Magnetic Sensor Packaging With Spiral Hysteresis Coil

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Solution Overview

Problem

Existing magnetic sensor chip packaging technologies, such as those using on-chip reset straps, result in large and expensive sensor chips, while prior art LGA packages with hysteresis coils do not effectively reduce size or cost.

Innovation Solution

A magnetic sensor packaging structure featuring a spiral hysteresis coil on an LGA substrate, with magnetoresistive sensor push-pull bridges and a pulse generating circuit to apply bipolar current pulses, reducing overall resistance and hysteresis, and incorporating a cost-effective manufacturing process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If on-chip reset straps are used to align magnetization of sensor elements, then magnetization alignment is achieved, but sensor chip size and cost increase significantly

Engineering Contradiction:

Improvemagnetization alignmentVSAvoidsensor chip size

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The invention extracts the magnetization alignment function from the sensor chip itself and relocates it to an external hysteresis coil on the substrate. The reset strap is removed from the chip, and its functionality is transferred to the external coil that generates magnetic field pulses to align magnetization in the sensor elements.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention introduces a hysteresis coil as an intermediary component between the control system and the sensor elements. This coil acts as a mediator that generates magnetic field pulses to align the magnetization of sensor elements without requiring on-chip reset straps, thereby reducing chip size while maintaining alignment capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If on-chip reset straps are used to align magnetization, then magnetization alignment is achieved, but sensor chip cost increases significantly

Engineering Contradiction:

Improvemagnetization alignmentVSAvoidsensor chip cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention extracts the magnetization alignment function from the sensor chip and relocates it to an external hysteresis coil on the substrate. This extraction eliminates the need for expensive on-chip reset straps and associated control circuitry, thereby significantly reducing sensor chip cost while maintaining alignment capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces expensive, complex on-chip reset strap structures with a simpler, external hysteresis coil implementation. The external coil approach uses standard substrate materials and conventional coil structures, which are much cheaper to manufacture than integrated on-chip reset mechanisms.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Power

If conventional LGA package wiring with etched copper is used for hysteresis coil, then current carrying capacity increases and resistance decreases, but manufacturing complexity increases

Engineering Contradiction:

Improvecurrent carrying capacityVSAvoidmanufacturing complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The invention changes the physical parameters of the hysteresis coil by using thick etched copper traces (35 or 70 microns) instead of standard thin traces. This parameter change increases the cross-sectional area of the conductors, thereby increasing current carrying capacity and reducing resistance while maintaining compatibility with standard LGA manufacturing processes.

Inventive Principle:

Principle #35Parameter changes

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 solution enables smaller, more cost-effective magnetic sensors with reduced hysteresis and improved current carrying capacity, while maintaining performance and simplifying the manufacturing process.

Implementation Method 1

a spiral hysteresis coil on the substrate... a magnetic field generated by the spiral hysteresis coil

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

sensor bridge arms are deposited on the sensor chip and are electrically interconnected to form a magnetoresistive sensor push-pull bridge

Methodology Applied

Scientific EffectMagnetoresistance: Magnetoresistance

Data Source

PatentUS11852698B2Magnetic sensor packaging structure with hysteresis coil

Publication Date: 2023.12.26 MULTIDIMENSION TECH CO LTD

AI summary

A magnetic sensor packaging structure with a hysteresis coil comprising a substrate, a sensor chip, a spiral hysteresis coil on the substrate, and wire bonding pads. The sensor bridge arms are composed of magnetoresistive sensing elements. The sensor bridge arms are deposited on the sensor chip, and the sensor bridge arms are electrically interconnected to form a magnetoresistive sensor bridge that is located on the hysteresis coil. The magnetic field generated by the spiral hysteresis coil is collinear with a sensitive axis of the sensor bridge. The magnetoresistive sensor bridge is located on the substrate and encapsulated. By placing the spiral hysteresis coil on the substrate, it is capable of supporting larger currents with smaller resistance value. This allows the sensor hysteresis to be effectively eliminated. In addition, the packaging structure manufacturing process is simple and cost effective.