LED Package Structure With Integrated Drivers for Backside 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, which is difficult with conventional passive-matrix driving methods, and to reduce manufacturing costs compared to active matrix driving methods.
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, allowing the active devices to drive the LEDs, and enabling the removal of the carrier to expose the bottom surface for soldering, while using a dielectric and surface treatment layers for protection and connection.
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 requiring a large number of driving chips
Solution Approach 1:
The patent merges the driving function directly into the display panel by integrating active devices (TFTs) and LEDs on the same substrate, eliminating the need for separate driving chips. This integration combines multiple functions (display and driving) into a single structure, thereby reducing the number of components and manufacturing cost while maintaining driving capability.
2Ease of manufacture
If active matrix driving TFT backplane is used, then manufacturing cost decreases, but soldering of electronic devices on the back surface of glass substrate becomes difficult
Solution Approach 1:
Instead of soldering electronic devices on the back surface of the glass substrate, the patent inverts the approach by making the front surface (with the active devices and LEDs) the functional surface. The display panel is designed so that the active devices are accessible on the same side as the display elements, enabling soldering and electrical connections to be made on the front surface rather than the back surface.
3Ease of manufacture
If a carrier is used during manufacturing, then LED transfer and alignment are facilitated, but the carrier must be removed to expose the bottom surface for soldering
Solution Approach 1:
The carrier is introduced at the beginning of the manufacturing process to facilitate LED transfer and alignment. The carrier serves as a temporary support structure that enables precise placement of LEDs on the substrate. After the LEDs are transferred and positioned correctly, the carrier is removed, revealing the completed structure ready for soldering. This preliminary action simplifies the complex task of transferring and aligning numerous small LEDs.
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.