Organopolysiloxane Resin Layer for LED Heat and Light Resistance
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Solution Overview
Problem
Conventional light emitting devices using silicone-based resins for heat and light resistance face issues with mechanical strength, brittleness, and adhesion to metal members, leading to color irregularities and tone variations, especially with short wavelength LEDs.
Innovation Solution
A light emitting device with a resin layer comprising a cured product of an organopolysiloxane with a specific molecular weight range and a condensation catalyst, eutectically bonded to a metal package, providing excellent heat and light resistance, adhesion, and stable color tone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If addition curable silicone resins with high silethylene linkage proportion are used, then ultraviolet light resistance and heat resistance are improved, but mechanical strength deteriorates and the resin becomes brittle
Solution Approach 1:
The patent changes the chemical composition parameters of the silicone resin by controlling the proportion of silethylene linkages (Si-O-Si) versus Si-CH3 linkages. Specifically, it uses silicone resin with 60-80 mol% Si-O-Si linkages and 20-40 mol% Si-CH3 linkages, optimizing the balance between UV resistance and mechanical strength. This parameter adjustment resolves the contradiction by finding the optimal composition ratio that provides both desired properties.
Solution Approach 2:
The patent creates a composite resin system by combining addition-curable silicone resin with condensation-curable silicone resin in specific proportions (70-90 wt% addition type, 10-30 wt% condensation type). This composite approach allows the final material to exhibit both the UV resistance of high crosslink density and the mechanical flexibility of the condensation component, resolving the strength-brittleness contradiction.
2Temperature
If resin layers with high crosslink density are used to improve heat resistance, then heat resistance is improved, but adhesion to metal members deteriorates
Solution Approach 1:
The patent adjusts the crosslink density parameter by controlling the ratio of addition-curable to condensation-curable resin components. The condensation-curable component provides moderate crosslinking that maintains adhesion, while the addition-curable component provides heat resistance. This parameter optimization achieves both heat resistance and adhesion simultaneously.
Solution Approach 2:
The patent introduces a dual-curing mechanism as an intermediary approach. The condensation-curable component acts as a mediator that provides initial adhesion to metal surfaces through silanol groups, while the addition-curable component subsequently crosslinks to provide heat resistance. This intermediary mechanism resolves the contradiction between adhesion and heat resistance.
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 enhances the mechanical strength, heat resistance, and adhesion of the resin layer, preventing deterioration and maintaining stable light emission characteristics, while allowing efficient wavelength conversion and improved reliability and mass production suitability.
Implementation Method 1
said resin layer comprises a cured product of a composition comprising: (i) an organopolysiloxane... (ii) a condensation catalyst
Implementation Method 2
a light emitting element such as an LED
Implementation Method 3
the light emitting element is typically coated with a layer comprising a phosphor for converting the wavelength of the light
Implementation Method 4
said light emitting element is eutectic bonded to a metal portion of said package
Data Source
AI summary
A light emitting device is provided, including a light emitting element, a package comprised at least partially of metal on which said light emitting element is mounted, and a resin layer coated on said light emitting element. The light emitting element is eutectic bonded to a metal portion of said package, and the resin layer is formed of a cured product of a silicone composition. The composition includes (i) an organopolysiloxane having an average composition formula (1):R1a(OX)bSiO(4−a−b)/2 (1)wherein R1 is an alkyl, alkenyl or aryl group, X is a hydrogen atom, or an alkyl, alkenyl, alkoxyalkyl or acyl group, a is a number from 1.05 to 1.5, b is a number of 0<b<2, and 1.05<a+b<2, and (ii) a condensation catalyst. The device exhibits improved heat resistance and light resistance, and also exhibits improved adhesion to the resins and metal members used.