Packaged Current Sensor Layout for Isolation and Low Singulation Stress
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Solution Overview
Problem
Conventional current sensors face challenges in achieving effective isolation and reduced manufacturing stress during singulation, particularly in high-current applications, due to the design of primary and secondary conductors and the manufacturing processes involved.
Innovation Solution
The integrated circuit package includes a primary conductor with reduced area edges and secondary leads offset and encapsulated by a package body, ensuring a minimum creepage distance and enhanced isolation, along with a singulation process that minimizes stress on the package and tool wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional current sensors are positioned near current-carrying conductors to sense magnetic fields, then current sensing capability is achieved, but isolation between primary and secondary conductors becomes difficult to maintain
Solution Approach 1:
The patent transitions from planar conductor arrangement to three-dimensional spatial separation by offsetting the secondary lead in the vertical dimension (z-axis) relative to the primary conductor. The secondary lead is positioned at a different height level, creating vertical isolation that maintains electrical insulation while allowing magnetic field sensing. This dimensional change resolves the contradiction by providing isolation without compromising sensing capability.
Solution Approach 2:
The patent introduces an insulator portion as an intermediary element between the primary conductor and secondary lead. This insulator serves as a mediator that provides electrical isolation and mechanical support, enabling the secondary lead to be positioned close to the primary conductor for effective magnetic coupling while maintaining required creepage distances for safety and reliability.
2Area of stationary object
If primary and secondary conductors are positioned close together for compact design, then device size is reduced, but manufacturing stress during singulation increases
Solution Approach 1:
The patent employs asymmetric design where the secondary lead is offset from the primary conductor rather than being symmetrically positioned. This asymmetric arrangement creates non-uniform stress distribution during singulation that can be more easily managed by the package structure, reducing peak stresses while maintaining compact dimensions.
Solution Approach 2:
The patent incorporates an insulator portion that is pre-positioned between the primary conductor and secondary lead before the singulation process. This preliminary placement of the insulator provides stress relief and structural support that prevents excessive stress concentration during the subsequent singulation operation, enabling compact packaging without compromising manufacturability.
3Area of stationary object
If secondary leads are positioned close to primary conductor for compact packaging, then space is optimized, but creepage distance requirements become difficult to meet
Solution Approach 1:
The patent utilizes the vertical dimension (z-axis) to satisfy creepage distance requirements. By offsetting the secondary lead vertically from the primary conductor plane, the design achieves the required creepage distance in the vertical direction while maintaining minimal horizontal separation. This allows compact packaging footprint while meeting isolation requirements through three-dimensional spatial arrangement.
Solution Approach 2:
The insulator portion acts as an intermediary that establishes and maintains the required creepage distance between the primary conductor and secondary lead. The insulator provides a controlled isolation barrier that ensures precise spacing, allowing the secondary lead to be positioned close to the primary conductor horizontally while maintaining the necessary electrical clearance through the insulator's thickness and positioning.
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 achieves reinforced isolation and reduced manufacturing stress, facilitating high-current applications while maintaining reliability and efficiency in current sensing.
Implementation Method 1
at least one magnetic field sensing element supported by the semiconductor die
Implementation Method 2
The at least two magnetic field sensing elements can be Hall effect elements
Data Source
AI summary
A current sensor circuit package includes a primary conductor having an input portion into which a current flows, an output portion from which the current flows, and an exposed portion, wherein the input and output portions have a reduced area edge. A secondary lead has an elongated portion that is offset with respect to the exposed portion of the secondary lead. 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 enclosing the semiconductor die and a portion of the primary conductor includes a first cutout in a first side edge configured to expose the reduced area edge of the input portion of the primary conductor and a second cutout on a second side edge configured to expose the reduced area edge of the output portion of the primary conductor, wherein the first side edge of the package body is substantially parallel with respect to the second side edge of the package body.