Ceramic PCB

Multilayer thick film ceramic PCB is an advanced type of printed circuit board that uses specialized ceramic materials and embedded thick film conductive wires. This is a method of forming conductive wires and electrodes by screen printing on a substrate, directly depositing a slurry, and sintering it at high temperatures. This method is suitable for most ceramic substrates. After sintering at high temperatures, it will form a strong adhesive film on the ceramic circuit board, which, after many repetitions, will generate a multi-layer interconnect structure containing a resistor or capacitor circuit.

Multilayer thick film ceramic PCBS are also known as hybrid thick film ceramic circuits, but there is an important difference between them is that hybrid thick film technology has a resistor on its surface, while multilayer thick film ceramics only have a conductor.

1. DPC Ceramic PCB: DPC ceramic PCB, also known as direct copper-plated ceramic PCB, is a printed circuit board made of ceramic material, where the copper layer is directly plated on the ceramic substrate. Based on thin film technology, the ceramic surface can be metallized by magnetron sputtering, the thickness of the electric copper layer is greater than 10 microns, and the thickness can be increased by electroplating. This technology has several advantages over traditional copper-covered PCBS.

2. DBC Ceramic PCB: Featuring a copper layer bonded directly to a ceramic substrate, it is known for its excellent thermal conductivity and is suitable for high power applications such as inverters and motor drives. Because DBC ceramic PCBS are made by sintering, the conductor thickness can exceed 100 microns (up to 300 microns). Unlike DPC ceramic PCBS, DBC technology cannot be designed through or through holes, as this would affect the insulation function.

3. The full name of AMB is Active Metal Brazing technology, which is a further development of DBC technology. The working principle is to use the active metal elements in brazing (such as Ti/Ag/Zr/Cu) to achieve the combination of ceramics and metals. In terms of performance, the bonding in the AMB ceramic substrate is achieved by chemical reaction of the ceramic and the active metal filler metal at temperature, and the Si3N4 ceramic used in AMB has higher thermal conductivity than the traditional Al2O3 ceramic substrate (>90W/mK 25 ° C), close to the thermal expansion coefficient of silicon (2.6 x10-6 /K). Therefore, AMB substrate has higher bonding strength and reliability.

4. HTCC ceramic circuit boards are manufactured at high temperatures (around 1300 ° C), so they can withstand extreme temperatures and have excellent thermal stability, and are commonly used in aerospace, telecommunications and high-reliability applications. Its use is limited due to its complex manufacturing process and expensive raw materials.
   

5. Unlike HTCC ceramic boards, LTCC PCBS are processed at lower temperatures (around 850 ° C to 1000 ° C), allowing for the integration of passive components and are widely used in RF and microwave modules, sensors and telecommunications. As with multilayer thick film ceramic PCBS, both HTCC and LTCC technologies can manufacture multilayer PCBS.

6. Multi-layer thick film ceramics and other types of ceramic PCB have a big difference, the biggest difference is that the thick film technology can print resistors on its surface, as the technology matures, we can make all the resistors have the same value, or on the same board for different resistors design different values. At the same time, using thick film technology, we can place resistors, capacitors, conductors, semiconductors and interchangeable conductors on ceramic plates, after the manufacturing step of printing and sintering at high temperatures. However, due to the limitations of conductive paste and screen size, the minimum line width of thick film ceramics is difficult to be less than 60 microns (0.6 mm), and it is impossible to manufacture three-dimensional graphics, so it is not suitable for the production of fine circuit boards. The conductor of the thick film ceramic circuit can be gold paste and silver paste (other paste needs to be evaluated), under normal circumstances, the sintering temperature is 850 ° C, but if the glass glaze is needed as the welding cover, then the sintering temperature should be around 600 ° C.