phenix fvtx status of mechanical and thermal design work eric ponslet, shahriar setoodeh, roger...

PHENIX FVTX

Status of Mechanical and Thermal Design Work

Eric Ponslet, Shahriar Setoodeh, Roger SmithHYTEC Inc.

FVTX Collaboration MeetingAlbuquerque, NMMarch 12, 2007

HPS-111006-0010 – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 2

Latest Baseline Design• Still Evolving…

• Modular Design– Detector module (“wedge”) Half disk Half Cage (“clamshell”) FVTX

• Wedge is Built on a Graphite Fiber/Cyanate Ester Thermal Backplane– Serves as structural support and heat transfer path to edge cooling– 0.76mm thick K13CU/CyE

• Very high stiffness and thermal conductivity fiber• Symmetric, balanced layup (won’t warp from temperature changes)

• Wedges are Fastened to Support Panel– Two alignment pins (ceramic?) and 3 screws (nylon) per wedge– Thick RT-cured silicone bridge provides thermal interface to cooled support panel– Allows replacement of single defective wedge

• BUT: requires cutting the Silicone thermal bridge

• Half-Disk Support Panel and Support Cage– Sandwich construction: Graphite fiber (M55J) faces and aluminum honeycomb

• Liquid Cooling– Tube embedded in panel in place of core, near OD of half disk– Single phase coolant at high flow rate (turbulent)


Wedge Design

Backplane (0.76mm graphite fiber composite)

Screw (nylon)

Pin hole(for alignment)

Pin hole (for alignment)

HDI

Connectors for extension cables

Detector

ROC’s (26)

Screw (nylon)

All bonded with rigid epoxies

HDI

Detector

ROC’s

Backplane

Rigid, thermally conductive epoxy

Rigid epoxy


Half-Disk Assembly

Silicone bond(for heat transfer)

HDI

Detector

ROC

Screw

Pin

Support Tab

Support Tab

Support Panel

Support Tab


Cooling and Tab Detail

Screw hole (mounting to cage)

Pin hole (mounting to cage)Hose barb for coolant

Screw (holds wedge on disk)

Silicon detectors, HDIs, and back-planes made transparent for clarity

Pin (aligns wedge on disk)

ROC

Built-in cooling tube

Silicone heat transfer bridge(RT-cured, 2-part silicone)

Silicon detector


Half-Disk Assembly: Details

Thermally conductive

Silicone

Plastic inserts for screws and pins

Single piece plastic insert for screws and pins

Standoff plate

Foam core

Honeycomb core


Support Panel Construction

Locating pinInsert for pin (TBD plastic)

Insert for screw (TBD plastic)

GFRP Face sheet (0.25mm)

Honeycomb core (4.76mm, 32 kg/m3)

Foam core(TBD mat’l)

Core insert for pins and screws (TBD plastic)

Cooling tube

Hose barb

GFRP Face sheet (0.25mm)

Standoff plate (TBD Plastic)

Mounting tab


Half Cage Assembly

Cooling hose (silicone)

Sta

tion 1

Sta

tion 2

Sta

tion 3

Sta

tion 4

Z

Y


FVTX Assembly

VTX Pixel barrel (#4)




Too close!(move FVTX station 1 back?)

FVTX

Sta

tion 1

FVTX

Sta

tion 2

FVTX

Sta

tion 3

FVTX

Sta

tion 4

57mm 54.5mm 54.5mm


Modularity & Testability• Three Levels of Subassemblies

– Can all be tested independently– Test stands will be designed– Single Wedge stand will need to incorporate cooling feature

Detector Module (aka Wedge)

Half Disk Module Half Cage Module


Summary of Key Requirements• Environment

– Operate in dry Nitrogen at atmospheric pressure and RT– Radiation dose: <200 kRad over 10 years (very low)– 10 year design life

• Functional– Detector modules must be individually removable during initial integration– FVTX must be assembled around beam line (“clamshell design”)

• Heat Dissipation– 100μW/channel, 128 channels/ROC– 26 ROC’s/detector (stations 2, 3, 4)– 10(?) ROC’s/detector (station 1)

• Temperature Limits (ROC and detector)– Not specified

• Radiation Length Limit of Station– Not specified

• Dimensional Accuracy/Stability– See next slide


Dimensional Accuracy Requirements• Initial Alignment or Surveying Tolerance

– Detector relative to station• Initial assembly/surveying of half-disks

X,Y < ±10μm

Z < ±200μm (75μm goal)– Station location

• Initial assembly/surveying of half cages and complete system

X,Y,Z < ±200μm

• Static Deformations– Non-rigid-body deformations such as temperature-induced bowing of detectors

