Small NdFeB Magnets in Smartphones
Neodymium (NdFeB) magnets are an invisible part of every smart phone. These tiny magnets are critical to the function of the phone, working quietly behind the scenes inside the phone case. These internal magnets are typically used in the speaker, receiver, vibration mode motor, taptic feedback motor, and camera auto-focus mechanism. Small NdFeB Magnets in Smartphones
External smart phone uses for NdFeB magnets include ear buds, earphones and wall chargers –the kind of wall chargers that use magnetic connectors. Since speaker designs use 3-5 magnets per speaker, the quantity of magnets-per-phone adds up quickly. Smart phones can have up to 14 small magnets inside.
Neodymium N48 and N52 Speaker Phone Magnets
The first speaker phone magnets were single-magnet designs. But smart phones have gotten thinner, and consumers demand higher-quality sound and reliability from their smart phones, so now the number of magnets in the speaker has increased to 2-5 magnets as designers create form factors that are compatible with these new requirements.
Figure 1. N48 Neodymium three-magnet speaker phone assembly. Gray-colored steel parts are bonded to the whitish-colored Neodymium N48 or N52 magnets and attached to the rest of the assembly during a later operation. Approximate assembly dimensions: 2x8x10mm.
These magnets get glued into an assembly that is subjected to elevated temperatures during processing, so the engineers must select magnet grades that can withstand the heat of these processes. Since the magnets are so small, designers use N48 and N52 magnets –two of the strongest available grades- because performance-per-unit volume is critical in such tight spaces. These strong magnets are also supplied in high-temperature grades due to the temperatures they see during the bonding process.
Neodymium (NdFeB) magnets come in temperature grades that withstand temperatures of up to 230 degrees C. Our technology team is pushing the limits of Neodymium magnet technology even further as our customers demand magnets with a high Energy Product combined with the ability to withstand high temperatures for many New Energy and High Technology applications.
The magnet surface must have enough texture for the adhesive to hold onto, so the surface roughness must be managed within exacting parameters. We have developed special processes for creating the exact surface roughness required to fulfill these precise specifications.
Receiver Magnets
The receiver is the telephone microphone. Like speaker phones, receivers were originally made with a single magnet, but they are now typically a two-magnet design, and as with speaker magnets, the two-magnet design is due to the thinner design of the latest high-tech smart phones.
Receivers made with high-energy-product Neodymium magnets have a greater dynamic range, delivering a high-fidelity reproduction of sound to the downstream digital processing equipment.
Autofocus Motor for Smart Phone Camera
It might be surprising to note that the autofocus motor is actually a voice coil motor. A voice coil motor is what drives an audio speaker, but Voice Coil Motors are used in other applications where precision is important.
Autofocus cameras typically use voice coil motors (VCMs) because VCMs are very quick and precise over a short distance, and they are designed to move a speaker dome in the same manner that camera lenses move. Autofocus motors use 2-4 magnets per camera.
Neodymium magnets are used for voice coil motors in smart phones because even a very small magnet is very powerful and can actuate the auto-focus mechanism in a fraction of a second. The high strength of NdFeB magnets has been a major factor in driving improvements in smart phone camera technology and has led to better and cheaper cameras.
Vibration Motors and Taptic Feedback Motors
The vibration motor has been around a long time. It’s the silent ring motor for when you set your phone to vibrate. Vibration motors use one magnet.
Most smart phones now have a second vibration motor. It’s the taptic feedback motor. You know that little “bump” you feel when you push the keys on your smart phone? That “bump” comes from the taptic feedback engine.
Earbuds, Earphones and Headsets
Have you noticed how much better earphones and headsets have gotten in the last few years? NdFeB magnets have a lot to do with that. Each earphone/earbud or headset uses 2-4 magnets. That’s 1-2 magnets per side.
Neodymium magnets have made earphones smaller, and the sound quality has greatly improved compared to older earphones made with older technology. High-quality earbuds would not exist without the miniaturization made possible by high-tech NdFeB magnets.
Earbud magnets are so small that the volume of material is small. That's true, but we make millions of these tiny magnets every year, so the total volume of these tiny magnets is substantial.
Wall Chargers
Maybe you’ve bought a new electronic device with a magnetic clasp for the wall charger. It’s very likely that this Neodymium magnet came from BJMT/Ideal Magnet Solutions, Inc. We have supplied -and continue to supply- super-strong Neodymium magnets for wall chargers, and consumers continue to enjoy the high technology and convenience this feature brings to their user experience.
