Opto-coupler Folded Leadframe and Lens for High DTI
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Solution Overview
Problem
Opto-couplers face challenges in maintaining reliability and safety while ensuring sufficient Distance Through Insulation (DTI) due to the trade-off between insulation thickness and efficiency, where thin insulation increases electrostatic stress but thicker insulation decreases performance.
Innovation Solution
The design incorporates a folded leadframe and an optical efficiency enhancer, such as a lens or air gap, between the light source and photodetector to increase DTI while maintaining performance and safety, using nonconductive materials to resist electric charge flow and enhance light transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the insulation medium is increased to reduce electrostatic stress and improve reliability, then the DTI and safety are improved, but the optical coupling efficiency and performance of the opto-coupler significantly decrease
Solution Approach 1:
The insulation medium is segmented into multiple layers with different properties: a first insulation layer with higher refractive index close to the LED, and a second insulation layer with lower refractive index closer to the photodetector. This segmentation allows each layer to be optimized for its specific function - the first layer for electrical insulation and stress reduction, and the second layer for optical efficiency - thereby resolving the contradiction between reliability and optical performance
Solution Approach 2:
Different regions of the insulation medium are assigned different optical properties (refractive indices). The first insulation layer has a higher refractive index to reduce electrostatic stress and improve reliability, while the second insulation layer has a lower refractive index to enhance light transmission and optical coupling efficiency. This local differentiation of material properties allows simultaneous optimization of both reliability and optical performance
2Productivity
If the thickness of the insulation medium is decreased to improve optical coupling efficiency, then the performance is improved, but the electrostatic stress on the insulator increases and reliability decreases
Solution Approach 1:
The insulation path is divided into two distinct layers, allowing the overall insulation thickness to be reduced for better optical performance while the critical regions maintain sufficient thickness for reliability. The first layer provides the necessary electrical insulation strength, while the second layer optimizes optical transmission
Solution Approach 2:
The refractive index parameter is varied across different layers of the insulation medium. By changing the refractive index from higher in the first layer to lower in the second layer, the patent optimizes both the electrical stress distribution and optical transmission characteristics, enabling reduced overall thickness without compromising reliability
3Use of energy by moving object
If a traditional optically-transparent insulation medium is used to create the light path, then the light transmission is achieved, but the DTI is limited and cannot satisfy stringent design rules for high voltage applications
Solution Approach 1:
The patent transitions from a conventional planar insulation structure to a folded leadframe configuration that utilizes three-dimensional space. By folding the leadframe, the DTI is extended in the vertical dimension while maintaining a compact horizontal footprint, thereby satisfying stringent DTI requirements without compromising light transmission performance
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 approach significantly increases DTI, improving the reliability and safety of opto-couplers by balancing insulation thickness with optical efficiency, allowing them to handle higher voltages without compromising performance.
Implementation Method 1
A typical opto-coupler includes a light source, such as a Light Emitting Diode (LED)
Implementation Method 2
an opto-coupler includes a light source, such as a Light Emitting Diode (LED), a photodetector
Implementation Method 3
The insulation medium not only acts to allow the transmission of light from the LED to the photodetector
Implementation Method 4
the efficiency enhancer may comprise a converging lens oriented such that light output from the light source is focused toward the photodetector
Implementation Method 5
the efficiency enhancer may comprise one or more lens elements configured to direct light
Data Source
AI summary
An optoelectronic device is disclosed. The optoelectronic device may be employed as a single or multi-channel opto-coupler that electrically isolates one circuit from another circuit. The opto-coupler may include one or more folded leads that establish an enhanced isolation gap. The enhanced isolation gap may include an interruption in the insulation of the opto-coupler between the light source and the light detector. In addition, this interruption may further include a efficiency enhancer, or lens, to direct light emitted from the light source. Accordingly, the creepage distance and operational voltages of the opto-coupler can be increased while maintaining high efficiency levels.