Electromagnetic shielding film is a material used for electromagnetic shielding, which confines electromagnetic waves within a certain range and suppresses or attenuates their electromagnetic radiation, serving as an effective method to inhibit electromagnetic interference. In electronic devices, when electronic components are in operation, capacitors and other components generate electric fields, while inductors and other components generate magnetic fields, all of which can excite electromagnetic waves. Unnecessary electromagnetic waves may interact with the electrical signals of the components themselves or other electronic components, causing signal transmission processes to be affected by electromagnetic interference, leading to signal distortion. To avoid such issues, after the flexible printed circuit (FPC) is laminated with a cover film, another layer of electromagnetic shielding film is laminated on top to block external electromagnetic interference, thereby ensuring that the FPC circuits can operate normally. The shielding principle of electromagnetic shielding film against electromagnetic waves can be divided into reflection attenuation and absorption attenuation. Both principles can be superimposed or multiple layers of the same principle can be stacked to further enhance the shielding effect.
With the rapid development of domestic smartphones, automotive electronics, and communication devices such as 5G, the overall demand and market size for electromagnetic shielding film are steadily expanding. Data shows that in 2020, China's electromagnetic shielding film market size reached 2.13 billion yuan, and it is expected to exceed 6 billion yuan by 2025. By 2025, China's demand for electromagnetic shielding film is expected to exceed 3.6 million square meters, and by 2030, the overall demand is expected to break through 6 million square meters.
The growth in consumer electronics, automotive electronics and other fields is the main driving force behind the increase in demand for flexible printed circuits (FPCs), which in turn brings high prosperity to the electromagnetic shielding film industry. Taking smartphones as an example, in addition to the original voice call function, features such as photography, video playback, data transmission, wireless local area network, fingerprint recognition, positioning, and gravity sensing have become prevalent. The trend towards higher frequency and speed of components will be even more pronounced in the future. Under the drive of high-frequency and high-speed development, the resulting electromagnetic interference inside and outside electronic components and their assemblies, as well as signal attenuation during transmission, are becoming increasingly serious. Suppressing electromagnetic interference and reducing signal transmission loss have become important topics in the development of FPCs. The market demand for electromagnetic shielding films continues to grow. In terms of automotive electronics, with the rapid development of new energy vehicles and the rise in vehicle intelligence, there is an increasing demand for electronic components in devices such as lighting systems, display systems, powertrain systems, battery management systems, and sensors. Automotive FPCs, with their advantages of lightweight, relatively simple structure, and good safety performance, are gradually gaining popularity in new energy vehicles, creating more application scenarios for electromagnetic shielding films.
The electromagnetic shielding film industry faces barriers in technology, market, capital, and scale, resulting in a high threshold for entry. In the early days, both domestic and global market shares of electromagnetic shielding films were completely occupied by developed countries, primarily Japan. In recent years, domestic companies such as Fangbang Electronics, Shenzhen Konobridge, and Zhongchen Group have expanded their research and development investments to increase production capacity, gradually expanding their market share and significantly narrowing the gap with Japanese enterprises. Among them, Fangbang Electronics' market share is close to 20%, ranking second globally and first in China. The global market for electromagnetic shielding films is dominated by Toshiba Corporation, with Fangbang holding the second-largest share, while other manufacturers have smaller shares. Toshiba, Fangbang, and Toyo Keimei are the main players in this market. In 2000, Toshiba was the first to develop electromagnetic shielding films. In 2012, Fangbang successfully developed an electromagnetic shielding film product with independent intellectual property rights. Toyo Keimei followed suit and successfully researched its own version. Toshiba holds a leading position globally, accounting for over 50% of the global market share in 2018.
