Applications of Neodymium Magnets in 3C Consumer Electronics Products

3C consumer electronics products mainly include: smartphones, tablets, laptops, smartwatches, headphones, wireless charging devices, smart home devices, digital accessories, etc. Taking Apple products as an example, they include iPhone, iPad, Mac, Apple Watch, AirPods, MagSafe, HomePod, etc. Permanent magnetic materials, especially NdFeB magnet play an important role in improving performance of these devices. This article will explore the applications of NdFeB magnet, their operating principles and the magnet requirements of different assemblies.

NdFeB magnets are mainly used in three types of modules in 3C products: acoustic modules, motor modules and magnetic modules.

1. Acoustic Modules

The acoustic modules in devices produce sound, typically called speaker. The performance of speaker directly affects the voice quality of device. When an audio signal current flows through the coil of speaker, the voice coil generates a magnetic field. This magnetic field interacts with the NdFeB magnet in speaker, causing the diaphragm to vibrate and produce sound. The high performance of NdFeB  magnet is crucial to achieve excellent sound quality of speaker.

• Smartphones: These devices require compact and lightweight speakers. Using high-performance, compact NdFeB permanent magnets to ensure lightweight performance without sacrificing sound quality. For example, in high-end smartphones, speaker modules often use high-performance NdFeB magnets of N52 grade. These magnets have a high magnetic energy density, which allows for the use of smaller magnets to achieve the required magnetic flux density. As a result, valuable space is saved for the battery and the mainboard. 
• Tablets and Laptops: Because of their larger size, these devices can accommodate larger speakers. These devices use slightly lower-performance NdFeB magnet, which are larger and produce a stronger magnetic field, thus improving sound quality. These devices typically use N45 magnets and enhance the low-frequency response as well as the overall sound pressure level by expanding the magnetic circuit system, resulting in a more immersive audio experience.
• Smartwatches: Smartwatches are small in size, which requires small speakers as well. Neodymium magnets are beneficial for achieving compact speaker designs. At the same time, most customers do not have high requirements for the sound quality of speakers in smartwatches, so low-performance neodymium magnets such as N40 are sufficient, which reduces costs while ensuring functionality.

2. Motor Modules

NdFeB magnet mainly used in voice coil motor (VCM) and linear resonance actuator (LRA).

• Voice Coil Motor

The VCM motor plays an important role in the autofocus and lens switching functions of a camera module. Compared to other magnets, neodymium magnets can provide the same performance in a smaller size, which is beneficial for enabling compact designs of camera modules.  In addition, high-grade neodymium magnets, such as SH and above, have high intrinsic coercivity, which can ensure the stable operation of the motor in the high-temperature environment caused by frequent operation.This is essential for high-speed focusing and optical image stabilization in smartphone photography.

• Linear Resonance Actuator

LRA is widely used in smartphones and wearable devices to provide tactile feedback. When current flows through a coil, it interacts with the magnetic field generated by NdFeB magnet, driving the motor to vibrate and produce tactile feedback. Vibration motors can produce different vibration patterns by varying the frequency, providing sensitive and rich vibration feedback to suit different device interaction scenarios. The performance of magnets directly determines the intensity and response speed of vibrations. This will affect the user experience, such as the level of immersion in games and the clarity of notification alerts.

3. Magnetic Modules

Magnetic modules are used to fix or support various assemblies, especially in magnetic accessories such as wireless chargers, phone holders and magnetic attachments. NdFeB magnets are widely used in these applications because of compact size and high performance.

• Wireless Charging: Modern wireless charging primarily utilizes MagSafe technology, which relies on permanent magnets for convenient, efficient and intelligent charging. Neodymium magnets possess extremely high magnetic energy, ensuring rapid and precise automatic alignment between the charging pad and the phone.
• Magnetic Attachments: Due to the strong magnetic force of NdFeB magnets, they are widely used as magnetic components in protective covers, casings or stands to secure electronic devices.

4. Requirements for NdFeB Magnets in 3C Applications

• Miniaturization: NdFeB magnets must be compact to be used in the tight spaces of 3C devices.
• High Performance: In 3C applications, high-performance NdFeB magnets generate strong magnetic fields. High BH_max and Br are key indicators, they directly affect the sensitivity of speakers, the efficiency of motors, and the holding force of magnetic components. 
• Thermal Stability: Neodymium magnets must possess excellent thermal stability (meaning high intrinsic coercivity) to cope with the heat generated in high-power applications (such as motors).
• Reliability and Durability: In consumer electronics, permanent magnets are often exposed to various environmental factors such as mechanical stress, moisture, and temperature fluctuations. Uncoated NdFeB magnets are easily to be oxidized and corroded. Therefore, magnets with high corrosion resistance are a design priority. NdFeB magnets used in 3C always require surface protection. Common coating methods include nickel plating, zinc plating, and epoxy coating, all of which are designed to ensure the long-term reliability of the magnets in demanding usage environments.

NdFeB magnets are indispensable in the modern 3C consumer electronic products. They can achieve high-performance acoustic systems, high-efficiency motor and reliable magnetic attraction. Meanwhile, they can also meet compactness, slightness and stability requirements of devices. The continued demands of smaller and more powerful magnets will drive innovative applications of magnetic materials in the electronics industry.