Semiconductor Light Emitter Packaging for Thermal Stress Relief
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Solution Overview
Problem
Conventional semiconductor light emitting devices experience excessive stress due to the significant difference in linear expansion coefficients between the substrate and the transparent member, leading to thermal expansion and contraction issues.
Innovation Solution
The semiconductor light emitting device incorporates a substrate with a semiconductor light emitting element and a drive element, where the transparent member has a higher linear expansion coefficient than the substrate, and an encapsulation resin with a lower linear expansion coefficient than the transparent member, reducing the thermal stress by minimizing the difference in thermal expansion between the substrate and the encapsulation resin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a transparent member with high light transmissivity is used to cover the light emitting surface, then light emission efficiency is improved, but excessive stress is generated due to the large difference in linear expansion coefficient with the substrate
Solution Approach 1:
An encapsulation resin layer is introduced as an intermediary between the substrate and the transparent member. This resin has a linear expansion coefficient that is smaller than that of the transparent member, serving as a buffer to reduce the thermal expansion difference and thereby minimizing stress transmission to the semiconductor light emitting element while still allowing light to pass through.
Solution Approach 2:
The patent employs a composite structure consisting of multiple materials with different thermal expansion properties: the substrate, the encapsulation resin, and the transparent member. By carefully selecting materials with progressively different linear expansion coefficients, the composite structure accommodates thermal expansion differences and reduces overall stress in the assembly.
2Adaptability or versatility
If the linear expansion coefficient difference between substrate and transparent member is large, then each component can be optimized for its specific function, but thermal expansion and contraction produce excessive stress in the device
Solution Approach 1:
The encapsulation resin acts as a mediator layer between the substrate and transparent member, buffering the thermal expansion coefficient mismatch. This allows each component to maintain its optimized properties while the resin absorbs the differential expansion stress, preventing device failure.
Solution Approach 2:
The patent changes the physical parameter (linear expansion coefficient) of the encapsulation resin to be intermediate between the substrate and transparent member. This parameter optimization allows the resin to serve as a stress buffer while maintaining structural integrity and functionality across temperature variations.
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 configuration effectively reduces stress in the semiconductor light emitting device by aligning the linear expansion coefficients, enhancing its thermal stability and reliability.
Implementation Method 1
Since the substrate and the transparent member greatly differ in linear expansion coefficient, the difference may produce excessive stress in the semiconductor light emitting device
Data Source
AI summary
This semiconductor light-emitting device includes a substrate having a substrate main surface, a semiconductor light-emitting element having a light-emitting element main surface mounted on the substrate main surface and facing the same side as the substrate main surface, and a light-emitting element side surface that is a light-emitting surface facing a direction intersecting the light-emitting element main surface, a switching element and a capacitor mounted on the substrate main surface and serving as drive elements used in driving the semiconductor light-emitting element, a translucent member formed from a material having a greater linear expansion coefficient than the substrate and transmitting light emitted from the light-emitting side surface, the translucent member covering the light-emitting element side surface, and a sealing resin formed from a material that has a smaller linear expansion coefficient than the translucent member, the sealing resin sealing the semiconductor light-emitting element, the switching element, and the capacitor.