Photocoupler High-Frequency Transmission with Integrated MOSFETs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-frequency photocouplers required for applications like machine tool control and semiconductor testers face challenges in achieving high-frequency passing characteristics above 5 GHz, and existing designs often result in increased size and complexity due to the need for multiple units, necessitating a compact and high-density mounting solution.
Innovation Solution
The design incorporates a photocoupler with a surface-mounted package featuring a semiconductor light emitting element, a light receiving element, and MOSFETs, sealed within a resin layer, with a lead structure made of iron-nickel or copper alloy, and a translucent bonding layer to enhance high-frequency transmission characteristics and reduce size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional photocoupler designs are used to achieve high-frequency passing characteristics above 5 GHz, then transmission performance is improved, but device size and structural complexity increase
Solution Approach 1:
The patent combines multiple functional elements (light emitting element, light receiving element, MOSFETs, and lead structure) into a single integrated photocoupler device. The lead structure serves dual purposes as both electrical connection and inductance reduction element, merging structural support with electrical function optimization.
Solution Approach 2:
The lead structure is designed to perform multiple functions: providing electrical connection between terminals and internal elements, reducing inductance for high-frequency performance, and serving as part of the overall package structure. This multi-functionality reduces the need for separate dedicated components.
2Adaptability or versatility
If multiple photocoupler units are used to meet system requirements, then functional capability is improved, but mounting density decreases
Solution Approach 1:
The patent integrates multiple functional capabilities into a single photocoupler unit. By combining the light emitting element, light receiving element, and MOSFETs in one package, the design reduces the number of separate components needed, thereby reducing the overall mounting footprint while maintaining functional capability.
3Area of stationary object
If compact packaging is implemented to reduce footprint, then mounting density is improved, but mechanical strength and reliability may deteriorate
Solution Approach 1:
The patent employs a composite package structure combining resin material for sealing and bonding with metal lead frames for mechanical strength. The resin layer provides hermetic sealing and stress distribution, while the metal leads provide structural integrity and electrical connection, creating a balanced composite structure that achieves both compactness and reliability.
4Speed
If inductance is reduced to improve high-frequency characteristics, then transmission performance is improved, but structural design complexity increases
Solution Approach 1:
The lead structure is designed to serve dual purposes: providing necessary electrical connections and simultaneously functioning as the inductance reduction mechanism. By integrating the inductance control function into the existing lead structure rather than adding separate components, the design achieves low inductance without proportionally increasing structural complexity.
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 improves high-frequency transmission characteristics up to 19 GHz, reduces waveform distortion, and enhances mechanical strength and reliability by minimizing inductance and resin stress, while allowing for a smaller footprint and higher density mounting.
Implementation Method 1
a semiconductor light emitting element connected to the input terminal and capable of emitting emission light toward the light receiving region
Implementation Method 2
a semiconductor light receiving element joined to each other and having a light receiving region provided in a central part of a surface on opposite side from a surface joined to the first and second MOSFETs
Data Source
AI summary
A photocoupler of an embodiment includes an input terminal, an output terminal, a first MOSFET, a second MOSFET, a semiconductor light receiving element, a semiconductor light emitting element, and a resin layer. The first MOSFET is joined onto the third lead. The second MOSFET is joined onto the fourth lead. The semiconductor light receiving element is joined to each of the first junction region and the second junction region. The semiconductor light receiving element includes a light receiving region provided in a central part of a surface on opposite side from a surface joined to the first and second MOSFET. The resin layer seals the first and second MOSFETs, the semiconductor light receiving element, the semiconductor light emitting element, an upper surface and a side surface of the input terminal, and an upper surface and a side surface of the output terminal.