Conformal Phosphor Film Packaging for Lower-Cost White LEDs
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Solution Overview
Problem
Existing processes for incorporating phosphor in LED systems are costly and complex, contributing to high production costs, as they often require cavities, dams, or direct deposition on the LED die, which increases manufacturing expenses and reduces efficiency.
Innovation Solution
A conformal phosphor film is used, supported by a carrier or substrate, which is heated to conform around the LED and wire bonds, eliminating the need for cavities or direct deposition, allowing for a more uniform and cost-effective distribution of phosphor elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If phosphor is deposited directly on the LED die or placed in cavities/dams, then the LED produces suitable light emission characteristics, but the manufacturing cost and process complexity increase significantly
Solution Approach 1:
The phosphor application process is segmented into separate stages: first forming the LED die with bond pads, then applying phosphor to specific regions (side walls and bottom) while leaving bond pad areas clear, and finally completing electrical connections. This segmentation allows each step to be optimized independently, reducing overall process complexity while maintaining light emission quality.
Solution Approach 2:
The phosphor is applied to the side walls and bottom surfaces of the LED die before the final electrical connections are made. This preliminary action ensures that phosphor does not interfere with subsequent bonding operations, eliminating the need for complex cavity structures or dams while still achieving uniform light emission characteristics.
2Illumination intensity
If phosphor is applied in existing methods (cavity filling, dam construction, or direct deposition), then white light is produced, but production costs increase due to additional manufacturing steps
Solution Approach 1:
The invention extracts and eliminates unnecessary intermediate structures (cavities and dams) from the manufacturing process. By applying phosphor directly to the LED die surfaces in a simplified sequence, the process removes redundant steps while maintaining the ability to produce high-quality white light, thereby reducing production costs.
Solution Approach 2:
Instead of building complex containment structures (cavities/dams) and then filling them with phosphor, the invention inverts the approach by applying phosphor directly to the die surfaces first and then completing connections. This reversal simplifies the manufacturing process while achieving the same optical results.
3Manufacturing precision
If phosphor is deposited on the LED die, then the phosphor distribution can be controlled, but electrical connections to bond pads become difficult to establish
Solution Approach 1:
The invention applies phosphor selectively to specific local regions of the LED die (side walls and bottom surfaces) while deliberately leaving the bond pad areas free of phosphor. This local quality approach ensures uniform phosphor distribution in the light-emitting regions while maintaining clear access to bond pads for electrical connections, resolving the contradiction between phosphor uniformity and connection ease.
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 approach reduces manufacturing steps and costs by enabling a more uniform phosphor distribution, conforming to the LED and wire bonds without disrupting electrical connections, and allowing for separate production of phosphor films, thus lowering the overall cost of LED packaging.
Implementation Method 1
manufacturers coat such LEDs with a phosphor that absorbs a portion of the emitted blue light and re-emits the light as yellow light, producing a composite light emission that is white or at least approximately white
Implementation Method 2
A conformal phosphor film is used, supported by a carrier or substrate, which is heated to conform around the LED and wire bonds
Data Source
AI summary
Packaged LEDs with phosphor films, and associated systems and methods are disclosed. A system in accordance with a particular embodiment of the disclosure includes a support member having a support member bond site, an LED carried by the support member and having an LED bond site, and a wire bond electrically connected between the support member bond site and the LED bond site. The system can further include a phosphor film carried by the LED and the support member, the phosphor film being positioned to receive light from the LED at a first wavelength and emit light at a second wavelength different than the first. The phosphor film can be positioned in direct contact with the wire bond at the LED bond site.