LED Package Structure With Redistribution Layer for Glass Backplane Soldering
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Solution Overview
Problem
The challenge is to create a cost-effective LED package structure that allows electronic devices to be soldered on the back surface of a glass substrate, as existing passive-matrix driving methods are expensive and active-matrix methods face manufacturing difficulties with large-scale displays.
Innovation Solution
A manufacturing method involving a carrier with a redistribution layer, active devices, and LEDs, where the LEDs are electrically connected to the redistribution layer, and a molding compound encapsulates them, enabling the active devices to drive the LEDs, thus overcoming the soldering limitation and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If passive-matrix driving PCB backplanes are used, then driving capability is achieved, but manufacturing cost increases due to large number of driving chips required
Solution Approach 1:
The patent replaces the mechanical/electrical connection system of PCB backplanes with driving chips with a glass substrate backplane using TFT active devices integrated directly on the substrate. This substitution eliminates the need for separate driving chips and complex PCB assemblies, thereby reducing manufacturing cost and device complexity while maintaining driving capability.
2Ease of manufacture
If active-matrix driving TFT backplane is used, then manufacturing cost decreases, but large-scale display production becomes difficult due to inability to solder electronic devices on glass substrate back surface
Solution Approach 1:
The patent transitions from a two-dimensional planar connection approach to a three-dimensional vertical connection approach by forming conductive vias that extend through the molding compound to reach the back surface of the glass substrate. This dimensional change enables electronic devices to be electrically connected to the TFT backplane from the back surface, facilitating large-scale display production while maintaining cost effectiveness.
3Reliability
If LEDs are transferred onto redistribution layer, then electrical connection is achieved, but additional manufacturing steps are required
Solution Approach 1:
The patent combines the redistribution layer formation with the LED transfer process by forming the redistribution layer on the carrier substrate before transferring LEDs, and then removing the carrier to expose the back surface. This merging of steps integrates multiple functions into a unified process flow, reducing the number of separate manufacturing steps while ensuring reliable electrical connections between LEDs and TFT devices through the redistribution layer and conductive vias.
Data Source
AI summary
A manufacturing method of a light emitting diode (LED) package structure includes the following steps. A carrier is provided. A redistribution layer is formed on the carrier. A plurality of active devices are formed on the carrier. A plurality of LEDs are transferred on the redistribution layer. The LEDs and the active devices are respectively electrically connected to the redistribution layer. The active devices are adapted to drive the LEDs, respectively. A molding compound is formed on the redistribution layer to encapsulate the LEDs. The carrier is removed to expose a bottom surface of the redistribution layer.