Edge-Sealed Barrier Films for Moisture Diffusion Control
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Solution Overview
Problem
Multilayer, thin film barrier composites face issues with lateral moisture and gas diffusion at their edges, compromising the encapsulation of environmentally sensitive devices, as the polymer layers deposited over the substrate expose edges to contaminants, leading to finite diffusion rates that eventually compromise the encapsulation.
Innovation Solution
The implementation of edge-sealed barrier film composites, where a decoupling layer is deposited using a thermal gradient adjacent to the environmentally sensitive device, and a barrier layer with an area greater than the decoupling layer is applied to seal the edges, preventing ambient moisture, oxygen, and contaminants from diffusing to the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymer layers are deposited over the entire surface of the substrate, then the edges of the polymer layers are exposed to oxygen, moisture, and other contaminants, but this allows lateral diffusion of contaminants into the encapsulated device
Solution Approach 1:
The barrier composite is segmented into multiple alternating layers of barrier material and polymer material, creating a multilayer structure. This segmentation provides multiple diffusion paths and reduces the permeability of the overall structure, while the barrier layers specifically address the edge diffusion problem by providing low-permeability paths at the edges of the polymer layers.
Solution Approach 2:
Different layers in the composite serve different local functions: barrier layers (such as aluminum oxide, silicon oxide, or nitrogen-doped carbon) provide low permeability to moisture and oxygen at critical edge regions, while polymer layers provide structural support and moisture barrier in the center regions. This local differentiation of material properties optimizes the overall barrier performance.
2Object-affected harmful factors
If long edge diffusion paths are provided to reduce lateral diffusion, then the area of the substrate usable for active environmentally sensitive devices decreases
Solution Approach 1:
The barrier structure is segmented into alternating thin layers rather than using a single thick barrier layer. This allows the barrier to be effective with minimal lateral extension, preserving usable substrate area while still providing sufficient diffusion path length through the vertical stacking of multiple layers.
Solution Approach 2:
Instead of extending the barrier laterally in the horizontal plane (which would reduce usable area), the solution adds vertical dimensionality by stacking multiple alternating barrier and polymer layers. This creates diffusion paths in the vertical dimension while maintaining a compact lateral footprint, thus preserving usable substrate area.
3Ease of manufacture
If a multilayer barrier composite is scribed and separated to create individual components, then edge diffusion problems arise at the cut edges
Solution Approach 1:
The barrier layers are deposited to extend beyond the edges of the polymer layers before any scribing or separation occurs. This preliminary extension creates an inherent edge seal that protects against diffusion at cut edges, ensuring reliability is maintained even after the composite is separated into individual components.
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 significantly reduces oxygen and water vapor transmission rates, providing a barrier that is several orders of magnitude better than traditional coatings, ensuring the encapsulation integrity by preventing edge diffusion and maintaining device performance over extended periods at high humidity and temperature conditions.
Implementation Method 1
depositing a decoupling layer using a thermal gradient, the decoupling layer adjacent to the environmentally sensitive device
Implementation Method 2
a barrier layer with an area greater than the decoupling layer is applied to seal the edges, preventing ambient moisture, oxygen, and contaminants from diffusing to the device
Data Source
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AI summary
A method of making an edge-sealed, encapsulated environmentally sensitive device comprising: providing an environmentally sensitive device on a substrate; depositing a polymeric decoupling layer using a thermal gradient, the polymeric decoupling layer adjacent to the environmentally sensitive device, the polymeric decoupling layer having a discrete area and covering the environmentally sensitive device; and depositing a first barrier layer adjacent to the polymeric decoupling layer, the first barrier layer having an area greater than the discrete area of the polymeric decoupling layer and covering the polymeric decoupling layer, the polymeric decoupling layer being sealed between the edges of the first barrier layer and the substrate or an optional second barrier layer.