What is a ceramic PCB, and what are the types of ceramic PCBs?

What is a Ceramic PCB?

Ceramic PCBs (printed circuit boards) are circuit boards that use ceramic materials as substrates. They are made using ceramic powders (like aluminum oxide, aluminum nitride, or beryllium oxide) combined with organic binders. Their thermal conductivity typically ranges between 9-20 W/m·K, which makes them excellent for managing heat. They also have a low coefficient of thermal expansion (CTE) and stable electrical characteristics. They’re made using techniques like Laser Activated Metallization (LAM), which makes them perfect for electronic devices that operate in high-power, high-frequency, and high-temperature environments.

Types of Ceramic PCBs

Based on material systems and manufacturing processes, ceramic PCBs are primarily categorized into the following types:

1. HTCC (High-Temperature Co-fired Ceramic)

• Materials: Alumina-based ceramics with tungsten/molybdenum metal pastes.
• Process: Co-firing in a hydrogen atmosphere at 1600–1700°C for up to 48 hours.
• Features: High structural strength and precision, suitable for high-reliability aerospace and military applications.

2. LTCC (Low-Temperature Co-fired Ceramic)

• Materials: Crystal glass + ceramic composite materials with gold-based pastes.
• Process: Sintering at approximately 900°C, followed by lamination and forming.
• Features: Low shrinkage tolerance and high mechanical strength, widely used in RF modules and sensors.

3. Thick-Film Ceramic PCB

• Process: Screen printing of silver/gold-palladium pastes onto ceramic substrates, followed by high-temperature sintering (≤1000°C).
• Features: Conductor layer thickness of 10–13 μm, supports integration of passive components such as resistors and capacitors, suitable for complex circuit designs.

4. Thin-Film Ceramic PCB

• Process: Formation of micron-level metal circuits through vacuum deposition or sputtering.
• Features: High circuit precision, ideal for high-frequency microwave circuits.

5. DBC/DPC (Direct Bonded Copper/Direct Plated Copper Ceramic Substrate)

• Process: Direct bonding of copper foil onto ceramic surfaces at high temperatures (DBC) or circuit formation via electroplating (DPC).
• Features: Excellent thermal conductivity and current-carrying capacity, making them the preferred choice for power semiconductors (e.g., IGBTs) and LED lighting.

Advantages of Ceramic PCBs

1. High Thermal Conductivity:
   Thermal conductivity is much higher than traditional FR-4 substrates (e.g., aluminum nitride can reach 170-230W/m·K), effectively addressing heat dissipation in high-power devices.
2. Excellent High-Frequency Performance:
   Low dielectric loss and stable dielectric constant, suitable for 5G, RF, and microwave communications.
3. High-Temperature Stability:
   Can operate in environments above 350°C, making them ideal for automotive electronics, aerospace, and other high-temperature applications.
4. Mechanical and Chemical Durability:
   High mechanical strength, resistance to vibration, corrosion, and chemical erosion.
5. Dimensional Stability and Low CTE:
   The coefficient of thermal expansion is close to that of silicon chips, reducing connection failures caused by thermal stress.
6. High-Density Integration Capability:
   Supports fine line widths, microvias, and multilayer stacking, suitable for miniaturized designs.

Manufacturing Process of Ceramic PCBs

1. Design and Layout:
   Circuit design using CAD software, optimizing thermal management and signal integrity.
2. Substrate Preparation:
   Ceramic substrates (Al₂O₃, AlN, SiC, etc.) are cut and polished to target dimensions.
3. Conductive Layer Deposition:
   Silver/gold-palladium conductive paste is applied via screen printing or inkjet technology.
4. Via Drilling and Filling:
   Laser or mechanical drilling, with conductive materials filling the vias for interlayer connections.
5. Co-firing and Sintering:

• HTCC: Sintered in a hydrogen environment at 1600-1700°C.
• LTCC: Low-temperature sintering at around 900°C.
  Multilayer circuits require stacking before co-firing.

1. Component Assembly and Testing:
   SMD components are soldered, followed by electrical, environmental, and reliability tests.
2. Protective Coating and Packaging:
   Protective layers are applied to enhance environmental resistance, followed by final functional testing and packaging.

When to Choose Ceramic PCBs?

Ceramic PCBs are suitable for the following scenarios:

• High-Power Devices: Such as IGBT modules, power management systems, and LED automotive lights.
• High-Frequency Applications: 5G base stations, radar systems, satellite communications.
• High-Temperature Environments: Aerospace engine controls, automotive electronics.
• High-Reliability Requirements: Medical devices (e.g., laser surgical instruments), military equipment.
• Chemically Corrosive Environments: Oil exploration, industrial automation.

Considerations:

• Ceramic PCBs are relatively expensive, making them suitable for high-performance needs rather than consumer-grade products.
• Designs must account for material brittleness to avoid mechanical stress concentration.
• High process complexity requires collaboration with suppliers with mature technical expertise.

Application Fields