Jul 203 min read

Magnetic film electroplating technology used for magnetic sensor applications

Hello, this is TZ from the Sales Department.

Our plating technology started with magnetic film plating, which is our specialty. Recently, we have seen a significant increase in inquiries from customers dealing with magnetic sensors. In this article, we will introduce the field of electronic device products that use our magnetic plating equipment for processes involving electroplated magnetic thin films.

Types, Principles, and Applications of Magnetic Sensors

"Magnetic sensors" are devices that detect changes in magnetic fields and convert them into electrical signals. They are used in various applications according to their specific characteristics. The selection of sensors depends on the specific requirements and environment.

1. Hall Effect Sensor

- Principle: The Hall effect sensor operates on the principle of detecting the Hall effect (deflection of charge) that occurs when a magnetic field is applied perpendicular to a conductor carrying an electric current.

- Applications: It is used in motor control, position detection, and magnetic field measurement.

2.Magnetoresistive Sensor (GMR, TMR)

- Principle: The magnetoresistive sensor utilizes the principle of changes in sensor resistance due to changes in the magnetic field. It includes Giant Magnetoresistance (GMR) and Tunnel Magnetoresistance (TMR).

- Applications: It is used in magnetic recording heads, angle sensing, magneto resistive memory, and geomagnetic detection.

3. Magnetic Impedance Sensor (MI Element)

- Principle: The magnetic impedance sensor operates on the principle of detecting changes in magnetic impedance relative to the current flowing through a coil.

- Applications: It is used in biomagnetic activity measurement, non-destructive testing, detection of brain magnetic fields.

4. Fluxgate Sensor

- Principle: The fluxgate sensor detects changes in the magnetic flux within a coil when the magnetic field changes.

- Applications: It is used in directional sensing for aircraft and ships, as well as bio magnetic measurements.

5. Magnetic Reed Switch

- Principle: The magnetic reed switch contains a small magnet internally and operates based on changes in switch states due to external magnetic fields.

- Applications: It is used in door sensors, security alarms, and magnetic switches.

Product Fields for Magnetic Plating Equipment

In this method, the wafer process is adopted, and a plating process that forms uniform thin films with fine patterns is required. The two main applications are HDD magnetic heads and magnetic sensors, which are needed for the miniaturization of devices such as smartphones and drones.

１． HDD Magnetic Head Manufacturing Process

In the manufacturing process of HDD magnetic heads, our company has been providing magnetic electroplating equipment for many years for the formation of magnetic thin films used in GMR and TMR magnetic heads (currently, the TMR method is predominant).

For magnetic heads, alloy plating such as NiFe, FeCo, and NiFeCo is used according to the required magnetic properties. The magnetic heads require a very thin film thickness of less than 1 μm.

Advanced process technology is required to achieve a uniform film thickness distribution within the wafer with a thickness variation of less than ±5%, as well as to obtain a uniform composition distribution in alloy plating. This includes concentration analysis and management of the plating solution.

２．Magnetic Sensors

In magnetic sensors, the plating process is employed in the production of the "magnetic flux concentrator." The magnetic flux concentrator is a component that serves to concentrate the magnetic field onto the sensor.

For example, in magnetic compasses used in smartphones and drones, the magnetic flux concentrator is used to amplify the very weak geomagnetic field, thereby improving sensitivity.

The key characteristic required for magnetic flux concentrators is permeability, which indicates how easily the material can conduct magnetic fields. Materials with higher permeability are better at concentrating magnetic fields.

Permalloy (NiFe alloy) is a magnetic material with high permeability that can be uniformly deposited at micron-order thicknesses using electroplating.

In the deposition process for magnetic flux concentrators in magnetic sensors manufactured using wafer processes, a plating film is deposited on a wafer patterned with resist by photolithography, achieving a uniform shape with high dimensional accuracy.

Our Initiatives

For over 30 years, we have been supplying automatic plating equipment for mass production to manufacturers of HDD magnetic heads and magnetic sensors.

Currently, we also support wafer plating processes for manufacturers' R&D departments and university research institutions. Moving forward, we will continue to contribute as professionals in magnetic alloy thin film plating processes and equipment technology.

For research, development, prototyping, and mass production electrolytic plating equipment for electronic devices requiring magnetic plating, please consult with us.