LED Package Sub-Mount With Through-Hole Electrodes
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Solution Overview
Problem
The existing LED packages with plastic materials for the package body and PCB exhibit low heat transfer rates, leading to degraded heat discharge and optical characteristics, making it difficult to implement uniform illumination in applications like backlights, and causing issues with size, light uniformity, and cost, as well as potential productivity and reliability problems due to precise wire bonding.
Innovation Solution
A sub-mount for mounting light emitting devices is developed with through holes in a substrate, electrodes connected via these holes, and a reflective layer to enhance light emission, using materials like silicon, aluminum, or photo-sensitive glass substrates, and incorporating adhesion and diffusion barrier layers for improved electrical and thermal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If plastic materials are used for package body and PCB, then manufacturing cost is reduced and ease of manufacture is improved, but heat transfer rate deteriorates leading to degraded heat discharge
Solution Approach 1:
The package structure is segmented into distinct functional zones: a heat-generating LED mounting area with metal sub-mount for efficient heat dissipation, and a plastic package body for cost-effective manufacturing. This segmentation allows each material to be optimized for its specific function without compromising overall performance.
Solution Approach 2:
Different materials are applied locally to different regions of the package: metal sub-mount with high thermal conductivity is used specifically at the LED mounting location where heat generation occurs, while plastic materials are used for the package body where cost reduction is prioritized. This local quality approach ensures heat discharge is optimized at the critical heat source area.
2Device complexity
If conventional LED package structure is used, then manufacturing simplicity is maintained, but light uniformity deteriorates making it difficult to implement uniform illumination
Solution Approach 1:
A reflective layer is introduced at the bottom of the package cavity, adding a new dimensional element to the light emission path. This reflective surface redirects light that would otherwise be lost, contributing to more uniform illumination distribution while maintaining the overall simplicity of the package structure.
3Reliability
If precise wire bonding is used for electrical connection, then electrical connection reliability is improved, but manufacturing complexity increases and productivity decreases
Solution Approach 1:
The complex wire bonding process is extracted and replaced with a simpler direct electrical connection method. The metal sub-mount with integrated contact pads provides direct electrical pathways to the LED, eliminating the need for separate wire bonding operations and associated precision requirements.
Solution Approach 2:
The metal sub-mount structure is designed to provide both mechanical support and electrical connection functions simultaneously. The inherent conductivity and structural design of the sub-mount enable direct electrical contact with the LED, making the system self-sufficient and eliminating the need for additional wire bonding components or processes.
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 enables uniform intensity of illumination and brightness in light emitting devices, improving heat dissipation and reducing the need for precise wire bonding, thus enhancing the reliability and productivity of LED packages while addressing size and cost concerns.
Implementation Method 1
a reflective layer arranged on one of the electrodes arranged on the mount, the reflective layer having a recess to which the light emitting device is mounted
Implementation Method 2
A sub-mount for mounting light emitting devices is developed with through holes in a substrate, electrodes connected via these holes... improving heat dissipation
Data Source
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AI summary
A light emitting device package is disclosed. The light emitting device package includes a substrate (10) having through holes (12, 13); a seed metal (40) disposed inside the through holes (12, 13) and on an upper surface and a lower surface of the substrate (10); and an electrode (50) disposed inside the through holes (12, 13) and on the upper surface and a lower surface of the substrate (10), the electrode (50) including a diffusion barrier layer between an adhesion layer of Ti or Cr and an electrode gold layer, the diffusion barrier layer preventing the electrode gold layer from being degraded in electrical characteristics.