m. gilchriese local support r&d update atlas pixel upgrade meeting april 9, 2008 m. cepeda, s....

M. Gilchriese

Local Support R&D UpdateATLAS Pixel Upgrade Meeting

April 9, 2008M. Cepeda, S. Dardin, M. Garcia-Sciveres, M. Gilchriese and R. Post

LBNLW. Miller and W. Miller

iTiC. Daly, B. Kuykendall, H. Lubatti

University of Washington

M. Gilchriese2

Module Dimensions for Studies

• Have defined multi-chip and single-chip dimensions(two alternatives) as basis for studies.

• Assumption is that multi-chip used for outer layers and single-chip used for innermost layer(s). Exact break in radius is TBD.

• See backup for more information• Also basis for understanding possible cost reductions in bump deposition

and flip-chip (not discussed here)

34.8

34.8

37.5

Active 32.8 x 32.8

10.0

15.0Flex pigtail (connector plugs into page)

Pixel orientation

Flex down to chip w-bonds

0.2

(vertical inter-chip gap 0.1mm)

Optimize module size assuming6” planar sensor wafers

M. Gilchriese3

Outer Stave Concept• Staves for outer barrel layers for multi-chip modules.

• Based on foam, thin carbon-fiber facings AND flex-cable laminated to stave under modules (bus-cable)

• Bus-cable routes power, signals, HV to end-of-stave cards. Studies started to see if this works electrically.

• Bus-cable worst case thermally

• If bus-cable concept bad…revert to “Type I cables”

• Modules on both sides (staggered for coverage)

• Connector from module to connector on bus-cable

• Dimensions shown for CO2(thicker for C3F8)

CARBON FOAM

M. Gilchriese4

Outer Layer Layout Example

M. Gilchriese5

Double-Outer Layer Concept

• Support two outer layers of staves from single shell?

• Doesn’t look impossible

• Obviously lots of details……

Composite shell and inner support rings combine assembly into one unit

M. Gilchriese6

Sensors Heating• From Dawson et al. (radiation task force) and temperature

parameterization of Unno

• Figure is for 6000 fb-1

• Table except 1016 assumes 6000 fb-1. Short strips are at about 30 cm

• W/cm2 shown in table

TShort-StripPower

Pixel@16 cm

Pixel@21 cm

Pixel@1e16

-35 0.001628 0.003039 0.002195 0.016886-30 0.003145 0.005871 0.00424 0.032619-25 0.005922 0.011054 0.007983 0.06141-20 0.010882 0.020312 0.01467 0.112847-15 0.019545 0.036484 0.02635 0.202691-10 0.034358 0.064136 0.04632 0.35631-5 0.059183 0.110474 0.079787 0.6137450 0.1 0.186667 0.134815 1.0370375 0.16592 0.309717 0.223684 1.720649

10 0.270584 0.50509 0.364787 2.806054

M. Gilchriese7

FEA Thermal ModelFEA Thermal Model• Pixel Arrangement

– Modules alternate top to bottom, total 5 modules

– Take an array of 3 on top to obtain reasonable symmetry in heat spreading for middle module, leaving two on the bottom

VG VG 77

Inputs for thermal runaway calculations

0

20

40

60

80

100

120

-35 -25 -15 -5 5 15 25 35

Sensor peak surface temperature -(C)

Hea

ting

mW

/mm

2

Surface heating16cm radius

Surface heatingfrom 1E16 fluence

M. Gilchriese8

Pixel Thermal Model-BaselinePixel Thermal Model-Baseline

• Thermal Solution– Carbon foam core K=6W/mK

• Peak Differential Temperature Center Module– 7.63ºC

VG VG 88

Cooling Tube Inner Wall Reference Temperature 0ºC

M. Gilchriese9

Thermal Performance - I• Include detector heating (worst case shown is for total fluence of about 1016.

Best case shown is for R ~ 16 cm(and 6000 fb-1).

