Light-emitting device with 3D wiring for dense packing
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Solution Overview
Problem
Existing Chip-on-Board (COB) light-emitting devices face challenges in densely packing light-emitting elements due to limited space for wiring, which affects heat dissipation and light output, especially when using multi-layer wiring boards with low thermal conductivity materials.
Innovation Solution
A light-emitting device design featuring a mounting board with first and second wiring, where the first wiring is on the board surface and the second wiring is on the lower surface or lateral surfaces of a light-transmissive member, allowing for dense packing of light-emitting elements while maintaining efficient heat dissipation and light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multi-layer wiring boards are used to provide wiring areas, then wiring space is improved, but heat dissipation performance deteriorates due to low thermal conductivity insulating materials
Solution Approach 1:
The patent transitions from planar wiring on the board surface to three-dimensional wiring that utilizes the vertical space above the board. By placing wiring on the lower surface of the light-transmissive member and using lateral surfaces, the invention creates additional wiring dimensions that do not interfere with heat dissipation paths in the board plane.
Solution Approach 2:
The light-transmissive member serves as an intermediary structure that carries wiring on its lower surface and lateral surfaces. This mediator allows electrical connections to be made without requiring additional wiring layers within the board itself, thus preserving the board's thermal conduction pathways.
2Productivity
If light-emitting elements are arranged at narrow pitches to increase output, then light output is improved, but wiring space deteriorates making it difficult to secure areas for wiring
Solution Approach 1:
By moving wiring from the two-dimensional board surface to the three-dimensional space above the board (on the lower surface and lateral surfaces of the light-transmissive member), the invention decouples wiring space requirements from the board plane, allowing light-emitting elements to be densely packed without compromising wiring availability.
3Reliability
If sufficient creepage distances are secured for parallel arrangement, then reliability is improved, but wiring space deteriorates reducing available areas for wiring
Solution Approach 1:
The invention satisfies creepage distance requirements by utilizing the vertical dimension and lateral surfaces of the light-transmissive member for wiring placement. This allows sufficient electrical clearance to be maintained between parallel wiring paths without consuming valuable planar space on the mounting board.
Data Source
AI summary
A light-emitting device includes a mounting board, a first wiring, a plurality of light-emitting elements, a first light-transmissive member, and a second wiring. The first wiring includes a plurality of electrodes which are disposed away from each other on the mounting board. The plurality of light-emitting elements is provided on the mounting board and is electrically connected to the first wiring. The first light-transmissive member is disposed above the plurality of light-emitting elements. The second wiring is disposed on a lower surface of the first light-transmissive member and electrically connects between electrodes among the plurality of electrodes of the first wiring.