1. MEMS Two-Phase Vapor Escape Heat Exchanger
Milnes David
Tarun Khurana
Christopher Anderson

2. Hydrophobic PTFE, AdvantecMFS
Concepts
Evaporator with hydrophobic, porous membrane
Liquid channel
Vapor channel
Hydrophobic, porous membrane
Vapor outlet
Liquid inlet
Silicon
Heat flux
Hydrophobic PTFE, AdvantecMFS
Wet etched pores combined with porous membrane. Etched pores act as bubble traps [Meng, 06]
Polycarbonate, GE

3. Process Flow Diffusion Clean Oxide Growth Al. Sputter
Backside Pattern (heaters & sensors)
Al Etch
Ashing
PRX 1000 Clean
Backside LTO deposition
Backside protect
Front-side Oxide Etch (HF)
Front-side pattern (channels)
Front-side channel etch (STSDRIE)
Backside pattern (bond pads)
Pad etch

4. Process Layout Backside pattern (through etch) Through etch (STS DRIE)
Final released device
Adhesive coat on transfer substrate
Contact printing of adhesive
Membrane attachment via UV curing
Attachment of patterned double sticky tape (vapor channel)
Top cover integration

5. Materials Acquired: Membranes: Adhesives:
Polycarbonate – 0.1 um. 0.2 um, 0.4 um and 3 um
Teflon – 0.2 um
Membrane characterization apparatus has been built.
Teflon coating of Polycarbonate membranes using similar setup.
Adhesives:
5 different types on order.
Challenge:
Temperature Stability (chosen adhesives stable to 180 oC).
Adhesion to membrane and silicon.
3 of chosen adhesives work well with Polycarbonate and Si
2 of chosen adhesives work well with Polycarbonate and SiO2.
No appropriate adhesive for Tefon and Si.
Characterization apparatus to be designed.

6. Membrane Test Structure
Acrylic Structure
Membrane
Fluid in

7. Membrane Test Setup Pressurized Liquid Chamber Membrane Test Structure
Pressure Sensor
Membrane Test Structure
Pressurized Liquid Chamber
Membrane Test Structure
Pressure Sensor

8. Temperature Sensor Electronics

9. Power Supply