• “Baseline” parameters assumed in thermal model – see backup

• Looks promising for outer layers. Need higher K’s for 1016 (see next page) unless assume colder fluid(<-30) than current C3F8

Remember needto include effectof T frompressure drops

-30

-25

-20

-15

-10

-5

0

5

10

15

20

25

30

-40 -35 -30 -25 -20 -15 -10 -5 0

Coolant Tube Inner Wall Temperature-(C)

Pe

ak

Se

ns

or

Te

mp

era

ture

-(C

)

no surface heating1.87mW/mm2 @ 0 C10.67mW/mm2 @ 0 C

M. Gilchriese10

Thermal Performance - II• Results below all for 1016 fluence and changes in stave-component K

values.

• Need to optimize for 1016. Different designs for inner(most) and outer layers

• Unless CO2. Note CO2 also significantly lower in radiation length

Higher K foamCarbon-carbon facingsCVD diamond facingsNo bus cableCombinations…..

Note that these studies alsoapply to 2cm wide stavewith single pipe that is more likely at innermost R -35

-30

-25

-20

-15

-10

-5

0

5

10

-35 -30 -25 -20 -15 -10 -5 0


Pe

ak

Se

ns

or

Te

mp

era

ture

-(C

)

baseline foam 6 W/mK

foam=15W/mK

foam=15W/mK, CC=250/25/250

foam=15W/mK, Cable=200W/mK

M. Gilchriese11

Pixel Monolithic StructurePixel Monolithic Structure

VG VG 1111

Alternating: Inner and Outer Layer

Older module dimensions used for this study

M. Gilchriese12

Thermal FEA-Based on 0.6W/cmThermal FEA-Based on 0.6W/cm22

VG VG 1212

Differential from silicon to coolant wall is 10.6˚C. Need improvement to prevent thermal runaway with C3F8….to be studied

Foam K=10 W/mK

M. Gilchriese13

Thermally Conducting Foam Update• Obtained additional foam samples – three vendors

• Made additional small thermal prototypes and measured (see backup for details). Preliminary results.

Foam (g/cc) K(W/m-K) Tmax

Allcomp 1 0.18 ~ 6We measured

~ 10

Allcomp 2 0.21 Not known ~ 9

POCO 0.09 ~ 17(z)

~ 6(x-y)Vendor supplied

~ 11

Koppers* 0.21 ~ 30(z?)Vendor supplied

~ 8

Averagemax at 0.64W/cm2 on one side

* Have 2 other higher density and K samples from Koppers

Old prototype, shown last meeting

New

res

ults

, ne

w s

amp

les

M. Gilchriese14

Foam Mechanical Properties

• Important to measure mechanical properties of foam

• Being done at University of Washington• Allcomp 1 results – see presentation at meeting link at

http://phyweb.lbl.gov/atlaswiki/index.php?title=ATLAS_Upgrade_RandD_-_Mechanical_Studies#Pixel_Upgrade_Support.2FCooling_Structure_Studies

M. Gilchriese15

Outlook

• Optimize thermal performance, radiation length, mechanical properties combining foam(s), facing materials and support. Likely to result in different inner and outer staves. Monolithic still option for innermost layer.

• Biggest impact on radiation length is choice of coolant…

• Starting on disks. Layout not as easy as barrel…..particularly in case of two-part system, one inside support tube

• Overall layout issues and electrical interfaces that drive layout – started some work on this (with UCSC, SLAC, OSU, SMU..)

• Thermally conducting, carbon foam continues to look promising. Multiple vendors interested (are there more?). Need to optimize and get more samples of what we want. Vendors willing to develop lower density.

M. Gilchriese

Backup

M. Gilchriese

2x2 module & stave layouts

M. Garcia-Sciveres

M. Gilchriese18

2 options• “Small chip”• “Big chip”• Boundary between “small” and “big” is determined by the 6” sensor wafer layout

that must be compatible with bump bonding (will become clear later)• “Small” chip has also a more natural number of rows & columns, but this is

probably a minor issue for chip design.

