2025-04-30
what is a ceramic pcb?
what is a ceramic pcb?
Definition and Core Features of Ceramic PCB
Ceramic PCB (Ceramic Printed Circuit Board) is an inorganic ceramic material (such as alumina, aluminum nitride, etc.) as a substrate for the circuit board, instead of the traditional FR-4 (glass fiber reinforced epoxy resin) or other polymer substrates, designed for high power, high temperature, high frequency and other extreme environments. Its core features include:
- High Thermal Conductivity: Thermal conductivity up to 9-280 W/m-K (depending on the material), far exceeding FR-4's 0.8-1.1 W/m-K, to efficiently dissipate heat and prevent heat buildup.
- Low Coefficient of Thermal Expansion (CTE): Close to that of silicon chips (e.g., CTE of 4.5 ppm/°C for AlN), minimizing connection failures due to thermal stress.
- Excellent electrical properties: High dielectric strength (>10 kV/mm) and low dielectric loss (0.0005-0.002) for high frequency circuits.
- High temperature and chemical resistance: long-term operation above 300°C, resistance to moisture, acids and alkalis, and radiation
Material Composition and Types
Substrate material selection for ceramic PCBs directly affects performance, and common types include:
| material | Thermal conductivity (W/m-K) | specificities |
| Aluminum oxide (Al₂O₃) | 20-30 | Low cost, high mechanical strength, widely used in medium power scenarios |
| Aluminum Nitride (AlN) | 170-220 | Best thermal conductivity for high power density chips (e.g. IGBTs, LEDs), but higher cost |
| Beryllium oxide (BeO) | 250-300 | Excellent thermal conductivity, but toxic, limiting its industrial application |
| Boron Nitride (BN) | 30-60 | Good high frequency performance for microwave communication and radar systems |
In addition, ceramic PCBs are categorized by process:
- HTCC (High Temperature Co-fired Ceramics): Sintering temperature up to 1600-1700°C, Requires tungsten/molybdenum metal wiring, Used in aerospace and military.
- LTCC (Low Temperature Co-fired Ceramics): Sintering temperature around 850°C, passive components can be integrated, suitable for RF modules.
- Thick-film ceramic PCBs: circuitry is formed by silk-screening metal pastes, lower cost, used for automotive sensors
- HTCC (High Temperature Co-fired Ceramics): Sintering temperature up to 1600-1700°C, Requires tungsten/molybdenum metal wiring, Used in aerospace and military.
- LTCC (Low Temperature Co-fired Ceramics): Sintering temperature around 850°C, passive components can be integrated, suitable for RF modules.
- Thick-film ceramic PCBs: circuitry is formed by silk-screening metal pastes, lower cost, used for automotive sensors
Key steps in the manufacturing process
1. Substrate preparation: ceramic powder (e.g. Al₂O₃) is mixed with organic binder and molded, sintered and densified at high temperature .
2. Metallization: Deposition of a copper layer on the substrate surface by magnetron sputtering or electroplating to form conductive lines.
3. patterning and etching: photolithography defines the circuits and chemical etching removes excess metal 7.
4. Drilling and Through-Hole Filling: Laser drilled holes are filled with conductive materials (e.g., silver paste) to realize interconnections between layers.
5. Surface Finishing: Gold/silver plating to improve solderability, or soldermask coating to protect the circuitry
Core Advantages and Application Scenarios
Advantages over conventional FR-4 PCB
| parameters | Ceramic PCB | FR-4 PCB |
| heat conductivity | 9-280 W/m-K | 0.8-1.1 W/m·K |
| Maximum working temperature | ＞300°C | 130-150°C |
| dielectric loss | 0.0005-0.002 | 0.02-0.03 |
| mechanical strength | High (bending and impact resistance) | moderate |
| (manufacturing, production etc) costs | High (complex materials and processes) | lower |
| Applicable Scenarios | High frequency, high power, extreme environments | General Electronics, Consumer Products |
Typical application areas
1. High power electronics: e.g. electric vehicle inverters, solar inverters, utilizing high thermal conductivity to manage the heat of IGBT modules.
2. LED Lighting: Ceramic substrates are used for high power LED chips to extend life and improve brightness. 3. 3. Aerospace: Radar systems, satellite communication equipment require high temperature and radiation resistance.
4. Medical equipment: High frequency coils for MRI equipment and X-ray generators rely on the stable dielectric properties of ceramic PCBs.
5. 5G communications: zirconia ceramic PCBs support millimeter-wave frequency bands with stable dielectric constants and low signal loss.
Limitations and Suggestions for Selection
1. High cost: Material and manufacturing complexity results in a price 5-10 times higher than FR-4. 2.
2. Brittleness: ceramic substrates are fragile, mechanical shock must be avoided, and stress distribution must be considered during design.
3. Difficulty in processing: laser drilling and high temperature sintering require specialized equipment and long lead time (about 3-6 weeks).
Suggestions for selection:
- Preferred scenarios for ceramic PCBs: high frequency (>10 GHz), power density >100 W/cm², operating temperature >200°C or long-term reliability (e.g., aerospace equipment).
- Alternative: If the budget is limited, you can use metal substrates (such as aluminum-based MCPCB), which has a thermal conductivity of 1-3 W/m-K and lower cost .
Future trends
1. Material innovation: Developing composite ceramics (e.g. AlN-SiC) to balance thermal conductivity and cost .
2. Multilayer: LTCC process to realize high-density interconnections with more than 10 layers to meet the demand of 5G and AI chips. 3.
3. Eco-friendly manufacturing: Reduce the use of toxic materials (e.g. BeO) and promote lead-free soldering process. As a key component of high-performance electronic systems, ceramic PCBs will continue to drive the progress of semiconductor, new energy and communication technologies.