These kinds of wall chargers are not limited to smart phones. As seen in the photo below, magnetic wall chargers are also becoming popular with notebook computers and other portable electronic devices.
Figure 2: Typical wall charger magnetic assembly for notebook computer uses multiple small N48 Neodymium magnets.
Achieving Excellence in Small Magnets for Smart Phones
How did BJMT/Ideal achieve this level of prominence in such a specialized and competitive market? Established in 1987, BJMT/Ideal began business only 5 years after the invention of the NdFeB magnet, making us one of the oldest NdFeB magnet companies in the world.
Our management recognized very early the importance of becoming a patent licensee. We were the first independent company in China to sign onto the Hitachi NdFeB magnet patents (formerly Sumitomo) back in 2000 and we remain a Hitachi licensee today.
We have invested in the personnel and equipment to make magnetic parts for many significant high-tech applications in automotive, aerospace, industrial, medical and consumer industries where magnets are playing a more vital role in improving the performance of many critical parts and systems.
Small Magnet Processing Steps
First, we make high-quality NdFeB N48 magnets using processes that are detailed here. Smart phone magnets are very small, so we cut them from NdFeB blocks with very precise wire-cutting equipment that uses extremely thin wires to minimize kerf losses.
Figure 3: Magnet blocks ready for abrasive wire cutting.
Our engineers and processing specialists diligently reduce waste and variability at every step of the process, so we can deliver components at low cost for very cost-sensitive applications. We use dedicated grinding equipment to produce millions of tiny parts to extremely tight tolerances.
Figure 4. Very precise wire cutting equipment uses a very fine abrasive wire to cut magnet blocks to their finish size. Vertical wires in this photo are so fine that they are difficult to see.
We coat the magnets with nickel-copper-nickel electroplate at our own in-house plating facility. We use special proprietary techniques to create a textured surface on magnets so that adhesives will stick when applied to them during some of the downstream processes.
Quality and 100% Inspection
100% of our smart phone magnets undergo a thorough inspection of numerous critical dimensions and surface finishes.
Due to the small size of each magnet, -even in a relatively low-cost labor market like China- a cost-competitive human inspection is impossible, so we have invested in a small army of high-tech automatic inspection machines that systematically measure every critical dimension and automatically reject all nonconforming parts.
Figure 5. High-throughput Automatic Inspection Machines measure small magnets quickly and accurately, and automatically reject nonconforming parts.
These inspection machines represent the latest optical inspection technology. They quickly and accurately measure multiple dimensions of small magnets at a very high production rate. These machines can be quickly and easily reprogrammed to inspect new parts, giving BJMT/Ideal the capability of responding to a customer’s request for a new design.
Earning our Customer’s Trust
BJMT/Ideal Magnet Solutions Inc. has established a team of small-magnet specialists who have developed strong knowledge and understanding of the customer’s needs in the highly competitive consumer electronics market.
Our team is multidisciplinary, consisting of professionals from materials engineering, process engineering, surface treatment and quality engineering, logistics, and sales engineering.
This team is responsible for lead times and pricing that make BJMT/Ideal the go-to source for small magnets, and here’s why:
- A fast lead time measured in days, not weeks or months
- We impose strict control on all dimensions to highly exacting tolerances
- High-yield process controls that make us a pricing leader
- Selection of magnet grades -optimizing performance for downstream processes- as well as end-use applications
- Our processing and inspection equipment give our customers the confidence and peace of mind that every magnet will be delivered on-time and according to specifications. This is extremely important to customers who run very lean operations and rely on a supply chain partner who can deliver top-quality parts on-time and keep the production lines running.
Small NdFeB Magnets in Smart Phones and Personal Electronics
BJMT/Ideal Magnet Solutions, Inc. is the premier long-term provider of high-tech NdFeB magnets to the smart phone and personal electronics industry. Practically every smart phone and tablet on the planet (and many other personal electronic devices, like earbuds, head phones, Bluetooth and magnetic charging devices) has magnets from BJMT/Ideal, including the best-known consumer brands on the planet.
We have provided our magnets to these high-tech consumer electronics suppliers for almost 15 years, establishing BJMT/Ideal as the dominant force in this market.