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face finish was tested for intermetallic growth, solder ball brittle failures, and insertion loss. e results showed that this surface finish per- forms better than other currently available Ni- free surface finishes, such as ENIG, DIG, and EPIG/EPAG, due to its thinner intermetallics, lack of brittle solder joint failures, and extremely low insertion loss similar to bare copper. is Ni-less surface finish with nano-engineered bar- rier layer is a good solution to the current need for a reliable surface finish for high-frequency, HDI PCB applications. PCB007 Acknowledgements The authors would like to thank John Coonrod and his team at Rogers Corporation for assistance with insertion loss testing and invaluable technical discussions. References 1. "Effects of Surface Finish on High Frequency Signal Loss Using Various Substrate Materials," by D. Cullen, IPC APEX EXPO Conference Proceedings, 2001. 2. "Surface Finish Effects on High-Speed Signal Degradation," by X. Wu, IEEE Transactions on Ad- vanced Packaging, pp. Vol 31, No 1, 2008. 3. "The Effects of PCB Fabrication on High-Fre- quency Electrical Performance," IPC APEX EXPO Conference Proceedings, 2016. 4. "Ambiguous influences affecting insertion loss of microwave printed circuit boards," by J. Coonrod, IEEE Microwave Magazine, pp. Vol. 13, No. 5, 2012. 5. "Revisit Nickel Characterization Effect on High- Speed Interconnect Performance," by Y. Tao, in IEEE MTT-S International Conference on Numeri- cal Electromagnetic and Multiphysics Modeling and Optimization (NEMO), 2015. 6. "How Are 4G and 5G Different?," by T. Fisher, July 3, 2019. 7. "Propagation Channel Characterization for 28 and 73 GHz Millimeter-Wave 5G Frequency Band," by T. Abbas, IEEE 15th Student Conference on Re- search and Development (SCOReD), 2017. 8. "High-Frequency, High-Speed: An Opportunity for China CCLs to Lead," by Tulip Gu, I-Connect007, July 24, 2017. 9. "The future development trend of PCB and Flexi- ble PCB industry," J. Ding, LinkedIn, June 4, 2018. 10. "Solder Joint reliability of Gold Surface Finishes (ENIG, ENEPIG, and DIG) for PWB Assembled with Lead-Free SAC Alloy," by G. Milad and D. Gudecza- uskas, Uyemura International Corporation. 11. "Evaluation of DIG (Direct Immersion Gold) as a New Surface Finish for Mobile Applications," by D. Kim, Intel Corporation, 2005. 12. "Characteristics of EPIG Deposits for Fine Line Applications," by G. Milad and D. Gudeczauskas, Uyemura International Corporation. 13. "Scaling Cu pillars to 20 um pitch and below: critical role of surface finish and barrier layers," by T.-C. Huang and M. Tomic, in IEEE 67th Electronic Components and Technology. Kunal Shah is president of LILOTREE.