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14 PCB007 MAGAZINE I SEPTEMBER 2025 D R I V I N G I N N OVAT I O N Mastering Panel Warpage by Simon K hesin, S chmoll America During the complex and multi-step process of PCB fabrication, a panel's flatness is constantly at risk. A host of factors can introduce warpage, bending, and unevenness, presenting a fundamental challenge to achieving high-precision results. This deformation (sometimes referred to as "bow and twist"), even on a microscopic scale, can lead to critical defects during subsequent stages, such as component sur- face mounting (e.g., tombstoning, solder opens) and the PCB's long-term functional reliability. The primary reasons for warpage are well known: • Lamination: The application of heat and pressure can cause internal stress • Thermal and chemical processes: The various heating, curing, and chemical etching steps can cause material expansion and contraction • Improper handling: Manual mishandling or improper machine-to-machine transfer can cause mechanical stress to the panel • Imbalanced copper distribution: An asym- metrical distribution of copper layers or a non-symmetrical design can create internal tension, causing the panel to warp • Storage conditions: Inconsistent temperature and humidity can alter the material properties over time While it is critical for manufacturers to minimize warpage through careful process control, it cannot always be fully eliminated. Therefore, a modern PCB production line must be equipped with machinery that can adapt and compensate for these unavoid- able imperfections. In this article, we will explore