Dual-Electrode LED Chips for Small-Pitch Display Pin Reduction
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Solution Overview
Problem
The existing small-pitch LED display screens face difficulties in welding operations due to the increasing number of pins, leading to inefficiencies and low location accuracy during the die bond process of LED light-emitting chips.
Innovation Solution
The proposed solution involves a circuit board with a pixel unit array where dual-electrode LED light-emitting chips have electrodes A and B on the same side, connected by lines directed in the same direction, allowing for efficient die bonding with a single die bonder without adjusting the working position, and a display panel with a reduced number of pins for improved accuracy and compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If independent packaging devices with multiple pins are used to increase pixel unit density, then the pixel pitch is reduced, but the number of pins increases leading to difficulty in welding operation and complex PCB circuit
Solution Approach 1:
The patent combines multiple independent packaging devices into a single integrated packaging module. Specifically, four light-emitting units (each with anode and cathode) are integrated into one module that shares common anode and cathode bonding pads, reducing the total pin count from 16 individual pins to 8 shared pins, thereby simplifying the PCB circuit and welding operations while maintaining high pixel density
2Device complexity
If mirror symmetric arrangement of bonding zones is adopted to reduce pin bonding pads, then the number of pins is reduced, but the die bond efficiency decreases and location accuracy is low due to required orientation adjustments
Solution Approach 1:
The patent adopts an asymmetric arrangement for the bonding zones within each light-emitting unit. The anode bonding zone and cathode bonding zone are positioned at different locations rather than being mirror symmetric, allowing all LED light-emitting chips to be bonded in the same orientation direction. This eliminates the need for die bonder orientation adjustments between adjacent columns, significantly improving die bond efficiency and location accuracy while still reducing the number of pin bonding pads through shared common electrodes
3Device complexity
If mirror symmetric arrangement of bonding zones is adopted, then pin bonding pads are reduced, but the location accuracy of LED light-emitting chip after die bond is low
Solution Approach 1:
The asymmetric positioning of anode and cathode bonding zones within each light-emitting unit enables all LED chips to be bonded in a uniform orientation. This consistent bonding direction ensures precise location accuracy for each chip while the shared common electrode bonding pads reduce the overall number of bonding locations required on the PCB
Data Source
AI summary
Provided is a light-emitting diode (LED) display unit group and a display panel. The LED display unit group includes a circuit board, and a pixel unit array located on the circuit board. The pixel unit array includes a plurality of pixel units arranged in n rows and m columns, n and m are both positive integers and greater than or equal to 2. Each of the pixel units includes multiple LED light-emitting chips of at least two colors, each of the LED light-emitting chips includes an electrode A and an electrode B of opposite polarities. The LED light-emitting chip of each of the pixel units includes at least one dual-electrode chip, the dual-electrode chip has the electrode A and the electrode B located on a same side of the dual-electrode chip. All dual-electrode chips in the plurality of pixel units of a same color have connecting lines from the electrode A to the electrode B directed in a same direction.