N4700 is Strontium titanate-based dielectric ceramic material system A typical representative, it belongs to the core dielectric system of Class II ceramic capacitors (high dielectric constant class).
Case Details
N4700 is Strontium titanate-based dielectric ceramic material system A typical representative, it belongs to the core dielectric system of Class II ceramic capacitors (high dielectric constant class). Unlike single-component materials, N4700 is a formulation series that achieves a wide range of dielectric constants from 400 to 4000 by regulating the chemical composition, while maintaining similar temperature characteristics and loss behaviors, providing flexible adaptability for the engineering design of high-voltage ceramic capacitors.
- Dielectric constant adjustability：With doping modification, the N4700 material system can achieve continuous regulation of dielectric constant (εᵣ) from 400 to 4000, supporting a wide range of design requirements from "low capacity high voltage" to "high capacity medium voltage".
- Law of temperature coefficient：Within the same material system, ceramics follow the rule that "the smaller the dielectric constant, the better the temperature stability" (that is, the formula with a lower dielectric constant has a smaller temperature drift (TCC)). The typical temperature characteristic curve of N4700 ceramic is "high on the left and low on the right" (the capacitance change rate is slightly higher in the low-temperature section and more stable in the high-temperature section, which needs to be defined in combination with the actual TCC curve), and the tangent of the loss Angle (tanδ) always remains at a minimum, ensuring the low-loss characteristic at high frequencies.
N4700 dielectric ceramic It has excellent voltage gradient performance：
- The DC withstand voltage reaches 7 kV/mm (electric field strength), and the AC withstand voltage reaches 3 kV/mm, supporting the compact design of high-voltage (even ultra-high-voltage) ceramic capacitors (by reducing the dielectric thickness to increase the voltage density).
- This characteristic stems from the grain boundary insulation strengthening mechanism of strontium titanate-based ceramics, combined with the dense structure formed by the dry-pressing sintering process, effectively suppressing the risks of partial discharge and electrical breakdown.
The N4700 material series, with its combined advantages of "high dielectric constant, high voltage withstand, and low loss", is widely used in scenarios such as high-voltage pulses, power coupling, and industrial discharge.：
- Electromagnetic pulse/electronic countermeasure：By leveraging the high-frequency pulse response capability, rapid coupling and filtering of electromagnetic signals are achieved, making it suitable for pulse power modules of devices such as radars, directional energy lasers, and particle accelerators.
- High-voltage ignition system：For instance, the high-voltage ignition capacitors in air purifiers and industrial burners, relying on their high voltage gradient and pulse shock resistance characteristics, ensure stable energy in a single discharge.
- Online power supply device：As a high-voltage power supply capacitor, it couples the induced voltage of power lines to supply power to smart meters and online monitoring modules, taking into account both high-voltage tolerance and small-signal coupling capabilities.
- Medium-voltage carrier communication：In the 10-35 kV distribution network, as a coupling capacitor for carrier communication, it realizes the cross-phase transmission of high-frequency signals at the tens of kHz level and supports the power line carrier communication (PLC) technology.
- Security inspection and imaging equipment：In the high-voltage generators of X-ray and CT machines, the N4700 capacitor is used to store and release pulse energy to drive the X-ray tube to work. The power supply module of the ionization chamber of the security inspection machine also relies on its high-voltage stability.
- Industrial discharge application：In scenarios such as plasma discharge (like ozone generators), electrostatic precipitation (establishment of high-voltage electrostatic fields), and electron irradiation (power supply for acceleration tubes), the high voltage gradient and pulse endurance characteristics are utilized to ensure the energy control during the discharge process.
In pulse applications, attention should be paid to N4700 dielectric ceramics “Dielectric constant lifetime correlation”：
- When the pulse frequency is high and the peak current is large,Give priority to choosing the N4700 formula with a smaller dielectric constant(e.g. εᵣ=400-1000 range) can significantly reduce temperature drift and dielectric loss and extend product life。
- If the installation space is limited and a high-capacity design is required, a formula with a higher dielectric constant can be selected. However, the decline in temperature stability should be compensated by derating (such as reducing the working voltage or optimizing heat dissipation).
As a classic Class II dielectric ceramic system, N4700 has the advantages of controllable cost, strong voltage tolerance, and good high-frequency pulse adaptability. However, it lags behind new dielectrics such as GAC in terms of wide-temperature range stability and ultra-low voltage discharge control。Therefore：
- The N4700 is more suitable for non-extreme temperature environments and cost-sensitive high-voltage pulse scenarios (such as low-voltage AC systems and indoor stable environment equipment).
- The harsh outdoor working conditions of power equipment (such as a wide temperature range of 55℃ to +125℃ and partial discharge of less than 3 pC) rely on breakthroughs in new-generation dielectric technologies like GAC.
In conclusion, through materialized design, N4700 dielectric ceramic has established a "performance-cost" balance fulcrum in the high-voltage pulse field and is one of the most widely used core dielectrics in the high-voltage ceramic capacitor industry. With the upgrading of the demand for "higher voltage, higher frequency and wider temperature range" in power electronics technology, the N4700 material system is also continuously iterated (such as introducing nano-doping and gradient sintering processes), constantly expanding the technological boundaries.
