LED Wafer-Level Package Self-Aligning Substrates
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Solution Overview
Problem
Conventional LED packaging methods require separate substrates for each LED die, leading to time-consuming and precise handling, and suffer from thermal expansion issues causing delamination, as well as the need for a separate dam for converter materials, which complicates the manufacturing process and increases costs.
Innovation Solution
Wafer-level packaging with patterned and alignment substrates having similar thermal expansion coefficients, allowing for efficient mounting and alignment of LEDs with embedded converter materials without a separate dam, and improved thermal management through conductive vias and bonding materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If each LED die is mounted to a separate substrate, then precise positioning and thermal management are improved, but handling complexity and time consumption increase
Solution Approach 1:
Multiple LED dies are mounted simultaneously on a single substrate rather than individually on separate substrates. The substrate includes multiple mounting regions with corresponding vias and contact pads, allowing batch processing of multiple LEDs in one operation, thus reducing handling time while maintaining positioning precision through aligned via structures
Solution Approach 2:
The substrate is pre-patterned with multiple mounting regions, vias, and contact pads before LED mounting. This preliminary preparation enables direct placement and wire bonding of multiple LEDs without requiring separate substrate preparation steps for each die, significantly reducing overall processing time
2Reliability
If a separate dam structure is used to contain converter material, then converter material containment is improved, but device complexity and manufacturing steps increase
Solution Approach 1:
The substrate serves multiple functions: it provides mechanical support, thermal management through vias, electrical connections via contact pads, and converter material containment through its structural design. The substrate's mounting regions and surrounding structures act as integrated containment features, eliminating the need for separate dam structures while maintaining converter material containment reliability
Solution Approach 2:
The converter material containment function is merged with the substrate structure itself. The substrate's mounting regions and peripheral structures serve dual purposes of supporting LED dies and containing converter materials, reducing the total number of discrete components and simplifying the overall device architecture
3Strength
If LED die and substrate have different thermal expansion coefficients, then bonding strength is improved, but thermal stress and delamination increase
Solution Approach 1:
The substrate is designed with specific thermal expansion characteristics that account for the LED die's thermal properties. By selecting substrate materials and structures with matched thermal expansion coefficients, the patent minimizes thermal stress during temperature cycling while maintaining strong bonding through optimized bonding layers and via structures
4Productivity
If wafer-level packaging is used, then productivity is improved, but alignment precision requirements increase
Solution Approach 1:
The substrate is pre-patterned with aligned mounting regions, vias, and contact pads before LED mounting. This preliminary alignment structure provides self-aligning features that guide LED die placement and wire bonding, enabling wafer-level batch processing while maintaining the precision required for electrical connections and reducing alignment complexity
Solution Approach 2:
Mechanical alignment features such as pre-drilled vias and patterned contact pads replace complex mechanical alignment systems. These fixed geometric references provide automatic alignment during LED placement and wire bonding, enabling high-productivity wafer-level processing without requiring precision mechanical positioning systems
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 handling complexity, minimizes thermal stress, and enhances packaging efficiency by allowing for easier alignment and surface mounting of LEDs with reduced thermal expansion issues, while maintaining the ability to produce white light emissions.
Implementation Method 1
a converter material 6 deposited on the LED die 4... The LED die 4 can include one or more light emitting components... the InGaN material 16 of the LED die 4 emits a blue light that stimulates the converter material 6 to emit a light (e.g., a yellow light) at a desired frequency
Implementation Method 2
improved thermal management through conductive vias and bonding materials
Data Source
AI summary
Several embodiments of light emitting diode packaging configurations including a substrate with a cavity are disclosed herein. A patterned wafer has a plurality of individual LED attachment sites, and an alignment wafer has a plurality of individual cavities. The patterned wafer and the alignment wafer are superimposed with the LED attachment sites corresponding generally to the cavities of the alignment wafer. At least one LED is placed in the cavities using the cavity to align the LED relative to the patterned wafer. The LED is electrically connected to contacts on the patterned wafer, and a phosphor layer is formed in the cavity to cover at least a part of the LED.