1. 1 CTIS # 29946 Prepared By John Yurtin Updated 2-9-2005 Connection Systems Training Terminal Plating

2. 2 Having a good technical understanding of the design and performance of terminals can help you properly apply them within the vehicle. Plating should be clearly understood as to it reasons and effect on performance. This training help you understand why we plate terminals and the significance of the platings used. Excellence Performance Goal: Do it right the first time, every time Method: Innovation and continuous improvement

3. 3 Agenda u Why Use Plating u Types and Selection of Plating u Contact Physics & Technology u Gold vs Tin Plating u Fretting Corrosion u Analysis Of Wear u Lubricants u Field Observations u Plating Mix Guidelines u Summary

4. 4 Types and Selection of Plating

5. 5 Why Use Plating?

6. 6 Contact Probe Testing Function: Measure surface electrical resistance Uses: Evaluate contact material systems Compare aged material systems Specifications: Force: 0 -1kg range, 1 gram resolution Displacement: 100 cm range, 0.3 m resolution Instrumentation: 4-wire m meter Computerized motion control and data acquisition Gold Probe Tip Test Sample X - Y Sample Positioner Load Cell Electrical Isolation Low Noise Motor 20X Gear Reducer Programmable Precision Table

7. 7 Properties of Terminal Plating

8. 8 Contact resistance is a function of contact force and material. Contact area and contact pressure influence wear properties and resistance to contaminants Goal is to design for the highest contact pressure that will meet requirements for the maximum number of mating cycles –Typically 2 to 4 large radius contact spots –Ten mating cycles typical for tin and silver-plated terminals –Hard gold or gold-flashed palladium used when more mating cycles are required Contact Technology

9. 9 Contact Resistance Calculations R Connection = R bulk + R film + R constriction R bulk = resistance of the terminal material R film = resistance from oxidation, corrosion, etc. R constriction = resistance through a clean interface (good approximation for ring terminal resistance) R constriction = Rc = Constriction Resistance in Ohms = Resistivity of Contact Material (Plating or coating) in Ohm-cm H= Hardness of Contact Material in kg/mm2 W= Contact Force in kg

10. 10 Contact Force & Contact Resistance

11. 11 White-Light Profilometer –Used to study fretting and wear damage Coupon Wear Tracks Dimple Fretting Under High Power Dimple-on-Coupon configuration for fretting tests Fretting Under Low Power Fretting Under High Power Analysis of Wear

12. 12 Fretting corrosion - The formation of oxidized wear debris caused by microscopic relative motion between contact surfaces. (generally10 to 100 microns movement) Fretting Corrosion - Definition: Contact Interface Review

13. 13 Fretting Machine Operation –Sample holder –Feedback loop –Debris particle Contact Physics Infrastructure Sample Normal Load Sample holder Position sensor Electrodynamic drivers Aluminum rod Tower

14. 14 Contact Physics Infrastructure Fretting Wear Basic research »Fretting parameters »Power Applied research »Material comparison »Lubricant evaluation Unpowered Powered Unpowered Powered Fretting Wear Tracks

15. 15 Lubricant Requirements General Requirements –Ability to withstand terminal operating temperatures –Environmentally acceptable –Ability to be applied and detected easily –Chemically compatible with all terminal and connector housing materials –Should remain on contacts to help reduce friction and wear –Non-conductive –Non-corrosive –Low cost

16. 16 Contact Lubricants Sliding Wear A graph showing changes in the coefficient of friction under sliding wear conditions for un-lubricated and lubricated conditions. The addition of Nyosil M25 lowered the coefficient of friction –Decreasing the frictional force –Lowering the insertion force Not lubricated 4 l Nyosil M25

17. 17 Effect of Lubricants on Fretting

18. 18 Connection System Technology Vibration Analysis Vibration is a challenging requirement to design around because of the variables –Frequency –Intensity –Duration Vibration Simulation Program –Complete for the Micro64 Connection System –Development started for 100W Connection System »Terminal contact geometry »Natural Frequency »Actual testing Design of Experiments –Lubricants –High flex cable –Bolt together connection –Rubber mounts

19. 19 Micro64 Vibration Simulation Data

20. 20 Micro64 Vibration Simulation Data

21. 21 Connection System Technology Vibration Analysis Vibration profiles need to be evaluated individually for each Connection System –Multiple variables make it difficult to compare profiles Vibration Simulation is conservative estimate of connection system performance –Enables us to do an intensity vs frequency analysis »Mounting geometry »Dampening/rubber mounts Work closely with OEMs and Module suppliers to design the most cost effective system that will perform in the specified environment.

22. 22 Connection Systems Training Gold Plating vs. Tin Plating

23. 23 General Guidelines - Gold vs. Tin Terminal Plating When do we use tin-plating? –Terminals with contact force over 5N (280MP and larger) –In areas where tins resistance to vibration has been proven –Some customers specify gold-plated terminals for low-current circuits, but we have seen no physical low current limit for tin-plated terminals When do we use gold-based plating? –When mating connector or device uses gold –When low terminal contact force causes fretting and wear issues with tin. ( typically around 5 N) » Gold normally used for 100W, Micro64 » Gold-to-gold or tin-to-tin used on Micro-Pack 100, 150MP, and GT depending on severity of the environment –When max. continuous operating temperature exceeds 125C »Regular gold-plating not acceptable above 125C »Special, silver or gold-based coatings used for 125C to 340C

24. 24 Acceptable Plating Combinations Tin-Plated Terminals –Compatible with mating terminals coated with tin or tin-lead –Tin-to-silver is similar or slightly better than tin-to-tin –Tin-to-gold not recommended »Tin oxide can build up quickly on contact spots and cause increased resistance. Gold-Plated terminals –Compatible with mating terminals coated with gold, gold-flashed palladium, and gold alloys –Gold mated to silver-plated terminals can be compatible, depending on terminal design –Gold mated to tin plated terminals not recommended – (see above)

25. 25 Connector Testing – Gold vs. Tin Gold and Tin perform about the same if connector and terminal designs resist fretting corrosion

26. 26 Fretting Corrosion - Definition: Fretting corrosion - The formation of oxidized wear debris caused by microscopic relative motion between contact surfaces. (generally10 to 100 microns movement)

27. 27 This is fretting corrosion! Fretting Corrosion

28. 28 Effect of Terminal Contact Materials

29. 29 Conclusions Gold plating is normally used for low contact force connections that are susceptible to fretting corrosion Tin plating can be used in many automotive connections if fretting corrosion is eliminated

30. Are most connector troubles caused by vibration? Severe Vibration can cause harmful wear of contact interfaces Mild vibration can cause fretting corrosion Thermal changes can cause movement and fretting Steps in the development of fretting corrosion on a tin plated terminal interface Fretting Corrosion

31. 31 What about Plating and Lubricants? u Gold Plating will result in improved performance u Gold to Tin is not recommended by Delphi and other industry experts. (AMP clearly does not recommend tin to gold interfaces!) (http://www.amp.com/products/technology/metrology.stm) u Lubricants can reduce the effect of fretting u Thermal changes can cause movement and fretting Fretting Corrosion

32. This is fretting corrosion! Fretting Corrosion

33. Sensor terminal after GMI12590 Fretting corrosion can be caused by micro-movement from temperature changes as well as from mechanical vibration. Fretting Corrosion

34. Symptoms of connections with fretting corrosion –Problem disappears after connector is bumped –Changing the device (sensor, computer, etc.) makes the problem go away temporarily –Problem appears when the weather changes Field Observations