LED Flip-Chip Insulation Layer Adhesion
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Solution Overview
Problem
Conventional flip-chip light emitting devices face reliability issues due to weak adhesion between reflective layers, such as silver, and other layers, leading to potential peeling and reduced device performance.
Innovation Solution
Incorporating an insulation layer with higher adhesion properties into through-holes within the reflective layer, which strengthens the connection between the reflective layer and the transmissive conductive layer or second conductive semiconductor layer, thereby enhancing the structural integrity and reliability of the light emitting device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a reflective layer made of silver is used to reflect light, then light reflection efficiency is improved, but adhesion strength to other layers deteriorates
Solution Approach 1:
An insulation layer is introduced as an intermediary between the reflective layer and the through-holes. This insulation layer has higher adhesion to the surrounding layers compared to the reflective layer, thereby preventing peeling while allowing the reflective layer to maintain its light reflection function.
Solution Approach 2:
The insulation layer is selectively positioned at the through-holes where adhesion is critical, rather than uniformly across the entire structure. This local application provides enhanced adhesion strength precisely where needed (at the interface between reflective layer and contact layer) without compromising the overall light reflection efficiency.
2Quantity of substance
If the reflective layer is made thinner to reduce material usage, then manufacturing cost is reduced, but adhesion reliability deteriorates
Solution Approach 1:
The insulation layer acts as a mediator that compensates for the reduced adhesion reliability caused by using thinner reflective layers. By providing enhanced adhesion at the critical through-hole interfaces, the insulation layer ensures reliable bonding even when the reflective layer thickness is minimized for cost efficiency.
3Illumination intensity
If through-holes are enlarged to improve light extraction, then light emission efficiency is improved, but structural integrity deteriorates
Solution Approach 1:
The insulation layer is strategically placed at the through-holes where structural weakness occurs due to enlargement. This localized reinforcement provides the necessary structural integrity at the critical stress points without restricting the through-hole size needed for efficient light extraction.
Solution Approach 2:
The combination of reflective layer, insulation layer, and surrounding structural layers creates a composite structure. The insulation layer, with its superior adhesion properties, reinforces the through-hole regions and prevents peeling, thereby maintaining structural integrity even when through-holes are enlarged for improved light emission.
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 solution effectively prevents metal peeling and improves the reliability of the light emitting device by increasing the adhesion between the reflective and conductive layers, ensuring better light emission efficiency and durability.
Implementation Method 1
the insulation layer being embedded in the first through-hole... the insulation material having greater adhesion to the second conductive semiconductor layer than adhesion of the reflective layer to the second conductive semiconductor layer
Data Source
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AI summary
Embodiments provide a light emitting device including a substrate, a light emitting structure including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer, disposed under the substrate, a reflective layer disposed under the second conductive semiconductor layer, the reflective layer having at least one first through-hole formed in a first direction, the first direction being a thickness direction of the light emitting structure, a contact layer embedded in at least one second through-hole penetrating the reflective layer, the second conductive semiconductor layer, and the active layer so as to be connected to the first conductive semiconductor layer, and an insulation layer disposed between the contact layer and each of the reflective layer, the second conductive semiconductor layer, and the active layer, the insulation layer being embedded in the first through-hole.