Semiconductor Package Underfill Structure for Heat-Cycle Fatigue
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Solution Overview
Problem
Existing semiconductor device assembly technologies face challenges such as separation and breakage of semiconductor device packages from support structures due to forces, deterioration of additional components over time, and thermo-mechanical fatigue leading to cracking or separation during heat cycling.
Innovation Solution
The implementation of an underfill structure on a support structure to at least partially support a semiconductor device package, which includes a patterned attach layer with gaps between attach structures and a dam structure to contain the underfill material, providing structural support and improving thermal and mechanical durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a semiconductor device package is mounted directly onto a support structure without additional components, then the device complexity is reduced, but the reliability deteriorates due to separation and breakage under thermal and mechanical stress
Solution Approach 1:
An underfill structure is introduced as an intermediary material between the semiconductor device package and the support structure. This underfill material fills the gap and provides mechanical support, preventing separation and breakage while maintaining a relatively simple overall structure. The underfill acts as a mediator that absorbs thermal expansion differences and mechanical stresses, thereby improving bonding reliability without significantly increasing device complexity.
2Reliability
If additional components are added to improve bonding reliability, then the reliability improves, but the device complexity increases
Solution Approach 1:
Instead of adding multiple additional components throughout the structure, the underfill material is applied locally in the gap region between the semiconductor device package and the support structure. This localized approach provides the necessary mechanical support and stress relief only where needed, improving bonding reliability while minimizing the increase in overall device complexity.
3Strength
If a continuous attach layer is used to bond the semiconductor device package to the support structure, then the bonding strength is improved, but the thermo-mechanical fatigue resistance deteriorates due to cracking during heat cycling
Solution Approach 1:
The attach layer is segmented into discrete attach structures rather than forming a continuous layer. This segmentation allows the attach structures to move independently under thermal expansion and contraction, preventing the propagation of cracks that would occur in a continuous layer. The gaps between attach structures act as stress relief zones, maintaining bonding strength while improving fatigue resistance during heat cycling.
4Length of moving object
If the attach layer is made thinner to reduce device height, then the device height is reduced, but the bonding strength deteriorates under thermal and mechanical stress
Solution Approach 1:
The bonding system uses a composite structure combining the attach layer with the underfill material. The attach layer provides initial bonding strength, while the underfill material provides additional mechanical support and stress distribution. This composite approach allows for a thinner overall structure while maintaining or even improving bonding strength under thermal and mechanical stress conditions.
Data Source
AI summary
Power semiconductor device assemblies are provided. In one example, a power semiconductor device assembly includes a semiconductor device package with one or more terminals. The semiconductor device package comprises one or more wide bandgap semiconductor die. The power semiconductor device assembly includes a support structure. The semiconductor device package is mounted onto the support structure. The power semiconductor device assembly includes an underfill structure. The underfill structure is at least partially on the support structure and the semiconductor device package.