Semiconductor Package Corner Dam Structures for Underfill Reliability
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Solution Overview
Problem
The formation of integrated circuits faces challenges in preventing cracking or delamination of underfills at the corners of semiconductor packages due to mismatched coefficients of thermal expansion between the package structure, underfill, and dam structures.
Innovation Solution
The use of dam structures with a thermal expansion coefficient that closely matches the package structure, positioned adjacent to the corners, and embedded within the underfill to minimize the thickness of underfill layers, thereby reducing stress and preventing cracking or delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the underfill is formed between the package structure and substrate without dam structures, then the manufacturing process is simpler, but cracking or delamination occurs at the corners due to mismatched coefficients of thermal expansion
Solution Approach 1:
The patent introduces dam structures as intermediary elements between the underfill and the package structure corners. These dam structures act as a mediator that absorbs and redistributes thermal stress, preventing the direct transmission of stress that causes cracking and delamination. The dam structures are positioned at strategic locations where thermal expansion mismatch creates maximum stress concentration.
Solution Approach 2:
The patent modifies the physical and material parameters of the dam structures, including their composition, height, and positioning, to optimize stress distribution. By changing these parameters, the dam structures can effectively bridge the coefficient of thermal expansion mismatch between the package structure and substrate, preventing corner cracking while maintaining manufacturing feasibility.
2Reliability
If dam structures are positioned close to the package structure, then the underfill layer thickness is minimized and stress is reduced, but the manufacturing precision required increases
Solution Approach 1:
The dam structures are formed and positioned in advance, before the underfill is applied. This preliminary positioning ensures that the dam structures are already in their optimal locations to prevent corner cracking, and the underfill can be applied uniformly without requiring high precision during the underfill formation process itself.
Solution Approach 2:
The dam structures provide localized reinforcement only at the critical corner regions where thermal stress concentration occurs. Rather than requiring high precision throughout the entire package structure, the local quality principle allows manufacturing tolerances to be relaxed in non-critical areas while maintaining high reliability at the specific locations where dam structures are positioned.
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 enhances the long-term reliability of semiconductor packages by minimizing underfill cracking and delamination at the corners, ensuring better structural integrity.
Implementation Method 1
The coefficient of thermal expansion of the package structure matches more closely to that of the dam structures than to that of the underfill
Data Source
AI summary
A semiconductor package including one or more dam structures and the method of forming are provided. A semiconductor package may include an interposer, a semiconductor die bonded to a first side of the interposer, an encapsulant on the first side of the interposer encircling the semiconductor die, a substrate bonded to the a second side of the interposer, an underfill between the interposer and the substrate, and one or more of dam structures on the substrate. The one or more dam structures may be disposed adjacent respective corners of the interposer and may be in direct contact with the underfill. The coefficient of thermal expansion of the one or more of dam structures may be smaller than the coefficient of thermal expansion of the underfill.