Protective Substrate Cavities for IC Mechanical and Thermal Management
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Solution Overview
Problem
Integrated circuits face challenges in mechanical stress protection, heat dissipation, and warpage issues during fabrication and operation, particularly with thin interposers that are brittle and difficult to handle.
Innovation Solution
A protective substrate with cavities is attached to the wiring substrate, providing mechanical support, thermal conductivity, and pressure to strengthen the die-to-substrate attachment, while allowing for thermal expansion and reducing warpage, and the interposer is initially thick for easier handling before being thinned for shorter signal paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the interposer is made thin to shorten signal paths, then signal transmission efficiency is improved, but mechanical strength and ease of handling deteriorate
Solution Approach 1:
The interposer structure is segmented into multiple functional layers including a first substrate, second substrate, and third substrate, each performing specific functions. This segmentation allows the thin interposer to maintain mechanical integrity while achieving short signal paths through the layered construction.
Solution Approach 2:
The interposer uses composite material construction with multiple substrates and encapsulants. The combination of different materials (substrates with cavities, encapsulants filling spaces) creates a composite structure that provides both mechanical strength and efficient signal transmission pathways.
2Length of moving object
If the interposer is made thin to reduce vertical dimension, then device compactness is improved, but ease of handling and fabrication deteriorate
Solution Approach 1:
The encapsulant is applied in advance to fill the cavities and spaces within the interposer structure before final assembly. This preliminary action of filling cavities with encapsulant provides mechanical support during fabrication and handling, making the thin interposer easier to manufacture despite its reduced vertical dimension.
Solution Approach 2:
The encapsulant acts as a flexible protective shell that conforms to the cavity structures. This flexible encapsulation provides mechanical protection and ease of handling to the thin interposer during fabrication while maintaining the compact vertical dimension.
3Strength
If the protective substrate applies pressure on the die, then mechanical attachment strength is improved, but die warpage and thermal stress increase
Solution Approach 1:
The protective substrate applies pressure locally at specific contact points with the die rather than uniform pressure across the entire die surface. This localized pressure application strengthens the mechanical attachment while allowing other areas to accommodate thermal expansion and contraction, reducing overall warpage and thermal stress.
Solution Approach 2:
The system accommodates parameter changes in the die during operation by allowing controlled movement and deformation. The protective substrate's localized pressure application adapts to thermal expansion and contraction of the die, maintaining attachment strength while preventing excessive warpage through parameter adjustment rather than rigid constraint.
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 solution enhances the mechanical stability and thermal management of integrated circuits, facilitating easier handling and fabrication of thin interposers, while maintaining efficient signal transmission and reducing thermal stresses.
Implementation Method 1
The protective substrate may or may not have its own circuitry connected to the dies or to the wiring substrate
Implementation Method 2
the die or the solid material physically contacts the cavity surface at some but not all operating temperatures (e.g. the physical contact may exist only at higher temperatures at which the die expands)
Data Source
AI summary
Dies (110) with integrated circuits are attached to a wiring substrate (120), possibly an interposer, and are protected by a protective substrate (410) attached to a wiring substrate. The dies are located in cavities in the protective substrate (the dies may protrude out of the cavities). In some embodiments, each cavity surface puts pressure on the die to strengthen the mechanical attachment of the die the wiring substrate, to provide good thermal conductivity between the dies and the ambient (or a heat sink), to counteract the die warpage, and possibly reduce the vertical size. The protective substrate may or may not have its own circuitry connected to the dies or to the wiring substrate. Other features are also provided.