A LOW COST METHOD FOR ENVIRONMENTAL TESTING AT CRYOGENIC TEMPERATURES

1. A LOW COST METHOD FOR ENVIRONMENTAL TESTING AT CRYOGENIC TEMPERATURES Testing electronics at cryogenic temperatures requires special equipment Paul Anderson University of Idaho

2. Overview • Why Create a Cryogenic Testing Chamber? • Requirements • Low Cost Chamber • Low Cost Chamber Control • Test Results • Improvements to the Design • Does the Chamber Meet the Requirements? • Conclusion / Recommendations Paul Anderson

3. Why Create a Cryogenic Testing Chamber? University of Idaho’s Microelectronics Research and Communications Institute (MRCI) recognized a need for a low-cost cryogenic temperature environmental chamber for the development and testing of electronics over a wide temperature range. Paul Anderson

4. Requirements • Portable: One person can move the chamber • Efficient: It must use less than one standard transfer cylinder of liquid nitrogen for one 8 hour test • Capable of any temperature below room temperature to -180°C • Safe • Automated real-time temperature monitoring • Easy to use for MRCI personnel with a short training period • Adaptable to any type of package pin configuration • Low-cost: less than $5,000 Paul Anderson

5. Low Cost Chamber • Aluminum cylinder with removable top • 4 thermocouples • 2-64pin sockets • 4 D-Sub connectors for connection of test signals • GN2 gas purge for water abatement • ½ inch lines for liquid nitrogen input and exhaust of gas out of the chamber Paul Anderson

6. Low Cost Chamber • Liquid Nitrogen supply is from a standard 180L transfer cylinder pulsed into the chamber through a cryogenic solenoid valve • The system is controlled with bench top instruments, GPIB architecture, and NI LabVIEW Paul Anderson

7. Low Cost Chamber Control • LabVIEW Program • Controls the temperature in the chamber • Shows real-time temperature of the chamber • Saves the temperature data to file Paul Anderson

8. 5°C ripple Test Results- • Reached -190°C • 5°C ripple around the set point • Initial Overshoot of desired temperatures Paul Anderson

9. Improvements • Spray Bar • New Lid • Change in Thermocouples • DAQ Integration • Future Improvements? Paul Anderson

10. Improvements: Spray Bar • Capped brass pipe with 18 holes drilled into the walls of the pipe • Adaptor made to allow the use if pipes • Injects LN2 more uniformly into the chamber • Restricts flow of LN2 Paul Anderson

11. Improvements: Spray Bar • Results: • Less Ripple • 1C instead of 5C • Removed micro-pulsing of valve, reducing valve wear • Cost: • $100, Parts and labor Paul Anderson

12. Improvements: New Lid • Screw-on lid damaged during a test • New lid designed for ease of use • New Lid design can be opened faster than old lid could • Easily repairable: if threads on bolts are damaged, old bolts my be cut off and replaced Paul Anderson

13. Improvements: New Lid • Easily repairable: if threads on bolts are damaged, old bolts my be cut off and replaced • Cost: Approximately the same as previous lid Paul Anderson

14. Improvements: Thermocouples • Change from K-Type Thermocouples to E-Type Thermocouples • K-Type: 0.75% Error • E-Type: 0.5% Error • Cost Difference Negligible Paul Anderson

15. Improvements: DAQ Integration • NI PXI-6289 DAQ system with embedded controller • Interface with NI SCB-68 shielded thermocouple terminal block Paul Anderson

16. Improvements: DAQ Integration Paul Anderson

17. Improvements: DAQ Integration • Four Thermocouples sense the temperature inside the chamber • The voltage of each thermocouple measured by four input channels on the NI PXI-6289 DAQ system, coupled with the NI SCB-68 Connector Block. • Benefits: • more accurate than a system using DMMs • faster than a system using DMMs Paul Anderson

18. Final Cost of Materials *Not including DAQ, DMM, LabVIEW license, or other MRCI equipment. Some Assembly Required Not responsible for injury or death. If you are reading this, I must be really boring. Paul Anderson

19. Does the Chamber Meet All the Requirements? • Yes! • Portable • One person can move the chamber • Efficient • Two or more tests on one 180L transfer cylinder of liquid nitrogen • Low temperature of -196°C possible • Safe • Fails to a safe condition • Automated • LabVIEW controlled with real-time monitoring • Easy to use with only a brief training period • Adaptable to any package configuration • Low cost • $2,300 for chamber materials Paul Anderson

20. Acknowledgments • Dr. Herb Hess - University of Idaho • Tracey Windley - University of Idaho • Matthew Braley – University of Idaho • Kevin Buck - University of Idaho • Dr. Mohammad Mojarradi - JPL • Scott Cozy - JPL • NASA Jet Propulsion Laboratory • NASA EPSCoR Paul Anderson

21. Questions or Comments Paul Anderson