LHCb VELO Hybrid

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LHCb VELO Hybrid

• T. BowcockUniversity of Liverpool

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LHCb Vertex Locator
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Silicon Module

• Components
• Sensors
• Substrate
• Hybrid
• Cooling
• Paddle
• Base
• Cables
• Module-0 04

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Silicon Modules

• 50 modules
• Approximately 500,000 bonds
• Operation at 5C
• Thermal issues over assembly at 21C
• Vacuum
• Movement several times a day
• But very small magnetic field

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Silicon Module

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

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Substrate

• CF encapsulated TPG
• Thermal conductivity
• Mass
• Big relative CTE to kapton

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Module Assembly

• All glued
• Combination of film and robot dispensed glue
• Test of procedures for vacuum operation
• Removing air VERY important
• How do we stop glue oozing out through holes
  (kapton), edges?

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Prototype

• 2002 prototype
• Bonded with SCT-VELO chips
• Single Sided(!)
• KS 8090 pattern recognition
• Sensors
• 150-300microns
• Kapton and Fanouts at CERN

Glass Fanouts
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Prototype

• Problems
• 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

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2003 Prototype

• Beetle 1.2/1.3
• Substrate
• Lamination
• Bounce
• Jig
• Flatness
• Double Sided
• Kapton fanouts

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Beetle 1.2 5100 ? 6100?m chip is very small
4 row bonding

• Row to row centres are 150 um. Pitchwithin a
  row is
• 160um so the effective pitch for the four row
  bonding is 40um

Pads 120 ? 95?m SMALL
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Pads at angle to Fanout? Sensor Pads under
design and review Straight Line? Circle?
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Proposed Fanouts

• The fanouts have two metal layers
• pitch 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 layer
• The copper is coated with nickel and flash gold.

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Liverpool Semiconductor Centre

• KS 8090
• HK 710(2)
• Wirepull
• Dage
• Class 100
• 100m2

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Bonding

• Lengths up to 3mm
• Fanout to Sensor TO BE IMPROVED
• 17micron Al wire
• Height Difference 0.5mm
• Smallest Pitch dominated by Beetle
• Multi-loop height
• Wire pull tests
• Strengths gt6g

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Problems Expected

• Fabrication 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

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Problems

• We cannot afford to test at the same level as
  ATLAS/CMS
• cycling, radiation damage etc
• Procedures have to be right
• 20 modules 50 of the production!
• Need to learn from ATLAS,CMS,