DCB Ceramic PCB

What is DBC Ceramic PCB?

A ceramic substrate refers to a specialized board where copper foil is directly bonded to the surface of an alumina (Al₂O₃) or aluminum nitride (AlN) ceramic base (either single-sided or double-sided) through a high-temperature process. The resulting ultra-thin composite substrate offers excellent electrical insulation, a low coefficient of thermal expansion, high thermal conductivity, superior solderability, and strong adhesion. These substrates can be etched into various patterns, similar to PCBs, and exhibit a high current-carrying capacity.

As a result, ceramic substrates have become a foundational material for high-power electronic circuit structures and interconnect technologies. They are widely used in applications such as high-power LED lighting, automotive headlights, automotive LiDAR, semiconductor lasers, power electronic devices, microwave systems, optical communications, VCSELs, and RF devices. Common ceramic substrate materials include alumina, zirconia, silicon carbide, and silicon nitride.

The Structure of DBC Ceramic PCB

The DBC process yields a super-thin base and eliminates the need for the thick, heavy copper bases that were used prior to this process, so its structure also is very simple. A DBC ceramic circuit board is made of a layer of conductor (generally copper foil) and a ceramic substrate (they can be aluminum oxide (Al2O3), aluminum nitride (ALN) and zirconia (rarely to use)). The most common substrate thickness we use is 0.635mm.

ALUMINA PCB (96% & 99.6%)

Alumina Oxide (Al2O3) PCB (96% & 99.6%)

The most common material used for Ceramic PCBs is Alumina Oxide (96%). A naturally excellent electrical insulator with strong thermal properties. The thermal conductivity of Alumina is not as high as Aluminium Nitride, however it is still noticeably higher than the best performing Metal Clad PCB materials with a Thermal Conductivity in the region of 24W/mK. Another variant of this is Al2O3 (99.6%) which has a higher Thermal Conductivity, in the region of 29W/mK.

A high light reflectivity, along with good thermal properties makes Alumina Oxide well suited for LED applications. Whilst low values of thermal expansion and signal loss make it suitable for a range of applications including sensor modules, high-frequency systems and cooling systems.

Advantages

• High values of Thermal Conductivity (24-29W/mK)
• High substrate operating temperatures to over 800°C
• Low CTE
• Suitable for high frequency applications due to low signal loss
• High light reflectivity
• Possibility for Hermetic packages with 0% water absorption

ALUMINIUM NITRIDE PCB

Aluminium Nitride (AlN)

If a higher thermal conductivity is required then Aluminium Nitride (AlN) will be required. AlN has a superior thermal conductivity; depending on options, the conductivity achieved will be between 150-170W/mK.

This, along with a very low CTE and high operating temperatures makes AlN suitable for a variety of applications including; High power LEDs, testing, sensors, Integrated Components (ICs) and more.

Advantages

• Superior values of Thermal Conductivity (Up to 170W/mK)
• High substrate operating temperatures to over 800°C
• Very low CTE
• Suitable for high frequency applications due to low signal loss
• Possibility for Hermetic packages with 0% water absorption

Beryllium Oxide (BeO)

 BeO is a ceramic PCB substrate material renowned for its exceptional thermal conductivity, which is approximately 6–10 times higher than that of Al₂O₃ and even surpasses metallic aluminum. The standout characteristic of beryllium oxide ceramics is their superior thermal conductivity. BeO exhibits better chemical stability than AlN and provides high electrical insulation comparable to Al₂O₃. It is commonly used in PCB applications requiring high-temperature resistance or in high-density PCBs where space constraints demand efficient cooling, either through air or liquid.

 

Automotive DBC Ceramic PCB Stackup

DBC Ceramic PCB Stackup The DBC Ceramic PCB surface finishing is ENIG or ENIPIG. And the Copper from Min.5um up to 500um. DBC Ceramic PCB Ceramic material is Al2O3,Ain,BeO, and the ceramic pcb thickness is 0.25,0.381,0.5,0.635,1.0mm,1.5mm,2.0mm. Please see the bellow 1 Layer and 2 Layer DBC Ceramic PCB Stackup.   1 Layer DBC Ceramic PCB 2 Layers DBC Ceramic PCB.

