LED Sealing Structure for Optical Axis Alignment and Adhesion
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Solution Overview
Problem
Existing light emitting devices face issues of positional deviation and optical axis deviation between the lens and light emitting elements due to molding inaccuracies and thermal expansion coefficient differences, leading to suboptimal light distribution and adhesion problems.
Innovation Solution
A light emitting device design featuring a substrate with semiconductor elements surrounded by an annular frame, sealed by a sealing portion composed of a first resin portion with a concave surface and a second resin portion forming a convex external surface, integrated to form a high-precision optical element with rotational symmetry, using resins with matching thermal expansion coefficients to minimize deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a lens is molded by injection of a resin, then the lens can be formed, but a positional deviation of the lens with respect to a light emitting element occurs due to a deviation during molding
Solution Approach 1:
The patent applies preliminary action by forming a sealing portion that precisely covers and fixes the light emitting element before the lens is molded. The sealing portion includes a top surface that serves as a precise positioning reference for the lens mold, ensuring the lens is formed at the correct position relative to the light emitting element without deviation during the molding process.
2Device complexity
If a single-layer sealing resin is used, then the structure is simple, but peeling occurs due to a difference in the thermal expansion coefficient between the sealing resin and the lens
Solution Approach 1:
The patent applies segmentation by dividing the sealing resin into multiple layers with different material properties. The first sealing resin layer has a thermal expansion coefficient matched to the lens to prevent peeling at the lens interface, while the second sealing resin layer provides adhesion to the light emitting element. This layered structure resolves the thermal expansion mismatch problem while maintaining structural integrity.
Solution Approach 2:
The patent uses composite materials by combining different resin materials in the sealing portion. Each layer is made of a resin with specifically controlled thermal expansion properties - the first layer uses a resin whose thermal expansion coefficient is within ±5 ppm/K of the lens material, while the second layer uses a different resin optimized for bonding to the light emitting element, creating a composite sealing structure that addresses both adhesion and thermal compatibility.
3Reliability
If the sealing portion and lens are integrated, then adhesion is improved, but positional deviation and optical axis deviation occur due to molding inaccuracies
Solution Approach 1:
The patent applies preliminary action by first forming the sealing portion that precisely positions the light emitting element, then using the top surface of the sealing portion as a reference to form the lens. This sequential approach with built-in positioning references ensures both strong integration/adhesion and minimal optical axis deviation, as each component is formed in its optimal position before the next is added.
Data Source
AI summary
Semiconductor light emitting elements are configured to be mounted on the substrate, a frame is configured to be vertically provided on the substrate in an annular or oval-annular shape so as to surround the semiconductor light emitting elements, and a sealing portion is configured to seal an inner wall of the frame, an upper surface of the substrate inside the frame, and the semiconductor light emitting elements. The sealing portion includes a first resin portion configured to have a concave surface having at least one rotational plane having a central axis of the frame as a rotational axis, and a second resin portion configured to cover the concave surface of the first resin portion and having a convex external surface, and the sealing portion has an external surface in which an external surface of the first resin portion and an external surface of the second resin portion are integrated.