Resin Viscoelasticity Control for LED Contact Stability
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Solution Overview
Problem
Light emitting diode (LED) apparatuses used in outdoor or high-temperature, high-humidity environments face contact failure due to significant changes in the viscoelasticity of the resin used to hold the light emitting elements, leading to electrical connection loss and reduced reliability.
Innovation Solution
A light emitting apparatus with a resin layer having a temperature for maximum mechanical loss tangent tan δ of 117° C. or higher, formed from a thermosetting resin with specific viscoelastic properties, is used to maintain stable electrical connectivity between the conductor layer and light emitting elements, even under severe environmental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resin layer with conventional viscoelastic properties is used to hold light emitting elements, then the apparatus can be manufactured with standard materials, but the electrical connection fails under high-temperature and high-humidity conditions due to significant changes in resin viscoelasticity
Solution Approach 1:
The patent changes the key parameter of the resin's viscoelastic characteristics by selecting materials whose glass transition temperature (Tg) is 100°C or higher. This parameter change ensures that the resin maintains stable mechanical properties and viscoelasticity in the operating temperature range, preventing contact failure between the conductor layer and LED electrodes under high-temperature and high-humidity conditions.
Solution Approach 2:
The patent employs composite material selection by combining specific resin materials (epoxy resin, polyimide resin, or polyester resin) with controlled viscoelastic properties. This composite approach creates a resin layer that simultaneously provides mechanical support, electrical insulation, and dimensional stability, resolving the contradiction between manufacturability and reliability in harsh environments.
2Reliability
If the resin viscoelasticity is stabilized to prevent contact failure, then electrical connectivity is maintained, but the resin must have specific high-temperature properties that limit material selection
Solution Approach 1:
The patent establishes a clear parameter threshold (glass transition temperature Tg ≥ 100°C) that defines the boundary between acceptable and unacceptable resin materials. This parameter-based approach provides design guidance while maintaining material selection flexibility within the acceptable range, allowing engineers to choose from multiple resin types that meet the thermal stability requirement.
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 significantly enhances the reliability and longevity of the light emitting apparatus by maintaining electrical connectivity and preventing contact failure, ensuring the apparatus remains functional for extended periods in harsh environments.
Implementation Method 1
the resin used to hold the light emitting element on the substrate has characteristics such as viscoelasticity that change as a temperature or humidity changes
Data Source
AI summary
Disclosed is a light emitting apparatus including: a first substrate having light transmissive property and flexibility with a conductive layer; a second substrate having light transmissive property and flexibility and arranged to face the first substrate; a plurality of light emitting elements including an electrode connected to the conductive layer and arranged between the first and second substrates; and a resin layer having light transmissive property and flexibility and arranged between the first and second substrates to hold the plurality of light emitting elements. A temperature for a maximum mechanical loss tangent tan δ in dynamic viscoelasticity of the resin layer is 117° C. or higher.