Screen-Printed Silicone Resin Layer for LED Color Uniformity
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Solution Overview
Problem
Conventional silicone resins used in light emitting devices, especially with short wavelength LEDs, suffer from heat and light degradation, leading to mechanical weakness, color irregularities, and tone variations due to high silethylene linkages and poor resin layer uniformity when applied using traditional methods.
Innovation Solution
A light emitting device with a screen-printed silicone resin layer composed of an organopolysiloxane, condensation catalyst, solvent, and finely powdered inorganic filler, which eliminates silethylene linkages, ensuring excellent heat and light resistance, mechanical strength, and uniform film thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If addition curable silicone resin with high silethylene linkages is used, then the resin can be cured effectively, but the cured product becomes prone to deterioration from light and heat, leading to mechanical strength loss and resin bleed-out
Solution Approach 1:
The patent changes the chemical composition parameters of the silicone resin by specifying an organopolysiloxane with a particular average composition formula (1) where the molar ratios of R1 groups, X groups, and oxygen atoms are controlled within specific ranges. This compositional parameter change reduces silethylene linkages in the cured product, improving heat and light resistance while maintaining mechanical strength.
Solution Approach 2:
The patent creates a composite resin system by combining the organopolysiloxane with specific additives including a condensation catalyst, solvent, and finely powdered inorganic filler. This composite approach enhances the overall performance of the resin layer, providing both durability and proper screen printing characteristics.
2Ease of manufacture
If resin is applied using the dripping method, then the application process is simple, but the film thickness uniformity is poor, causing color irregularities during light emission
Solution Approach 1:
The patent replaces the dripping method with screen printing, substituting a simple mechanical application method with a more controlled process that uses a mesh screen and squeegee to deposit the resin paste. This mechanical substitution enables precise control over film thickness and uniformity while maintaining ease of manufacture through a straightforward printing process.
3Manufacturing precision
If screen printing method is used to apply the resin, then the film thickness uniformity is improved, but the resin must exhibit ready separation from the metal mask during printing and superior adhesion after curing
Solution Approach 1:
The patent adjusts the physical and chemical parameters of the resin composition to satisfy screen printing requirements. The resin is formulated as a paste with specific viscosity characteristics that enable easy separation from the metal mask during printing. The composition parameters are optimized to ensure proper flow and release properties during the printing process.
Solution Approach 2:
The patent develops a composite resin paste formulation that combines the organopolysiloxane with condensation catalyst, solvent, and inorganic filler in specific proportions. This composite composition provides both the necessary printability (easy separation from mask) and post-curing performance (superior adhesion to light emitting element).
4Ease of operation
If low molecular weight silicone components are present in the resin, then the resin is easier to process, but the components bleed out, causing color irregularities and tone variation
Solution Approach 1:
The patent controls the molecular weight parameters of the organopolysiloxane by specifying an average molecular weight within a particular range and controlling the distribution of molecular weights through the average composition formula. This parameter control prevents excessive low molecular weight components that would bleed out, while maintaining sufficient processability of the resin.
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 provides a light emitting device with enhanced heat and light resistance, mechanical strength, and stable optical characteristics, reducing color irregularities and improving durability and reliability.
Implementation Method 1
a cured product of a curable silicone resin composition comprising: (i) an organopolysiloxane... (ii) a condensation catalyst
Data Source
AI summary
A light emitting device, including a light emitting element, and a resin layer that has been screen printed to coat said light emitting element is provided. The resin layer is formed from a curable silicone resin composition, which includes (i) an organopolysiloxane with a polystyrene equivalent weight average molecular weight of at least 5×103, (ii) a condensation catalyst, (iii) a solvent, and (iv) a finely powdered inorganic filler. The uniformity of the film thickness is excellent, thus resulting in little color irregularities during light emission from the light emitting element.