High Strength/High Conductivity Cu Fabricated by Pulsed Electrodeposition

1. High Strength/High Conductivity Cu Fabricated by Pulsed Electrodeposition Francisco Luongo Stanford University Supervisors: Ke Han and Baozhi Cui, MS&T REU Presentation 7/27/05

2. Outline • Motivation/Project Objectives • Experimental Setup/Parameters • Data and Results • Conclusions

3. Motivation Resistive Magnet: ~35 T World Record NHMFL: User Facility To build stronger magnets, strong and highly conductive materials are required… Copper Stamping for Resistive Magnet

4. Project Objectives • Produce High Strength High Conductivity Cu by pulsed electrodeposition • Determine effect of varying factors on deposition • Electrolyte concentration • Current density • Cathode substrate • Deposition rate • Why Copper? • Relatively affordable • Widely applicable • Copper wiring integral to electronics • Data readily available Copper wiring1 1) “Coiled Copper wire rod.” http://www.mining-technology.com/projects/kghm/kghm7.html

5. Experimental Procedure • Deposition of Cu coat on electrode • Ions supplied by anode and electrolyte • Pulsed instead of DC • Rate Dependent on 3 parameters • Ton (.02s) • Toff (2.0s) • Ipulse (0.5 A/cm2 - 2.0 A/cm2) • Deposition for 24 hours Deposition Model1 .02s Ton Toff Current (A) 2.0 s Time 1) “The Evolution of Framecoat Electrocoat.” http://www.pfonline.com/articles/ec0203.html

6. Sample Preparation • Produced 8 distinct Cu samples for testing • Electrolyte concentration (5 g/L, 28 g/L, 50 g/L) • Current density (0.5, 1.0, 1.5, 2.0 A/cm2 ) • Substrate (Steel or Co-Ni Alloy) • Samples examined using 3 methods • X-ray diffraction • Vickers hardness • Resistivity

7. X-ray Diffraction (Cu on Steel) • Depositions on Steel resemble pure Cu 5 g/L, 0.5 A/cm2, Steel

8. X-ray Diffraction (Cu on Co-Ni Alloy) • Depositions on Co-Ni alloy show stacking in (110) plane 5 g/L, 2.0 A/cm2, Alloy

9. Vickers Hardness • Values based on six measurements per sample 28 g/L, 0.5 A/cm^2 28 g/L, 2.0 A/cm^2

10. Resistance/Conductivity • Measured using 4 point setup • Resistance measured at 10 points with .05 A intervals

11. Resistivity Data

12. Hardness and Conductivity ** ** *Annealed Cu standard = 20.35 **Need to be retested

13. Conclusions • General Trends • Increasing conc. -> higher resistivity -> higher hardness • An optimum deposition rate seems to be achieved at about 28 g/L and a current density of 1.0 A/cm2 • Co-Ni alloy substrate produced harder Cu • No conclusive trend with regard to conductivity and substrate • Substrate has effect on deposited Cu • More work needs to be done on other factors and their effect on deposition rates • Investigate relative influence of parameters

14. Acknowledgements • Many thanks to Ke Han and Baozhi Cui for their guidance and support • Jun Lu for all of his help with resistance measurements • Gina LaFrazza, Pat Dixon, and the CIRL staff for all of their help • NSF for funding and continued support of the REU program