X,Y < ±10μmZ < ±14μm

• Stability– Unsteady Deformations and displacements (vibrations,…)

X,Y < ±10μmZ < ±14μm


Radiation Length Status (1/2)• Total RL of Station 2, 3, or 4

– Area averaged to active area (45mm IR, 170mm OR) = 2.2%– Worst case local value = 4.3% (going through cooling tube)

Distribution of area-averaged, normal incidence RL

0.000%

0.100%

0.200%

0.300%

0.400%

0.500%

0.600%

0.700%

See notes on next slide


Radiation Length Status (2/2)

Distribution of worst-case, normal incidence RL

0.000%

0.200%

0.400%

0.600%

0.800%

1.000%

1.200%

1.400%

1.600%

Notes:•Assumes 35cm RL (X0/ρ) for coolant (no data)•Assumes 1.2cm RL (X0/ρ) for Nickel (no data)•Honeycomb core is treated as uniform mass distribution•Titanium fittings not included (outside of active area)•Screws not included (type TBD; likely nylon so small impact) •Alignment pins not included (material TBD; may be removable)


Cooling Assumptions• Keep FVTX (and VTX) near Room Temperature

– Eliminates difficulties with cold gas enclosure• flow dry nitrogen at RT

– Mitigates thermal stress and dimensional stability issues

• Power Removed– 8W per half disk (stations #2, 3, 4)

• Cooling Tube Embedded in 3/16” Support Panel– Square cross section (3/16” by 3/16”) with super-thin (<50μm) nickel wall

• Coolant– 3M Novec HFE-7000– Completely harmless to (even live) micro-electronics– Environmentally friendly– Dense (1.4 × water)

• Flow Regime– Single phase– Strongly turbulent

• Re ~ 10,000• Flow velocity ~ 0.7 m/sec• Flow rate ~ 20 g/sec = 14 mL/sec = 0.86 L/min (per ½ cage)

– Flow-induced vibrations?


Coolant to ROC Thermal Path• Use Simple Correlations to Evaluate

– Pressure drops– Temperature drop from fluid to cooling tube

Approximate temperatures with 10°C coolant flowing at Re~10,000(0.76mm K13CU backplane, 50μm Nickel tube, 0.2 W/mK epoxy, 0.75 W/mK silicone)

Inside of F.S: 12.2°C

Outside of F.S: 12.6°C

Warmest ROC: 20.3°C

Tube wall: 11.3°C

backplane (K13CU)

HDI

Panel core (Al HC)

Bulk coolant: 10°C

Back of wedge backplane: 15°C

Nickel tube (TBC)

Inner

Rad

ius

Oute

r R

ad

ius

Foam (TBC)Thermally Conductive Epoxy

Thermally Conductive Silicone


Liquid Cooling Circuit

FVTX Inlet: 10°C, ~5 psig

ROC station 4: ~20.6°C

Outlet plane 4: 10.3°C

FVTX Outlet: 11.1°C, ~3 psigROC station 3: ~20.9°C

ROC station 2: ~21.2°C



Warmest ROC, station 1: ~21.4°C

• Run 4 Half-disks in Series


Wedge Analysis: Assumptions• Bonds:

– Silicon detector to HDI: rigid, RT-cured epoxy– ROC to HDI: rigid, RT-cured, thermally conductive (1.5W/mK) epoxy– HDI to backplane: rigid, RT-cured epoxy

• HDI– Multi-layer Kapton HN/Cu (2 ground planes, 2 signal planes)– Total thickness 0.176mm

• Backplane– QI [0°/60°/-60°]2S K13CU/CyE graphite fiber composite

– Total thickness: 0.762mm

• Power Dissipation– 26 chips per wedge (stations 2, 3, 4)– 0.0128W/chip

• Effective Backplane Thermal Conductivities– Estimated, based on historical test data (conservative)

– Kx = Ky = 130 W/m.K (~5 times lower than encapsulated TPG)

– Kz=1 W/m.K

• Boundary Conditions– Bolted connections at 3 points– Silicone thermal bridge near OD– 15°C at back side of backplane, near cooling tube


Wedge Analysis: Temperature Distribution

3-D Temperature Contour

Max Tº = 20.3ºCWarmest ROC

Min Tº = 15ºC (Boundary condition at back side of backplane)

Radial Temperature Variation

Radius (from beam CL, meters)

Tem

pera

ture

(°C

)