Flat nickel powder typically exhibits high purity, generally reaching 99.7% or above, ensuring the stability and reliability of its performance. With a fine particle size, common mesh numbers such as 200, 300, and 400 are available, precisely meeting different process requirements. The aspect ratio is approximately 20:1, with a thickness of about 1 micron, which endows it with excellent filling and covering capabilities. It demonstrates superior resistivity, with an extremely low value, indicating good conductivity. Particles are in sheet and chain forms, forming a three-dimensional chain structure like a finely woven power grid. Compared to traditional electrolytic, fogged, and carbonyl nickel powders, the conductive pathway is more efficient and unobstructed. Its chemical stability is exceptional; it remains unaffected by various chemicals in organic adhesives and coatings, as well as in corrosive and temperature-variable complex environments. During storage, its properties remain stable, and after coating, the film is firm and durable. Moreover, flat nickel powder possesses good ferromagnetic properties, giving it a natural advantage in electromagnetic fields and laying the foundation for subsequent electromagnetic shielding functions.
In electromagnetic shielding applications, flake nickel powder exhibits significant advantages. When electromagnetic waves strike, its unique flaky structure efficiently reflects the waves, acting like a dense array of tiny shields that block and reflect a large amount of incoming electromagnetic waves back along their original path. At the same time, based on its own electromagnetic properties, flake nickel powder can also absorb and attenuate electromagnetic waves, converting part of the energy into heat or other forms for dissipation, reducing penetration. Compared with other shielding materials, flake nickel powder, when used in multilayer composite structures, can be tightly arranged and fill gaps due to its flaky shape, greatly enhancing the overall density of the shielding film, making it impossible for electromagnetic waves to penetrate, thereby significantly improving the shielding performance. This ensures that the internal circuits of electronic devices are protected from external electromagnetic interference and guarantees the purity and stability of signal transmission.
The key role of flaky nickel powder in the electromagnetic shielding film for flexible printed circuits (FPCs) is based on its unique physical and electromagnetic properties. When evenly dispersed within the shielding film material system, its flaky shape and pearl-chain particle arrangement can construct a continuous and intricate three-dimensional conductive network within the membrane. When external electromagnetic waves strike, first, the flaky nickel powder, with its good conductivity, guides the electromagnetic waves to conduct along this conductive network rather than penetrating through the membrane, making the electromagnetic waves like being trapped in a maze, greatly reducing their likelihood of continued propagation, which is a microscopic manifestation of the reflection attenuation principle. At the same time, based on the ferromagnetic properties of nickel powder, it can strongly interact with the magnetic component of the electromagnetic wave, converting part of the electromagnetic wave energy into heat energy consumption in forms such as hysteresis loss and eddy current loss, realizing absorption attenuation of the electromagnetic waves. Through the synergistic effect of reflection and absorption, flaky nickel powder significantly enhances the overall shielding performance of the electromagnetic shielding film, ensuring that FPC lines are not interfered by complex external electromagnetic environments and ensuring stable transmission of electronic signals.
The application methods of flaky nickel powder in FPC electromagnetic shielding film are diverse. One is the direct addition method, where precisely measured flaky nickel powder is mixed with a certain proportion directly into the basic polymer material of the electromagnetic shielding film, such as common polyester resin and polyimide resin, using high-speed stirring, ultrasonic dispersion and other processes to ensure uniform distribution of nickel powder, followed by forming the shielding film through casting, coating and other means. This method is relatively simple to operate and can fully exert the original characteristics of nickel powder. The second is the slurry coating method, which mixes flaky nickel powder with appropriate amounts of binders, solvents, etc., to form conductive slurries with good fluidity and coating properties, then uses screen printing, scraper coating and other technologies to coat accurately on the surface of FPC or preformed base films, forming a dense shielding layer after drying and curing. This method has strong controllability over membrane thickness and nickel powder distribution. The third is composite application with other materials, which combines flaky nickel powder with carbon fiber, nanosilver wire and other materials that have conductivity and shielding functions to complement each other's advantages, such as the high strength of carbon fiber and the high conductivity of nanosilver wire, synergistically improving the comprehensive performance of the shielding film to meet the stringent requirements for electromagnetic shielding in fields such as aerospace and high-end communication equipment.
