Light-Emitting Substrate Pad Protection Against ENIG Short Circuits
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Solution Overview
Problem
The existing light-emitting substrates face issues with passivation layer climbing portions being prone to breakage, leading to poor pad protection, reduced reliability, and increased risk of short circuits due to static electricity and conductive metal formation during the ENIG process, which negatively impacts product yield.
Innovation Solution
The light-emitting substrate includes first, second, and third protective patterns on the passivation layer, covering climbing portions and extending away from pads, with distances maintained to prevent shielding openings and electrostatic damage, enhancing pad protection and preventing short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the passivation layer is formed with openings close to pads to enable electrical connection, then the electrical connectivity is improved, but the climbing portions of the passivation layer become prone to breakage
Solution Approach 1:
The patent applies beforehand cushioning by forming protective patterns (first protective pattern covering the first climbing portion, second protective pattern covering the second climbing portion) before the ENIG process. These protective patterns act as a buffer against static electricity and mechanical stress that would otherwise cause the climbing portions to break during subsequent manufacturing steps.
Solution Approach 2:
The protective patterns serve as an intermediary layer between the climbing portions and the harmful environment during the ENIG process. They mediate the interaction by providing electrostatic protection and physical support, preventing direct damage to the vulnerable climbing portions while allowing the manufacturing process to proceed.
2Ease of manufacture
If the ENIG process is performed without protective measures, then the manufacturing process is simplified, but static electricity causes climbing portion breakage and conductive metal formation leading to short circuits
Solution Approach 1:
The patent applies preliminary action by forming the protective patterns before the ENIG process. The first protective pattern and second protective pattern are created in advance to cover the climbing portions, and the third protective pattern is formed to cover the target region, preparing the structure to withstand the upcoming ENIG process without causing short circuits or damage.
Solution Approach 2:
The protective patterns provide preliminary anti-action by counteracting the harmful effects of static electricity generated during the ENIG process. The patterns are designed with appropriate reflectivity and coverage to neutralize electrostatic damage before it can affect the climbing portions or create conductive metal bridges between adjacent pads.
3Reliability
If protective patterns are added to cover climbing portions, then pad protection and reliability are improved, but the device structure becomes more complex
Solution Approach 1:
The protective patterns serve multiple functions simultaneously: they protect the climbing portions from electrostatic damage, provide mechanical support during the ENIG process, prevent short circuits between adjacent pads, and maintain appropriate reflectivity for light extraction. This multi-functionality justifies the additional structural elements.
Solution Approach 2:
The protective patterns are applied locally rather than uniformly across the entire substrate. The first protective pattern covers the first climbing portion, the second protective pattern covers the second climbing portion, and the third protective pattern covers the target region, with each pattern having specific reflectivity requirements tailored to its location and function.
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
The protective patterns improve the reliability of the substrate by preventing pad exposure and short circuits, thereby increasing product yield and maintaining high reflectivity for enhanced light exit efficiency.
Implementation Method 1
maintaining high reflectivity for enhanced light exit efficiency
Data Source
AI summary
A light-emitting substrate includes a substrate, and a first conductive layer, a passivation layer and a first protective pattern that are disposed on the substrate sequentially. The first conductive layer includes a plurality of pad groups each including a plurality of pads. The passivation layer is provided with a plurality of openings therein, an opening is located on a side of a pad away from the substrate, and the opening and an edge of the pad have a distance therebetween. The passivation layer includes a first climbing portion covering a sidewall of a first edge of the pad and a second climbing portion covering a sidewall of a second edge of the pad. The first protective pattern covers the first climbing portion and extends to a side of the passivation layer away from the pad, and the first protective pattern and the opening have a distance therebetween.