KGD-LED Chip Assembly on Redistribution Substrate
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Solution Overview
Problem
Increasing the size of light-emitting diode (LED) chips to achieve higher brightness and lower degradation leads to significant yield loss, hindering the adoption of large-chip LEDs.
Innovation Solution
The process of forming known good die (KGD)-LED components into larger optically coherent LED chips involves singulating and flip chip bonding onto a mounting substrate with redistribution layers, under-filling gaps with a transparent material, and roughening surfaces for enhanced light extraction, allowing for scalability, high efficacy, and high brightness while maintaining high yield and low cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the LED chip size is increased to achieve higher brightness and lower degradation, then the brightness and efficacy are improved, but the manufacturing yield deteriorates significantly
Solution Approach 1:
The patent divides a large LED chip into multiple smaller LED chips that are bonded together on a substrate. Each smaller chip can be manufactured independently with high yield, and when combined, they function as a large-chip LED device, thus achieving high brightness without sacrificing manufacturing yield.
Solution Approach 2:
The patent combines multiple smaller LED chips into a single integrated device by bonding them to a common substrate with conductive patterns. This merging allows the device to achieve the optical output of a large chip while maintaining the manufacturing advantages of smaller individual chips.
2Reliability
If the LED chip size is increased to achieve higher brightness, then the current density is reduced and degradation is minimized, but the manufacturing cost and complexity increase
Solution Approach 1:
By segmenting the large chip into smaller chips, each chip operates at lower current density, reducing degradation. The segmentation is achieved through standard bonding processes rather than requiring complex monolithic fabrication, thus managing complexity.
Solution Approach 2:
The substrate serves multiple functions: it provides mechanical support, electrical interconnection through conductive patterns, and thermal management. This multi-functionality reduces the need for additional components and simplifies the overall device structure despite the multi-chip configuration.
3Productivity
If multiple LED chips are bonded together to form a larger device, then the yield is maintained, but the device complexity and manufacturing process steps increase
Solution Approach 1:
The substrate with conductive patterns is prepared in advance, and LED chips are bonded to predetermined locations. This preliminary preparation of the substrate allows for systematic assembly of multiple chips, reducing the complexity of real-time alignment and connection during the bonding process.
Solution Approach 2:
The substrate acts as an intermediary that simplifies the bonding process by providing a pre-configured platform with conductive patterns. This intermediary structure enables straightforward electrical interconnection of multiple chips without requiring complex wire bonding or direct chip-to-chip alignment.
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
This method enables the creation of larger LED chips with high brightness, high efficacy, and low cost, overcoming the yield loss issues associated with increasing LED chip size, while ensuring efficient light extraction and electrical connections.
Implementation Method 1
The gaps and spaces are under-filled with a transparent material... a surface of the transparent material may be roughened for purposes of light extraction
Implementation Method 2
a surface of the transparent material may be roughened for purposes of light extraction
Implementation Method 3
redistribution layers (RDLs) that facilitate electrical connections between the KGD-LED components and an operating device
Data Source
AI summary
Disclosed herein are technologies for forming a plurality of known good die (KGD)-light emitting diode (LED) components into a larger size optically coherent LED chips or devices. This Abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.