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46 PCB007 MAGAZINE I DECEMBER 2023 In a previous column on the fundamentals of electrolytic copper plating of printed circuit boards, the subject matter covered the general function of organic addition agents and the role of these additives on the grain structure, plating uniformity, and physical properties of the subsequent copper deposit. Here, I will explore the many other critical plating parameters that influence throwing power, copper deposit thickness, and metal- lurgical properties. In a future column, I will explore the additives and their functionality in more detail. Key Plating Parameters It is important to recognize and understand that these parameters can be controlled. First and foremost, the process engineering team must have a control plan in place to ensure these parameters remain in a tight operating window. ese key parameters are listed in Table 1. It is not only about the organic addition agents. Many other factors play significant roles. All the factors shown in Table 1 can be controlled or manipulated by the fabricator with the exception of the overall circuit board design (the circuit pattern) and the aspect ratio. With respect to the former, the fabrica- tor can work with the circuit board designer to alter the design, if plausible, to enhance the overall manufacturability of the circuit board (also known as DFM). Aspect ratio (the thick- ness of the circuit board divided by the diame- ter of the via) is not as simple. e aspect ratio is determined by how many layers the board will have, along with the dielectric thickness of each layer as designed, as well as the diame- ter of the via (Figure 1). e higher the aspect ratio, the more difficult it will be to achieve optimal throwing power. rowing power is defined as the thickness of the plated copper on the surface divided by the plating thickness in the center of the hole. Electrolytic Copper Plating, Part 5 Trouble in Your Tank by Michael Carano, IPC CONSULTANT Table 1: Key parameters for the process engineering team.