Embedded Stress Absorber Layout for Package Corner Cracking
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Solution Overview
Problem
Existing integrated circuit packages face challenges in managing stress due to differences in thermal expansion coefficients between device dies and package components, leading to encapsulant cracking and delamination.
Innovation Solution
Incorporating stress absorbers with a lower Young's modulus than the encapsulant, positioned near the corners of the package, to absorb stress generated by thermal expansion differences, using materials like epoxy-based resins with filler particles to enhance viscosity and stress absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stress absorbers with lower Young's modulus are incorporated into the package, then stress levels are reduced and encapsulant cracking is minimized, but device complexity increases
Solution Approach 1:
Stress absorbers are positioned at specific locations (corners and edges) of the package before the encapsulant is applied. These stress absorbers are pre-placed to intercept and absorb thermal expansion stresses before they can propagate through the encapsulant, preventing cracking and delamination in advance
Solution Approach 2:
Stress absorbers are strategically positioned at corners and edges of the package where stress concentration occurs due to thermal expansion differences. This localized placement targets the specific regions most susceptible to cracking, providing enhanced protection where it is most needed rather than uniformly throughout the entire package
2Reliability
If stress absorbers are positioned near package corners, then stress absorption effectiveness is improved, but manufacturing precision requirements increase
Solution Approach 1:
The stress absorbers are positioned on the package component surface before the encapsulant is applied, allowing for pre-placement and alignment at corner and edge locations. This preliminary positioning enables accurate placement at stress-critical areas before the encapsulant process begins
Solution Approach 2:
The package is divided into critical stress zones (corners and edges) and non-critical zones. Stress absorbers are selectively placed only at the critical corner and edge locations where thermal expansion stresses concentrate, rather than uniformly distributing them across the entire package surface
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
Reduces stress levels by up to 62% and minimizes encapsulant cracking and delamination, while maintaining moisture resistance and structural integrity.
Implementation Method 1
Stress absorbers are also molded in the encapsulant, and are located close to the corners of the resulting package. The stress absorbers may have a Young's modulus lower than the Young's modulus of the encapsulant, so that it may absorb the stress generated due to the difference between the device die and the underlying package components
Data Source
AI summary
A method includes bonding a first package component over a second package component. The second package component includes a plurality of dielectric layers, and a plurality of redistribution lines in the plurality of dielectric layers. The method further includes dispensing a stress absorber on the second package component, curing the stress absorber, and forming an encapsulant on the second package component and the stress absorber.