COB LED Layout With Insulating Substrate for Dense Light Emission
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Solution Overview
Problem
Conventional high voltage chip on board (COB) light sources face challenges in reducing the light-emitting area and achieving effective thermoelectric separation due to the spacing requirements of LED vertical chips and limitations in packaging.
Innovation Solution
A light-emitting device with a lead frame and insulating substrate, where light-emitting units are formed on the substrate and connected via electrodes and bonding wires to a patterned conductive layer, allowing for reduced spacing between units and improved heat dissipation through the insulating substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LED vertical chips are spaced apart by at least 50 μm for electrical isolation, then electrical isolation is achieved, but the total light-emitting area cannot be reduced
Solution Approach 1:
The patent introduces an insulating substrate as an intermediary between adjacent LED chips. This insulating substrate provides electrical isolation through its material properties rather than requiring large physical spacing, allowing chips to be positioned closer together while maintaining proper electrical isolation.
Solution Approach 2:
The patent transitions from achieving electrical isolation through horizontal spacing (2D approach) to achieving it through vertical layering with insulating substrates (3D approach). This dimensional change allows reduced footprint while maintaining isolation requirements.
2Ease of manufacture
If conventional packaging methods are used for COB light sources, then manufacturing is simplified, but thermoelectric separation is difficult to achieve
Solution Approach 1:
The patent segments the packaging structure into distinct functional layers: insulating substrate layer, heat dissipation layer, and electrical connection layer. This segmentation allows each layer to specialize in its function, with the heat dissipation layer specifically designed to conduct heat away from the LED chips while the insulating substrate provides electrical isolation.
Solution Approach 2:
The patent employs composite material structures combining insulating materials and thermally conductive materials in specific configurations. The insulating substrate uses materials with low thermal conductivity for electrical isolation, while the heat dissipation layer uses materials with high thermal conductivity for heat removal, creating a composite packaging structure that addresses both electrical and thermal requirements.
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 configuration enhances optical power density and facilitates effective thermoelectric separation, enabling operation under high current density while minimizing the light-emitting area.
Implementation Method 1
an insulating substrate, wherein the insulating substrate is formed on the first surface of the lead frame
Implementation Method 2
improved heat dissipation through the insulating substrate
Implementation Method 3
Each of the bonding wires is disposed to electrically connect a respective one of the first electrode and the second electrode to the patterned conductive layer
Implementation Method 4
Each of the light-emitting units includes a first semiconductor layer, an active layer and a second semiconductor layer that are sequentially disposed on the insulating substrate in such order
Data Source
AI summary
A light-emitting device includes a lead frame having a first surface on which a patterned conductive layer is provided, and a light-emitting element. The light-emitting element includes an insulating substrate formed on the first surface, a plurality of light-emitting units formed on the insulating substrate, at least one first electrode, at least one second electrode and at least a pair of bonding wires. The first and second electrodes are respectively placed in electrical connection with a first one and a second one of the light-emitting units, and are disposed outward of the light-emitting units. Each of the pair of bonding wires is disposed to electrically connect a respective one of the first and second electrodes to the patterned conductive layer.