LED Package With Recessed Light Reflecting Portion
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Solution Overview
Problem
Current LED packaging techniques face issues with deformation, high thermal resistance, increased cost, and reduced light collecting efficiency due to differences in expansion factors between molding compounds and substrates, as well as long conductive paths leading to heat absorption and structural weaknesses.
Innovation Solution
A light emitting device design featuring a light emitting element with electrodes on its output surface mounted in a base member with a recess and lead portions for electrical connection, along with a thermal conductor for heat dissipation, and a light reflecting portion to enhance collimated light emission, allowing for a thinner package structure with reduced series thermal resistance and improved light collecting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional packaging techniques with aluminum or ceramic substrates are used, then electrical connection is achieved, but the conductive path becomes very long resulting in high thermal resistance and heat absorption
Solution Approach 1:
The substrate is divided into multiple insulating substrate layers with conductive patterns embedded within. This segmentation allows the conductive path to be distributed across multiple thin layers rather than requiring a single thick substrate, thereby reducing the overall conductive path length and thermal resistance while maintaining electrical connection functionality.
Solution Approach 2:
The conductive path is transitioned from a planar two-dimensional path on the substrate surface to a three-dimensional path embedded within multiple substrate layers. This dimensional change allows for optimized current distribution and reduced path length through vertical stacking of conductive patterns across different layers.
2Ease of manufacture
If molding compound and substrate with different expansion factors are used, then packaging is achieved, but deformation and stripping occur
Solution Approach 1:
The substrate is constructed as a composite structure with multiple insulating substrate layers, each potentially having different material properties. This composite construction allows for tailored thermal expansion characteristics that can better match the molding compound, reducing deformation and stripping issues while maintaining packaging functionality.
3Productivity
If several chip products are applied to the aluminum or ceramic substrate, then production capacity is increased, but the substrate becomes weak requiring preprocessing
Solution Approach 1:
The substrate is segmented into multiple thin insulating substrate layers rather than using a single thick aluminum or ceramic substrate. This layered structure distributes the mechanical stress from multiple chip products more effectively, maintaining substrate strength even when several chips are mounted, thereby enabling increased production capacity without preprocessing.
4Ease of manufacture
If the recess depth is made shallow to facilitate front side processes, then manufacturing is easier, but light collecting efficiency is reduced
Solution Approach 1:
The light guiding function is moved from the vertical dimension (deep recess) to the horizontal dimension through the light guiding structure extending within the substrate. This allows for shallow recess depth that facilitates front side processes while maintaining effective light collection through the extended light guiding path in the substrate plane.
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 solution results in a low-thickness, cost-effective LED package with reduced series thermal resistance and enhanced light collecting efficiency, facilitating easier mounting and improved reliability.
Implementation Method 1
a light reflecting portion disposed in the recess adjacent to the light output surface, so that light emitted from the light emitting element can be reflected to walls of the recess to form a substantially collimated light beam
Implementation Method 2
a thermal conductor attached to a surface of the light emitting element opposite to the light output surface for heat dissipation
Data Source
AI summary
A light emitting device includes a light emitting element having at least two electrodes disposed at the side of the light output surface thereof; and a base member having a recess and lead portions corresponding to the electrodes, the light emitting element being mounted on the base member and received in the recess, wherein the light output surface faces toward opening of the recess that becomes smaller while approaching the light output surface, and the electrodes are respectively in electrical connection with the lead portions that extend from the connection positions to outer edge of the base member for power connection, and a light reflecting portion is disposed in the recess adjacent to the light output surface such that the light emitted from the light emitting element can be reflected to walls of the recess to form a substantially collimated light beam so as to improve light efficiency.