A Simplified Method for Analyzing PCB Warpage During Reflow: Focusing on Warpage Change and Initial Warpage Shape

Printed circuit boards (PCBs) often experience warpage during reflow soldering due to thermal stresses. This study presents a simplified approach to analyze PCB warpage by focusing on warpage change instead of absolute warpage. Absolute warpage is difficult to simulate accurately due to challenges in defining temperature loads, boundary conditions, and the zero stress-strain temperature. Warpage change, which compares warpage at elevated temperatures (e.g., $150~^{\circ }$ C) with a baseline ( $30~^{\circ }$ C), isolates thermal deformation and simplifies the simulation process. The study also introduces an image processing method to accurately identify the Cu distribution in each PCB layer, which is critical for determining material properties. Using finite element method (FEM) and incorporating both Cu distribution and initial warpage, this method provides more consistent and reliable warpage predictions. Simulation and experimental results demonstrate that warpage change is a more effective metric for evaluating PCB thermal deformation, offering valuable insights for improving PCB design and manufacturing.