Semiconductor Package Structure With Dummy Bars for Void-Free Underfill
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Three-dimensional integrated circuits (3DICs) face challenges related to voids or cavities between the circuit substrate and the redistribution layer, which affect yield and process cost, particularly in the fabrication of semiconductor packages with stacked semiconductor dies.
Innovation Solution
Incorporation of dummy bars between the circuit substrate and the redistribution layer, encapsulated by underfill, to provide capillary force for smoother underfill filling, reducing voids and cavities, and optimizing process cost and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional packaging techniques are used without dummy bars, then the fabrication process is simpler, but voids or cavities form between the circuit substrate and redistribution layer, reducing yield
Solution Approach 1:
Dummy bars are formed in advance before underfill dispensing. These pre-formed structures serve as capillary channels that guide the underfill material flow, ensuring complete filling of the gap between the circuit substrate and redistribution layer before the bonding process completes, thereby preventing void formation.
Solution Approach 2:
The dummy bars act as intermediary structures that facilitate the underfill material's capillary flow. These temporary structures mediate between the underfill dispensing process and the final void-free bonding interface, enabling smooth material distribution throughout the gap.
2Manufacturing precision
If dummy bars are added to provide capillary force for underfill filling, then voids and cavities are reduced, but the device structure becomes more complex
Solution Approach 1:
The dummy bars are designed with porous or channel-like internal structures that exploit capillary action. These porous structures provide multiple flow paths for the underfill material, ensuring uniform distribution and complete filling of the gap between bonding layers through capillary forces rather than relying solely on external pressure.
3Productivity
If dummy bars are incorporated into the package structure, then yield is improved through better underfill filling, but additional fabrication steps are required
Solution Approach 1:
The formation of dummy bars is merged with existing fabrication processes such as photolithography or additive manufacturing steps already present in the package assembly line. By integrating dummy bar creation into these existing workflows rather than adding completely separate processes, the yield improvement is achieved with minimal disruption to the overall manufacturing simplicity.
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 use of dummy bars enhances the yield of the package structure by ensuring smoother underfill filling, thereby reducing defects and improving the overall fabrication process efficiency.
Implementation Method 1
the dummy bars provide capillary force for the underfill, which may be filled between the circuit substrate and the redistribution layer more smoothly
Data Source
AI summary
A package structure is provided. The package structure includes a circuit substrate and a redistribution layer over the circuit substrate. The package structure includes an interconnect chip disposed between the circuit substrate and the redistribution layer. The package structure includes a plurality of conductive connectors around the interconnect chip. The package structure includes a plurality of dummy bars between the interconnect chip and the conductive connectors. The dummy bars are electrically insulated from the conductive connectors. The package structure also includes an underfill disposed between the circuit substrate and the redistribution layer and encapsulating the interconnect chip, the dummy bars and the conductive connectors.