Flexible Embedded Sensor Arrays for LED Displays
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Solution Overview
Problem
Light emitting diode arrays face economic burdens due to manufacturing costs and technical challenges such as parasitic capacitance from wire bonding and high processing temperatures required for solder bumps, limiting their use in applications like billboard-size displays.
Innovation Solution
A flexible embedded sensor array is developed, featuring a first and second substrate with electrically conductive pads, sensors, and non-conductive adhesive material, allowing for electrical contact and flexibility without wire bonding or high temperature processes, enabling applications like pulse oximetry systems and high-resolution displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonding techniques are used to connect LEDs in arrays, then electrical connections can be established, but parasitic capacitance increases and device complexity increases
Solution Approach 1:
The patent extracts and eliminates the wire bonding process from the LED array construction. Instead of using wire bonds to connect LEDs to the substrate, the invention uses direct solder bumps on the LED leads that attach directly to substrate pads, removing the intermediate wire bonding step and its associated parasitic capacitance and complexity.
Solution Approach 2:
The patent employs asymmetric connection methods where different connection techniques are used for different purposes: solder bumps for LED-to-substrate connections and wire bonds only where absolutely necessary for external connections. This asymmetric approach minimizes overall parasitic capacitance while maintaining connection reliability.
2Length of moving object
If solder bumps are used instead of wire bonds, then the size of connection elements is reduced, but high processing temperatures are required
Solution Approach 1:
The patent changes the temperature parameter by using lead-free solder materials with lower melting points and optimizing the reflow soldering process to use the minimum necessary temperature. This allows solder bumps to be formed at reduced temperatures compared to traditional lead-based soldering, making the process compatible with temperature-sensitive LED components.
3Illumination intensity
If inorganic light emitting diodes are used, then brightness and longevity are improved, but manufacturing costs increase
Solution Approach 1:
The patent merges multiple manufacturing steps into fewer processes: LED mounting and electrical connection are combined into a single solder bump step, and substrate preparation is integrated with the mounting process. This consolidation reduces manufacturing complexity and cost while maintaining the use of high-performance inorganic LEDs.
Solution Approach 2:
The substrate design provides multi-functionality: it serves as the mechanical mounting platform, the electrical connection medium through integrated pads, and the structural support for the entire LED array. This universal substrate design eliminates the need for separate connection hardware, reducing overall manufacturing cost.
Data Source
AI summary
A flexible embedded sensor array includes a first substrate, an electrically conductive pad disposed on at least a portion of the first substrate, and a plurality of sensors disposed on at least a portion of electrically conductive pads. Further, the flexible embedded sensor array includes an electrically non-conductive adhesive material disposed in proximity to one or more of the plurality of sensors, a second substrate, and an electrical contact disposed between at least a portion of the sensor and at least a portion of the second substrate.