Curved WLCSP Interface Reduces Crack Formation
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Solution Overview
Problem
Wafer level chip scale packaging (WLCSP) technologies face challenges with cracks forming between layers of package structures, which can lead to moisture and impurity ingress, affecting the reliability and performance of semiconductor chips.
Innovation Solution
A WLCSP structure with a curved interface surface between the molding compound and protective tape, formed through a specific manufacturing method involving dummy wafers and differential cutting tools, enhances adhesion and reduces crack formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flat interface surface is used between molding compound and protective tape, then the manufacturing process is simple, but cracks are frequently generated between layers
Solution Approach 1:
The interface surface between the molding compound and protective tape is designed with a curved profile instead of a flat surface. This curvature distributes stress more evenly across the interface, preventing crack initiation and propagation that commonly occur at sharp corners or flat interfaces under thermal and mechanical stress.
2Ease of manufacture
If cracks are present between layers, then manufacturing is easier, but moisture and impurities can erode components inside
Solution Approach 1:
The curved interface surface eliminates sharp angles and flat boundaries that serve as stress concentration points and crack initiation sites. By creating a continuous curved transition, the design prevents crack formation that would otherwise allow moisture and impurities to penetrate into the package structure.
3Strength
If a curved interface surface is created, then adhesion between layers is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The curved interface surface increases the surface area and improves stress distribution, enhancing adhesion between the molding compound and protective tape. The curvature creates a more gradual transition zone that allows for better material bonding while reducing stress concentration points.
Solution Approach 2:
The manufacturing process controls the curvature radius and profile of the interface surface as key parameters. By optimizing these geometric parameters, the design achieves improved adhesion strength while managing the complexity of the manufacturing process through precise but achievable geometric specifications.
Data Source
AI summary
A wafer level chip scale package (WLCSP) structure and a manufacturing method are disclosed. The WLCSP structure comprises a semiconductor die and a stack. The stack comprises a protective tape and a molding compound. A portion of a first interface surface between the molding compound and the protective tape is curved. The manufacturing method comprises the steps of forming a semiconductor structure; attaching the semiconductor structure on a dummy wafer; performing a first dicing process using a first cutting tool; depositing a molding compound; removing the dummy wafer; performing a second dicing process with a second cutting tool. A first aperture of the first cutting tool is larger than a second aperture of the second cutting tool. The portion of the first interface surface being curved reduces the possibility of generation of cracks in the WLCSP structure.