Optical Coupler Polyimide Resin Oxidation Prevention
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Solution Overview
Problem
Optical coupling devices face issues with light absorption and oxidative discoloration due to the use of polyimide resin, leading to reduced light transmission and reliability, especially in high withstand voltage types with longer distances between light emitting and receiving surfaces.
Innovation Solution
Incorporating a polyimide resin that covers the light emitting surface of the light emitting element and is in direct contact with the transparent resin portion, while maintaining a thin thickness to minimize light absorption and prevent oxidative discoloration, along with strategic application on non-light emitting surfaces to enhance adhesion and prevent air entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyimide resin is used to cover the light emitting element, then adhesion and insulation are improved, but light absorption increases and oxidative discoloration occurs
Solution Approach 1:
The patent divides the polyimide resin coverage into two distinct regions: a light-shielding portion that covers the light emitting surface (preventing oxidative discoloration) and a non-light-shielding portion that covers non-emitting surfaces ( providing adhesion and insulation). This segmentation allows different functional requirements to be met in different areas, resolving the contradiction between protection and light transmission.
Solution Approach 2:
The patent applies different properties of polyimide resin to different locations: the light-shielding portion has light-blocking properties to prevent oxidation, while the non-light-shielding portion maintains transparency or light-transmission properties for adhesion. This local differentiation of material properties resolves the contradiction by optimizing each region's function.
2Reliability
If transparent resin portion thickness is increased to improve insulation, then withstand voltage improves, but light transmission distance increases causing reduced light transmission
Solution Approach 1:
The patent segments the transparent resin portion into two functional zones: a light-shielding region near the light emitting surface that blocks light to prevent oxidation, and a non-light-shielding region that allows light transmission. This segmentation enables the resin to provide both insulation thickness for high withstand voltage and optimized light transmission paths, resolving the contradiction between insulation distance and light transmission efficiency.
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 configuration enhances the reliability and characteristics of optical coupling devices by maintaining light transmission and preventing oxidative discoloration, even at high temperatures, and improves adhesion and insulation, thus enhancing the device's performance and longevity.
Implementation Method 1
preventing oxidative discoloration, even at high temperatures
Implementation Method 2
maintaining light transmission
Data Source
AI summary
An optical coupling device of an embodiment includes: a first lead frame; a light emitting element provided on the first lead frame; a second lead frame; a light receiving element provided on the second lead frame and facing the light emitting element; a polyimide resin covering a light emitting surface of the light emitting element; a transparent resin portion provided between the light emitting element and the light receiving element; and a light-shielding resin molded body accommodating the light emitting element and the light receiving element.