Dam Structures Encircling Air Gaps in PoP Packages
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Solution Overview
Problem
Conventional package-on-package (PoP) processes face challenges in effectively managing thermal insulation and optimizing the integration of packages, as existing methods do not adequately address the thermal dissipation between stacked dies and the structural integrity of the bonded packages.
Innovation Solution
The implementation of a dam structure encircling an air gap between the top and bottom packages, where the dam is formed over the device die and made of low thermal conductivity materials, allowing for the creation of a thermal insulation layer that separates the dies and optimizes the bonding process by preventing the filling of molding material into the air gap, thus maintaining air pressure balance and thermal insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If molding material is filled into the space between top package and bottom package, then structural integrity is improved, but thermal insulation between dies deteriorates
Solution Approach 1:
The space between top and bottom packages is segmented into two regions: an air gap region for thermal insulation and a molding material region for structural integrity. The dam structure divides the cavity to prevent molding material from entering the air gap region, allowing simultaneous achievement of thermal insulation and structural strength.
Solution Approach 2:
The dam structure acts as an intermediary element that separates the air gap region from the molding material region. This mediator prevents direct contact between molding material and the air gap, enabling the coexistence of thermal insulation (air gap) and structural integrity (molding material) in the same package assembly.
2Adaptability or versatility
If packages are bonded tightly together, then integration level is improved, but thermal dissipation deteriorates
Solution Approach 1:
The package assembly is segmented to include a dedicated air gap region that provides thermal insulation while maintaining the bonded integration of top and bottom packages. The dam structure enables this segmentation by preventing molding material from filling the entire space, thus preserving thermal dissipation pathways.
3Ease of manufacture
If air gap is completely filled with molding material, then manufacturing simplicity is improved, but thermal management deteriorates
Solution Approach 1:
The air gap region is extracted from the molding material filling process by using the dam structure to prevent molding material from entering this specific region. This selective extraction allows the majority of the space to be filled with molding material for structural integrity while preserving the air gap for thermal management.
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 thermal insulation between stacked dies, reduces heat dissipation to adjacent dies, and maintains structural integrity by optimizing the bonding process and air gap formation, effectively addressing thermal management and integration challenges in PoP structures.
Implementation Method 1
enhances thermal insulation between stacked dies, reduces heat dissipation to adjacent dies
Data Source
AI summary
A device includes a bottom package component that includes a bottom die, and a dam over a top surface of the bottom die. The dam has a plurality of sides forming a partial ring, with an air gap surrounded by the plurality of side portions. The air gap overlaps the bottom die. A top package component is bonded to the bottom package component, wherein the air gap separates a bottom surface of the top package component from the bottom die.