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22 The PCB Magazine • May 2015 Abstract Microfill TM through-hole fill (THF) electro- lytic copper is a new process designed to offer outstanding through-hole fill, particularly for substrates intended for use as core layers in build–up applications, producing planar, solid copper plugs in high-volume production plat- ing equipment. This technology is intended to replace resin or paste plugging, and offers many advantages, including improved reliability, higher electrical and thermal conductivity, in- creased productivity and reduced process costs. by Elie Najjar, Leon Barstad, Jayaraju Nagarajan, Marc Lin, Maria rzeznik and Mark Lefebvre Dow eleCTRoniC MaTeRials A Novel and High- Productivity Process Electroplating Through-Holes with Different Geometry: This paper describes a novel copper through- hole fill electroplating process designed for use with insoluble anodes and direct current (DC) rectification. The copper through-hole fill chemistry is formulated to operate over a broad range of operating conditions, and offers end- users outstanding production flexibility in ei- ther panel or pattern plate operating mode. The paper addresses electrolytic copper through-hole filling performance for a variety of substrate thicknesses and hole diameters. The impact of the hole formation method and hole quality on filling ratio and void formation will be discussed. In this work, production scale tests were performed on 100 μm and 200 μm thick substrates. The impacts of varying current density and solution flow on hole filling were examined. With optimized deposition condi- FEaturE