Wiring Substrate Auxiliary Pad for LED Mounting Misalignment
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Solution Overview
Problem
Inorganic light-emitting diodes (mini-LEDs or micro-LEDs) mounted on a wiring substrate can experience increased resistance in the coupling part if the mounting position is misaligned, leading to reduced contact area with the pads.
Innovation Solution
A wiring substrate design that includes an auxiliary pad with electrical conductivity, disposed near the ends of the anode and cathode pads, which can be crushed and expand to maintain electrical contact even if the light-emitting diode is misaligned.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the mounting position of the inorganic light-emitting diode is misaligned with respect to the wiring substrate, then the contact area of the anode or cathode with the pad is reduced, but this results in increased resistance of the coupling part
Solution Approach 1:
The pad structure is segmented into a main pad and an auxiliary pad. The auxiliary pad is positioned separately from the main pad and is designed to be crushed by the electrode during mounting, expanding to fill gaps and ensure electrical contact even when alignment is imperfect. This segmentation allows the system to tolerate positioning errors while maintaining low resistance.
Solution Approach 2:
The auxiliary pad acts as a pre-positioned cushioning element that compensates for potential misalignment issues before they affect the main electrical connection. By being disposed in a floating state near the end of the main pad, it provides a buffer zone that absorbs positioning errors and maintains reliable electrical contact.
2Reliability
If the contact area of the anode or cathode with the pad is reduced due to misalignment, then the electrical resistance increases, but this is not desirable for device performance
Solution Approach 1:
The electrical contact path is segmented into multiple potential contact points through the main pad and auxiliary pad configuration. This allows the current to find alternative paths if the primary contact area is reduced due to misalignment, maintaining ease of operation and mounting tolerance.
Solution Approach 2:
The auxiliary pad serves as an intermediary element between the electrode and the main pad. When misalignment occurs, the auxiliary pad crushes and expands to mediate the electrical connection, ensuring that reduced contact area does not directly translate to increased resistance or operational difficulty.
3Manufacturing precision
If small-sized parts such as mini-LEDs and micro-LEDs are used, then the display resolution improves, but these parts have a small tolerance for misalignment and are likely to lead to an increase in resistance of the coupling part
Solution Approach 1:
For small-sized parts like mini-LEDs and micro-LEDs, the pad is segmented into a main pad and an auxiliary pad positioned in close proximity. The auxiliary pad acts as a backup contact point that can be activated if the small electrode does not align perfectly with the main pad, thereby maintaining low resistance despite the tight tolerances required for high-resolution displays.
Solution Approach 2:
The auxiliary pad is disposed in a floating state near the end of the main pad, adding a spatial dimension to the contact mechanism. This floating position allows the auxiliary pad to expand into the gap created by misalignment, providing a three-dimensional solution to a two-dimensional alignment problem, which is particularly valuable for small components with minimal tolerance.
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 auxiliary pad configuration effectively suppresses the increase in electrical resistance of the coupling part, ensuring reliable electrical connectivity even when the light-emitting diode is misaligned during mounting.
Implementation Method 1
The auxiliary pad is disposed in a floating state near an end of the anode pad and the cathode pad... The auxiliary pad has a bulge coupled to the anode pad or the cathode pad disposed adjacently to the auxiliary pad in the planar direction
Data Source
AI summary
A wiring substrate includes a substrate, an insulating film stacked on the substrate, an anode pad stacked on a first surface of the insulating film and electrically coupled to an anode of an inorganic light-emitting diode, a cathode pad stacked on the first surface of the insulating film and electrically coupled to a cathode of the inorganic light-emitting diode, and an auxiliary pad provided to the first surface of the insulating film and having electrical conductivity. The auxiliary pad is disposed in a floating state near an end of the anode pad and the cathode pad.