1 Layer DBC Ceramic PCB

2 Layer DBC Ceramic PCB

The main process of DBC ceramic PCB manufacturing

1. Preparation of the ceramic substrate

Cut the substrate material into the required size and shape, and any surface imperfections are removed. The most used substrates are aluminum oxide (Al2O3) or aluminum nitride (ALN), which are known for their excellent thermal conductivity and electrical insulation properties.

2. Deposition of copper

The next step involves depositing a thin layer of copper (usually less than 10 µm) on the ceramic substrate using various techniques such as electroless plating, sputtering, or evaporation. The thin layer of copper serves as a bonding layer for the thick copper layer that will be applied in the next step.

3. Bonding of copper

Once the thin layer of copper is deposited, the substrate is subjected to a high-temperature sintering process (usually at temperatures above 1000°C, it depends on the substrate we use), which causes the copper to bond with the ceramic substrate, forming a thick copper layer. The thickness of the copper layer is typically 100 µm to 200 µm, thicker of 300um also is available.

4. Etching of copper

Now the copper has been bonded to the ceramic substrate, at this step, we should remove the excess copper by etching process, leaving only the desired copper traces/circuits and pads. The etching process can be done using various techniques such as chemical etching or plasma etching.

5. Surface finishing

The final step involves finishing the DBC ceramic PCB by applying a protective coating or solder mask (but DBC ceramic PCB is rarely apply solder mask) to the copper circuits and pads. The protective coating helps to prevent oxidation and corrosion, which can degrade the performance of the PCB over time.

Manufacturing process of ceramic PCB produced by QFPCB

HTCC (High-temperature Co-fired Ceramic)

HTCC (High-temperature Co-fired Ceramic) PCB is ceramics whose main components are alumina, mullite (the main body is Al2O3-SiO2) and aluminum nitride. It is met by printing a high melting point metal heat resistance paste, which includes tungsten, molybdenum, manganese, and other metals, onto a flow ceramic green billet with 92-96% alumina content. A sintering agent of 4-8% is added, and the billet is then laminated to create a multilayer structure.The common HTCC green ceramic tapes are alumina ceramics, aluminum nitride ceramics and zirconia ceramics, etc. The thickness of green ceramic tapes prepared by tape casting method generally ranges from 50 μm to 700 μm.

HTCC materials are sintered in an environment higher than 1500°C~1700°C，that is very suitable for applications in ultra-high temperature environments. Conductive and resistive materials are deposited onto the substrate using a specialized thick-film printing process, creating a solid and stable PCB that can perform reliably even under the most demanding conditions.

LTCC (Low-Temperature Co-fired Ceramic)

LTCC (Low Temperature Co-fired Ceramics) is a multilayer glass-ceramic substrate is also “glass-ceramic” because its composition consists of glass and alumina.  In this technology, inorganic aluminum oxide powder and about 30% ~ 50% glass material are added with an organic binder to make it evenly mixed into a mud-like slurry.  Then, the slurry is scraped into flakes by a scraper, and then the flake slurry is formed into thin pieces by a drying process.  Then, through-holes are drilled according to the design of each layer as the signal of each layer. The inner circuit of LTCC uses screen-printing technology to fill holes and paint lines on the green embryo respectively.  The inner and outer electrodes can use  Au, Ag, alloys (for example Pd/Ag, Pt/Ag), and other metals respectively.  Finally, each layer is stacked and placed in a sintering furnace at 900 ~ 1000 ℃ for sintering and molding.At this temperature, the ceramic substrate is easy to bond with the copper layer and forms a high-density circuit without interference in three-dimensional (3D) space. In some ways, it also can be made into a 3D subgrade board with passive components.

The LTCC ceramic technology can fabricate multilayer ceramic PCBs in three-dimensional design. It allows high-density circuits with a delicate trace space/width and reduces the product’s size. LTCC ceramic PCBs have good conductivity, low dielectric constant, and low dielectric loss, so they are suitable for RF, microwave, and millimeter wave devices. LTCC ceramic technology can be used to manufacture electronic components and integrate them with front-end modules.

DBC (Direct Bonded Copper)

Direct copper coating technology (DBC) ceramic circuit board is to use copper oxygen-containing eutectic liquid to directly bond copper to ceramics. The basic principle is to introduce an appropriate amount of oxygen between copper and ceramics before or during the bonding process. , in the range of 1065℃~ 1083℃, because the preparation method of DBC has requirements on the thickness of copper foil, generally not less than 150 ~ 300 microns, so the width-to-depth ratio of such ceramic circuit boards is limited. Copper and oxygen form a Cu-O eutectic liquid. DBC technology uses this eutectic liquid to chemically react with the ceramic substrate on the one hand to form CuAlO2 or CuAl2O4 phase, and on the other hand to infiltrate the copper foil to realize the combination of the ceramic substrate and the copper plate.

