Is High-Purity Magnesium Oxide Used in Multi-Layer Ceramic Capacitors (MLCC)?

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Messi Biology states that high-purity magnesium oxide (MgO) is a critical functional material in the manufacturing of MLCCs (Multi-Layer Ceramic Capacitors). Its value is demonstrated by enhancing heat resistance, mechanical strength, and dielectric properties to meet the demands of high-end electronic devices. The industry has established clear purity standards (such as HG/T2573-2012) and optimized addition ratios (2–8%). With the growing demand for high-frequency and high-voltage MLCCs in 5G and new energy vehicles, the application of high-purity magnesium oxide is set to expand further.

MLCC

I. Basic Raw Material Composition of MLCCs

  • Ceramic Dielectric Components
    The ceramic dielectric of an MLCC is primarily composed of Barium Titanate ( BaTiO3BaTiO_3BaTiO3​ ), supplemented by other oxides such as Zirconium Dioxide ( ZrO2ZrO_2ZrO2​ ) and Calcium Oxide ( CaOCaOCaO ). The composition varies depending on the type of MLCC:
    • C0G Class: Primarily based on Strontium Zirconate ( SrZrO3SrZrO_3SrZrO3​ ) or Barium Strontium Titanate ( BaSrTiO3BaSrTiO_3BaSrTiO3​ ). These offer a stable dielectric constant and excellent temperature characteristics.
    • X7R/X5R Class: Based on Barium Titanate ( BaTiO3BaTiO_3BaTiO3​ ), with rare earth oxides (e.g., Y2O3Y_2O_3Y2​O3​ ) and transition metal oxides (e.g., MgOMgOMgO , MnOMnOMnO ) added to regulate dielectric performance.
  • Role of Additives
    Magnesium oxide (MgO), as a secondary component, is often added alongside Silicon Dioxide ( SiO2SiO_2SiO2​ ) and Calcium Oxide ( CaOCaOCaO ) to optimize sintering performance and dielectric properties.

II. Functions of High-Purity Magnesium Oxide in MLCCs

  • Performance Optimization
    1. High-Temperature Resistance: MgO has a melting point as high as 2852°C, which improves the stability of MLCCs in high-temperature environments, allowing them to maintain electrical performance above 150°C.
    2. Mechanical Strength: By filling microscopic defects in the ceramic structure, it enhances material density and improves resistance to impact and wear.
    3. Electrical Insulation: It reduces ceramic conductivity and increases insulation resistance, making it suitable for high-voltage and high-frequency circuits.
  • Process Improvement
    1. Sintering Aid: Magnesium oxide can lower the sintering temperature (to approximately 1320–1350°C), promote ceramic densification, and shorten production cycles.
    2. Dielectric Regulation: By adjusting the crystal structure, it optimizes the dielectric constant ( ϵ=9.8–10.2\epsilon = 9.8–10.2ϵ=9.8–10.2 ) and dielectric loss to meet the requirements of different MLCC models.

III. Technical Standards and Addition Ratios

  • Purity Requirements
    High-purity magnesium oxide must reach a MgO content of ≥98%\ge 98\%≥98% (industrial grade) or ≥99.9%\ge 99.9\%≥99.9% (electronic grade), with impurities such as calcium and iron controlled at the ppm (parts per million) level.
  • Typical Addition Amounts
    1. General-Purpose MLCCs: The addition ratio is typically 2–3 mol% (approx. 0.5–1.5 wt%). Excessive amounts may cause a decline in dielectric performance.
    2. High-Frequency MLCCs: The addition of nano-magnesium oxide (particle size < 500 nm) can be increased to 5–8% to improve high-frequency signal transmission loss.

IV. Application Cases and Industry Practices

  • Practical Applications
    1. High-Voltage MLCCs: High-purity magnesium oxide from Messi Biology serves as an insulating medium, keeping dielectric constant fluctuations within ±2%\pm 2\%±2% and enhancing product consistency.
    2. 5G Communication Devices: Adding 3–8% magnesium oxide to silicon nitride ceramic substrates optimizes thermal conductivity and signal integrity.
  • Differences by Type
    1. C0G Class: Magnesium oxide is mainly used to regulate the Curie temperature ( TcT_cTc​ ). Every 1 mol% of MgO added to Barium Titanate lowers the TcT_cTc​ by 3–5°C, satisfying low-temperature stability requirements.
    2. X7R Class: It acts as a grain boundary modifier to inhibit dielectric constant drift over temperature changes, ensuring that ΔC/C≤±15%\Delta C/C \le \pm 15\%ΔC/C≤±15% .

Recommendations

If specific formulas or process parameters are required, please refer to the technical manuals provided by electronic-grade magnesium oxide suppliers (such as Messi Biology) or adjust doping strategies based on the specific MLCC type (C0G/X7R).

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