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62 PCB007 MAGAZINE I JULY 2025 T he rise of artificial intelli- gence (AI) applications has become a pivotal force driv- ing growth in the server indus- try. Its challenging requirements for high-frequency and high-den- sity computing are leading to an increasing demand for develop- ment of advanced manufactur- ing methods of package sub- strates with finer features, higher hole densities, and denser inter- connects. These requirements are essential for modern multi- layer board (MLB) designs, which play a critical role in AI hardware. However, these intricate designs introduce considerable manufac- turing complexities. The Critical Role of Electrolytic Copper Plating Electrolytic copper plating is a key process in package sub- strate manufacturing, signifi- cantly impacting subsequent stages such as etching. A major challenge in electrolytic plating is ensuring uniform copper dis- tribution across the entire panel, whether in areas with a high density of holes or more iso- lated sections. Such high hole- density regions are integral to Editor's note: The following technical paper, originally titled "Cutting-Edge Pulse Plating Solutions for Uniform Deposition of Copper with Enhanced Reliability in State-of-the-Art Server Technology," was first presented at IPC APEX EXPO 2025's Technical Conference, with original work published within the conference proceedings. T EC H N I CA L PA P E R by D i r k Ru es s a n d M u sta fa O ez ko e k , M KS' Atote c h Advancing Electrolytic Copper Plating for AI-driven Package Substrates ▼ F i g u re 1 : Low - a n d h i g h - d e n s i t y a re a a n d s u r fa c e t h i c k n e s s g a p. modern multilayer board (MLB) designs, despite introducing sev- eral manufacturing complexi- ties. Traditional plating methods often result in inconsistent cop- per thickness across regions with varying hole densities, lead- ing to discrepancies known as the "surface thickness gap." This can lead to inconsistencies in etching and overall circuit per- formance. Moreover, achiev- ing high throwing power is cru- cial to ensure sufficient copper is deposited within through-holes without excessive surface copper. Breakthroughs With Pulse Plating Technology Recent innovations in pulse plating technology, particularly when inte- grated into vertical conveyorized plating systems, are transform- ing the way copper is deposited in high-density package substrates. Pulse plating enables more con- sistent copper distribution, signif- icantly improving surface unifor- mity and throwing power—even in panels with a high concentration of through-holes. This technique is especially valuable in AI-focused applications, where hundreds of