Update on Micro Channel Cooling Collaboration Meeting , G. Nüßle

Outline Micro channel clamp system Microchannel cooling test stand Next Steps

Micro Channel Clamps - Concept Silicon wafer is clamped between (red) metal blocks Seal material is present between blocks and wafer 2 blue plates are sufficiently rigid to ensure homogeneous force distribution on the wafer Micro channels are fed via grooves inside the red blocks

Micro Channel Clamps - Design First design for test configuration to validate the clamp concept The round holes in the transparent blocks connect the external cooling circuit to internal grooves These longitudinal grooves feed the micro channels in the silicon wafer

Clamps: single compression test Setup: 2 identical blocks top and bottom Seal: 2mm silicone foam Test object: 0.5mm thick Si wafer Result: Reached compression force of more than 10kN without failure Seal is compressed to less than 50% of its original thickness Conclusion: Seal is too soft, danger of contact metal to silicon

Clamps: parallel compression and pressure test Setup: 2 identical blocks on the bottom 2 identical blocks on top Seals: 1.6mm NBR Seals have openings in the center resembling the grooves in the blocks One block connected to N 2 bottle for pressure test Results: Reached compression force of more than 10kN and 15 bar pressure without failure Seal compression not visible Conclusion: Seal hardness is good Parallel compression with possible

Clamps: parallel compression and pressure test Comments: Pressure caused an outward force on the seal of ~200N Conservative approach with a friction coefficient of 0.2 asks for a compression force of 200N/0.2 = 1kN to keep the seal in place A vertical displacement of the seal is not visible

Micro Channel Cooling Test Stand 3d design for instrumentation and piping is finalized Most components have arrived Rack has been mounted Arrival of the booster pump is estimated for mid- December Pump for C 6 F 14 cooling unit is being installed

3d design has been finalized Most components have arrived Missing: booster pump Test stand PID

Next steps Build micro channel clamps prototype Investigate leak tightness of clamp system Test the micro channels with gas and liquid Build up test stand

Microchannel cooling – Status Cooling plate prototype: design finished, production at EPFL started prototype EPFL with Pyrex(Glass) cover plate, later silicon connections in design process Thermal interface: max. Temperature allowed 170°C? test kit for soldering at low temperature will be obtained test of technique from electronic design (Staystic) Test stand: C 6 F 14 cooling unit has been recovered, pump ordered design for test stand has been finalized booster pump for test circuit has been ordered valves, piping, instruments: awaiting offer material for rack construction has been ordered

ComponentMaterialThickness [μm]X0 [%] SensorSi Bump BondsPb-Sn~ Readout ChipSi Cooling PlateSi~150~0.15 Sum~0.47 Materials in the sensor area The total material budget (material in the beam) allowed for the GTK module is 0.5% X 0 (radiation length).

C 6 F 14 cooling liquid of choice C 6 F -20°CH 2 +20°C Density  kg/m 3 ] Viscosity  [10 -7 m 2 /s] Heat capacity c p [J/(kg K)] Thermal conductivity  [10 -2 W/(m K)] radiation hard thermally and chemically stable nonflammable, nontoxic, nonconducting known and used at CERN (CMS and Atlas Tracker) used in liquid phase C 3 F 8 is an option in case of to high pressure in the cooling plate for C 6 F 14

Fluid temperature difference 12bar pressure drop2bar pressure drop Temperature difference between inlet and outlet for channels of 50  m x 50  m