Semiconductor Die Fillet Barrier for Underfill Flow Control
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Solution Overview
Problem
Electrical devices face issues with unwanted spreading of underfill materials and large keep-out zones, which increase package sizes and complexity, restrict design, and impact throughput in semiconductor package technologies.
Innovation Solution
A method involving the use of a thixotropic fillet material and a low-viscosity underfill material, where the fillet material is dispensed at the edges of semiconductor dies before underfill material, reducing unwanted spreading and keep-out zones by forming a barrier that constrains underfill flow and minimizes material volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If underfill material is dispensed to fill the gap between semiconductor die and carrier, then the gap is filled and structural support is provided, but the underfill material spreads uncontrollably creating large keep-out zones
Solution Approach 1:
The patent segments the gap-filling function into two separate materials: underfill material for filling the gap and fillet material for forming the barrier. This segmentation allows each material to be optimized for its specific function, preventing the underfill from spreading while maintaining reliable gap filling.
Solution Approach 2:
The fillet material acts as an intermediary barrier between the underfill material and the external environment. By dispensing the fillet material first at the edges, it creates a containment structure that mediates and controls the underfill material's behavior, preventing unwanted spreading.
2Manufacturing precision
If multiple dispensing processes are used for underfill and fillet materials, then material constraints are satisfied, but manufacturing complexity and process time increase
Solution Approach 1:
The fillet material is dispensed in advance before the underfill material. This preliminary action creates the barrier structure needed to control underfill spreading, allowing the subsequent underfill dispensing to be simpler and more controlled.
Solution Approach 2:
The patent changes the viscosity parameter by using a low-viscosity underfill material that can be easily dispensed and controlled within the constrained space defined by the fillet barrier, while the fillet material has higher viscosity to maintain its barrier shape.
3Productivity
If underfill material viscosity is reduced for better flow, then gap filling improves, but material spreads beyond intended areas
Solution Approach 1:
The patent converts the potential harm of low-viscosity material spreading into a benefit by first creating a physical barrier with the fillet material. The low-viscosity underfill material's natural flow tendency is redirected and contained by the fillet barrier, transforming what would be harmful spreading into beneficial complete gap filling.
Solution Approach 2:
The patent applies different material properties to different locations: the fillet material with higher viscosity and barrier-forming properties is placed at the edges where containment is needed, while the underfill material with low viscosity for efficient flow is placed in the gap area where filling is needed.
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
This approach reduces underfill material volumes and keep-out zone sizes, leading to smaller electrical device sizes, simplified package design, and improved throughput by decoupling the material properties for underfill and fillet requirements.
Implementation Method 1
A method involving the use of a thixotropic fillet material and a low-viscosity underfill material, where the fillet material is dispensed at the edges of semiconductor dies before underfill material
Data Source
AI summary
A method for forming an electrical device includes attaching a semiconductor die on a carrier. The method further includes dispensing a fillet material at at least one edge of the semiconductor die arranged on the carrier. The method further includes dispensing an underfill material into a gap between the semiconductor die and the carrier after dispensing the fillet material.