In the intricate inner workings of modern smartphones, there are many components that are invisible to the naked eye yet play a crucial role. One such component is the flat magnet (also known as a sheet magnet). Despite its small size, it plays an indispensable role as an “invisible assistant” enabling various convenient functions. This article will introduce the typical dimensions, materials, and important functions of flat magnets used in smartphones.
Space inside a mobile phone is at a premium, so the flat magnets used must be small and precise. Their typical dimensions are usually measured in millimeters (mm), and common shapes include circular, rectangular, and special custom shapes.
From the picture, we can see the material and shape of the magnets used in mobile phones. Different mobile phones have different shapes, sizes, and grades of magnets.

As seen in the mobile phone above, the three pcs magnets are all special neodymium magnets, designed to better fit the internal structure of the mobile phone, featuring small size and thinness.
In terms of size, flat magnets used in mobile phones are usually small, with a thickness of 0.5 - 2 mm and a length of no more than 10 mm.
When it comes to magnet materials, flat magnets in mobile phones are almost exclusively made of neodymium (NdFeB), which is currently the strongest permanent magnet material commercially available and is known as the “magnet king.” It can be easily processed into various ultra-thin sizes and special shapes to meet the needs of mobile phone internal design.
In terms of functionality, flat magnets in mobile phones mainly serve the following purposes: attaching the phone cover/back cover, securing internal components, wireless magnetic charging, and assisting other sensors.
For example, some mobile phones are equipped with magnets on the left and right inner support edges, which are used to fold and fix and attach the protective cover.
In some mobile phones with wireless charging capabilities, more than 10 curved (arc) or block magnets are arranged in a circle. This is mainly to ensure better alignment during wireless charging and achieve the best wireless charging results.
In the aperture adjustment mechanism of a mobile phone, when the coil inside the camera is energized, the magnetic force generated attracts the magnet, driving the opening and closing of the shutter in the adjustable aperture mechanism, thereby changing the amount of light entering the lens and achieving the effect of changing the aperture.
The above is an introduction to the material, shape, size, and function of flat magnets in mobile phones. They play an important role in various functional modules of phones.
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