TMR Magnetic Sensor Static Electricity Protection via Substrate Routing
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Solution Overview
Problem
Conventional TMR magnetic sensors are prone to degradation in accuracy due to electrical discharge currents from static electricity, which also introduces magnetic noise, and existing countermeasures are ineffective until a conductive film is connected to a specific voltage potential.
Innovation Solution
A TMR magnetic sensor design featuring a conductive material connected to the substrate with a passivation film surrounding the sensor element and conductive material, where the conductive material is formed before the TMR film, allowing static electricity to flow through the substrate, reducing the risk of breakdown and magnetic noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive material is surrounded by a magnetic material in a shape of ring and connected to a fixed voltage potential to countermeasure against static electricity, then the static electricity protection is improved, but the degree of angle detecting accuracy is degraded due to magnetic noise
Solution Approach 1:
The conductive material is divided into two distinct parts: a ring-shaped conductive material surrounding the TMR sensor element for static electricity protection, and a separate conductive material connected to the substrate for signal transmission. This segmentation allows each part to perform its specific function independently, preventing magnetic noise from affecting the sensing accuracy while maintaining effective static electricity countermeasures.
Solution Approach 2:
The signal transmission function is extracted from the static electricity protection function. The patent introduces a separate conductive material that is electrically connected to the substrate specifically for transmitting sensor signals, while the ring-shaped conductive material focuses solely on static electricity protection. This extraction eliminates the magnetic noise interference that would occur if both functions were combined in a single conductive structure.
2Reliability
If the conductive material is connected to a fixed voltage potential to countermeasure against static electricity, then the static electricity protection is improved, but the countermeasure effect cannot be obtained until the connection is made
Solution Approach 1:
The conductive material is formed in the same manufacturing process as the TMR sensor element, combining the formation of both components into a single integrated process. This merging allows the conductive material to be created simultaneously with the sensor element, eliminating the need for separate connection steps and enabling static electricity protection to be established throughout the manufacturing process rather than only after final assembly.
3Reliability
If a conductive material is formed to countermeasure against static electricity, then the protection effect is improved, but magnetic noise is generated by the electrical discharge current
Solution Approach 1:
The signal transmission function is extracted from the static electricity protection function. The patent introduces a separate conductive material that is electrically connected to the substrate specifically for transmitting sensor signals, while the ring-shaped conductive material focuses solely on static electricity protection. This extraction eliminates the magnetic noise interference that would occur if both functions were combined in a single conductive structure.
Solution Approach 2:
The patent introduces an insulating film between the TMR sensor element and the ring-shaped conductive material. This insulating film acts as an intermediary that prevents direct electrical contact, thereby blocking the path for electrical discharge currents that would generate magnetic noise, while still allowing the conductive material to provide static electricity protection through the substrate connection.
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 effectively protects the TMR sensor element from static electricity-induced breakdown and maintains high accuracy by routing static electricity through the substrate, eliminating the need for a conductive material to be connected to a fixed voltage potential, thus reducing magnetic noise and manufacturing costs.
Implementation Method 1
a conductive material formed on the first face of the substrate, being electrically connected to the substrate
Implementation Method 2
a passivation film surrounding a surface of the TMR sensor element and that of the conductive material
Implementation Method 3
when a magnetization direction of a fixed layer and a magnetization direction of a free layer are in parallel with each other, a current flowing through a tunnel oxide film becomes larger, and a resistance value of the magnetic sensor becomes smaller
Data Source
AI summary
A tunnel magneto-resistance (TMR) magnetic sensor and its manufacturing method are provided in which its degradation of the degree of accuracy of angle detection or the like is not caused due to an electrical discharge current by static electricity. The TMR magnetic sensor includes a TMR sensor element formed on a first face of a substrate with an insulation film interposing therebetween; a conductive material formed on the first face of the substrate, being electrically connected to the substrate; and a passivation film surrounding a surface of the TMR sensor element and that of the conductive material, wherein at least a portion of the conductive material faces toward an opening portion formed in the passivation film.