Flip-Chip LED Reflection Layer Layout for Wide-Angle Light Spreading
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Solution Overview
Problem
Flip chip type light emitting diodes experience significant light loss due to the use of metal reflection layers, which also affect their reflectivity over time, and emit light upward causing spot phenomena on display surfaces.
Innovation Solution
A flip chip type light emitting diode chip design featuring a substrate with a first and second insulating reflection layer, including a distributed Bragg reflector, that spreads light without a diffusion plate, reducing light loss and improving luminous efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a metal reflection layer is used to achieve both light reflection and electrical connection, then both functions are accomplished simultaneously, but light loss increases due to insufficient reflectivity
Solution Approach 1:
The invention separates the metal reflection layer into two distinct functional layers: a dielectric reflection layer (first insulating reflection layer) for light reflection and a separate metal layer (second insulating reflection layer or contact electrode) for electrical connection. This segmentation allows each layer to optimize its specific function without compromising the other, achieving high reflectivity while maintaining electrical conductivity.
Solution Approach 2:
The dielectric reflection layer acts as an intermediary between the light emission source and the metal electrical connection layer. This intermediate layer enables the metal to perform its electrical function without directly interfering with light reflection, thereby reducing light loss while maintaining electrical connectivity.
2Ease of operation
If a diffusion plate or filter is disposed on the light emitting diode to spread light, then the spot phenomenon is prevented, but optical loss occurs
Solution Approach 1:
Instead of using a diffusion plate that adds optical components in the light path, the invention utilizes the substrate's geometric dimensions and the angular distribution of light emission. By controlling the viewing angle through the substrate's major and minor axes, light is spread across the display surface without requiring additional optical elements that would cause optical loss.
Solution Approach 2:
The invention changes the parameter of light emission by controlling the viewing angle characteristics through the substrate geometry and reflection layer configuration. This allows light to be distributed more evenly across the display surface without the need for diffusion plates or filters, thereby preventing spot phenomena while minimizing optical loss.
3Adaptability or versatility
If a metal reflection layer is used for light reflection, then electrical connection is achieved, but reflectivity decreases over extended usage time
Solution Approach 1:
The invention segments the reflection and electrical connection functions into separate layers. The dielectric reflection layer maintains stable reflectivity over time as it is not subject to oxidation or degradation, while the separate metal layer provides electrical connection. This segmentation ensures long-term reliability of both functions independently.
Solution Approach 2:
The invention uses a composite structure combining dielectric materials for reflection and metal materials for electrical connection. This composite approach leverages the advantages of each material type: dielectric materials provide stable, durable reflection properties, while metals provide reliable electrical conductivity, together creating a system with enhanced long-term reliability.
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 design achieves wide-area light spreading, reduces light loss, and enhances viewing angles by utilizing insulating reflection layers, resulting in a structurally simple and reliable light emitting diode chip.
Implementation Method 1
a first and second insulating reflection layer, including a distributed Bragg reflector
Implementation Method 2
utilizing insulating reflection layers, resulting in a structurally simple and reliable light emitting diode chip
Data Source
AI summary
A light emitting device includes a substrate including a roughened surface; a light emitter disposed on the substrate, which includes a first conductivity layer; and a mesa disposed on a partial region of the first conductivity layer. An ohmic electrode can be disposed on the mesa; and a contact electrode can be disposed on the first conductivity layer. The light emitting device further includes a first reflection layer; a first pad electrode and a second pad electrode; and a second reflection layer. The first reflection layer covers at least a portion of the light emitter, the ohmic electrode and the contact electrode. The second reflection layer is disposed on an opposite side of the substrate.