Micro LED Electrode Pad Groove for Stable Conductive Ball Bonding
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Solution Overview
Problem
The thermal compression process in micro LED chip manufacturing can cause conductive balls in the anisotropic conductive film to be pushed out of the electrode pad and substrate interface, leading to faulty connections due to pressure, which reduces the reliability of electrical connections between the micro LED chip and the panel substrate.
Innovation Solution
The micro LED chip features an electrode pad with a groove structure that increases in depth from the edge to the center, which helps to maintain conductive balls between the electrode pad and the substrate during thermal compression, preventing them from being pushed out and ensuring stable electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal compression process is used to bond micro LED chip to panel substrate, then electrical connection is achieved, but conductive balls are pushed out of electrode pad interface leading to faulty connections
Solution Approach 1:
The electrode pad is designed with a groove structure that creates different depths at different locations. The groove has a first depth at the interface with the anisotropic conductive film and a second depth greater than the first depth at the interface with the panel substrate. This local variation in depth confines the conductive balls within the groove structure, preventing their displacement during thermal compression while maintaining reliable electrical connections.
2Strength
If pressure is applied during thermal compression to ensure bonding, then adhesion is improved, but conductive balls are forced into outer region between electrodes
Solution Approach 1:
The groove structure creates localized depth variations that act as physical barriers to confine conductive balls. The first depth region provides initial containment while the second depth region provides enhanced confinement at the substrate interface, ensuring conductive balls remain in position even under compression pressure.
Solution Approach 2:
The groove structure introduces a vertical dimension (depth variation) to the otherwise planar electrode pad interface. By creating depth differences between the first and second interfaces, the design uses the vertical dimension to confine conductive balls horizontally, preventing their displacement to outer regions during compression.
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 prevents connection failures by ensuring a consistent flow of conductive balls within the groove structure, maintaining the integrity of the electrical connections between the micro LED chip and the panel substrate, thereby enhancing the reliability of the micro LED display.
Implementation Method 1
a photon corresponding to a band gap is emitted as an electron injected from an electrode to a semiconductor and a hole recombine over the band gap in the P-N junction part and thereby, observed as light to a naked eye of a person
Implementation Method 2
The micro LED chip may be manufactured through a thermal-compression process after being disposed on a display panel substrate laminated with an anisotropic conductive film including conductive balls at a surface thereof
Data Source
AI summary
A micro light emitting diode (LED) chip includes: a first semiconductor layer doped with an N-type dopant; a second semiconductor layer provided at a lower surface of the first semiconductor layer, and doped with a P-type dopant; an active layer provided between the first semiconductor layer and the second semiconductor layer, and configured to emit light; and an electrode pad provided at a lower surface of the second semiconductor layer, wherein the electrode pad may include a groove structure having a depth that increases from an edge of the electrode pad towards a center of the electrode pad.