Optocoupler Package With Overlapping Devices
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Solution Overview
Problem
Conventional optocouplers have low photoelectrical transition efficiency due to the LED and phototransistor devices not being directly aligned, resulting in less than 10% effective light transfer, and limited flexibility in device configuration.
Innovation Solution
A leadframe structure is used to position the LED device above the phototransistor device, ensuring direct alignment and improved light transfer efficiency, with the leadframe also serving as a heat sink for high-power applications, and allowing for standard footprints like BGA or LGA without solder balls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the LED device and phototransistor device are positioned using conventional substrate pads, then the device configuration is fixed and manufacturing is simplified, but the photoelectrical transition efficiency is low (less than 10% effective light transfer) due to misalignment
Solution Approach 1:
The patent transitions from a planar substrate pad arrangement to a three-dimensional configuration using a leadframe structure. The leadframe extends vertically above the substrate, allowing the LED device to be positioned directly above the phototransistor device in the vertical dimension, achieving direct alignment and high photoelectrical transition efficiency while maintaining manufacturing simplicity
Solution Approach 2:
The leadframe structure serves as an intermediary component between the substrate and the LED device. It provides a support structure that positions the LED device directly above the phototransistor device, enabling precise alignment without requiring complex substrate pad configurations or additional alignment mechanisms
2Productivity
If the LED device and phototransistor device are directly aligned to improve light transfer efficiency, then the photoelectrical transition ratio increases to over 80%, but the device configuration flexibility is reduced
Solution Approach 1:
The leadframe structure serves multiple functions: it provides mechanical support for the LED device, enables direct alignment with the phototransistor device for high efficiency, acts as a heat sink for thermal management, and allows for standard footprint configurations. This multi-functionality achieves direct alignment and high efficiency while maintaining configuration flexibility and adaptability
3Device complexity
If conventional substrate-based positioning is used, then the package structure is simple, but heat dissipation capability is insufficient for high-power applications
Solution Approach 1:
The leadframe structure serves multiple functions: it provides mechanical support for the LED device, enables direct alignment with the phototransistor device for high efficiency, acts as a heat sink for thermal management, and allows for standard footprint configurations. This multi-functionality achieves direct alignment and high efficiency while maintaining configuration flexibility and adaptability
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 design enhances the photoelectrical transition ratio to over 80% and supports high-power LED optocouplers, providing efficient light transfer and heat dissipation while allowing for flexible package configurations.
Implementation Method 1
An LED (light emitting diode) device 16 including an optical emitter surface 16(a)
Implementation Method 2
covered by an optically transmissive medium 22
Implementation Method 3
The output current generated by phototransistor (diode) device 12 is low (e.g., about several nA, the same level as noise) due to the low efficiency of the phototransistor 12 device to receive very limit light emitting by LED
Data Source
AI summary
A die package is disclosed. The die package includes a substrate, a first device attached to the substrate, and a leadframe structure attached to the substrate. The leadframe structure includes a portion disposed over the first device, and a second device is attached to the first portion of the leadframe structure.