1. Microfluidic devices for thermal management
Timothée Frei
Neuchâtel, 6 June 2017

2. outline
Intro to CERN, HEP, silicon detectors and their thermal management.
NA62 microfluidic cooling
Closed loop cooling with Micro-engineered enhanced interconnection.. My thesis
To get started silicon microchannels with RTDs for CO2 tests
We still need connectors
This is how we did
Could we do it better?
CSEM – soldered option
3D printing
Neuchâtel, 6 June 2017

3. NA62 Silicon Microchannel Cooling
1. LASER welding
1/16” SS capillaries to KOVAR connectors
3. NICROBRAZ brazing
1/16” SS capillaries to SS manifolds
4. Au-plating
KOVAR connectors
5. Vacuum brazing
KOVAR connectors do Si
2. Bending of the capillaries
1/16” SS capillaries with 0.1 mm wall thickness
3 detector modules
Liquid C6F14
Top below -10ºC
Power dissipation 25W-48W over 6x4cm2
Kovar, Cu-plated
-> Au-100nm, Ni-350nm, Ti-200nm + SnPb wire (dia 0.5mm)
A. Mapelli et al JINST 7 C01111
P. Petagna et al., Microelec. Journal 44 (2013) 612–618
G. Romagnoli et al., Microelec. Eng. 145 (2015)
Neuchâtel, 6 June 2017

4. Cooling System Schematic
ON-DETECTOR COOLING SYSTEM
Microchannels
Single or two-phases flows
Heat transferred to external cooler
Fluidic lines come near the detector
Neuchâtel, 6 June 2017

5. Thermal Management in HEP and Space Applications
Dissipate heat generated by electronics
Extend service-life of components
Vacuum + Radiation
Silicon embedded microchannel cooling (e.g. NA62 GTK)
Cooling
Plant
Connection to main cooling circuit is challenging

6. Envisioned Cooling System Schematic
ON-DETECTOR COOLING SYSTEM
Two cooling circuits
Primary circuits transfer heat from detector to the secondary cooling circuit
Secondary circuit transfer the heat to external cooler
Micro-engineered enhanced interconnection
Transfer heat from primary circuit’s condenser to secondary circuit evaporator
Re-workability
Activation Control system
Additional heat if required
What we want to implement in the future
Neuchâtel, 6 June 2017

7. Primary circuits
Monolithic oscillating heat pipe (OHP), also known as pulsating heat pipe (PHP) for high energy physic and space applications
Non-linear stochastic phenomena
Few CFD analyses and models
Transfer several kW to distances of the order of 1 m
Sensible to orientation with respect to gravity (depending on the diameter)
Made of Si, wickless
Heater in Activation Control System is used to start oscillations of vapor 𝑔
Si detector
Bump bond
iramis.cea.fr
Read-out chips
Thermal interface
PHP
Neuchâtel, 6 June 2017

8. Micro-engineered enhanced interconnection
Transfer heat from primary circuit’s condenser to secondary circuit evaporator
Re-workability
Secondary cooling system stays closed / No intervention on the refrigerant
Neuchâtel, 6 June 2017

9. Open issues
Neuchâtel, 6 June 2017

10. Vacuum flask with refrigerant
Filling procedure
Back-filling process
OHP/PHP
Valve 2
Valve 1
H. Ma, Oscillating Heat Pipes, 2015
Vacuum Sensor
Mass balance
Valve 3
Vacuum Pump
Valve 4
Cold Trap
Vacuum flask with refrigerant
Quick-filling process
Vacuum Sensor
Valve 1
Valve 2
Vacuum Pump
Valve 3
Ruler
OHP/PHP
Refrigerant
Neuchâtel, 6 June 2017

11. Test Test performance in different positions𝜃 𝜙
Test performance in different positions
Test performance with different filing ratio
Test performance with different power inputs, refrigerants, and refrigerant temperatures
Thermal performances using RTDs or IR imagery
Flow visualization using high speed camera
Filing ratio of ~30% (left) and ~60% (right)
Neuchâtel, 6 June 2017

12. ALICE ITS Microfluidic Interconnect
3D printed interconnector (3D Systems printer/Accura 25)
Connects two silicon frames
Liquid C4F10
Replace out-of-plane connection for in-plane connection
T. Morais, 2016
Neuchâtel, 6 June 2017

13. ALICE ITS Microfluidics Connectors
3D printed connector glued to silicon frame (3D Systems printer/ Accura 25)
Connects Ø1.2mm tubing to Ø0.6mm inlet
Liquid C4F10
A. Toros, 2015
Neuchâtel, 6 June 2017