LED Substrate Peripheral Edge Design for Adhesion Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional light-emitting diodes experience adhesion issues between the substrate and sealing resin due to thermal expansion differences and light-induced deterioration, leading to reduced adhesion strength and potential unsticking at the outer peripheral adhered portion.
Innovation Solution
A light-emitting diode design featuring a substrate with a first and second peripheral edge, where the second edge is positioned relative to an imaginary line connecting the light-emitting facet edge and the first peripheral edge, and a shoulder or inclined plane formed between these edges to enhance adhesion by blocking light and increasing contact area with the sealing resin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrodes are formed to extend from upper surface to lower surface of substrate via edge surface, then electrical connection is achieved, but adhesion strength between substrate and sealing resin deteriorates due to reduced direct contact area and material incompatibility
Solution Approach 1:
The patent segments the electrode structure by introducing through-holes that penetrate the substrate, separating the electrode function from the edge surface extension. This allows the sealing resin to directly contact the substrate over a larger area while electrodes are confined to specific regions on the upper surface, resolving the conflict between electrical connection and adhesion area.
Solution Approach 2:
The patent introduces an intermediary structure where the substrate itself serves as the primary adhesion interface between the sealing resin and the mounting board, rather than relying on electrode-substrate adhesion. This mediator approach transfers the adhesion function from the electrode-substrate interface to the substrate-sealing resin interface.
2Reliability
If light-emitting diode element is mounted on substrate, then light emission function is achieved, but outer peripheral portion of substrate deteriorates due to direct light exposure causing adhesion loss
Solution Approach 1:
The patent extracts the harmful light exposure from the outer peripheral portion by positioning the second peripheral edge along the extension line of the light-emitting facet, creating a geometric relationship that prevents direct light from reaching the vulnerable outer edges. This extracts the light source's harmful effect from the adhesion-critical regions.
Solution Approach 2:
The patent uses dimensional geometry by defining the second peripheral edge's position relative to the light-emitting facet's extension line, creating a spatial arrangement where the substrate's edge geometry blocks light paths. This dimensional approach solves the light exposure problem without adding physical barriers.
3Temperature
If substrate and sealing resin are thermally expanded during operation, then thermal management is achieved, but strain concentrates at outer peripheral adhered portion causing resin to unstuck
Solution Approach 1:
The patent segments the adhesion interface by creating distinct peripheral edge definitions (first and second peripheral edges), which distributes and manages thermal expansion strains more effectively throughout the substrate-sealing resin interface, preventing concentration at a single critical point.
Solution Approach 2:
The patent provides beforehand cushioning by designing the substrate geometry with specific peripheral edge relationships that preemptively accommodate thermal expansion strains. The geometric configuration acts as a built-in strain relief mechanism that prevents adhesion failure before it occurs during thermal cycling.
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 configuration effectively prevents light-induced deterioration and maintains strong adhesion between the substrate and sealing resin, even under thermal expansion, ensuring reliable adherence for a longer period.
Implementation Method 1
a light-emitting diode element mounted on a substrate and encapsulated in a sealing resin
Implementation Method 2
when the substrate and the sealing resin are each thermally expanded due to heat generated during the operation of the light-emitting diode
Data Source
AI summary
The outer peripheral portion of a substrate is provided with a first peripheral edge and a second peripheral edge. The first peripheral edge is provided on the edge portion of a first upper surface of the substrate on which a light-emitting diode element is mounted. The second peripheral edge is formed either on an extension of an imaginary line connecting an edge of the light-emitting facet of the light-emitting diode element and the first peripheral edge or inwardly of the extension. The second peripheral edge is located at a position where the first peripheral edge blocks direct light from the light-emitting diode element. This configuration prevents the second upper surface of the substrate provided between the first peripheral edge and the second peripheral edge from becoming deteriorated due to the direct light.