Integrated Circuit Current Sensor with Inverted Substrate
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Solution Overview
Problem
Conventional current sensors are undesirably large and lack sensitivity due to the physical separation between the Hall effect element and the current conductor, which affects the magnetic field concentration and linearity of the output voltage.
Innovation Solution
An integrated circuit current sensor design with a lead frame and substrate configuration where the magnetic field transducers are positioned close to the current conductor, optimizing the flux density and sensitivity by reversing the conventional substrate orientation and using a T-shaped or rectangular current conductor cross-section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the Hall effect element is positioned close to the current conductor to improve sensitivity, then the magnetic field concentration and sensitivity are improved, but the device size and manufacturing complexity increase
Solution Approach 1:
The patent merges the current conductor and substrate into a single integrated structure where the substrate serves dual purposes: as the mounting platform for the Hall effect element and as the current conductor itself. This integration eliminates the need for separate current conductor components, reducing device complexity while maintaining close proximity between the sensing element and current flow path for improved sensitivity.
Solution Approach 2:
The substrate is designed to perform multiple functions simultaneously: it acts as the mechanical support structure, the electrical current conductor, and the mounting platform for the Hall effect element. This multi-functionality reduces the total component count and simplifies the overall device architecture while enabling close coupling for enhanced magnetic field detection.
2Length of stationary object
If the substrate is oriented upside-down to reduce device height, then the circuit board area is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent inverts the conventional substrate orientation by positioning the first surface (with the Hall effect element) closer to the current conductor rather than having it face away. This inversion allows the substrate to be mounted in a configuration that minimizes the distance between the sensing element and current path, thereby reducing device height and circuit board area while the integrated design maintains manufacturing feasibility.
3Measurement precision
If the current conductor cross-section is modified to T-shaped or rectangular to improve flux density, then the magnetic field concentration is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent modifies the current conductor cross-section to T-shaped or rectangular specifically at the region where the magnetic field concentration is most critical - near the Hall effect element. This localized geometric modification optimizes the magnetic flux density distribution where it matters most for sensing accuracy, while the rest of the conductor maintains simpler geometry for ease of manufacturing.
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
The design results in improved sensitivity and reduced size of the current sensor, achieving better magnetic field concentration and linearity of the output voltage, while maintaining manufacturing tolerance insensitivity.
Implementation Method 1
one type of conventional current sensor uses a magnetic field transducer (for example a Hall effect or magnetoresistive transducer) in proximity to a current conductor. The magnetic field transducer generates an output signal having a magnitude proportional to the magnetic field induced by a current that flows through the current conductor.
Implementation Method 2
The magnetic field transducer generates an output signal having a magnitude proportional to the magnetic field induced by a current that flows through the current conductor.
Data Source
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AI summary
An integrated circuit current sensor includes a lead frame having at least two leads coupled to provide a current conductor portion, and a substrate having a first surface in which is disposed one or more magnetic field sensing elements, with the first surface being proximate to the current conductor portion and a second surface distal from the current conductor portion. In one particular embodiment, the substrate is disposed having the first surface of the substrate above the current conductor portion and the second surface of the substrate above the first surface. In this particular embodiment, the substrate is oriented upside-down in the integrated circuit in a flip-chip arrangement.