Light Emitting Device Conductor Pattern Slits Heat Dissipation
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Solution Overview
Problem
Chip On Board (COB) type light emitting devices experience cracking and reduced heat dissipation due to differences in linear expansion coefficients between the light emitting device substrate and the housing substrate, leading to disconnection of the conductor pattern and poor heat dissipation characteristics.
Innovation Solution
Incorporating a conductor pattern with slits or holes on the rear surface of the light emitting device substrate, where the slits or holes prevent separation of the conductor pattern into two parts, increasing the outer peripheral length and ensuring a minimum width of the conductor pattern to control cracking and bubble retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conductor pattern is made continuous without slits or holes, then the structural integrity is maintained, but bubbles are difficult to remove and likely to be remained during manufacturing
Solution Approach 1:
The conductor pattern incorporates slits or holes that create a porous structure, allowing bubbles to escape during manufacturing while maintaining structural integrity. The slits/holes are designed to fail to separate the conductor pattern into two parts, ensuring connectivity is preserved while providing bubble escape paths.
2Temperature
If the conductor pattern area is increased for heat dissipation, then heat dissipation performance is improved, but the bubble is difficult to remove and likely to be remained
Solution Approach 1:
The heat dissipation pattern incorporates slits or holes creating a porous structure that allows bubbles to escape during manufacturing. The pattern maintains large area for heat dissipation while the slits/holes provide bubble escape paths, resolving the contradiction between heat dissipation performance and ease of manufacture.
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 design effectively prevents cracking and bubble retention, enhancing the durability and heat dissipation performance of the light emitting device by increasing the cycle number of temperature changes before cracking occurs and maintaining efficient heat dissipation.
Implementation Method 1
a difference in a linear expansion coefficient between a light emitting device substrate and a housing substrate in which the light emitting device is installed. Thus, a junction between the light emitting device and the housing cracks by repeatedly lighting on and off with temperature change.
Implementation Method 2
heat caused in the light emitting device can be effectively emitted to, for example, a housing side heat sink through the conductor pattern for heat dissipation.
Data Source
AI summary
A light emitting device includes a wiring substrate, a light emitting element disposed on a front surface of the wiring substrate, and a conductor pattern formed on a rear surface of the wiring substrate. The conductor pattern includes a slit or a hole that fails to separate the conductor pattern into two parts.