Quantitative analysis of the interface strength of ultra-thin dielectric films based on fan-out packaging

With the rapid development of fan-out packaging, the interconnect density and complexity of redistribution layers (RDL) have increased. As a commonly used dielectric layer in RDL, it is necessary to assess the interface strength between photosensitive polyimide (PI) and other key packaging materials. Lower interface strength can lead to reliability issues such as PI delamination and PI dielectric cracking. To mitigate these risks during the material selection stage, three types of photosensitive polyimide (PSPI) were chosen for interface strength characterization. In this study, the interface strength PI/SiO 2 and PI/Cu were evaluated using peeling test, shear test, and pull test, respectively. In addition, some shear test specimens were also treated for reliability to investigate the long-term reliability of PI films. The experimental results show that the adhesive strength of negative photosensitive is higher than that of positive polyimide. Among them, PI 1 shows the best adhesion, with an average shear strength of 174.192MPa and a tensile strength exceeding 112MPa. After UHAST accelerated aging, most of the specimens showed a decrease in shear strength, with the PI/Cu interface exhibiting a more significant decline.