Leadless Current Sensor Package for High-Voltage Isolation
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Solution Overview
Problem
Existing sensor packages face challenges in efficiently coupling current sensor dies to secondary leads while maintaining electrical isolation and ensuring reliability, especially when dealing with high voltage and current applications.
Innovation Solution
A sensor package design that includes a lead frame with a primary conductor and secondary leads separated by a dielectric material, an isolation structure for electrical isolation, a current sensor die for measuring current, and an interposer with conductive traces to couple the sensor die to the secondary leads, utilizing wire bonds for connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an interposer with conductive traces is used to couple the current sensor die to secondary leads, then the reliability of electrical connection is improved, but the device complexity increases
Solution Approach 1:
An interposer is introduced as an intermediary component between the current sensor die and the secondary leads. The interposer includes conductive traces that provide reliable electrical coupling while isolating the sensor die from direct exposure to high voltage on the primary conductor. This mediator structure resolves the contradiction by enabling stable connections without requiring the sensor die to directly interface with high-voltage terminals, thus improving reliability while managing complexity through modular design.
Solution Approach 2:
The package structure is segmented into distinct functional components: the primary conductor for high voltage, the dielectric material for isolation, the current sensor die for measurement, and the interposer for signal coupling. This segmentation allows each component to be optimized independently, with the interposer handling the complex task of electrical coupling while the sensor die remains simple and focused on sensing, thereby improving overall reliability without unnecessarily complicating the entire system.
2Object-affected harmful factors
If a layer of dielectric material is disposed between the primary conductor and secondary leads, then electrical isolation is improved, but the area of the lead frame increases
Solution Approach 1:
Instead of increasing the planar area of the lead frame to accommodate both isolation and connection requirements, the solution transitions to a three-dimensional arrangement. The dielectric material is positioned in the vertical dimension between the primary conductor and secondary leads, allowing effective electrical isolation without proportionally increasing the footprint area. This dimensional transition enables compact packaging while maintaining necessary isolation distances.
3Device complexity
If the current sensor die is directly coupled to secondary leads, then the device complexity is reduced, but the reliability in high voltage applications deteriorates
Solution Approach 1:
The interposer serves as a necessary mediator that protects the current sensor die from direct exposure to high voltage conditions on the primary conductor. While the interposer adds a component to the structure, it significantly enhances reliability by providing galvanic isolation and preventing voltage breakdown paths. The conductive traces on the interposer provide controlled impedance paths that are more reliable than direct coupling in high-voltage environments, making the added complexity worthwhile for achieving functional safety.
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 effectively isolates the current sensor die from high voltage, ensures reliable coupling to secondary leads, and maintains the mechanical stability required for high-current applications, while being cost-effective and manufacturable using standard packaging techniques.
Implementation Method 1
a layer of dielectric material that is disposed between the primary conductor and the plurality of secondary leads
Implementation Method 2
magnetic field sensing elements, such as a Hall effect element
Implementation Method 3
magnetic field sensing elements, such as a Hall effect element or a magnetoresistive element
Data Source
AI summary
A sensor package comprising a lead frame, a current sensor die, and an interposer. The lead frame includes: (i) a primary conductor, (ii) a plurality of secondary leads, and (iii) a layer of dielectric material that is disposed between the primary conductor and the plurality of secondary leads. The current sensor die includes one or more sensing elements. The current sensor die is configured to measure a level of electrical current through the primary conductor of the lead frame. The interposer is disposed over the layer of dielectric material. The interposer includes a plurality of conductive traces that are configured to couple each of a plurality of terminals of the current sensor die to a respective one of the plurality of secondary leads.