Wavelength Converting Material Deposition on LED Bond Pads
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Solution Overview
Problem
Existing methods for patterning wavelength-converting materials on light-emitting devices, such as LEDs, face challenges in precision and accuracy, particularly in avoiding deposition on electrically conductive bond pads, leading to inefficiencies and light scattering due to the use of micro-voids and discontinuities in the coating layer.
Innovation Solution
A method involving the use of a mask material, like photoresist, to pattern the wavelength-converting material over a substrate, followed by grinding to remove excess material and expose underlying conductive regions, allowing for precise control over the coating thickness and uniformity without micro-voids or discontinuities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If wavelength-converting material is deposited over the entire substrate surface, then complete coverage is achieved, but light scattering increases and luminous efficacy decreases due to deposition on conductive bond pads
Solution Approach 1:
The substrate surface is segmented into distinct regions: emission surfaces where wavelength-converting material is deposited, and conductive bond pad areas where material is excluded. This segmentation allows selective deposition that prevents light scattering from conductive regions while maintaining complete coverage of emission areas, thereby improving luminous efficacy without sacrificing coverage.
2Loss of energy
If conventional patterning methods are used to avoid depositing on bond pads, then light scattering is reduced, but manufacturing precision and accuracy deteriorate due to micro-voids and discontinuities in the coating layer
Solution Approach 1:
A mask layer is introduced as an intermediary element during the deposition process. The mask layer temporarily covers conductive bond pad regions, preventing wavelength-converting material from depositing on these areas. After deposition, the mask layer is removed. This intermediary approach enables precise spatial control of material deposition without creating micro-voids or discontinuities in the wavelength-converting material layer, maintaining both uniformity and accuracy.
3Temperature
If the wavelength-converting material layer is made thicker to improve color conversion, then color temperature control is enhanced, but light scattering increases due to material discontinuities
Solution Approach 1:
The deposition process utilizes a slurry suspension system where wavelength-converting material particles are suspended in a liquid carrier. This hydraulic approach allows the slurry to flow uniformly across the substrate surface and fill in potential voids, creating a dense, continuous material layer. The uniform distribution of particles throughout the thickness of the layer enhances color temperature control while eliminating light scattering from discontinuities.
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 approach enables precise patterning of wavelength-converting materials, reducing light scattering and improving luminous efficacy by ensuring the wavelength-converting material only covers emission surfaces while leaving conductive areas accessible, allowing for controlled color temperature and uniform thickness across the device.
Implementation Method 1
Regions comprising wavelength-converting materials can absorb light having a first wavelength from a light-generating region (e.g., semiconductor region within an LED) and emit light having a second, different wavelength
Data Source
AI summary
Systems and methods related to the arrangement of regions containing wavelength-converting materials, and associated articles, are provided.