LED Device Insulator Softening Temperature Bonding
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Solution Overview
Problem
The existing light emitting devices using LEDs face challenges in achieving reliable electrical connections between the conductive circuit layers and the electrodes of LED chips, particularly due to insufficient thickness of the transparent insulating resin and material properties, leading to inconsistent and unreliable connections, especially under bending or thermal cycles.
Innovation Solution
A light emitting device design that incorporates a third light transmissive insulator with a Vicat softening temperature between 80°C and 160°C and a tensile storage elastic modulus of 0.01 GPa to 10 GPa, embedded between the first and second light transmissive insulators, which enhances the electrical connection reliability by maintaining contact between the conductive circuit layers and electrodes through vacuum thermocompression bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the transparent insulating resin sheet is reduced to press the conductive circuit layers against the LED chip electrodes, then the electrical connection should improve, but the connection reliability becomes insufficient due to material properties and arrangement interval variations
Solution Approach 1:
The patent changes the physical and chemical parameters of the transparent insulating resin by specifying a Vicat softening temperature of 80°C or higher and a tensile storage elastic modulus of 0.01 GPa or more. These parameter changes enable the resin to maintain appropriate softness for electrical connection while providing sufficient mechanical strength and dimensional stability, resolving the contradiction between connection reliability and thickness control precision.
Solution Approach 2:
The patent employs a composite structure consisting of the transparent insulating resin with specifically controlled Vicat softening temperature and tensile storage elastic modulus, combined with the conductive circuit layers and LED chips. This composite material approach allows the system to achieve both softness for good electrical contact and structural integrity for reliable manufacturing.
2Reliability
If vacuum thermocompression bonding is performed to bond the insulating substrates and electrodes, then the electrical connection should be improved, but the process complexity increases
Solution Approach 1:
The patent merges the electrical connection function and the structural bonding function into a single vacuum thermocompression bonding process. By specifying the transparent insulating resin with appropriate Vicat softening temperature and tensile storage elastic modulus, the process simultaneously achieves reliable electrical contact between conductive layers and LED electrodes, while also providing mechanical bonding of the insulating substrates, thus improving reliability without proportionally increasing process complexity.
3Reliability
If the transparent insulator thickness is made smaller than the LED chip thickness to ensure contact, then the electrical connection should improve, but the connection becomes unreliable under bending or thermal cycles
Solution Approach 1:
The patent addresses the reliability issue under stress by changing the material parameters of the transparent insulating resin. By specifying a Vicat softening temperature of 80°C or higher and a tensile storage elastic modulus of 0.01 GPa or more, the resin maintains appropriate thickness (smaller than LED chip thickness for contact) while providing sufficient mechanical strength and elasticity to withstand bending and thermal cycling, ensuring stable electrical connection under stress.
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
The solution significantly improves the reproducibility and reliability of electrical connections between the conductive circuit layers and electrodes, maintaining contact even under bending and thermal cycles, thus enhancing the overall performance and durability of the light emitting device.
Implementation Method 1
The electrical connection between the electrodes of the LED chips and the conductive circuit layers in the transparent light emitting device is sometimes made, for example, by vacuum thermocompression bonding a stack composed of the first transparent insulating substrate, a transparent insulating resin sheet in which the LED chips are arranged in the through holes, and the second transparent insulating substrate.
Implementation Method 2
A light emitting device using a light emitting diode (LED) is widely used for optical devices such as indoor, outdoor, stationary, mobile display devices
Data Source
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Figure 5(a)~5(e)
AI summary
A light emitting device in an embodiment includes first and second light transmissive insulators and a light emitting diode arranged between them First and second electrodes of the light emitting diode are electrically connected to a conductive circuit layer provided on a surface of at least one of the first and second light transmissive insulators. Between the first light transmissive insulator and the second light transmissive insulator, a third light transmissive insulator is embedded which has at least one of a Vicat softening temperature of 80°C or higher and 160°C or lower and a tensile storage elastic modulus of 0.01 GPa or more and 10 GPa or less.