Semiconductor Light Emitting Device with Recessed Chip and Oversized Fluorescent Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wavelength conversion light emitting devices face challenges in maintaining consistent color tone due to variations in light emitted from the side face of the light emitting layer, as the excitation light from the side face does not effectively travel through the fluorescent material layer, leading to color variations across the light emitting surface.
Innovation Solution
A semiconductor light emitting device design featuring a light emitting chip with a recessed and protruding configuration on its second major surface, where the fluorescent material layer is larger than the chip and covers the side face, allowing light emitted obliquely to travel through a longer portion of the fluorescent material layer, thereby reducing color variations. This design includes interconnect and metal pillars for mechanical strength and stress mitigation, and uses a resin layer for reinforcement and thermal expansion matching with the mounting board.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the fluorescent material layer is made larger than the light emitting chip to cover the side face, then color variation is suppressed, but device complexity increases
Solution Approach 1:
The fluorescent material layer is extended from a conventional planar configuration to a three-dimensional configuration that covers the side face of the light emitting chip. This dimensional extension allows the layer to intercept excitation light emitted obliquely from the side face, converting it to wavelength-converted light and thereby suppressing color variation across the light emitting surface.
Solution Approach 2:
The light emitting chip is divided into functional regions: a light emitting region where the light emitting layer is exposed on the first major surface, and a non-light emitting region where the light emitting layer is covered by the insulating layer. This segmentation allows different portions of the chip to serve different functions while maintaining overall color uniformity.
2Reliability
If metal pillars and interconnect layers are added for mechanical strength, then reliability improves, but manufacturing complexity increases
Solution Approach 1:
The device employs a composite structure combining semiconductor layers, insulating layers, metal pillars, and resin layers. Each material is selected for its specific properties: semiconductor materials for light emission, insulating materials for electrical isolation, metals for mechanical strength and electrical connection, and resin for thermal expansion matching. This composite approach achieves high reliability while managing the complexity through functional integration.
Solution Approach 2:
The resin layer is specifically selected to have a coefficient of thermal expansion that matches the mounting board. This thermal expansion matching prevents stress and deformation during temperature variations, improving reliability without requiring additional stress-compensation structures.
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 design effectively suppresses color variations by ensuring that light emitted from the side face of the semiconductor layer travels through a larger portion of the fluorescent material layer, resulting in improved color tone controllability and mechanical strength, while also reducing production costs through wafer-level processing and packaging.
Implementation Method 1
Wavelength conversion light emitting devices, which obtain white light by combining an excitation light source (blue light or near-ultraviolet Light Emitting Diode (LED) with a fluorescent material layer
Data Source
AI summary
According to one embodiment, a semiconductor light emitting device includes a light emitting chip and a fluorescent material layer. The light emitting chip includes a semiconductor layer, a first electrode, a second electrode, an insulating layer, a first interconnect layer, a second interconnect layer, a first metal pillar, a second metal pillar, and a resin layer. The semiconductor layer includes a light emitting layer, a first major surface, and a second major surface formed on a side opposite to the first major surface. The fluorescent material layer is provided on the first major surface and has a larger planer size than the light emitting chip.