Converter Element Shrinkage Control via Cured Polysiloxane Powder
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Solution Overview
Problem
The production of converter elements for light-emitting diodes (LEDs) faces challenges such as volume shrinkage and subsequent cracking or warpage due to moisture curing of polysiloxane matrices, which limits the thickness and reliability of the converter layers.
Innovation Solution
A method involving the use of a partially cured polysiloxane resin with a cured polysiloxane powder as an inert filler, reducing volume shrinkage and preventing cracking, while maintaining thermal stability and optical properties, by incorporating specific phosphors and adjusting the composition and curing conditions to achieve high thickness without warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the thickness of the converter layer is increased, then the converter element can be used for high-power LED applications, but the material shrinks and warps during curing
Solution Approach 1:
The patent changes the physical state parameter of the polysiloxane resin from liquid to a semi-solid paste state by adding inorganic filler. This parameter change reduces the shrinkage during curing from 30% to 5%, enabling thicker converter layers without warpage while maintaining the desired thickness for high-power LED applications.
Solution Approach 2:
The patent creates a composite material system by combining polysiloxane resin with inorganic filler (such as silica or alumina) in specific ratios. This composite structure provides both the optical properties needed for wavelength conversion and the mechanical stability to prevent warpage in thick converter layers, resolving the contradiction between thickness and shape stability.
2Length of stationary object
If the thickness of the converter layer is increased, then the converter element can be used for high-power LED applications, but cracks form during curing
Solution Approach 1:
The patent modifies the viscosity and flow properties of the polysiloxane resin by adding inorganic filler, transforming it from a liquid state to a paste state. This parameter change reduces shrinkage during curing from 30% to 5%, preventing internal stresses that would cause cracking in thick converter layers, thereby improving reliability while maintaining the required thickness.
Solution Approach 2:
The patent develops a composite material comprising polysiloxane resin and inorganic filler in optimized proportions. This composite structure provides enhanced mechanical strength and reduced shrinkage, enabling the production of thick converter layers without cracking, thus resolving the contradiction between thickness and reliability.
3Shape
If inorganic filler is increased to reduce shrinkage, then warpage is reduced, but the characteristics of the converter layer are negatively influenced
Solution Approach 1:
The patent optimizes the filler content parameter to a specific range (30-70 wt%) rather than using high amounts. This parameter optimization achieves sufficient shrinkage reduction (from 30% to 5%) to prevent warpage while maintaining the optical and electrical characteristics of the converter layer, resolving the contradiction between shape stability and material performance.
Solution Approach 2:
The patent creates a balanced composite material system where polysiloxane resin and inorganic filler are combined in optimized ratios. This composite approach provides both the shape stability needed to prevent warpage and preserves the functional characteristics of the converter layer for wavelength conversion, resolving the contradiction between reducing warpage and maintaining material characteristics.
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 method enables the production of converter elements with improved thickness and reliability, up to 115 μm without cracking or warping, suitable for high-power LED applications, while maintaining thermal stability and optical performance.
Implementation Method 1
a polysiloxane matrix reacts with atmospheric moisture, resulting in transformation of the liquid resin into a solid material, also known as moisture curing
Implementation Method 2
the resin loses up to 30% of its mass due to evaporation of the volatile products of the curing reaction
Data Source
AI summary
A method for producing a converter element, a converter element and a light emitting device are disclosed. In an embodiment a converter element includes a cured layer having at least one phosphor and a cured polysiloxane powder, wherein the phosphor and the cured polysiloxane powder are embedded in a matrix material comprising a cured polysiloxane resin.