Die Bonding Material for Light Emitting Devices
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Solution Overview
Problem
Current die bonding materials for light-emitting devices do not provide optimal performance in terms of fixing light emitting elements at predetermined positions and enhancing optical extraction efficiency.
Innovation Solution
A die bonding material containing a specific curable polysilsesquioxane compound with a refractive index of 1.41 to 1.43 and a thixotropic index of 2 or more, along with a solvent, is developed. This material includes a curable polysilsesquioxane compound with a fluoroalkyl group and a nitrogen-containing silane coupling agent, which enhances the adhesive properties and optical extraction efficiency of light-emitting devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional curable compositions are used as die bonding materials, then basic adhesive function is provided, but optimal performance in fixing light emitting elements and enhancing optical extraction efficiency is not achieved
Solution Approach 1:
The patent optimizes the refractive index parameter to 1.41-1.43 and thixotropic index to 2 or more, which resolves the contradiction by achieving both reliable fixing performance and enhanced optical extraction efficiency through precise parameter control of the curable polysilsesquioxane compound
Solution Approach 2:
The patent uses a composite curable polysilsesquioxane compound containing both fluoroalkyl groups (for low refractive index and optical extraction) and nitrogen-containing silane coupling agents (for adhesive strength), resolving the contradiction by combining multiple functional components in a single material system
2Strength
If die bonding material with high adhesive strength is used to firmly fix light emitting elements, then fixing reliability is improved, but spreadability may be compromised
Solution Approach 1:
The patent controls the thixotropic index at 2 or more, which enables the material to exhibit shear-thinning behavior: high viscosity at rest for strong adhesion, but low viscosity under shear stress for excellent spreadability, thus resolving the contradiction between adhesive strength and spreadability
Solution Approach 2:
The patent introduces dynamic viscosity changes through thixotropic properties, allowing the die bonding material to adapt its flow characteristics based on applied stress: resistant during storage but flows easily during application, then sets to a strong bond after application
3Illumination intensity
If curable polysilsesquoxane compound with low refractive index is used to enhance optical extraction efficiency, then optical performance is improved, but adhesive properties may be reduced
Solution Approach 1:
The patent creates a composite polysilsesquioxane compound where fluoroalkyl groups provide low refractive index for optical extraction efficiency, while nitrogen-containing silane coupling agents provide strong adhesive properties, resolving the contradiction by integrating both functional aspects in one material
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 die bonding material effectively fixes light emitting elements and improves the optical extraction efficiency of light-emitting devices by providing excellent spreadability and adhesive strength, while maintaining a low refractive index and suitable thixotropic properties.
Implementation Method 1
a die bonding material containing a specific curable polysilsesquioxane compound... is capable of firmly fixing a light emitting element
Implementation Method 2
having a refractive index (nD) at 25° C. of 1.41 to 1.43 and a thixotropic index of 2 or more
Data Source
AI summary
The present invention provides a die bonding material containing the following component (A) and a solvent and having a refractive index (nD) at 25° C. of 1.41 to 1.43 and a thixotropic index of 2 or more, a light-emitting device including an adhesive member derived from the die bonding material, and a method for producing the light-emitting device. The die bonding material of the present invention is preferably used for fixing a light emitting element at a predetermined position.Component (A): a curable polysilsesquioxane compound having a repeating unit represented by the following formula (a-1) and satisfying predetermined requirements related to 29Si-NMR and mass average molecular weight (Mw)R1-D-SiO3/2 (a-1)[wherein R1 represents a fluoroalkyl group represented by a compositional formula: CmH(2m−n+1)Fn; m represents an integer of 1 to 10, and n represents an integer of 2 to (2m+1); and D represents a linking group (excluding an alkylene group) for connecting R1 and Si, or a single bond].