NdFeB Magnets in 3C Consumer Electronics Products

3C consumer electronics products mainly include six categories: mobile phones, tablets, laptops, watches, headphones and wireless charging devices. Taking Apple products as an example, they are iPhone, iPad, Mac, Watch, AirPods and Magsafe Parts.

1. Acoustic Module

As the name implies, the acoustic module is the sound unit, commonly known as the speaker. The performance of the speaker has a great impact on the sound quality.

A magnetic field is generated in a current-carrying wire. When an AC audio current passes through the coil of the speaker (i.e., voice coil), a corresponding magnetic field is generated in the voice coil. This magnetic field interacts with the magnetic field generated by the magnet on the speaker. This force causes the voice coil to vibrate in the permanent magnet magnetic field of the speaker along with the audio current. The speaker's diaphragm and voice coil are connected together. When the voice coil and the speaker diaphragm vibrate together, they push the surrounding air to vibrate, and the speaker produces sound. As shown in the figure below, this is the principle of the speaker.

Mobile phones such as iPhones are frequently used and have certain requirements for the weight of the mobile phone. Therefore, high-performance (54SH) small-volume magnets are needed to achieve the purpose of lightweighting.

On computers such as Mac or iPad, the sound quality needs to be considered on the one hand, and on the other hand, the size is larger than that of mobile phones, and there is more space available, so a magnet with slightly lower performance (52SH) and larger size and more diversified shapes will be used.

Watch products such as Watch are small in size and users generally require them to be able to make sounds, and do not require high sound quality, so a magnet with lower performance (50H) and smaller size is used.

2. Motor module: VCM voice coil motor and linear vibration motor

VCM voice coil motor is an important part of AF (Auto Focus) camera module. It can drag the lens up and down to switch between near focus and far focus, making the photo clearer. Similar to the principle of speakers, the magnet provides a permanent magnetic field in the camera module. The energized coil will be acted upon by force in the magnetic field, thereby dragging the lens forward and backward. Different lenses have different functions, and the shapes and performance of the magnets inside are very different.

Linear vibration motors are the main components for mobile phone products to achieve vibration functions. The energized coil is subjected to Ampere force in the magnetic field (the magnetic field is provided by NdFeB magnets), thereby driving the motor to vibrate. Among them, LRA (Linear Resonance Actuator) is a motor currently widely used in smartphones, providing tactile feedback through tactile effects. The performance of LRA directly affects the user's tactile experience. LRA is driven by AC, which can generate instantaneous high voltage, making the motor start and stop very quickly, and the vibration sense follows the hand. Changing the frequency of AC can achieve different vibration senses to match various mobile phone usage scenarios. Depending on the type of motor, the shape and performance of the magnet are completely different.

3. Magnetic module

The easiest way to understand magnetic attraction is to use the property of magnets to attract ferromagnetic materials. It is mainly used in various adsorption parts, such as various wireless charging adsorption parts, mobile phones and watches, etc. For example, the closure of computer screens and the support of tablets all have magnets to play an adsorption role. These adsorption parts have different shapes and performances according to different terminal products and are customized according to actual needs.