LED Electrode Groove Design for Wire Bonding Adhesion
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Solution Overview
Problem
Large-sized light emitting diodes face issues with light shielding and absorption by electrodes, leading to decreased light emitting efficiency, and existing solutions like adding an electric insulating layer can cause detachment during wire bonding.
Innovation Solution
A light emitting diode design with a second electrode that fills an opening in the transparent conductive layer and features a groove portion, increasing adhesion and counterforce against horizontal thrust, preventing detachment during encapsulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the electrode size is increased to match large-sized LED area, then the electrode coverage is improved, but light shielding and light absorption by the electrode increase, resulting in decreased light transmission and light emitting efficiency
Solution Approach 1:
The patent divides the electrode structure into multiple segments: a reflective layer, an electric insulating layer, and a conductive layer. This segmentation allows each layer to perform its specific function - the reflective layer redirects light, the insulating layer prevents electrical shorting, and the conductive layer provides electrical connection, thereby reducing overall light absorption while maintaining electrode functionality
Solution Approach 2:
The patent employs a composite electrode structure consisting of multiple materials with different properties stacked together. The reflective layer (e.g., aluminum), electric insulating layer (e.g., silicon oxide), and conductive layer (e.g., transparent conductive oxide) form a composite structure that combines optical reflection, electrical insulation, and electrical conductivity functions, solving the contradiction between electrode coverage and light efficiency
2Loss of energy
If an electric insulating layer is added under the electrode to form a reflective mirror structure, then light shielding and light absorption are reduced, but the flat upper and lower surfaces of the electrode cause detachment of welded metal ball or electrode during wire bonding
Solution Approach 1:
The patent introduces a groove structure with curved surfaces into the otherwise flat electrode. The groove features include a bottom surface and side surfaces that form curved geometries, which prevent the detachment of welded metal balls during wire bonding by providing mechanical interlocking and stress distribution, thereby improving electrode reliability without compromising the reflective function
3Reliability
If a groove portion is added to the electrode structure to prevent detachment, then adhesion and counterforce are improved, but the device structure becomes more complex
Solution Approach 1:
The patent applies the groove structure locally rather than throughout the entire electrode. The groove is positioned specifically at the electrode opening where wire bonding occurs, providing enhanced adhesion and counterforce only where needed. This localized approach improves reliability without significantly increasing overall device complexity, as the groove is a simple geometric feature integrated into the existing electrode layout
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
Enhances the adhesion between the electrode and epitaxial laminate, preventing detachment and improving light emitting efficiency by reducing light absorption and shielding.
Implementation Method 1
the position where the second electrode contacts the transparent conductive layer is arranged with a groove portion, and the second electrode is embedded in the transparent conductive layer, increasing the adhesion of the electrode
Implementation Method 2
an electric insulating layer is added under the electrode, forming a high reflection omnibearing reflecting mirror structure so as to reduce the light shielding or light absorption by the electrode
Data Source
AI summary
A light emitting diode includes: a substrate; a semiconductor light emitting laminate on the substrate, including from bottom up a first semiconductor layer, an active layer, and a second semiconductor layer electrically dissimilar to the first semiconductor layer; a transparent conductive layer with an opening portion; the first electrode electrically connected with the first semiconductor layer; and the second electrode electrically connected with the second semiconductor layer; the second electrode fills the opening portion, and the position where the second electrode contacts the transparent conductive layer is arranged with a recessed portion, and the second electrode is embedded in the transparent conductive layer. The recessed portion is formed on the second electrode, having the second electrode embedded in the transparent conductive layer, increasing the counter force of the second electrode against the horizontal thrust during encapsulation of the LED structure and avoiding detachment during wire bonding for encapsulation.