Side-View LED Terminal Structure Against Solder Penetration
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Solution Overview
Problem
Side-view type light emitting devices face challenges in achieving stability and accurate mounting due to the miniaturization and thinning of substrates, leading to issues with light flux distribution and reliability, particularly with the use of thin metallic films as terminals, which can result in element failure and reduced light extraction efficiency.
Innovation Solution
A light emitting device design featuring a substrate with protruding connection terminals, where the light emitting element is bonded using a molten material, and a light reflecting or sealing member is used to cover the terminals and the space between the substrate and the element, enhancing stability and accuracy of mounting while preventing solder penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the substrate is miniaturized and thinned to reduce occupied space, then the device size and thickness are reduced, but the mounting stability and light flux distribution deteriorate
Solution Approach 1:
The patent applies preliminary action by forming protruding portions on the connection terminals before mounting the light emitting element. These protrusions pre-establish mechanical interlocking features that enhance mounting stability even when the substrate is miniaturized and thinned, thus resolving the contradiction between reduced occupied space and maintained mounting stability.
2Length of stationary object
If metallic film terminals are used to reduce device thickness, then the device thickness is reduced, but the reliability and resistance to solder penetration deteriorate
Solution Approach 1:
The patent employs composite materials by combining the metallic film terminal with a protruding portion made of a different material (such as a alloy or composite structure) that provides enhanced mechanical strength and solder penetration resistance. This composite structure maintains thin device profile while improving reliability against solder penetration.
Solution Approach 2:
The patent applies dimensionality change by adding vertical protrusions to the otherwise thin metallic film terminal. This transforms the terminal from a purely two-dimensional thin film into a three-dimensional structure with enhanced mechanical properties, providing both thin profile and improved solder penetration resistance through the protruding geometry.
3Area of stationary object
If terminals are disposed closely to minimize occupied space, then the device width is reduced, but the allowable margin for solder penetration is reduced
Solution Approach 1:
The patent applies segmentation by dividing the terminal structure into distinct functional zones: the flat terminal surface for electrical connection and the protruding portion that acts as a separate mechanical barrier. This segmentation allows the terminal to perform both electrical function and physical protection against solder penetration, enabling close terminal spacing while maintaining reliability margins.
4Length of stationary object
If the substrate is thinned to achieve CSP form factor, then the device thickness is reduced, but the light extraction efficiency and thermal radiation properties deteriorate
Solution Approach 1:
The patent applies the intermediary principle by introducing a light reflecting member as a mediating structure between the light emitting element and the thin substrate. This intermediary component reflects light that would otherwise be lost through the thin substrate back toward the light extraction surface, thereby maintaining high light extraction efficiency despite the reduced device thickness.
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 enables stable and accurate mounting of light emitting elements without failure, improving light extraction efficiency and reliability by preventing solder penetration and enhancing thermal radiation properties.
Implementation Method 1
a light reflecting member covering the light emitting element
Implementation Method 2
bonding the pair of electrodes of the light emitting element and the pair of connection terminals, respectively, by a molten material
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5B
AI summary
A light emitting device (60) has a substrate including a pair of connection terminals (63) at least on a first main surface of a base material (62) of the substrate, a light emitting element (5a) connected to the connection terminals (63) by a molten material (6), and a light reflecting member (7) covering the light emitting element (5a), the connection terminals (63) each including a protruding portion configured to project from a first main surface of the connection terminal (63) at a region which is connected with the light emitting element (5a), the protruding portions and the molten material (6) being embedded in the light reflecting member (7). Each connection terminal (63) extends from the first main surface of the base material (62) through a through hole (62a) defined in the base material (62) to a second main surface of the base material (62) opposite to the first main surface of the base material (62).