Current Sensor Package Layout for Isolation and Clean Singulation
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Solution Overview
Problem
Conventional current sensors face challenges in achieving adequate isolation and reduced stress during singulation due to the design of their primary and secondary conductors, which can lead to manufacturing inefficiencies and potential errors in magnetic field sensing.
Innovation Solution
The current sensor integrated circuit package features a primary conductor with reduced area edges and offset secondary leads, providing a creepage distance of at least 2.0 mm and allowing for reduced stress during singulation, while also ensuring effective magnetic field sensing through strategically positioned magnetic field sensing elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional current sensor design is used with standard conductor spacing, then manufacturing process is simpler, but isolation distance is insufficient and stress during singulation increases
Solution Approach 1:
The patent applies asymmetry by offsetting secondary leads relative to the primary conductor, creating an asymmetric layout that maximizes isolation distance. The secondary leads are positioned at offset distances (e.g., 0.5mm, 1.0mm, 1.5mm) from the primary conductor centerline, while the primary conductor maintains centered positioning. This asymmetric arrangement achieves adequate creepage and clearance distances without requiring excessive spacing between all conductors.
Solution Approach 2:
The patent applies local quality by providing different spacing characteristics in different regions. The primary conductor has reduced area edges at specific locations (input and output portions) while maintaining full width in the sensing region. Secondary leads have varying offset distances at different positions along their length. This localized differentiation optimizes isolation where needed while preserving magnetic field sensing capability where it matters most.
2Ease of manufacture
If conventional conductor design without reduced area edges is used, then manufacturing is easier, but stress during singulation increases and package jamming occurs
Solution Approach 1:
The patent applies segmentation by dividing the primary conductor into distinct sections: full-width portions for mechanical strength and reduced-area edges for singulation. The reduced area edges create natural separation points that allow the package to be cleanly divided during singulation without compromising the structural integrity of the sensing regions or causing package jamming.
3Area of stationary object
If secondary leads are positioned close to primary conductor, then device footprint is smaller, but isolation distance and voltage breakdown resistance decrease
Solution Approach 1:
The patent applies asymmetry by offsetting secondary leads relative to the primary conductor, creating an asymmetric layout that maximizes isolation distance. The secondary leads are positioned at offset distances (e.g., 0.5mm, 1.0mm, 1.5mm) from the primary conductor centerline, while the primary conductor maintains centered positioning. This asymmetric arrangement achieves adequate creepage and clearance distances without requiring excessive spacing between all conductors.
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 isolation and reduces manufacturing stress, facilitating efficient production and accurate magnetic field sensing, meeting voltage isolation requirements and preventing package jamming during testing.
Implementation Method 1
at least one magnetic field sensing element supported by the semiconductor die
Implementation Method 2
sense a magnetic field generated by a current through the conductor. The current sensor generates an output signal having a magnitude proportional to the magnetic field induced by the current
Data Source
AI summary
A current sensor integrated circuit package includes a primary conductor having an input portion and an output portion, both with reduced area edges. Secondary leads each have an exposed portion and an elongated portion that is offset with respect to the exposed portion. A semiconductor die is disposed adjacent to the primary conductor on an insulator portion and at least one magnetic field sensing element is supported by the semiconductor die. A package body includes a first portion enclosing the semiconductor die and a portion of the primary conductor and a second portion enclosing the elongated portion of the plurality of secondary leads. The first package body portion has a first width configured to expose the input and output portions of the primary conductor and the second package body portion has a second width between a first and second package body side edges that is larger than the first width.