In contrast, baths designed for high current densities or for via filling will typically have much higher copper concentrations and lower acid concentrations. Baths designed for high PCB through hole throwing power applications will typically have copper sulfate concentrations below 75 g/L and sulfuric acid concentrations above 160 g/L (to provide high solution conductivity to minimize the potential drop across holes). Analysis of Inorganic Components A typical acid sulfate system contains copper sulfate (the primary source of cupric ions), sulfuric acid (for solution conductivity) and chloride ion (as a co-suppressor). This article will therefore focus on methods used with this class of bath. Combining low cost and convenient operation, such acid sulfate based systems have now been used in the PCB industry for over 50 years. Failure to properly control the organic additives can quickly result in inconsistent performance and reduced deposit quality. This paper provides an overview of methods used for copper electroplating bath control, including approaches to organic additive analysis, appropriate for use in PCB manufacturing.The vast majority of copper electroplating baths used in the PCB industry today are based on electrolytes consisting of copper sulfate and sulfuric acid. ![]() Perhaps the most critical aspect of copper electroplating bath control is the monitoring of organic additives. From thick-panel, high-aspect ratio backplanes to fine line HDI via fill applications, modern acid copper electroplating systems have been optimized to offer a variety of customized performance capabilities. Irrespective of the specific application,to allow consistent, predictable and reliable operation, the electroplating process parameters must be controlled within specifications. Maintaining electroplated copper deposit physical properties within specified ranges is critical to ensuring the reliability of PCBs.
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