Side-Emitting LED Package Structure for Warpage Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing surface-mounting type light-emitting diodes of the side light-emitting type face issues with warpage due to differences in thermal expansion coefficients between the substrate and the sealing resin, leading to potential cracks during solder joining and mounting.
Innovation Solution
A light-emitting device design featuring a resin substrate with cutout regions and through holes, metal wiring electrodes with varying thicknesses, and a resin body with light reflection properties, which helps to minimize warpage by balancing stress distribution during thermal changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a glass epoxy-based insulating substrate is used as the manufacturing substrate, then the substrate provides good electrical insulation and mechanical strength, but the difference in thermal expansion coefficients between the substrate and sealing resin causes warpage variation during solder joining, leading to cracks
Solution Approach 1:
The patent changes the material parameter of the substrate from glass epoxy-based insulating substrate to resin substrate. This material substitution fundamentally alters the thermal expansion characteristics to better match the sealing resin, thereby reducing warpage variation during temperature changes and preventing cracks in solder and light emitting diode elements while maintaining mechanical strength
Solution Approach 2:
The patent employs composite material structure by using resin substrate combined with resin body having light reflection property. This composite approach allows optimization of both mechanical properties and thermal expansion characteristics, achieving compatibility between substrate and sealing resin to eliminate warpage-induced cracks
2Ease of manufacture
If the wiring electrodes have uniform thickness, then the manufacturing process is simpler, but the stress distribution during thermal expansion is unbalanced, causing warpage of the mounting substrate
Solution Approach 1:
The patent applies asymmetry principle by designing wiring electrodes with non-uniform thickness distribution. The first wiring electrode has different thickness at different positions, and the second wiring electrode similarly has varied thickness. This asymmetric thickness design creates balanced stress distribution during thermal expansion, effectively preventing warpage of the mounting substrate
Solution Approach 2:
The patent implements local quality by making different portions of the wiring electrodes have different thicknesses. Specifically, certain regions of the first and second wiring electrodes are designed with greater thickness to provide localized stress compensation, achieving overall flatness of the mounting substrate through distributed local adjustments
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 reduces the variation in warpage of the mounting substrate between high and normal temperature states, enhancing manufacturing yield and preventing cracks in the light-emitting element.
Implementation Method 1
The resin body has a light reflection property
Implementation Method 2
The first wiring electrode is made of metal and includes an electrode portion and a wiring portion
Data Source
AI summary
A light-emitting device according to the present invention includes a resin substrate having a flat plate shape, a first wiring electrode made of metal, a second wiring electrode made of metal, a light-emitting element, and a resin body. The light-emitting element is mounted onto the electrode portions of the first wiring electrode and the second wiring electrode on the first principal surface side of the resin substrate. The resin body has a light reflection property, covers the first principal surface of the resin substrate, covers the respective wiring portions of the first wiring electrode and the second wiring electrode and forming a frame body surrounding the light-emitting element on the first principal surface, and covers a region exposed from the first wiring electrode and the second wiring electrode on the second principal surface of the resin substrate.