Composite Dielectric Layer for Fan-Out Package Reliability
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Solution Overview
Problem
The reliability of integrated fan-out packages is compromised due to issues like wrinkle defects and delamination caused by non-uniform solvent evaporation during the formation of composite dielectric layers, leading to rough surfaces and potential connection breakage.
Innovation Solution
A composite dielectric layer is formed using a two-step process with a buffer layer and an auxiliary buffer layer, both spin-coated and cured to ensure uniform solvent evaporation, reducing wrinkle defects and enhancing the smoothness of the surface for subsequent layers, thereby improving the reliability of the package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a single-layer dielectric structure is used to reduce package area, then integration density is improved, but wrinkle defects and delamination occur due to non-uniform solvent evaporation
Solution Approach 1:
The patent divides the composite dielectric layer into multiple sub-layers (first sub-layer and second sub-layer), each with controlled thickness and material properties. This segmentation allows uniform solvent evaporation in each thin layer, preventing wrinkle defects and delamination while achieving the required integration density in the final packaged structure.
Solution Approach 2:
The patent changes the physical and chemical parameters of the dielectric layers by controlling the thickness, material composition, and curing conditions of each sub-layer. By optimizing these parameters, the patent achieves uniform solvent evaporation and prevents defects, thereby improving package reliability without increasing area.
2Manufacturing precision
If composite dielectric layers are formed with multiple spin-coating steps, then surface smoothness is improved, but manufacturing complexity increases
Solution Approach 1:
The manufacturing process is segmented into multiple spin-coating steps, where each step forms a thin sub-layer with controlled thickness. This segmentation ensures uniform solvent evaporation and smooth surface formation in each layer, while the modular nature of the process allows for systematic control and optimization.
Solution Approach 2:
The patent optimizes process parameters such as spin-coating speed, solvent composition, and curing temperature for each sub-layer formation step. By carefully controlling these parameters, the patent achieves consistent surface smoothness across multiple layers while maintaining manufacturing efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution significantly reduces wrinkle defects from 100% to 0%, ensuring the reliability of the integrated fan-out packages by maintaining a smooth surface for conductive patterns and dielectric layers, preventing delamination, and enhancing the mechanical properties of the buffer layer.
Implementation Method 1
uniform solvent evaporation
Data Source
AI summary
A package includes a first redistribution structure, a die, a plurality of conductive structures, an encapsulant, and a second redistribution structure. The first redistribution structure includes a composite dielectric layer, a plurality of under bump metallization patterns, a dielectric layer, and a plurality of conductive patterns. The composite dielectric layer includes a first sub-layer and a second sub-layer stacked on the first sub-layer. The under bump metallization patterns are over the first sub-layer and penetrate through the composite dielectric layer. The dielectric layer is disposed on the second sub-layer of the composite dielectric layer. The conductive patterns are embedded in the dielectric layer. The die and the conductive structures are on the first redistribution structure. The encapsulant encapsulates the die and the conductive structures. The second redistribution structure is over the conductive structures, the encapsulant, and the die.