SSL Die Electrode Layout for Light Extraction and Wirebond Access
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Solution Overview
Problem
Light emitting dies with vertical electrodes face limitations in light extraction efficiency due to buried electrodes, which are not readily accessible and require precise alignment, leading to electrode mismatch and reduced light output.
Innovation Solution
The design incorporates a buried electrode configuration with an opening in the substrate for improved light extraction, where the first electrode is formed within this opening, and the second electrode is exposed and arranged vertically across the SSL structure, allowing for better current distribution and accessibility from the same side as the first electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vertical electrodes are used in light emitting dies, then current spreading is improved, but light extraction efficiency deteriorates due to blocked light paths
Solution Approach 1:
The patent extracts the light-blocking function from the electrode structure by removing the top electrode that blocks light, and placing electrodes only on the bottom surface. This allows light to escape unobstructed while maintaining electrical contact through the bottom electrodes, resolving the contradiction between current spreading and light extraction efficiency.
Solution Approach 2:
The patent transitions from a planar electrode configuration to a three-dimensional structure where electrodes are positioned on the bottom surface and extend vertically along the sidewalls. This dimensional change allows electrodes to provide current spreading pathways without blocking the light extraction path from the top surface.
2Loss of energy
If buried electrodes are used to improve light extraction, then light extraction efficiency is improved, but electrode accessibility and alignment precision deteriorate
Solution Approach 1:
Instead of burying electrodes deep within the structure requiring precise alignment, the patent inverts the approach by placing electrodes on the bottom surface where they are easily accessible. The electrodes extend upward along the sidewalls to provide electrical contact, eliminating the need for precise alignment while maintaining light extraction efficiency.
3Ease of operation
If lateral electrodes are used for accessibility, then electrode accessibility is improved, but light extraction efficiency deteriorates due to electrode blocking
Solution Approach 1:
The patent removes the top electrode that blocks light extraction while maintaining bottom electrode accessibility. This extraction of the light-blocking element resolves the contradiction by allowing both good light extraction and electrode accessibility to coexist.
Solution Approach 2:
The patent moves electrode placement from the top surface (blocking light) to the bottom surface (non-blocking), utilizing the vertical dimension to provide electrode accessibility without interfering with light extraction paths.
Data Source
AI summary
Various embodiments of light emitting dies and solid state lighting (“SSL”) devices with light emitting dies, assemblies, and methods of manufacturing are described herein. In one embodiment, a light emitting die includes an SSL structure configured to emit light in response to an applied electrical voltage, a first electrode carried by the SSL structure, and a second electrode spaced apart from the first electrode of the SSL structure. The first and second electrode are configured to receive the applied electrical voltage. Both the first and second electrodes are accessible from the same side of the SSL structure via wirebonding.