Taking the flagship smartphone of a well-known brand as an example, its internal motherboard integrates a large number of high-precision chips, RF modules and other electronic components. When working, it will produce complex and changeable electromagnetic signals, with a high risk of mutual interference. In the electromagnetic shielding film used in the FPC connection part, a specific particle size and proportion of flaky nickel powder are added, and the film is made into a thickness of only dozens of microns through optimized technology. After professional testing, within the commonly used frequency band of 600MHz - 6GHz, the electromagnetic shielding effect has been improved by 10 - 15dB, effectively ensuring the clarity and stability of mobile phone signals during calls, data transmission, and 5G high-speed network connections, reducing call noise and network jams, greatly improving user experience, and at the same time helping mobile phones to develop towards thinness and multi-functionality to meet the growing demand for performance.
In the application of FPC electromagnetic shielding film in core components such as computer motherboards and graphics cards, flake nickel powder is also indispensable. When a computer is running, processes like high-frequency CPU computing, massive data reading and writing, and high-speed graphics rendering by the graphics card will emit a large amount of electromagnetic waves. Without effective shielding, it can cause serious problems such as system crashes and data errors. Shielding films made from flake nickel powder with high purity and optimized diameter-to-thickness ratio can achieve more than 30 dB of shielding effectiveness within the frequency band of 0.5 GHz to 10 GHz, ensuring electromagnetic compatibility between various components and laying a solid foundation for the long-term stable operation of computers. Especially in products with strict stability requirements such as gaming computers and high-performance workstations, this ensures a smooth gaming experience for players and the successful completion of complex tasks for professionals.
Modern cars are highly electronic, with electronic control systems governing key functions such as engine ignition, power transmission, and airbag deployment. During driving, the car experiences vibrations, temperature changes, and a complex electromagnetic environment that is constantly changing. In its FPC electromagnetic shielding film, flake nickel powder is combined with high-temperature resistant and impact-resistant polymers to form a tough and efficient shielding layer. For example, in the battery management system FPC of new energy vehicles, this shielding film can effectively block electromagnetic interference from motor drive systems and external charging piles within the frequency range of 20 kHz to 2 GHz, maintaining a shielding effect of about 25 dB, ensuring precise monitoring of battery power and smooth charge and discharge control, guaranteeing reliable operation of the vehicle's electronic system, and enhancing driving safety and comfort.
The particle size of flaky nickel powder plays a crucial role in its application in flexible printed circuit (FPC) electromagnetic shielding films. Finer particles, such as those with a mesh size of 400 or even finer, can fill the microscopic pores of the membrane material more tightly, constructing a denser conductive network that significantly enhances the electromagnetic shielding effect at high frequencies. This is particularly beneficial for scenarios involving high-frequency electromagnetic wave interference, such as 5G communication and high-speed data transmission. However, excessively fine particles may lead to agglomeration issues, increasing dispersion difficulty and affecting coating uniformity, which can result in uneven local performance of the film. In terms of purity, high purity (99.7% or above) ensures stable electromagnetic properties of the nickel powder itself, reducing impurities' interference with the conductive pathway and guaranteeing the stability and reliability of the shielding effect. Regarding shape, ideal flaky nickel powder with an appropriate aspect ratio (around 20:1) forms a more continuous and efficient conductive layer within the film compared to spherical or irregularly shaped powders. This allows for higher shielding effectiveness with less addition, while also having minimal impact on the flexibility of the film, meeting the process requirements for bending and curling of FPCs and ensuring comprehensive performance of electromagnetic shielding films in line with the trend towards lightweight electronic device design.
