Stack Boat Weight Bar for Semiconductor Reflow Warpage

The patent applies preliminary anti-action by placing a weight bar on the semiconductor package before the reflow process to counteract the warpage force that will occur during heating. The weight bar exerts downward pressure to prevent the package from warping upward during thermal expansion, thereby preventing non-wet and short defects before they can occur.

The patent changes physical parameters by introducing a weight bar with specific weight and dimensions to alter the mechanical stress state of the semiconductor package during reflow. The weight bar's mass and contact area are carefully selected to apply sufficient pressure to prevent warpage while avoiding damage to the package structure.

The patent segments the reflow process into distinct stages: placing the weight bar on the package, performing the reflow process with the weight bar in position, and then removing the weight bar after cooling. This segmentation allows the complex task of warpage prevention to be handled as a separate, manageable step rather than requiring complex integrated system modifications.

The weight bar serves as an intermediary object between the semiconductor package and the external environment during reflow. It mediates the thermal and mechanical stresses by providing controlled downward pressure, acting as a simple mechanical mediator that prevents warpage without requiring complex active control systems or modifications to the reflow equipment itself.