• Warmest ROC is 5.3ºC Warmer than Back Edge of Backplane– 10.3ºC warmer than coolant


Wedge Analysis: Stresses and Distortions• Assuming Assembly at RT

– Max distortion of silicon detector = 10.4μm– Max normal stress in silicon = 0.5 MPa (<< 10MPa, conservative allowable)– Max shear stress in bonds = 0.8 MPa (< ~13MPa allowable)

Radius (from beam CL, meters)

Dis

tort

ion (

mete

rs)

Max deflection = 10.4μm

Zero deflection (boundary conditions)

Z deflection VS Radius


Wedge Design: Conclusions• GFRP Backplane is

– Conductive enough: 5.3°C from outer edge to ROC– Rigid enough: 340 Hz natural frequency

• HDI is Conductive Enough without Thermal Vias– Recommend using Kapton MT (higher conductivity)

• Distortions are Low– <11 μm with 10°C coolant (<14μm requirement)

• Stresses in Bond and Detector are Comfortably Low– No need for compliant adhesives


Disk-Level Modeling: Thermal distortion

Max deflection of detector ~8μm

Fundamental vibration mode: 164 Hz

• FEM of half disk, fully populated with detector modules• Used for stiffness & Deflection calculations

Distortion due to cooling


Assembly of Detector Module• Assembly Concept Based on

– Base tool• Vacuum chuck

– Keep backplane flat

• Holds backplane– Mechanically aligned (2 pins)

– Bonding tools • Aligned to base with two pins• Vacuum chucks

– Keep things flat

• One to hold HDI– HDI optically aligned (or use pins)

• Another to hold silicon detector– Detector optically aligned

– Two-step assembly1. Bond HDI to backplane2. Bond detector to HDI/backplane assembly

• Open Questions– Shim between tools to control bond thickness?– Continuous/discontinuous bonds?

1: bond HDI to Backplane

2: bond detector to HDI/Backplane


Key Remaining Technical Issues• Requirements:

– RL and ROC temperature requirements– Relate to science requirements and finalize

• Design:– Gas enclosure

• Concept & design

– Signal processing boards• Dimensions• Support structure• Cooling

– Cooling system• Refrigeration, pumping, and control system• Not currently within HYTEC’s scope

• Design Verification– Prototypes and performance testing

• Flow-induced vibrations• Cooling performance• Dimensional stability


Future Work: Before DOE Review• Finalize and Document Requirements (LANL)

– RL– Temperature limits

• Finish Preliminary Design (HYTEC, funded)– In progress, 3 more weeks

• Document Preliminary Design (HYTEC, funded)– In progress, report expected by April 6


Future Work: Before Construction Phase• Not Funded, but Manpower is currently available• Detailed Design

– Adhesive selection, inserts, station 1• System Design

– gas enclosure, “big wheel” • Cooling Hardware (not in HYTEC’s scope)

– Internal: tubing, clamps, etc.– External/system: refrigeration, circulation, and control system

• Prototyping– Detector module prototypes

• GFRP backplanes + dummy HDI + dummy SSD (passive silicon wafer) + resistive heaters (ROC heat)

• Used to– Test assembly tooling– Thermal cycling (stresses in bonds and SSD)– Heat transfer testing – Validate temperature induced deflections (TV Holography?)

– Station prototype• One half disk (large)• Supported by dummy structure (no cage)• Populated with dummy detector modules• Used to

– Test assembly and alignment concepts– Measure flow induced vibration (accelerometers)


Funding Issues• HYTEC has No Remaining FVTX Funds

– Will finish preliminary design work and write report by April 6

• Funding Needed Before DOE Review– Continue refining design and updating CAD and analysis – Support DOE review (if needed)

• Funding Needed Before Construction Phase– Complete and finalize design– Prototyping and testing

Without new funding by early April, current engineering team will have to be re-assigned to other projects


Concluding Remarks• Structural/Thermal Design is Settling

– Rigid– Stable – Modular

• Numerous Details still TBD– Adhesives, joint details, tooling,…

• Various System Issues still TBD– Gas enclosure, support and cooling of big wheel,…

• One Technical Question– Flow induced vibrations?

• Need disk prototype to evaluate

• Need Bridge Funding through end of FY– Continuity of engineering support

• Inevitable design changes to come

– Remaining design tasks– Prototyping and performance testing

phenix fvtx status of mechanical and thermal design work eric ponslet, shahriar setoodeh, roger...

Documents

fvtx station 457mm54

total rl of station

structural support

thermal interface

screws nylon

pin tbd plasticinsert

graphite fiber m55j

screw nylonall