Light Emitting Device Conductive Bump and Insulator Design
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Solution Overview
Problem
The electrical connection between the conductive circuitry layer and the electrodes in light emitting devices, particularly those using LEDs, is not sufficiently reliable, leading to issues with light intensity and connection stability.
Innovation Solution
A light emitting device design featuring a conductive bump with specific material and structural properties, such as a gold or gold alloy bump with a melting-point temperature above 180°C and dynamic hardness between 3 and 150, connected via vacuum thermal pressing, ensures reliable electrical contact between the LED electrodes and the conductive circuitry layer, while a light transmissive insulator with a Vicat softening temperature between 80°C and 160°C and a tensile storage elastic modulus above 0.1 MPa at this temperature enhances flexibility and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal compression bonding is applied to bond the conductive circuitry layer to the LED electrode, then electrical connection is achieved, but the reliability and reproducibility of the connection is insufficient
Solution Approach 1:
A light transmissive insulator is introduced as an intermediary layer between the conductive circuitry layer and the LED electrode. This insulator enables reliable electrical connection through vacuum thermal pressing while maintaining proper electrical insulation, resolving the contradiction between connection reliability and electrical isolation requirements.
Solution Approach 2:
The patent specifies precise parameter ranges for the light transmissive insulator: Vicat softening temperature between 80°C and 160°C, and tensile storage elastic modulus above 0.1 MPa at the Vicat temperature. These parameter controls ensure optimal bonding behavior during vacuum thermal pressing, achieving reliable connections without excessive complexity.
2Adaptability or versatility
If the light transmissive insulator is made flexible to ease device constraint, then adaptability improves, but connection stability under flexure deteriorates
Solution Approach 1:
The patent defines specific parameter ranges for the light transmissive insulator to balance flexibility and connection stability: Vicat softening temperature between 80°C and 160°C, and tensile storage elastic modulus above 0.1 MPa at the Vicat temperature. These parameters ensure the insulator remains flexible enough for device adaptability while maintaining sufficient rigidity to prevent short-circuits under flexure.
Solution Approach 2:
The light transmissive insulator functions as a composite material that combines electrical insulation properties with controlled mechanical flexibility. This composite nature allows the device to be constrained or flexible as needed while maintaining stable electrical connections, resolving the contradiction between adaptability and connection stability.
3Reliability
If the conductive circuitry layer is depressed against the LED electrode to ensure contact, then electrical connection is improved, but the risk of short-circuit increases
Solution Approach 1:
The light transmissive insulator serves as a mediator between the conductive circuitry layer and the LED electrode. It enables the circuitry layer to be depressed against the electrode for reliable electrical connection while simultaneously providing electrical insulation to prevent short-circuits, thus resolving the contradiction between connection reliability and short-circuit prevention.
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 solution improves the reliability and reproducibility of the electrical connection, maintaining light intensity and preventing short-circuits even under flexure, and enhances the thermal cycle resistance and flex resistance of the light emitting device.
Implementation Method 1
thermal compression bonding is typically applied to a laminated body that includes the first light transmissive insulation substrate, the light transmissive insulation resin sheet which has the through-hole in which the LED chips are laid out, and the second light transmissive insulation substrate
Implementation Method 2
connected via vacuum thermal pressing, ensures reliable electrical contact between the LED electrodes and the conductive circuitry layer
Implementation Method 3
a light transmissive insulator with a Vicat softening temperature between 80°C and 160°C
Data Source
AI summary
A light emitting device includes a first light transmissive supportive substrate having a first light transmissive insulator and a conductive circuitry layer provided on a surface of the first light transmissive insulator, a second light transmissive supportive substrate having a second light transmissive insulator and disposed in such a way that a surface of the second light transmissive insulator faces the conductive circuitry layer and so as to have a predetermined gap from the first light transmissive supportive substrate, a light emitting diode having a main body, and first and second electrodes provided on a surface of the main body and electrically connected to the conductive circuitry layer via a conductive bump, and laid out between the first and second light transmissive supportive substrates, and a third light transmissive insulator embedded in a space between the first light transmissive supportive substrate and the second light transmissive supportive substrate.