RGB-Stack Light Emitting Diode Modules with Transparent Glass Circuit Board and Oil Encapsulation

Area of Science:

• Solid-state lighting
• Optoelectronics
• Materials science

Background:

• Current light emitting diode (LED) submounts (PCBs, MCPCBs) are opaque, limiting light extraction efficiency.
• Transparent submounts are needed for high light output and effective color mixing in LED modules.

Purpose of the Study:

• To propose and demonstrate a novel three-dimensional (3-D) stacked flip-chip (FC) LED module.
• To enhance light output efficiency and achieve homogeneous light mixing.
• To address thermal management challenges in transparent submounts.

Main Methods:

• Development of a 3-D vertically stacked RGB LED module utilizing transparent glass circuit boards (GCB) as flip-chip package submounts.
• Implementation of a transparent cooling oil encapsulation (OCP) method to manage heat accumulation.
• Evaluation of light penetration, mixing characteristics, and thermal performance.

Main Results:

• The proposed 3-D stacked FC LED module with GCB facilitates light penetration and mixing between stacked LEDs.
• Demonstrated good output efficiency and homogeneous light-mixing characteristics.
• The OCP method effectively mitigated heat accumulation caused by the low thermal conductivity of GCB, preventing efficiency decrease.

Conclusions:

• The 3-D stacked FC LED module using GCB offers a viable solution for high-efficiency, well-mixed light output.
• The transparent OCP method successfully overcomes thermal limitations associated with glass submounts in LED applications.
• This approach advances solid-state lighting technology by improving both optical and thermal performance.