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AUGUST 2019 I PCB007 MAGAZINE 87 tems due to the low surface tension of the solvent. This advantage provides a benefit to form fine feature PCB designs with reliability and to improve the plating for semiconductor applications. For example, the microvias and plated through-holes (PTH) in PCBs are get- ting smaller and smaller. The uniformity of the catalyst is very important as well as cleanli- ness of the hole. The water-based system uses surfactant (chemical approach) and ultrasonic (mechanical approach) to mitigate defects, but it is a challenge as the hole feature size and aspect ratio become smaller and higher. The novel LMI catalyst system provides a good re- sult with less effort. Because the organic solvent system has lower surface tension, this provides better wettability naturally. Then, the LMI catalyst system can wet a sub-micron diameter hole, even if it is blind. Also, the layer deposition provides good interaction to the base resin, resulting in bet - ter adhesion compared to particle adsorption of the conventional method. This is similar to the vapor phase deposition, like the sputtered metal layer, and it delivers with a much simpler process and equipment as well as a lower cost. Some of the sputtered metal is physically pen - etrated into the resin skin. This improves the metal adhesion. The LMI catalyst process could allow a similar effect through thermal diffusion during the thermal metal deposition process. Summary A novel catalyst ink (LMI) has been devel- oped utilizing palladium carboxylate. This ink uses selected organic solvents and it provides high wettability and penetration of the catalyst to any feature of the substrate surface, includ- ing hole wall and pad of a blind via hole. The coated ink is cured by either heat or chemi- cal reducer. Very uniform palladium is formed over the substrate at a single layer of nano- scale thickness. This provides very high effi- ciency as a catalyst in both performance and economy. The chemical process over the ink provides sub-nanometer range particle which is very high activity as a catalyst. When this LMI is used for electroless copper plating, ul- trathin copper—such as 0.5 microns or less— can give enough conductivity uniformness to the entire panel to run the electrolytic copper plating. Therefore, the PCB can have fine fea- tures, such as sub-10 micron trace and space, when this ultrathin base copper is utilized for SAP processes. PCB007 Acknowledgment The authors would like to thank Tara Dunn from Omni PCB for her valuable inputs. References 1. S.K. Sharma, F. Fornasiero, J.S. Dhau, "U.S. Patent 8628818 B1." 2. K. Kubota, T. Nishiyama, K. Matsumoto, S. Yoshiyara, "Influence of Crystallographic Structure on Etching Rate of Copper by Using Ammonium Peroxodisulfate Solution," Journal of The Japan Institute of Electronics Packaging, 15(3), pp. 197–204, 2012. 3. Y.-S. Kim, G.A. Ten Eyck, D. Ye, C. Jezewski, T. Karaba- cak, H.-S. S., J.J. Senkevich, T.-M. Lu, "Atomic Layer Depo- sition of Pd on TaN for Cu Electroless Plating," Journal of The Electrochemical Society, 152(6), pp. C376–C381, 2005. 4. X. Wei, D.K. Roper, "Tin Sensitization for Electroless Plating Review," Journal of The Electrochemical Society, 161(5), pp. D235–D242, 2014. 5. E. Matijević, A.M. Poskanzer, P. Zuman, "The Char- acterization of the Stannous Chloride/Palladium Chloride Catalysts for Electroless Plating," Plating and Surface Finishing, 61(10), pp. 958–965, 1975. 6. A.M.T. van del Putten, J.-W.G. de Bakker, L.G.J. Fokkink, "Electrochemistry of Colloidal Palladium: An Experimental Study of Sol Formation and Electrocataly- sis," Journal of The Electrochemical Society, 139(12), pp. 3475–3480, 1992. This paper was first presented at the IPC APEX EXPO 2019 Technical Conference and published in the 2019 Technical Conference Proceedings. Steve Iketani is director, product and applications development, with Averatek Corporation in Santa Clara, California. Mike Vinson is president and COO of Averatek Corporation in Santa Clara, California.