Insulated Current Sensor Layout for Thin Packages and IC Stress Relief
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Solution Overview
Problem
Current sensors with magnetoelectric conversion elements face issues with thermal stress and insulation due to the use of metal members for IC supporting portions, leading to potential cracking of signal processing ICs and poor embeddability of mold resin, which compromises insulation between the primary conductor and signal processing IC.
Innovation Solution
A current sensor design featuring a supporting portion made of an insulating material with a low elastic modulus, separate IC and element supporting portions, and strategically placed lead terminals to reduce thermal stress and ensure reliable insulation, with the supporting portion being spaced apart from the conductor and not surrounding it, allowing for a thin package with improved resin embeddability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal member is used for the IC supporting portion, then the structural strength is improved, but thermal stress increases causing potential cracking of the signal processing IC
Solution Approach 1:
The patent changes the material parameter of the supporting portion from metal to insulating material with low elastic modulus. This parameter change reduces the thermal stress transmitted to the IC while maintaining sufficient structural strength through the selection of appropriate insulating materials with suitable mechanical properties.
Solution Approach 2:
The patent employs composite material structure where the supporting portion is made of insulating material rather than metal. This material substitution resolves the contradiction by providing both mechanical support and thermal stress isolation, preventing IC cracking while maintaining package integrity.
2Stability of the object's composition
If the supporting portion surrounds the conductor, then the structural stability is improved, but the embeddability of mold resin deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the supporting portion into separate functional regions: an IC supporting portion and an element supporting portion. This segmentation allows the resin to be properly embedded and insulated around the conductor while maintaining structural stability through the distributed support structure.
Solution Approach 2:
The patent introduces mold resin as an intermediary material between the supporting portion and the external environment. By ensuring the supporting portion does not completely surround the conductor, the resin can properly embed and insulate, resolving the contradiction between structural stability and manufacturability.
3Temperature
If the supporting portion is made of metal, then the thermal conductivity is improved, but the insulation reliability between conductor and IC deteriorates
Solution Approach 1:
The patent uses mold resin as an intermediary insulating material between the conductor and the IC, and between the supporting portion and the conductor. This intermediary layer provides reliable electrical insulation while the low elastic modulus of the insulating supporting portion provides thermal management without compromising insulation reliability.
Solution Approach 2:
The patent changes the material parameter from metal to insulating material for the supporting portion. This parameter change simultaneously addresses both thermal conductivity and insulation reliability by selecting insulating materials with appropriate thermal and electrical properties.
4Length of moving object
If the package thickness is reduced, then the compactness is improved, but the insulation distance between conductor and IC decreases
Solution Approach 1:
The patent optimizes the spatial arrangement in multiple dimensions by separating the IC and element supporting portions and strategically positioning lead terminals. This dimensional optimization allows reduced package thickness while maintaining adequate insulation distances through improved spatial configuration rather than simply increasing thickness.
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 enhances insulation reliability and maintains a thin package structure while reducing thermal stress on the signal processing IC, ensuring effective current measurement and output signal processing.
Implementation Method 1
a magnetoelectric conversion element that detects a magnetic field generated by the measurement current
Data Source
AI summary
A current sensor is configured by at least one magnetoelectric conversion element, a conductor, and a signal processing IC being encapsulated by an encapsulating portion. The current sensor includes a pair of first lead terminals that is partially exposed outside of the encapsulating portion, is electrically connected to the conductor, inputs the measurement current to the conductor, and outputs the measurement current from the conductor; a metal member that is partially exposed outside the encapsulating portion and is spaced apart from the conductor; and a supporting portion that supports the at least one magnetoelectric conversion element, the signal processing IC, and the metal member on a first surface, is separated from the conductor, and is separate from the metal member.