Chip Package Cover With Sidewall Windows For Warpage Resistance
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Solution Overview
Problem
Conventional chip packaging schemes face issues with out-of-plane deformation, leading to warpage and bending, which can cause solder connection failure and reliability issues, especially in larger assemblies, and existing designs do not provide robust enough access to the interior of the chip package.
Innovation Solution
A chip package design featuring a cover with elongated windows through its sidewalls that provides enhanced resistance to warpage while allowing access to the internal volume, allowing for processes like cleaning and encapsulation of the IC die, and ensuring robust attachment to the package substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a cover or tubular stiffener is utilized to stiffen the chip package against out of plane deformation, then the resistance to warpage is improved, but the cover itself may bend or twist or become delaminated, thus still permitting undesirable warpage and bending
Solution Approach 1:
The cover is divided into multiple segments or sections, each providing localized stiffening support. This segmentation allows the cover to maintain structural integrity while distributing stress across multiple points, preventing delamination and bending.
Solution Approach 2:
The cover utilizes composite material construction combining multiple layers with different mechanical properties. This composite structure provides enhanced stiffness and strength while maintaining resistance to delamination and warpage through the synergistic properties of the combined materials.
2Ease of operation
If corner posts are used to space a cover above a substrate to provide access to the interior, then access is provided, but an undesirable amount of warpage is still permitted
Solution Approach 1:
The solution transitions from point-based support (corner posts) to a continuous planar support structure. The cover extends as a continuous surface above the substrate, providing dimensional stability across the entire package while maintaining interior accessibility through controlled openings or transparent sections.
3Strength
If the cover is made more robust to prevent warpage, then warpage resistance is improved, but access to the internal volume becomes more difficult
Solution Approach 1:
The cover design implements local quality by providing robust, opaque, and stiffened regions for structural support while incorporating localized transparent or accessible regions for interior access. This allows different portions of the cover to serve different functions - structural integrity in some areas and accessibility in others.
Solution Approach 2:
Specific portions of the cover are extracted or removed to create access openings, windows, or transparent sections. This extraction allows access to the internal volume while the remaining cover structure maintains its robust warpage-resistant properties in the non-extracted regions.
Data Source
AI summary
A chip package and method for fabricating the same are provided which utilize a cover having one or more windows formed through one or more sidewalls to provide excellent resistance to warpage while allowing access to an internal volume of the chip package. In one example, the chip package includes a package substrate, an integrated circuit (IC) die, and a cover disposed over the IC die. The cover includes a lower surface facing the IC die, an upper surface facing away from the IC die, a lip extending from the lower surface, and a first sidewall extending from a first edge of the upper surface to the bottom of the lip. The lip is secured to the package substrate and encloses a volume between the lower surface and the package substrate. The IC die resides in the volume. A first elongated window is formed through the first sidewall and exposes the volume through the cover.