Delamination Firewall for Advanced Leadless Packages Through the Curing Process and Staging Time Control

Leadless packages are compact, highly integrated solutions that protect semiconductor devices like integrated circuits (ICs), microcontrollers, and sensors. Their small size and flat design make them ideal for space-constrained and high-performance applications. However, delamination a separation of layers within the package remains a significant challenge. Delamination can occur at material boundaries e.g. between the lead frame and the encapsulant, leading to reduced thermal conductivity, increased electrical resistance, and reducing structural integrity which potentially resulting in device failure. This study examines the factors contributing to delamination in leadless packages, including material characteristics, production methods, and mechanical stresses. It explores mitigation techniques focused on controlling the curing process and staging time. Experiments were conducted to analyze delamination occurrence under applied force after wet processes. Results indicate that moisture trapped within the package creates internal stress, which, when combined with external stress from the cutting process, leads to delamination. Implementing a curing process after the wet stage ensures the dissipation of internal stress. This study also shows that the package absorbs approximately p% moisture at room temperature during staging. Additionally, the ratio of filler to resin in the epoxy molding compound (EMC) significantly influences its moisture absorption properties, with higher resin content typically increasing the moisture intake. Changing the cutting starting point from mold gate area to the mold vent area can reduce the stress at mold gate area which have slightly higher resin. By optimizing staging time, changing cutting direction and the curing process, delamination can be effectively eliminated.