During the preparation process, different methods of producing flake nickel powder result in distinct characteristics. For instance, nickel powder prepared by the gas phase method is highly pure and has a small particle size, but it tends to sinter easily. If subsequent processing is not handled properly, the powder may agglomerate during the preparation of electromagnetic shielding film, affecting the uniformity and shielding performance of the film. Nickel powder produced by the liquid phase method has better control over shape and particle size, but crystallization issues may lead to instability in conductivity. In terms of coating technology, when using screen printing, the choice of mesh aperture needs to be precisely matched with the particle size of the flake nickel powder. A higher mesh number makes it difficult for the nickel powder to pass through, affecting the coating amount and film thickness, while a lower mesh number cannot guarantee pattern accuracy and film flatness, leading to fluctuating shielding effects. In blade coating, the coordinated regulation of blade angle, pressure, and coating speed is crucial. Inappropriate parameters can cause uneven distribution of nickel powder, resulting in stripes with inconsistent thicknesses and defects that reduce the overall quality of the shielding film. During the curing process stage, controlling temperature, time, and atmosphere directly relates to the bonding strength between flake nickel powder and resin matrix as well as the stability of electromagnetic properties. High temperatures or prolonged times may cause oxidation of nickel powder and aging of resin, weakening shielding effectiveness. Inadequate curing atmosphere, such as excessive oxygen content, can also negatively impact the performance of nickel powder and the film layer.
As electronic devices continue to advance towards miniaturization and high-frequency, high-speed capabilities, the demand for flexible printed circuit (FPC) electromagnetic shielding films is surging. Flake nickel powder, with its unique advantages, aligns perfectly with this trend. In the process of miniaturization, its high conductivity and flaky structure enable efficient shielding layers with less material, meeting the space-saving requirements of FPCs such as ultra-thin smartphones and miniature wearable devices, thus contributing to product weight reduction and thickness minimization. In high-frequency, high-speed scenarios, flake nickel powder's excellent electromagnetic shielding performance addresses challenges posed by high-frequency electromagnetic wave interference, ensuring stable operation of 5G communication modules and high-speed data transmission lines, reducing signal distortion and transmission loss, laying a solid foundation for the performance enhancement of the new generation of electronic devices, and offering promising market prospects.
At the technical R&D level, despite the outstanding advantages of flake nickel powder, with the rapid renewal of electronic technology, the performance requirements for it are constantly increasing. Challenges such as achieving ultra-strong shielding at higher frequency bands and adapting to new polymer matrixes urgently need to be overcome. The large investment and long development cycle test the technological foundation and financial strength of enterprises. In terms of cost control, the production process of high-quality flake nickel powder is complex, and the costs of raw materials, equipment, and energy consumption are not cheap. Coupled with market competition leading to price pressure, the profit margin of enterprises is squeezed, making cost management and quality balance quite challenging. In the field of market competition, there are various electromagnetic shielding materials, and competing products such as metal foils and conductive polymers continue to emerge. Moreover, international giants occupy the high-end market with their brand and technological advantages. Domestic companies not only have to compete with peers but also need to break through technological blockades and brand bottlenecks to secure a place in the global market. The path to breakthrough is difficult.
In response to the aforementioned challenges, enterprises should strengthen industry-academia-research cooperation, integrate the theoretical research capabilities of research institutions with the practical transformation capabilities of enterprises, accelerate technological breakthroughs; optimize production processes, introduce advanced equipment and lean management, reduce costs; focus on niche markets, meet specific needs with differentiated products, accumulate brand reputation, gradually enhance comprehensive competitiveness, and achieve stable and long-term development in the field of FPC electromagnetic shielding membranes.
Flat nickel powder has already occupied an important position in the FPC electromagnetic shielding film industry, thanks to its high purity, unique microstructure, superior conductivity, good chemical stability and ferromagnetic properties, which provide efficient solutions for electromagnetic shielding. The successful application cases in fields such as smartphones, computers, and automotive electronics demonstrate its key role in enhancing electromagnetic shielding performance and ensuring stable operation of electronic devices, effectively promoting product miniaturization and high-frequency high-speed development. However, the application of flat nickel powder is affected by factors such as particle size, purity, shape, and preparation, coating, curing processes, facing challenges such as technological bottlenecks, cost pressure, and fierce market competition. Looking ahead, with the continuous upgrading of the electronics industry, flat nickel powder needs to overcome difficulties in research and development, optimize production to reduce costs and improve efficiency. Enterprises should identify their positioning in the subdivided market, strengthen industry-university-research collaboration, drive development through innovation, and be able to move steadily forward in the field of FPC electromagnetic shielding films, unlock broader application potential and help electronic device performance reach new heights.
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