1. Nick Arnal, Jason Entenmann, Chris Thompson Dr. Gokhan Mucmu URL: www.interconnectcharacterization.weebly.com Test Fixture to Characterize Elastomeric Interconnects Critical Design Review (CDR) January 29, 2013 EEL 4914 Engineering Design II CHRIS ADD PIC

2. Problem Statement  Our task is to a characterize elastomeric interconnects for Harris Corporation  Measure S-parameters, continuity, and contact resistance  Characterize two different styles of elastomeric interconnects  All while undergoing 500 cycles of temperature cycling (-55°C to 125°C) Sample Elastomeric ConnectorTemperature Cycle Profile

3. Design Approach  We are designing a test fixture with multiple circuit boards to be placed in a temperature chamber  Elastomeric connectors conduct when compressed 10-15%. They will be sandwiched between a pair of circuit boards with RF cables running to outside of the oven.  2-3 elastomeric connectors per circuit board Example of Test Fixture in Oven MeasurementEquipment S-parametersVNA ContinuityCustom designed circuit Contact Resistance 4-probe multimeter

4. System Block Diagram

5. S-parameter Measurements  A 20GHz Agilent 8720ES VNA will be used  The S-parameters will be measured for one connector at a time  Cables pairs will be interchanged by hand  The VNA will be calibrated up to the cable mount  Characterized cables will be removed from the measurement by de- embedding (next slide)

6. De-embedding Process via MATLAB

7. Cable Measurement

8. Continuity Measurements  Continuity for each connector is determined by a comparator circuit (see next slide)  Digital HIGH sent to Arduino if RCONN>1000Ω (discontinuity)  Digital LOW sent to Arduino otherwise (continuity)  Sample rate = 10kHZ per connector (10,000 samples/second)

9. Continuity Test Circuit Channel  Max current through connector (R CONN =0, V S =5V)  Discontinuity Trigger voltage (R CONN ≥1kΩ)  R1/R2 Voltage divider sets V REF  Max current draw from Vs ≈ 2mA / channel  LM339 response time - 1.3µs

10. Temperature Sensing Circuit  LM35 will be mounted on the board to verify the temperature  -0.55V to 1.25V output shifted to 0.9V to 4.5V by the op-amp summer

11. Arduino Timing Diagram  The Arduino will process both the continuity test and the temperature  Continuity test results (# of discontinuities out of 10,000 per connector) and temperature recorded from Arduino to computer every second Communication process takes about 2ms  This cycles continuously repeats

12. RF Circuit Design  RF Circuit Design Requirements  Minimal design for truest results of connectors/interconnects  Frequency Range: 0.5 to 18GHz  Temperature Design: -55 to 125 C  Compression requirements: 15% +/- 5% (For Interconnect #1 and #2)

13. RF Circuit Design  Software / Calculations  ANSYS HFSS v.15 Simulation Software Full circuit design and simulation in frequency ranges  LineCalc Transmission line calculations  ADS AutoCAD and Gerber circuit files for fabrication

14. Circuit Design  GPO Connector / Interconnect Specifications  Three piece connection design  Impedance: 50 Ohms  Frequency: DC to 40GHz  Temperature Design: -65 to 165 C

15. Circuit Design  Interconnect #1 and #2 Specifications Custom Interconnects per Harris’ requirements  Compression Rating: 15% +/- 5%  Designed for frequency and temperature ratings  Correct alignment for true results PCB Heat Sink (Spacer) Interconnect

16. Circuit Design  Design and Simulation: GPO  Simple two layer, two board design  Microstrip lines on the inner side of boards  Stand-offs will be used to hold the system together

17. Circuit Design  Design and Simulation: GPO  Transmission Results, S21

18. Circuit Design  Design and Simulation: GPO  Reflection Results, S11

19. Circuit Design  Completed Design: GPO  Two connector/interconnect setups

20. Circuit Design  Design and Simulation: Interconnect #1 and #2  Simple two layer, two board design  Micro-strip lines on outer sides of boards  Aluminum Spacers are used on inside to act as heat-sink and alignment tool for interconnects PCB Heat Sink (Spacer) Interconnect

21. Circuit Design  Design and Simulation: Interconnect #2  Transmission Results, S21

22. Circuit Design  Design and Simulation: Interconnect #2  Reflection Results, S11

23. Circuit Design  Design and Simulation: Interconnect #1  S11 and S21 Results

24. Circuit Design  Completed Design: Interconnect #1  Three interconnect setup

25. Contact Resistance  Using a typical Multimeter  4 probe test  Only on one type of connector being tested  Boards are same size as other test boards  Wires soldered directly to board  DC test 25

26. Software and Equipment Design Tools  Board design  HFSS, Pspice  Fixture design  SolidWorks  Data processing and control  Programming in C#  MATLAB for data processing Measurement & Test Equipment  Agilent 20GHz VNA  Thermotron Temperature Chamber  4-point Multimeter  Arduino MEGA

27. Action Items Test Fixture Assembly and Test Readiness Review (TRR) – February 26 th Fabricate and build test fixture Manufacture all test boards Run software for one full cycle to validate functionality Test fit fixture and boards, test for contact resistance Product Testing – February 26 th – April 16 th Analyze Results / Final Report– April 16 th – May 14 th

28. Testing Plan

29. Summary/Accomplishments  Measurements  Test cable has been characterized, more have been ordered  MATLAB de-embedding program written and working  Continuity test written on Arduino  Temperature sensor circuit built  Software  Fully automated program to run tests and alert team of anomalies in the system during test has been created

30. Summary  Circuit Design  GPO, interconnect #1 and #2 Boards and interconnects designed in HFSS Boards and interconnects simulated from 0-20GHz Quotes from multiple companies for board fabrication  Fixture Hardware  Fixture designed in SolidWorks and CTE and vibrational testing has been simulated