Light-Emitting Device Adhesive Recess for Optical Output
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Solution Overview
Problem
Conventional light-emitting devices face issues with light absorption by the substrate due to adhesive dripping, leading to reduced optical output and potential thermal shock resistance problems.
Innovation Solution
A light-emitting device design where the adhesive is separated from the substrate, with a first light-transmissive member bonded to the light-emitting element and a second light-transmissive member positioned above, ensuring the adhesive covers the side surface of the first member without reaching the substrate, thereby preventing light absorption and enhancing optical output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive is used to bond the first light-transmissive member to the light-emitting element, then bonding strength is improved, but light absorption by the substrate increases due to adhesive dripping
Solution Approach 1:
The adhesive is extracted from the problematic location (between the light-emitting element and substrate) by using a recess structure. The adhesive is confined to the recess, preventing it from dripping onto the substrate and absorbing light, while still maintaining its bonding function between the light-transmissive member and light-emitting element.
Solution Approach 2:
The recess structure acts as an intermediary between the adhesive and the substrate, physically separating them. This intermediary structure allows the adhesive to perform its bonding function while preventing direct contact with the substrate that would cause light absorption.
2Reliability
If adhesive is applied generously to ensure complete coverage, then bonding reliability is improved, but adhesive penetration into gaps increases causing thermal shock resistance problems
Solution Approach 1:
The recess structure extracts the adhesive from the gap region between the light-emitting element and substrate, preventing penetration while maintaining adequate coverage for reliable bonding. The adhesive is contained within the recess boundaries, ensuring both bonding reliability and thermal shock resistance.
Solution Approach 2:
The recess structure creates a localized region with different geometric properties compared to the surrounding area. By confining the adhesive to this specific local region, the patent achieves complete coverage for bonding reliability while preventing unwanted penetration into gaps that would compromise thermal shock resistance.
3Loss of energy
If the first light-transmissive member is positioned with its peripheral edge inward, then adhesive separation from substrate is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The recess structure is formed in advance during substrate processing, creating a predetermined location for adhesive placement. This preliminary action eliminates the need for high-precision positioning during assembly, as the adhesive naturally conforms to the pre-formed recess geometry, reducing manufacturing precision requirements while achieving substrate separation.
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
This design effectively suppresses light absorption by the substrate, improves optical output, and maintains thermal shock resistance by preventing adhesive penetration into gaps between the light-emitting element and the substrate.
Implementation Method 1
a first light-transmissive member bonded to an upper surface of the light-emitting element via an adhesive
Data Source
AI summary
A light-emitting device includes a substrate; a light-emitting element mounted on the substrate; a first light-transmissive member bonded to an upper surface of the light-emitting element via an adhesive; and a second light-transmissive member placed on an upper surface of the first light-transmissive member. In a plan view of the light-emitting device, a peripheral edge of a lower surface of the first light-transmissive member is positioned more inward than a peripheral edge of the upper surface of the light-emitting element. The adhesive extends from the upper surface of the light-emitting element to a lower surface of the second light-transmissive member, the adhesive covers a side surface of the first light-transmissive member, and the adhesive is separated from the substrate.