Light Emitting Device Package with Microcracked Cover Film
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Solution Overview
Problem
Light emitting devices face durability issues due to decomposition of resin materials from heat and light exposure, which can lead to discoloration and reduced package longevity, especially when covered with a film that blocks oxygen supply.
Innovation Solution
A light emitting device is manufactured with a package that includes a resin base material and particles with different thermal expansion coefficients, integrated with a cover film that has microcracks to allow decomposition products to escape and maintain oxygen supply, preventing discoloration while enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inner peripheral face of the recess portion is covered with a cover film to protect the package, then package durability is improved, but decomposition products accumulate inside the package causing discoloration
Solution Approach 1:
The cover film is designed with microcracks that allow decomposition products to escape from the package interior while maintaining overall protective coverage. This porous structure resolves the contradiction by enabling harmful substance removal while preserving the protective function of the cover film.
Solution Approach 2:
The harmful decomposition products are extracted from the package interior through the microcracks in the cover film. This extraction mechanism prevents accumulation of decomposition products that would cause discoloration, while the cover film remains in place to provide durability protection.
2Reliability
If a cover film is applied to protect the package from heat and light, then package durability is improved, but oxygen supply to the package interior is blocked
Solution Approach 1:
The microcracked structure of the cover film creates pathways for oxygen diffusion into the package interior. This porous design allows the cover film to simultaneously provide protective coverage and maintain necessary gas exchange, resolving the contradiction between protection and oxygen supply.
3Ease of manufacture
If resin material is used for the package to provide flexibility and ease of manufacture, then ease of manufacture is improved, but the resin decomposes under heat and light exposure reducing durability
Solution Approach 1:
The package uses a composite structure combining resin base material with dispersed particles having different thermal expansion coefficients. This composite material provides both the manufacturing advantages of resin and enhanced resistance to thermal and light degradation, resolving the contradiction between ease of manufacture and durability.
Solution Approach 2:
The microcracks in the cover film, which could be considered defects, are converted into beneficial features that allow decomposition products to escape. This transforms what would normally be harmful trapped decomposition products into a controlled release mechanism, improving durability while maintaining the resin's manufacturing advantages.
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 effectively increases the durability of the light emitting device by allowing decomposition products to escape through microcracks in the cover film, reducing the risk of discoloration and ensuring adequate oxygen supply, thus extending the package's lifespan.
Implementation Method 1
the package including a base material and a plurality of particles, the base material including a resin, a coefficient of thermal expansion of the particles being different from a coefficient of thermal expansion of the base material
Data Source
AI summary
A method for manufacturing a light emitting device includes: integrally molding a package and a lead, the package arranged to form at least part of an inner peripheral face of a recess portion in which the light emitting element is housed, the package including a base material and a plurality of particles, the base material including a resin, a coefficient of thermal expansion of the particles being different from a coefficient of thermal expansion of the base material; and covering the inner peripheral face of the recess portion with a cover film, the cover film having light transmissive and electrical insulation.