidity is not the only factor.
– TL VCSEL replaced with AOC which is known to be humidity resistant. SCT has 13 channel failures, • 5 “infant mortality”, 8 “random”, in ~ 1 year operation.
Tony Weidberg
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New Developments for ATLAS
• Trying to develop a reliable backup solution for ATLAS that is backward compatible, ie new TX PCB that satisfy:– Fit in space on BOC– Same electrical connector– Optical MT connector, compatible with Infineon
SMC.
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iFlame
• Concept was to make minor tweak of commercial component (4 channel TRx)
• Design for integration in ATLAS very successful and demonstrated with 4 TRx next slide.
• Many problems– Difficulty producing devices with new wafer fab.– No useful reliability data– Devices never used in any applications – First 12x devices only recently available and not yet
meeting ATLAS specs
Tony Weidberg
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VCSEL in iFlame package
heat sink BPM-12 in BGA
MT guide pins
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iFlame 12X• Finally light from the
iFlame 12x integrated into an ATLAS TX
• Reasonable quality optical signal– Some x-talk visible but
probably acceptable– Optical power still low but
should be improved with better alignment of the lens/mirror array.
• Will it be reliable?
Tony Weidberg
0.00E+00 1.00E+01 2.00E+01 3.00E+01 4.00E+01 5.00E+01 6.00E+01 7.00E+01-2.00E-05
0.00E+00
2.00E-05
4.00E-05
6.00E-05
8.00E-05
1.00E-04
1.20E-04
1.40E-04
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LightABLE engine
• LightABLE engine is a commercial (Reflex Photonics) part.
• Small enough to fit.• We want to reuse new TX PCBs designed for
iFlames BPM-12 o/p LVDS driver Optical engine.
• Proof of principle tested and space model showed it can fit.
Tony Weidberg
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LightABLE ATLAS TX
• Integration into ATLAS BOC possible because:
• Small form factor compatible with space constraints in ATLAS BOC
• MT-12 connector• Contains laser driver ASIC• BPM-12 LVDS driver
LightABLE engineTony Weidberg
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LightABLE TX
Tony Weidberg
LightABLE engine
BPM-12
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Discussion
• Many reliability problems with custom packaging. – Even if we could produce a reliable package we couldn’t
afford sufficient testing to prove it (need ~ 1000 devices * >1000 hours operation).
• On-detector minimal changes to commercial components.
• Off-detector Stick to purely commercial components.
• Calorimeter optoelectronics: listen to Annie’s talk before discussion …
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Backup Slides
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LightABLE Dimensions
Tony Weidberg