Issue link: https://iconnect007.uberflip.com/i/1536435
JUNE 2025 I PCB007 MAGAZINE 79 cation. Boards with sparse component place- ment or significant variations in local copper density may encounter uneven plating or etch- ing, which can negatively affect reliability and performance. Copper thieving involves adding "dummy" pads (small copper patterns) onto the outer layers of the PCB to optimize cop- per distribution and balance the high- and low- density areas 3,4 . e main objective of copper thieving is to achieve an even distribution of plating current across the board (Figure 1). During the electroplating process, when the board is submerged in a copper solu- tion, areas with higher copper density tend to absorb more plating current than those with lower density. is uneven distribution causes copper-dense areas to receive less plating, while copper-sparse areas receive more. Copper thieving resolves this by add- ing small copper patterns, which help bal- ance the copper density and bring it closer to the board's overall average. Without proper current density distribu- tion, the plating process can result in several negative effects, particularly for vias. Boards with uneven copper distribution may pro- duce barrel plating that fails to meet qual- ity standards. If undetected, this uneven bar- rel plating can fail during high-temperature processes like solder reflow, leading to costly rework. Additionally, boards with low copper density or thin traces are more vulnerable to issues caused by inconsistent copper distri- bution. ese traces are prone to undercut- ting, where the center of the trace loses more material as the top copper layer dissolves. is results in a cross-sectional shape resembling an anvil, compromising both the structural integrity and electrical performance of the trace. On contrary, by implementing copper thieving and an effective strategy for optimiz- ing copper "dummy" pads placement on the board, the following benefits can be achieved: • Controlled copper thickness: Copper thieving helps balance the copper and dielec- tric percentages across the board's surface • Even plating and etching: It ensures uni- form current density distribution, espe- cially in sparse areas, resulting in consis- tent plating and etching • Reduction of outgassing, delamination, bow, and twist: A uniform copper distribution min- imizes the risk of these issues occurring • Reduced need for excessive etching: is lowers the consumption of chemical solutions and minimizes the frequency of cycled procedures To realize these benefits during the manu- facturing stage, copper thieving should be inte- grated into the PCB design process as part of design for manufacturability (DFM) prac- tices, contributing to the board's plateability analysis (activity similar to conducting signal and power integrity checks, as well as thermal analysis). is step is critical because, in most cases, fabrication (FAB) shops are not autho- rized to modify PCB design-related files. As a result, the responsibility should lie with PCB designers to provide FAB shops with detailed and comprehensive board information, includ- ing considerations for the board's plateability. Currently, plateability checks are not inte- grated into existing EDA solutions. While cop- per thieving can be added in various forms and patterns, these tools lack analysis of its impact on plating current distribution across the board. However, the market now offers a ded- icated, standalone technology with integra- tion options for EDA tools to automate cop- per thieving operations 3 . is advanced tech- nology utilizes the Finite Element Method (FEM) to calculate the optimal thieving (bal- ancing) fraction, representing copper den- sity within each finite element in the desig- nated balancing area. e process's efficiency depends primarily on the PCB design's com- plexity, reducing reliance on manual input from designers. By ensuring balanced cop- per pattern distribution and, therefore, bal- anced plated current distribution, this solu- tion streamlines fabrication and minimizes