POP IC Package Buffer Layer Thermal Conduction
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Solution Overview
Problem
Package on Package (POP) integrated circuit structures face thermal issues due to heat dissipation and mismatched thermal expansion coefficients from different materials used in combined packages, leading to inefficiencies in heat management and mechanical stability.
Innovation Solution
Incorporation of a buffer layer with good thermal conductivity and the use of stub blocks between packages to absorb stress and enhance thermal management, facilitating heat dissipation and mechanical reinforcement without providing electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple packages are stacked vertically to achieve higher density, then integration density is improved, but thermal management and mechanical stability deteriorate due to heat dissipation issues and mismatched thermal expansion coefficients
Solution Approach 1:
The patent introduces an underfill material as an intermediary substance between the integrated circuit die and the substrate. This underfill material serves as a thermal interface that facilitates heat transfer from the die to the substrate, resolving the thermal management issues caused by direct stacking of packages. The underfill acts as a mediator that bridges the thermal gap between components with different thermal expansion coefficients.
Solution Approach 2:
The patent employs composite material structures in the package assembly, combining materials with different thermal and mechanical properties. The underfill material is a composite that provides both mechanical support and thermal conduction pathways, while the substrate incorporates thermal vias and heat spreaders made of materials optimized for heat dissipation. This composite approach allows the system to achieve both high integration density and effective thermal management.
2Quantity of substance
If multiple packages are stacked vertically to achieve higher density, then integration density is improved, but mechanical stability deteriorates due to mismatched thermal expansion coefficients
Solution Approach 1:
The underfill material serves as a mechanical intermediary that absorbs and distributes thermal expansion stresses between the integrated circuit die and the substrate. By positioning this compliant material between the rigid components, the system can accommodate differential thermal expansion without compromising the mechanical integrity of the stacked package structure.
Solution Approach 2:
The patent modifies the mechanical parameters of the package assembly by introducing materials with specific elastic moduli and thermal expansion coefficients that are intermediate between those of the die and substrate. This parameter matching approach reduces thermal mismatch stresses and improves the overall mechanical stability of the high-density stacked configuration.
3Reliability
If buffer layers and support structures are added to improve thermal conductivity and mechanical strength, then thermal management and structural integrity are improved, but device complexity increases
Solution Approach 1:
The underfill material performs multiple functions simultaneously: it provides mechanical support, facilitates thermal conduction, absorbs thermal expansion stresses, and enables proper die-to-substrate bonding. By consolidating these functions into a single material layer, the patent avoids the need for separate buffer layers and support structures, thereby maintaining device simplicity while achieving improved thermal and mechanical performance.
Solution Approach 2:
The patent merges the functions of thermal management, mechanical support, and stress absorption into a single underfill material system. Additionally, the substrate integrates thermal vias and heat spreader functions directly into its structure. This merging approach eliminates the need for additional discrete thermal management components, reducing overall device complexity while maintaining reliable thermal pathways.
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
The solution achieves improved thermal conductivity and mechanical strength, reducing thermal-related issues and warpage in POP assemblies, while maintaining low profile and signal integrity.
Implementation Method 1
solder bumps between the first integrated circuit package and the second integrated circuit package
Implementation Method 2
mismatched thermal expansion coefficients
Implementation Method 3
stub blocks between packages to absorb stress
Data Source
AI summary
An integrated circuit package assembly includes a first integrated circuit package and a second integrated circuit package. The first integrated circuit package includes a first integrated circuit die mounted on a first substrate. The second integrated circuit package includes a second integrated circuit die mounted on a second substrate. The second integrated circuit package is disposed under the first integrated circuit package. Solder bumps are disposed between the first integrated circuit package and the second integrated circuit package and provide electrical signal connections between the first integrated circuit die and the second integrated circuit die. A buffer layer is disposed between the first substrate and the second integrated circuit die to facilitate thermal conduction between the first integrated circuit package and the second integrated circuit package.