M. Gilchriese19

Parameters

# cols total # rows total # ganged rows

# long cols Long col width

Small chip 64 324 0 0 0

Small 2x2 tile 128 654 6 4 450um

Small active edge

1x1 tile

64 324 0 2 450um

big chip 70 348 0 0 0

big 2x2 tile 140 702 6 4 450um

big active edge

1x1 tile

70 348 0 2 450um

Normal col. width x row height = 250um x 50um

M. Gilchriese20

“Small” 4-chip module

34.8

34.8

37.5

Active 32.8 x 32.8

10.0


Pixel orientation


0.2


M. Gilchriese21

“Big” 4-chip module

37.1

37.8

39.9

Active 35.8 x 35.1

10.0


Pixel orientation


0.2


M. Gilchriese22

Loaded module

20 position connector would be used. Replace 10.22 dimension by 6.52

glue

chips

sensorflex

conn

ecto

rReduced scale

1.0

mm

stiffener

M. Gilchriese23

“Small” module outer stave

…

End of stave card serving 8 modules (half a stave) along ZCan serve one face only (top or bottom) => 4 cards per staveOr can be a wrap-around end of stave card and serve both faces => 2 cards per stave.This way identical staves (including bus cable) design can be used over a wide radial range: 4 cards/stave at lower radius and 2 wrap-around cards per stave at higher radius

34.8 26.8

Module on back

986mm

38.4

M. Gilchriese24

“Big” module outer stave

…

End of stave card serving 7 modules (half a stave) along Z (or 8 modules for 1082mm active length)

Can serve one face only (top or bottom) => 4 cards per staveOr can be a wrap-around end of stave card and serve both faces => 2 cards per stave.This way identical staves (including bus cable) design can be used over a wide radial range: 4 cards/stave at lower radius and 2 wrap-around cards per stave at higher radius

37.8 29.8

Module on back

946mm

39.9

M. Gilchriese25

“Small” sensor 6 inch wafer

• Active area = 7508 mm^2

• Sensor tiles shown with darker line

• Wafer scale flip chip compatible. Chips shown with lighter line.

• The name “small” 2x2 tile comes from the wafer layout.

– A slightly larger chip and therefore larger 2x2 tile is possible, but only 6 such “large” 2x2 tiles will fit on a 6” wafer.

M. Gilchriese26

“Big” sensor 6 inch wafer

• Active area = 7539 mm^2• Sensor tiles shown with darker line

• Wafer scale flip chip compatible. Chips shown

with lighter line.

• OPTION to make 4 6-chip modules per wafer instead of 6 4-chip modules.

M. Gilchriese27

“Small” single chip module

• Using same chip as 4-chip module (hence “small”)• Active edge sensor• 2-side abuttable format

16.4

16.2

16.218.7

active

M. Gilchriese28

“Big” single chip module

• Using same chip as 4-chip module (hence “small”)• Active edge sensor• 2-side abuttable format

17.9

17.7

17.419.9

active

M. Gilchriese

Stave Concepts and FEA

W. Miller and W. Miller

M. Gilchriese30 VG VG 3030

Pixel ActivitiesPixel Activities• Analysis Analysis

– Analyze foam structure for inner Pixel Layer steady state chip heating Analyze foam structure for inner Pixel Layer steady state chip heating and thermal runawayand thermal runaway

• Thermal runaway evaluation covers different foam and facing thermal Thermal runaway evaluation covers different foam and facing thermal conductivitiesconductivities

• Design LayoutDesign Layout– Preliminary stages of evaluating packaging for layers at 16cm and Preliminary stages of evaluating packaging for layers at 16cm and

21cm radius21cm radius

• TestingTesting– Thermal solutions to compare with LBNL stave/carbon foam core Thermal solutions to compare with LBNL stave/carbon foam core

thermal teststhermal tests• Evaluation embraces several foam core thermal conductivities Evaluation embraces several foam core thermal conductivities

M. Gilchriese31

Pixel Stave Structure

• Stave Analysis- 1 meter length– In the near future an effort will be underway to assess structural aspects

of stave concept for pixels• For now focusing on thermal effects

– Pixel sensor is 34.85 mm by 34.85 mm

– Pixel chip footprint, 4 total, is 38.4 mm by 38.4mm

– Assumed pixel heat load is 0.6W/cm2

– Small diameter cooling tube (presumes CO2)

• Steps in process– 1st Order thermal analysis of sandwich structure (conductive carbon

foam core)

