Chip Package Underfill Cut Regions for Crack Resistance
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Solution Overview
Problem
Cracks form in the underfill material and microbump underfill material during handling and use of fan-out wafer level packages due to mechanical and thermal stress, affecting semiconductor dies, solder material portions, and dielectric layers.
Innovation Solution
The formation of cut regions in the underfill material using milling or laser ablation techniques, combined with an epoxy molding compound to enhance structural integrity and reduce delamination risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the underfill material is used to fill interfaces in fan-out wafer level packages, then mechanical stress and thermal expansion are managed, but cracks form in the underfill material and microbump underfill material during handling and use
Solution Approach 1:
The underfill material is segmented by forming cut regions that divide it into multiple sections. These cut regions act as stress relief zones that prevent crack propagation through the entire structure, while still maintaining adequate mechanical support and thermal management in each segment
Solution Approach 2:
Material is extracted by removing portions of the underfill material to create cut regions. This extraction creates deliberate voids or reduced-density zones that interrupt stress pathways and prevent crack formation, while the remaining underfill material continues to provide necessary mechanical and thermal functions
2Reliability
If milling or laser ablation is used to form cut regions in underfill material, then crack propagation is prevented, but manufacturing complexity increases
Solution Approach 1:
The mechanical milling process is replaced with laser ablation technology. The laser system uses focused light energy to precisely remove underfill material and create cut regions without mechanical contact, reducing tool wear, contamination, and process complexity while maintaining precise control over cut geometry
3Strength
If the underfill material contacts both redistribution structure and semiconductor die, then mechanical support is provided, but delamination occurs under mechanical and thermal stress
Solution Approach 1:
The continuous underfill material contact path is segmented by introducing cut regions that break up the stress transmission pathways. This segmentation prevents delamination by stopping crack propagation at the cut regions while maintaining local mechanical support where the underfill material remains intact
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
Enhances resistance to crack generation in microbump underfill material, minimizing delamination and maintaining structural integrity of semiconductor packages under mechanical and thermal stress.
Implementation Method 1
the formation of cut regions in the underfill material using milling or laser ablation techniques
Data Source
AI summary
Devices and method for forming a chip package structure including at least one semiconductor die attached to a redistribution structure, a molding compound die frame laterally surrounding the at least one semiconductor die, and a first underfill material portion located between the redistribution structure and the at least one semiconductor die and contacting sidewalls of the at least one semiconductor die and sidewalls of the molding compound die frame. The first underfill material portion may include at least one cut region, in which the first underfill material portion may include a vertically-extending portion having a uniform lateral width and a horizontally-extending portion having a uniform vertical thickness and adjoined to a bottom end of the vertically-extending portion within each of the at least one cut region.