Report on bump-bonding in AMS
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• Delivery 9/12/2002:
- 1 ladder + 2 singles
- reactive ion etching step: oxide developed on surfaces
- FE chips came off the detector
• Delivery 19/12/2002:
- 1 ladder based on non-working components
- increased temperature on sensor substrate
(from 90 to 100 °C)
- increased force applied (from 2500 to 3500 gr)
well attached after few minutes, still OK after 2 days,
but very weakly attached after 2 weeks
V. Manzari, SPD meeting - 4 Feb 2003
FE chip before flip-chip
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From one of the first deliveries
V. Manzari, SPD meeting - 4 Feb 2003
FE chip from delivery 19/12/02
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V. Manzari, SPD meeting - 4 Feb 2003
Sensor from delivery 19/12/02
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V. Manzari, SPD meeting - 4 Feb 2003
EDX measurements: delivery 19/12/02
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FE chip
Detector
V. Manzari, SPD meeting - 4 Feb 2003
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EDX measurements: from one of the first deliveries
FE chip
V. Manzari, SPD meeting - 4 Feb 2003
Sensor and FE from delivery 19/12/02
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Pix 0,0
Chip 5
Pix 32, 255
V. Manzari, SPD meeting - 4 Feb 2003
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Pix 0,0
Pix 0,up
Chip 5
Pix 0,center
Pix 0,255
V. Manzari, SPD meeting - 4 Feb 2003
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Pix 0,0
Pix 0,0
Pix 0,0
Chip 1 Chip 2
Chip 3
Chip 4
Pix 0,0
Chip 5
V. Manzari, SPD meeting - 4 Feb 2003
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 Why there is poor connection between detector and
electronics substrates?
 Some comments:
• bump shape has recently been improved
• bumps almost pure Indium (no evidence of important O and/or N and/or C
contamination)
• Thickness of the polyimide layer ( 3.5 mm)
• non uniformity of the bump height (8” deposition chain still not operational).
• Misalignment of bumps w.r.t. under-bump pads and between detector and
FE chip
• ……….
• Why ATLAS is not affected (2800 pixels/chip, cell size 50mm x 400mm)?
V. Manzari, SPD meeting - 4 Feb 2003
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What next?
• Complete SEM and optical microscope investigations of
different assemblies (next session at SEM on 6/02):
• ALICE
• Omega3
• ATLAS (?)
• Meeting with AMS next week:
What can be done to test and tune the flip-chip procedure.
V. Manzari, SPD meeting - 4 Feb 2003