Suppliers of coils in China are stepping up R&D
At the center of development activities are SMD and flat coils. The first is offered by more than 70 percent of makers. The variant will continue to account for a large part of companies’ total yield as demand from portable devices grows. The mainstream sizes are 7x7x3, 4x4x3.2, 4x4x1.2, 3.2×3.2×2 and 2x2x1.8mm, the last being the smallest achieved by China suppliers. Flat coils, although provided by only 20 percent of the manufacturing pool, are attracting attention because of their advantages over conventional models. These adopt flat enameled copper wire and are made using special winding machines. The products feature a low profile and a high current load. Compared with traditional units of the same size, these have a lighter weight, enhanced efficiency and lower noise. Such units also have an elevated Q value and can allow a large current to pass through.
In addition, flat versions are more stable and consistent because of the simpler structure. They likewise exhibit better heat dissipation properties and magnetic field efficiency given the small difference in external and internal temperatures. Applications cover low-power DC-DC converters, notebook computers, power supplies, and automotive and communication systems.
Performance upgrades are also an R&D objective. Companies are targeting higher frequency, Q value, power and current, and lower profile and EMI. To achieve these, enterprises cooperate closely with clients in selecting the most suitable wire and winding methods to match target requirements. Some have developed winding technologies to improve product reliability.
To enhance competitiveness, companies are reducing sample design turnaround and delivery lead times, and mass-producing different models to cater to a larger customer base.
To boost yield and efficiency, suppliers are investing more in new equipment. Many are taking advantage of the availability of low-cost locally made machines, including those for winding, which adopts digital automatic control and can perform paint peeling, tin soldering and molding in one step. There are also stranding and stripping devices.
Currently, a midsize coil manufacturer in China has about 100 winding machines, which turn out more than 100 million units a month.
As a quality measure, suppliers have shifted to leadless production certified to SGS or other third parties. They are also adopting advanced testing instruments such as impedance and network analyzers and fixtures to ensure a high Q value. Products meet RoHS and WEEE requirements.