Effective Build-Up Substrate Design for Warpage Reduction and Reliability Enhancement in Advanced Semiconductor Packages

Advanced semiconductor packages have evolved through multilayering and the increased use of dielectric materials, leading to mechanical issues that affect package yield and reliability. This study evaluates the impact of interlayer dielectric materials on the mechanical reliability of package substrates. Ajinomoto Build-up Film ® (ABF) is commonly used as an interlayer dielectric material for package substrates. To enhance mechanical strength, ABF-GCP was developed, featuring a “Glass-Cloth” impregnated dielectric layer and a “Primer” for the semi-additive process (SAP). Specifically, we focused on the warpage behavior and crack propagation suppression effects of the rigid material ABF-GCP. Experiments were conducted using $60 \times 60 ~\text{mm}^{2}$ package substrates with a 4-2-4 design, and the warpage behavior was measured using the shadow moiré, while the mechanical reliability was evaluated through thermal cycle tests. The results confirmed that ABF-GCP effectively suppresses the warpage during heating and the thermal degradation, as well as the crack propagation, thereby enhancing the overall reliability of the package. When stiffeners were used, it was shown that warpage behavior is dominated by the stiffeners, highlighting the importance of matching the Coefficient of Thermal Expansion (CTE) of materials. The use of ABF-GCP stabilizes the warpage behavior, allowing for more advanced implementations and greater flexibility in the component placement. These findings suggest that the appropriate placement of ABF-GCP can significantly improve the long-term durability and reliability of packages.