BTeV Pixel Detector Pixel Module Assembly and Half-Plane Assembly

1
BTeV Pixel DetectorPixel Module
AssemblyandHalf-Plane Assembly

• Guilherme Cardoso
• James Fast
• C. M. Lei

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Pixel Module Assembly Tooling

• Take advantages of ATLAS pixel detector
  experience
• Port card (PC) to provide needed electrical
  circuitry and HDI holding by vacuum suction
• Extra long tabs of high-density interconnects
  (HDI) to provide testing and burn in
• Assembly steps summary
• Align and glue a pixel module (consisting of the
  sensor bump-bonded with read-out chips) to an
  HDI Alignment tolerance 100 microns
• Wire bond all electrical connections except that
  for high voltage (HV)
• For HV, solder a flex circuit to the HDI and bond
  the other end to the back of sensor with epoxy

FPIX Chip

HDI

Wire Bonds

Wire Bonds



Data PIFC


Power PIFC

Decoupling Capacitors and Termination Resistors
Sensor

High Voltage
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Pixel Module Assembly Steps 1 2
Step 1
Step 2
Assemble PC on a vacuum chuck Align and glue HDI
on PC Wire bond HDI to PC Test HDI for opened
traces
Align pixel module (PM) to PM vacuum holder
PM vacuum holder
PM with alignment targets at corners exposed
PC vacuum chuck
Port card (PC)
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Pixel Module Assembly Step 3
Step 3
spacers
Position HDI with its vacuum chuck on to pixel
module alignment jig Place spacers for PM vacuum
plate (The thickness of the spacers will provide
some clearance between pixel module and HDI)
pixel module alignment jig
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Pixel Module Assembly Step4
Step 4
Stationary
Engage PM vacuum holder Align HDI to PM with
the aid of CMM then vacuum hold the HDI vacuum
chuck when done
HDI with its chuck are moved freely under
stationary PM
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Pixel Module Assembly Step 5
Step 5
Remove PM vacuum holder Change spacers (The
thickness of the spacers will provide 50 micron
glue between PM and HDI) Dispense epoxy on
HDI Re-engage PM vacuum holder, and start gluing
PM to HDI
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Pixel Module Assembly Step 6
Step 6
Flex circuit for HV connections
Glue flex circuit Complete HV connections Wire
bond PM to HDI
Note The flex circuit is already soldered to the
HDI at this point
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Pixel Module Assembly Step 7
Step 7
HDI cover plate
Transfer and fasten PC to HDI storage base
plate Install HDI cover plate Conduct module
burn in and testing
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Pixel Module Assembly Step 8
Step 8
cutting slots on PC
Remove HDI top cover plate and base plate Fasten
PC on its vacuum chuck Remove HDI to HDI wire
bonds Cut HDI at designated slots of PC Pixel
module formed and ready for half-plane assembly
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Half-Plane Assembly

• Module placement accuracy of 5 microns is
  required
• Modules will be held by the HDI (wider section)
  so that fiducial targets at the sensor corners
  can be seen optically from the top
• 4-axis stages will be used for precise
  positioning of modules
• Optical targets visible on both sides of the
  substrate will be used to tie the alignment of
  modules on one side of the substrate to the
  modules on the other side
• Reliable gluing process is needed which will not
  damage the substrate or the sensors
• Even, thin joints require significant gluing
  loads
• Substrate must be supported from the back side
  with vacuum plates
• For second side, support is through first side
  sensors

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Half Plane Assembly Steps
0. Glue flex cables on substrate
1. Align and load modules on vacuum plate
2. Engage substrate into substrate holder then
place on stage
3. Apply glue on substrate
4. Align substrate to modules and allow glue to
cure
5. Flip the half populated substrate and vacuum
plate holding the silicon modules
6. Repeat steps 1 and 4 with a new set of
modules and vacuum plate. Half-populated
substrate starts at step 2.
7. Wire bond HDIs to flex cables
8. Test all modules
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The Module Placement Setup
Vacuum plate for substrate
Module is loaded individually with HDI side down
onto module vacuum holder.
Vacuum plate for modules
4-axis stages on rail
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Align and Load Modules on Vacuum Plate
Module is aligned using 4-axis adjustment of pick
and place. A common coordinate system is used to
align a full set of modules.
Leaf springs provide vertical compliance.
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Engage Substrate into Substrate Holder then on
Stage
Substrate on substrate vacuum holder
All modules loaded ready for substrate
Cart for module installation moved away and
vacuum chuck rotated out of the way.
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Align Substrate to Modules and Allow Glue to Cure
Leaf springs provide vertical compliance.
4-axis adjustment of substrate to modules
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Flip the Half Populated Substrate and Vacuum Plate
Place the substrate with first set of modules
underneath on stage. Repeat Step 2.
Second side modules aligned on another modules
vacuum plate. Repeat Step 1 for another side of
modules placement
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Finishing the Half-Plane Assembly
Align substrate to modules and allow glue to
cure. Repeat Step 4 for another side of modules
placement
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Status of Half-Plane Assembly

• Detailed fabrication drawings completed.
• Parts are being made.

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Summary

• The pixel module assembly steps have been thought
  through. This design will be completed,
  prototyped and tested with prototype sensor and
  HDI when they are available.
• The design of the half-plane assembly steps have
  been completed. Parts are being made and will be
  tested.