– Several solutions made for thermal runaway• Looks workable without CVD diamond sandwich facings

– This model is still being evaluated

M. Gilchriese32

Basic Model Parameters-Baseline• Core

– Carbon foam, 6 W/mK

• Facing– Resin Composite, 0.14mm thick, 110, 1, 110 (X,Y,Z) W/mK

• Cable– Includes adhesive for bonding to chips and from cable to composite facing

– 2mils Al and 0.7mils of copper, plus adhesives, total compressed thickness=114microns

– Calculated: Kt=0.38W/mK and K (in-plane)=83W/mK 34.85

34.85

38.4

Sensor Chip heat 0.6W/cm2

M. Gilchriese33

FEA Thermal ModelFEA Thermal Model• Pixel Arrangement

– Modules alternate top to bottom, total 5 modules

– Take an array of 3 on top to obtain reasonable symmetry in heat spreading for middle module, leaving two on the bottom

VG VG 3333

Inputs for thermal runaway calculations

0

20

40

60

80

100

120

-35 -25 -15 -5 5 15 25 35

Sensor peak surface temperature -(C)

Hea

ting

mW

/mm

2

Surface heating16cm radius

Surface heatingfrom 1E16 fluence

M. Gilchriese34

Pixel Thermal Model-BaselinePixel Thermal Model-Baseline



VG VG 3434

Cooling Tube Inner Wall Reference Temperature 0ºC

M. Gilchriese35

Pixel Thermal ModelPixel Thermal Model



VG VG 3535

Very High Foam Conductivity alters peak differential by 3.58ºC

M. Gilchriese36

Thermal Runaway-Baseline

1*1016 fluence makes -25ºC impractical without design changes to sandwich material maheup

-30

-25

-20

-15

-10

-5

0

5

10

15

20

25

30

-40 -35 -30 -25 -20 -15 -10 -5 0


Pe

ak

Se

ns

or

Te

mp

era

ture

-(C

)

no surface heating1.87mW/mm2 @ 0 C10.67mW/mm2 @ 0 C

M. Gilchriese37

Thermal Runaway with Possible Mod’s

• Results show increasing conductivity of foam and facing thermal conductivity improve situation noticeably

• Thermal solution with CVD diamond facing still under evaluation, all indications is that it may be overkill

Fluence of 1*1016

-35

-30

-25

-20

-15

-10

-5

0

5

10

-35 -30 -25 -20 -15 -10 -5 0


Pe

ak

Se

ns

or

Te

mp

era

ture

-(C

)

baseline foam 6 W/mK

foam=15W/mK

foam=15W/mK, CC=250/25/250

foam=15W/mK, Cable=200W/mK

M. Gilchriese38

Design Layouts-In Process

• Beginnings of 210mm and 160mm layers

Composite shell and inner support rings combine assembly into one unit

M. Gilchriese39

Design Layouts-In Process

• Space between adjacent staves is very tight, suggesting that the stave support from the rings may best engage area between module dead-spaces

M. Gilchriese40

Design Layouts-In Process• First option for 1m length is three support rings, one in middle which

will provide the Z-restraint and the two at the ends reacting out gravitational effects, but allowing slip in Z

Ring locations

M. Gilchriese41

Carbon Foam Thermal TestsCarbon Foam Thermal Tests

• Following slides provide background on carbon foam thermal Following slides provide background on carbon foam thermal conductivityconductivity

VG VG 4141


FEA ModelFEA Model

• Primary ObjectivePrimary Objective– Compare FEA results with LBNL thermal tests of foam core structuresCompare FEA results with LBNL thermal tests of foam core structures

• Difficulty lies in assigning material propertiesDifficulty lies in assigning material properties– There are four solids, with three thermal interfaces on each side of the mid-planeThere are four solids, with three thermal interfaces on each side of the mid-plane

• Thermal interface thermal resistance becomes an assumption, as well as the thicknessThermal interface thermal resistance becomes an assumption, as well as the thickness

– Water coolantWater coolant• Flow results in turbulent flow and very high convection coefficient, less problematic Flow results in turbulent flow and very high convection coefficient, less problematic

than thermal interface resistancethan thermal interface resistance• Expect small variations in coolant temperature from test to testExpect small variations in coolant temperature from test to test


