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

Opto WG TWEPP 2012 3

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

4Tony Weidberg

CMS Tracker• CMS Analogue Opto Hybrid (AOH)• 3 channels laser drivers, lasers and fibres• Minor tweak of commercial OSA

5

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 $)

Opto WG TWEPP 2012 6

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

Opto WG TWEPP 2012 7

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

Opto WG TWEPP 2012 9

CMS Analog Receiever• 12 channel receiver: minimal mods to

commercial components:– Same 12 channel PD array– Replace the receiver ASIC

Tony Weidberg

Ceramic package (can be hermetically sealed).

PD array and ASIC

MPO adaptor

Opto WG TWEPP 2012 10

CMS Transceiver• 4 channel transceiver for control links• COTs

Tony Weidberg

Opto WG TWEPP 2012 11

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

Opto WG TWEPP 2012 12

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

Opto WG TWEPP 2012 13

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.

Tony Weidberg

Opto WG TWEPP 2012 14

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

15

VCSEL in iFlame package

heat sink BPM-12 in BGA

MT guide pins

Opto WG TWEPP 2012 16

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

Opto WG TWEPP 2012 17

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

Opto WG TWEPP 2012 18

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

Opto WG TWEPP 2012 19

LightABLE TX

Tony Weidberg

LightABLE engine

BPM-12

Opto WG TWEPP 2012 20

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 …

Tony Weidberg

Opto WG TWEPP 2012 21

Backup Slides

Tony Weidberg

Opto WG TWEPP 2012 22

LightABLE Dimensions

Tony Weidberg