LED Cushion Part Layout for Ejector Pin Stress Isolation
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Solution Overview
Problem
Conventional flip chip LED packaging processes damage LED chips due to mechanical stress from ejector pins, leading to cracks and short circuits during detachment from blue tape, compromising the reliability of the light-emitting elements.
Innovation Solution
Incorporating a cushion part on the light-emitting element, electrically isolated from conductive layers, which absorbs the detaching force of the ejector pin, preventing cracks and short circuits by distributing the mechanical stress effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an ejector pin is used to detach the LED chip from the blue tape, then the detachment process can be completed, but the LED chip is damaged due to mechanical stress
Solution Approach 1:
The cushion part serves as an intermediary element between the ejector pin and the LED chip. It absorbs and distributes the mechanical stress from the ejector pin, preventing direct contact with the chip and thus avoiding damage while still enabling the detachment process to proceed effectively.
Solution Approach 2:
The cushion part is pre-positioned on the LED chip before the detachment process. This beforehand cushioning provides protective support during the subsequent ejector pin operation, absorbing mechanical shocks and stresses that would otherwise directly damage the chip structure.
2Force
If the ejector pin pushes the LED chip directly, then detachment force can be applied, but cracks are produced in the chip
Solution Approach 1:
The cushion part acts as a mediator that receives the detachment force from the ejector pin and redistributes it across a larger area of the chip. This force distribution prevents concentration of stress at specific points, thereby avoiding crack formation while maintaining effective detachment capability.
Solution Approach 2:
The cushion part changes the mechanical parameters of force application by increasing the contact area and reducing pressure concentration. This parameter transformation allows the same detachment force to be applied without exceeding the chip's strength limits, preventing structural failure.
3Ease of operation
If the LED chip has insufficient mechanical strength, then the chip can be easily manipulated, but it is easily damaged during the detachment process
Solution Approach 1:
The cushion part is positioned on the chip beforehand to provide mechanical support during vulnerable operations. This pre-positioned cushioning compensates for the chip's insufficient inherent strength, allowing easy manipulation during assembly while protecting against damage during detachment and other stress-prone processes.
Solution Approach 2:
The cushion part functions as a flexible protective layer that conforms to the chip surface. This flexible structure provides cushioning and stress distribution without rigidly constraining the chip, maintaining ease of manipulation while enhancing damage resistance through elastic deformation and energy absorption.
Data Source
AI summary
A light-emitting element includes a semiconductor light-emitting stack including a first semiconductor layer, a second semiconductor layer formed on the first semiconductor layer, and an active layer formed therebetween; a first conductive layer disposed on the second semiconductor layer and electrically connecting the second semiconductor layer; a second conductive layer disposed on the second semiconductor layer and electrically connecting the first semiconductor layer; and a cushion part disposed on and directly contacts the first conductive layer, wherein in a top view, the cushion part is surrounded by and electrically isolated from the second conductive layer.