Substrate-Free LED Package via Wafer Level Fan Out
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Solution Overview
Problem
Conventional LED packages are hindered by thick substrates that increase size, impede heat removal, and are costly, limiting their efficiency and fabrication economics.
Innovation Solution
The method involves forming an LED package without a substrate using a Wafer Level Fan Out (WLFO) process, where the LED is mounted to a carrier, overmolded, and then processed to remove the carrier and substrate, allowing for enhanced heat dissipation and electrical performance while minimizing thickness and fabrication costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a substrate is used to mount the LED, then the LED structure is supported and electrical connections are established, but the package thickness increases and heat removal is impeded
Solution Approach 1:
The patent removes the substrate from the LED package structure entirely. The LED is mounted directly to the package body without an intervening substrate layer, eliminating the thickness contribution and heat barrier that the substrate would create while maintaining structural support and electrical connectivity through direct mounting to the package body.
2Reliability
If a substrate is used to mount the LED, then the LED structure is supported and electrical connections are established, but heat removal from the LED is impeded
Solution Approach 1:
The substrate is completely removed from the structure. The LED is mounted directly to the package body which provides both structural support and thermal management pathways, eliminating the thermal barrier that a substrate would create between the LED and the heat dissipation path.
3Reliability
If a substrate is used to mount the LED, then the LED can be electrically connected and structurally supported, but fabrication costs increase
Solution Approach 1:
The substrate is eliminated from the Bill of Materials and fabrication process. The LED is mounted directly to the package body using conventional bonding techniques, removing the need for substrate procurement, processing, and integration steps, thereby reducing fabrication costs while maintaining electrical connectivity.
4Reliability
If the LED is mounted to a carrier and overmolded, then the LED is protected and encapsulated, but the package thickness increases
Solution Approach 1:
The carrier and package body functions are merged into a single integrated structure. The LED is mounted to the package body which serves both as the mounting substrate and as the encapsulating package body, eliminating the need for separate carrier and package body layers and reducing overall thickness.
Data Source
AI summary
A method of forming a light emitting diode (LED) package includes mounting a LED structure to a carrier, overmolding the LED structure in a package body, backgrinding the package body to expose the LED structure, removing the carrier, and forming a redistribution layer (RDL) buildup structure comprising a RDL circuit pattern coupled to a LED of the LED structure. The LED package is formed without a substrate in one embodiment. By forming the LED package without a substrate, the thickness of the LED package is minimized. Further, by forming the LED package without a substrate, heat removal from the LED is maximized as is electrical performance. Further still, by forming the LED package without a substrate, the fabrication cost of the LED package is minimized.