LHCb VELO HybridT. BowcockUniversity of Liverpool

LHCb Vertex Locator

Silicon ModuleComponents Sensors Substrate Hybrid Cooling Paddle Base Cables

Module-0 ‘04

Silicon Modules50 modulesApproximately 500,000 bondsOperation at –5C Thermal issues over assembly at 21CVacuumMovement several times a day But very small magnetic field

Silicon ModuleDouble Sided Module Modification from TDR Two hybrids on one substrate Symmetry Mass Difficult to fabricate and bond

Substrate

CF encapsulated TPGThermal conductivityMassBig relative CTE to kapton

Module AssemblyAll gluedCombination of film and robot dispensed glueTest of procedures for vacuum operation Removing air VERY important How do we stop glue oozing out

through holes (kapton), edges?

Prototype2002 prototype Bonded with SCT-

VELO chips Single Sided(!) K&S 8090 pattern

recognitionSensors 150-300microns

Kapton and Fanouts at CERN Glass Fanouts

PrototypeProblems “Bad” design… Lineup of Fanouts and

sensor Angles of pads Two types of sensor

2 or more sets of fanouts

Sensor pads cannot be made the same

2003 PrototypeBeetle 1.2/1.3Substrate Lamination “Bounce” Jig Flatness Double SidedKapton fanouts

4 row bonding

Beetle 1.2 5100 6100m – chip is very small

Pads 120 95mSMALL

Row to row centres are 150 um. Pitchwithin a row is

160um so the effective pitch for the four row bonding is 40um

Pads at angle to Fanout?

Sensor Pads under design and review

Straight Line?Circle?

Proposed FanoutsThe fanouts have two metal layerspitch at the beetle end is the tightest with 40um tracks and gaps on each layer.the bottom layer protrudes out from under the top layer by about 400um. For four row bonding the two rows of beetle pads nearest the edge of the chip bond to the lower copper layer and the two other rows bond to the top copper layerThe copper is coated with nickel and flash gold.

Liverpool Semiconductor Centre

K&S 8090H&K 710(2)Wirepull DageClass 100 100m2

BondingLengths up to 3mm Fanout to Sensor: TO BE IMPROVED

17micron Al wireHeight Difference ~ 0.5mmSmallest Pitch dominated by BeetleMulti-loop height Wire pull tests Strengths >6g

Problems ExpectedFabrication of solid substrate/kapton that does not delaminate Flatness (helps bonding) Quality of bonding

Jig for Double Sided Bonding Non-trivial

Pattern Recognition and Programming of 8090. Bonding on arc. Problem solved. Memory + Shipping

Optimisation of Pad Layout Avoid foot being skewed relative to pads

ProblemsWe cannot afford to test at the same level as ATLAS/CMS cycling, radiation damage etcProcedures have to be right20 modules = 50% of the production!Need to learn from ATLAS,CMS,+…