Solution With FEA ModelSolution With FEA Model• Material PropertiesMaterial Properties

– Heater heat loads, 8.38WHeater heat loads, 8.38W

– Silicon heater, 148 W/mK, 0.28mm thickSilicon heater, 148 W/mK, 0.28mm thick

– Silicon heater adhesive, SE4445, 0.6 W/mK, 0.004in thick, two placesSilicon heater adhesive, SE4445, 0.6 W/mK, 0.004in thick, two places

– YSH70 open cloth fabric, one layer, 0.6 W/mK, 0.14mmYSH70 open cloth fabric, one layer, 0.6 W/mK, 0.14mm

– YSH70 adhesive, 1.55 W/mK, 0.002inYSH70 adhesive, 1.55 W/mK, 0.002in

– Foam properties varied, from 6 to 30 W/mKFoam properties varied, from 6 to 30 W/mK

– Al cooling tube, 180 W/mK, 2.8mm OD and 2.19mm IDAl cooling tube, 180 W/mK, 2.8mm OD and 2.19mm ID

– Water, convective film coefficient, 66,000 W/mWater, convective film coefficient, 66,000 W/m22K, 1.0L/minK, 1.0L/min• Set 20.25ºC on inner tube wallSet 20.25ºC on inner tube wall

– K13D2U facing, 1 W/mK, 0.28mm thickK13D2U facing, 1 W/mK, 0.28mm thick

– K13D2U adhesive, 1.55 W/mK, 0.002in thick K13D2U adhesive, 1.55 W/mK, 0.002in thick


Pixel Prototype ComponentsPixel Prototype Components

Tube with CGL7018

YSH-70 and K13D2U glued to foam

Tube in foam with CGL7018


LBNL Thermal Test Set-UpLBNL Thermal Test Set-Up

Silicon heater

M. Gilchriese46

Thermal Solutions for Single Tube Tests

Double heater Single heater

M. Gilchriese

Prototype Details

M. Gilchriese48

Old Results

0

2

4

6

8

10

12

14

16

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70

P/A(W/cm^2)

De

lta

T a

ve

rag

e

YSH-70 only

K13D2U only

YSH-70 sideHeat both

K13D2U sideHeat both

Note if CO2 used as coolantthen reference temperature could be about -30C. Thusdelta T of 10 => T of -20C.

FE

-I4

goal

FE

-I3

norm

al

Max

. sp

ecIncludes sensors & power conv. But not cables.

M. Gilchriese49

Old Results Table

• All relative to 20C water temperature, would be slightly lower if referenced to power off temperature.

P/A(W/cm2) YSH-70 only K13D2U only

YSH-70 sideHeat both

K13D2U sideHeat both

0.64 11.20.44 7.40.28 50.64 11.050.44 7.450.28 5.250.64 14.4 14.450.44 9.9 10.150.28 6.35 6.52

M. Gilchriese50

New Prototypes• Identical width, thickness and adhesives to older prototype

(Allcomp 1) but shorter in length (7.4 cm).

• YSH-70 facings on both sides.

• Heater only on one side. Compare at 0.64 W/cm2

• IR and water flow same as older prototoype(1.0 l/min)

M. Gilchriese51

IR Results• Example IR photo(Koppers)• Average T in boxes used• Small difference between power off T

and water T

Two different values for Allcomp 2 in table below. One(29 twice) I ignore apparent hot spot on heater. Other entry I don’t.Sample T Av Water T1(0 pwr) T2(0 pwr) T1(0.64) T2(0.64) DT(to water) DT(to 0 pwr)Allcomp 1 20.1 20.85 20.78 30.65 30.71 10.6 9.9Allcomp 2 20.05 20.41 20.44 29 29 9.0 8.6Allcomp 2 20.05 20.41 20.44 29 30.91 9.9 9.5POCO 20.15 20.84 20.83 31.48 32.66 11.9 11.2Koppers 20.2 20.63 20.6 28.92 29.2 8.9 8.4

m. gilchriese local support r&d update atlas pixel upgrade meeting april 9, 2008 m. cepeda, s....

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