Recessed Stiffener Ring Structure for Underfill Delamination Control
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Solution Overview
Problem
The existing semiconductor packaging technologies face challenges in reducing cracking and delamination of underfill materials, which affects the long-term reliability of semiconductor packages, particularly at the corner regions where stress concentrations occur.
Innovation Solution
A semiconductor package design incorporating a recessed stiffener ring with reduced stiffness in the recessed portion is introduced, which encircles the semiconductor dies or packages, reducing stress and preventing cracking and delamination of the underfill.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a stiffener ring is added to support the substrate and reduce warpage, then substrate stability is improved, but stress concentration occurs at corner regions causing underfill cracking and delamination
Solution Approach 1:
The stiffener ring incorporates recessed portions at corner regions with reduced thickness, creating local variations in stiffness. This allows the stiffener ring to provide overall substrate support while reducing stress concentration at critical corner areas where underfill cracking typically occurs, thus resolving the contradiction between substrate stability and underfill reliability
Solution Approach 2:
The stiffener ring is segmented with recessed portions that create distinct regions of different stiffness. This segmentation allows different parts of the stiffener ring to perform different functions: full-stiffness regions provide structural support while recessed regions reduce stress concentration, simultaneously achieving substrate stability and preventing underfill delamination
2Manufacturing precision
If the stiffener ring encircles the package component to provide support, then manufacturing precision is improved, but stress concentration at corners causes underfill delamination
Solution Approach 1:
The stiffener ring features localized recessed portions at corner regions that reduce thickness and stiffness specifically at these high-stress areas. This local modification reduces stress concentration and prevents underfill delamination while maintaining the overall encircling structure that provides manufacturing precision and package alignment
3Shape
If a complete ring structure is used to prevent warpage, then substrate flatness is improved, but cracking and delamination occur at corner regions
Solution Approach 1:
The stiffener ring incorporates recessed portions at corner regions with reduced thickness, creating local variations in mechanical properties. This allows the majority of the ring structure to maintain substrate flatness while the recessed corner regions reduce stress concentration, preventing underfill cracking and delamination
Solution Approach 2:
The continuous ring structure is segmented with recessed portions that create distinct stiffness zones. This segmentation enables the stiffener ring to maintain overall substrate flatness through the majority of its structure while reducing stress concentration at critical corner areas, thus preserving underfill integrity
Data Source
AI summary
A semiconductor package including a recessed stiffener ring and a method of forming are provided. The semiconductor package may include a substrate, a semiconductor die bonded to the substrate, an underfill between the semiconductor die and the substrate, and a stiffener ring attached to the substrate, wherein the stiffener ring encircles the semiconductor die in a top view. The stiffener ring may include a recess that faces the semiconductor die.