p. béné, f. cadoux, a. clark, d. ferrère , c. husi , m. weber university of geneva
DESCRIPTION
IBL Stave Loading Status. IBL General Week - 11, 12 February 2010. P. Béné, F. Cadoux, A. Clark, D. Ferrère , C. Husi , M. Weber University of Geneva. Summary of the activities at UniGe : Stavelet program for thermal interface investigation - PowerPoint PPT PresentationTRANSCRIPT
P. Béné, F. Cadoux, A. Clark, D. Ferrère, C. Husi, M. Weber University of Geneva
IBL General Week - 11, 12 February 2010
IBL Stave Loading Status
Summary of the activities at UniGe:- Stavelet program for thermal interface investigation- Electrical insulation of module versus stave
Stavelet – Loading with glue/grease test program
Purpose of the tests – glue versus grease:• Selection of candidates according to past experiences, thermal performances, viscosity, …• Evaluation of weight versus area• Optimization of the glue/grease dispensing technique (no glue overlap between the 2 chips)• Thickness uniformity and placement accuracy – XYZ metrology • Robustness to thermal cycling – XYZ metrology • Rework ability?
Removal and evaluation of time and risk for this operation Inspection of neighboring module edges Inspection of remaining surface loading again
• Does the use of Parylene® coating make a change?• Practical use
Independent tests to the stavelet program:• Radiation hardness of the glue and grease samples – Thermal performances, consistency…• Glue and grease mechanical and thermal characterizations• Others…
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Gluing and grease test program on C-foams stavelets
~20 mm
~150 mm
Glass pieces loaded with glue and or grease and various patterns
Glass references:- Glued on the 2 sides- Height > glass thickness- Hole for XY metrology- Top surface for Z plane
NB: Assembly of the 3 washers as much as possible in the same plane
Glued holding bar Glued holding bar
Procurements:- Glass pieces (20x40 mm2)1 or 2 mm thick to be cut by a diamond tip CERN stroe + cutting UniGe- C-foams to be coated with parylen. 1 or the 2 sides? Samples to be cut at UniGe + Comelec (coating) – C-foam in 0.25 g/cm3, 0.5g/cm3 et 0.9g/cm3
- Holding bars made of aluminum or plastic to be butt joined to the C-foam UniGe- Mechanical washers to be made & glued UniGe- Glue and grease candidates To be discussed with Marseille and IBL stave WG- Jigs to handle and load the glass pieces on this stavelet To be made by UniGe with the corresponding threads for the holding bars and placement accuracy- Tungsten wires for the rework with glue
3
Assembly jig allowing to glue the aluminum ends, but also the dummy glass modules
Features to reference the dummy glass modules
Area to glue gleass fiducial marks
Stavelet Jig Designs
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Stavelet Jigs
Stavelet assembly jig
Stavelet jigs for metrology, thermal cycling, storage
Features for dummy module assembly references
5
Glass Pieces Under fabrication
40
20
10
10
Dum
my
Glas
s Mod
ules
with
Fid
ucia
l Mar
ks
Glass pieces for Jig References
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Carbon Foam Electrical Insulation using Parylene® Coating – Investigation for IBL Stave
Concerns:- Carbon foams are electrical conductive materials- IBL module require an electrical insulation for the FEI4 backplane but as well as for the detector HV- Depending of the detector technology the potential at a distance of 300µm from the foam can be as high as 1000V.- Bare foams can easily release carbon dust that could cumulate and be oriented into the electric field and therefore reduce the insulating distance
Proposal is to use of a thin coating like Parylene® allowing:- To prevent electrical problems and limiting the thermal resistance- To contain and avoid releasing carbon dusts
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Pictures of the Foams under a MicroscopeCarbon Foam 0.25g/cm3 – No Parylene POCOFoam 0.55g/cm3 – No Parylene
POCOFoam 0.55g/cm3 – 5 µm Parylene POCOFoam 0.55g/cm3 – 20 µm Parylene
NB: No coating was made for carbon foam 0.25 (No sample available)
Mag
nific
ation
x10
0
500 µm 500 µm
500 µm 500 µm
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Set-up – 1st Testing Step
- Cupper foils were directly in contact with the foam samples- 3 samples tested for the resistivity (non coated, 5µm and 20µm)- 2 samples tested for HV insulation (5µm and 20µm)
HV
HV GND
Foam sample
insulator
insulator
Clamp
Clamp
Tested samples: POCOFoam ®Test setup: Coated foam samples clamped between 2 cupper foils and connected to the 2 HV polaritiesPressure to the coated surface: Unknown but not null
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Parylene® Coating Insulation to contact Breakdown Voltages [V]
No No 0
5 µm Yes 550 (over 10 microns)
20 µm Yes 1100 (over 40 microns)
Comments: The coated (5-20 microns) foams does not release any visible carbon dust.
Set-up pictures and Results
10
Pictures after Electrical Breakdown
NB: Breakdown possibly occurred where the clamps were applying the highest pressure
11
Second Testing Step with Shims
Electrical insulation in a new test conditions:- With 400µm gap between the cupper and the foam- Various samples: non-coated, 5µm and 20µm
HV
HV GND
Foam sample Insulating shims (~400µm)
Plastic stiffener
Plastic stiffener
Clamp
Clamp
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Set-up Pictures and Results with Shims
Parylene® Coating Breakdown Voltages [V] Equivalent insulation for 300µm air + coating
No 1100(over 800µm air)
400 V
5 µm 2400 (over 10 µm + 800 microns air)
1050 V
20 µm 3300V(over 40 µm + 800 microns air)
1500 V
NB: - Safety factor should be applied to the limit to get guaranty on long term QA- Considering a safety factor , the current design is acceptable with 10-20 µm Parylene®
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Pictures – Copper after Electrical Breakdown
5 µm Parylene 20 µm Parylene
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Si-detector backplane
Edge chipping and Si-debris often seen pointing in all directions
Additional Comment
Observed during SCT production and QA
Stave coating is clearly an advantage in such a case even for backplane/edge voltage like 100V
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Summary
• Stavelet Program - Goal is to test various thermal interfaces to evaluate the practicality for loading, the thermal stability, the weight, the rework-ability - Thermal evaluation of a selected grease interface will be done with dedicated thermal set-up- Time scale: ~3 months
• Module to stave electrical insulation- Parylene® coating have been made on POCOFoam samples: 5, 10 and 20 microns- Coating almost invisible under the microscope- No carbon dust release when touching the samples with the fingers- In IBL condition with ~300µm gap from the sensor edge to the stave it will be risky to operate it without an insulating coating. - The preliminary recommendations from this test is to coat the stave with 10 to 20µm Parylene®.- Remaining question: Is this 10 to 20µm enough when considering the aging, and the radiations
• Stave loading concept- Close connection between CPPM and UniGe- Common concept with a cradle and a manipulator- Progress to be made with a nominal stave design
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