Solid-State Element Device with Inorganic Sealing and Air Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional light emitting devices with Au bump electrodes face issues such as electrode separation due to thermal stress, non-uniform current distribution, and reduced light extraction efficiency, limiting the improvement of brightness and reliability.
Innovation Solution
A solid-state element device with a pad electrode smaller than the contact electrode, flip-mounted with an inorganic sealing portion having a thermal expansion coefficient matching the power receiving/supplying portion, and an air layer between the solid-state element and the power receiving/supplying portion, using a transparent conductive material like ITO and a small refractive index film to enhance light extraction and prevent electrode separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the Au bump electrode area is increased to improve heat radiation, then heat radiation property improves, but electrode separation occurs due to thermal expansion mismatch
Solution Approach 1:
The patent changes the material parameter of the bump electrode from Au (gold) to Cu (copper), which has a thermal expansion coefficient closer to that of the sapphire substrate. This parameter change resolves the thermal expansion mismatch issue while maintaining effective heat radiation from the LED element.
Solution Approach 2:
The patent applies different materials to different parts of the electrode structure: Cu bump electrodes for thermal management and Au electrodes for electrical connection. This local differentiation allows optimization of each function independently, preventing electrode separation while maintaining heat radiation efficiency.
2Temperature
If the Au bump electrode area is increased, then heat radiation improves, but current distribution becomes non-uniform
Solution Approach 1:
The patent differentiates the functions of different electrode parts: Cu bumps for heat dissipation and Au electrodes for current injection. This local quality differentiation ensures that current distribution remains uniform through the Au electrodes while heat radiation is improved through the Cu bumps, resolving the contradiction between heat management and current uniformity.
3Temperature
If the Au bump electrode area is increased, then heat radiation improves, but light extraction efficiency decreases due to metal reflection
Solution Approach 1:
The patent separates the heat radiation function (handled by Cu bumps) from the light extraction function (handled by Au electrodes and transparent contact layer). The Au electrodes provide good light extraction properties while Cu bumps provide thermal management, eliminating the energy loss to metal reflection while maintaining heat radiation efficiency.
Solution Approach 2:
The patent uses the sapphire substrate's optical properties (high transparency and refractive index) to extract light, copying the substrate's advantageous optical characteristics for light extraction rather than relying on metal electrodes, thereby reducing reflection losses.
4Temperature
If the Au bump electrode area is increased, then heat radiation improves, but device complexity increases due to separation issues
Solution Approach 1:
The patent simplifies the electrode structure by changing the bump electrode material to Cu and optimizing its size (diameter of 5-15 μm), which provides sufficient heat radiation without causing separation issues. This parameter optimization reduces device complexity while maintaining heat management effectiveness.
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 prevents electrode separation, improves light extraction efficiency, and allows for flexible electrode formation, enhancing the reliability and brightness of the light emitting device while maintaining stability under thermal stress.
Implementation Method 1
an inorganic sealing portion for sealing the solid-state element comprising an inorganic sealing material and a thermal expansion coefficient equal to that of the power receiving/supplying portion
Implementation Method 2
wherein the inorganic sealing portion defines an air layer between the solid-state element and the power receiving/supplying portion
Data Source
AI summary
A solid-state element device having: a solid-state element having a pad electrode smaller than a contact electrode, the solid-state element being flip-mounted; a power receiving/supplying portion for receiving/supplying a power, the power receiving/supplying portion being bonded to the solid-state element such that an element mounting surface thereof is nearly flush with a mounting surface of the solid-state element; and an inorganic sealing portion for sealing the solid-state element formed of an inorganic sealing material and a thermal expansion coefficient equal to that of the power receiving/supplying portion. The inorganic sealing portion defines an air layer between the solid-state element and the power receiving/supplying portion.