Flip-Chip LED Electrode Sidewall Extension for Solder Overflow Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The manufacturing of small-sized flip-chip LEDs faces challenges such as limited electrode area, solder paste overflow leading to short circuits, and poor heat dissipation due to small contact areas, as well as issues with crooked edges and non-uniform contours during the dicing process.
Innovation Solution
The design includes a light-transmissive substrate with a light-emitting unit and insulating layer, where the electrodes extend over the juncture between insulating portions, increasing their surface area, and a method involving trench formation to separate LEDs, reducing stress and deformation during dicing, thus enhancing production yield and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the LED size is reduced to mini-LED or micro-LED dimensions, then the device can be applied in high-resolution displays and backlight LCDs, but the electrode area becomes limited causing solder paste overflow and short circuits
Solution Approach 1:
The electrode structure transitions from a planar 2D configuration to a 3D configuration by having the electrode extend vertically along the sidewall of the light-emitting unit. This dimensional change increases the effective electrode surface area without increasing the horizontal footprint, thereby providing sufficient solder paste application area while maintaining small LED dimensions and preventing solder overflow that causes short circuits.
Solution Approach 2:
The electrode is divided into multiple segments: a first electrode portion on the light-transmissive substrate, a second electrode portion extending along the sidewall of the light-emitting unit, and a third electrode portion on the insulating layer. This segmentation allows the electrode to utilize vertical space efficiently, increasing total electrode area while maintaining compact horizontal dimensions suitable for mini-LED and micro-LED applications.
2Volume of moving object
If the LED size is reduced to mini-LED or micro-LED dimensions, then the device can be applied in high-resolution displays and backlight LCDs, but the contact area for heat dissipation becomes insufficient
Solution Approach 1:
The electrode structure extends into the vertical dimension along the sidewall of the light-emitting unit, transforming from a 2D planar contact to a 3D structure. This increases the total contact area between the electrode and the light-emitting unit, thereby improving heat dissipation capability while maintaining small LED dimensions suitable for high-resolution displays.
3Productivity
If conventional dicing methods are used to separate LEDs, then production can proceed efficiently, but crooked edges and non-uniform contours occur reducing production yield
Solution Approach 1:
The insulating layer is formed to cover the lateral surface of the light-emitting unit before the dicing process. This preliminary protective action prevents the dicing blade from directly contacting and damaging the light-emitting unit during separation, thereby eliminating crooked edges and non-uniform contours while maintaining production efficiency and improving manufacturing precision.
4Reliability
If the electrode area is increased to prevent solder paste overflow, then connection reliability improves, but the LED size increases reducing applicability in high-resolution displays
Solution Approach 1:
The electrode extends vertically along the sidewall of the light-emitting unit, utilizing the third dimension (height) to increase electrode surface area. This allows sufficient electrode area for reliable solder paste application and connection without increasing the horizontal footprint, thereby maintaining small LED dimensions suitable for high-resolution displays while improving connection reliability.
Solution Approach 2:
The electrode is segmented into multiple portions distributed in both horizontal and vertical spaces. This segmentation allows the total electrode area to be increased by utilizing vertical space along the sidewall, rather than expanding horizontally, thereby preventing solder paste overflow while maintaining compact LED dimensions for high-resolution display applications.
Data Source
AI summary
A light-emitting diode includes a light-transmissive substrate, a light-emitting unit disposed on the light-transmissive substrate, an insulating layer, a first electrode and a second electrode. The insulating layer includes a first insulating portion and a second insulating portion which respectively cover an upward surface and a lateral surface of the light-emitting unit. The first and second electrodes are separately disposed on the insulating layer. At least one of the first and second electrodes extends on the first insulating portion and over a juncture between the first insulating portion and the second insulating portion.