DPC （Direct Plated copper）

DPC Ceramic PCB, also known as Direct Plated Copper Ceramic PCB, is a type of printed circuit board made from ceramic materials with a copper layer directly plated onto the ceramic substrate. Based on the thin film technology, the metallization of the ceramic surface can be achieved by magnetron sputtering, and the thickness of the copper layer is greater than 10 microns by electroplating. This technology offers several advantages compared to traditional copper-clad laminate PCBs.

The preparation method of DPC includes vacuum coating, wet coating, exposure and development, etching and other process links. In addition, in terms of shape processing, DPC ceramic boards need to be cut by laser, which cannot be processed accurately by traditional drilling and milling machines and punching machines, so the bonding force and line width are also finer.

Key technology of DPC substrate

Bonding strength between metal circuit layer and ceramic substrate

Due to the large difference in thermal expansion coefficient between the metal and the ceramic, in order to reduce the interface stress, it is necessary to add a transition layer between the copper layer and the ceramic to improve the interface bonding strength. Since the bonding force between the transition layer and ceramics is mainly based on diffusion adhesion and chemical bonds, metals with high activity and good diffusivity such as Ti, Cr and Ni are often selected as the transition layer (and also as the electroplating seed layer).

Electroplating and Filling

Electroplating and hole filling is also a key technology for the preparation of DPC ceramic substrates. At present, pulse power supply is mostly used for electroplating and filling of DPC substrates. Its technical advantages include: easy to fill through holes, reduce coating defects in holes; surface coating structure is dense and uniform in thickness; high current density can be used for electroplating to improve deposition efficiency.

AMB Ceramic PCB

Active Metal Brazing (AMB) process is a further development of DBC technology. It uses a small amount of active elements such as Ti, Zr, Cr in the filler metal to react with the ceramic to form a reaction layer that can be wetted by the liquid filler metal, so as to bond the ceramic substrate with metal layer. AMB substrate is based on the chemical reaction of ceramic and active metal at high temperature to achieve the combination, so it has higher bonding strength and better reliability. The active metal layer also provides a metallization layer for the ceramic substrate, which can significantly reduce the processing time and cost of the PCB.

AMB Ceramic PCB Materials

According to different ceramic circuit board materials, the currently mature and applied AMB ceramic pcbs can be divided into: alumina(Al2O3), aluminum nitride(AIN) and silicon nitride (Si3N4) ceramic pcbs.

AMB Ceramic PCB Manufacturing Processing

According to different brazing materials, the AMB Ceramic PCB process is currently divided into two types: placing silver-copper-titanium solder sheets and printing silver-copper-titanium solder paste.

The process flow of Si3N4 AMB Ceramic PCB printing silver copper titanium solder paste is shown in the figure below. First, Ag, Cu, and Ti elements are directly mixed in the form of powder to make a slurry, and the Ag-Cu-Ti solder is printed on the silicon nitride ceramic substrate by screen printing technology, and then the copper foil is laminated on the silicon nitride ceramic substrate by hot pressing technology. On the solder, a silicon nitride AMB copper clad laminate that meets the requirements is finally prepared through sintering, photolithography, corrosion and Ni plating processes.

Thick Film Ceramic PCB

Thick Film Ceramic PCB also calls Thick Film Resistor Ceramic PCB is a technology to incorporate reliable carbon resistors printing on the Ceramic substrate using standard PCB processing. At present, Thick Film Ceramic PCB technology is quite mature that can be printed on a wide range of substrates — from high temperature ceramics to common FR4 PCB materials, or Polyimide (PI) Flex PCB Material. The printed resistor materials are based on a novel hydrophobic polyimide resin developed specifically to serve as a polymeric thick film resistors or thin film resistor material.

Thick Film Ceramic PCB technology is a new material that will improve the process of embedded resistors by eliminating the need for special termination treatment, such as immersion silver, silver palladium or gold palladium, and increase the reliability performance with a stable binder system. Thus far, the environmental and mechanical testing of Thick Film Ceramic PCB processing has also been successful. Continuing to test and formulate higher resistivity values will prove that the thick film resistor technology has a future in the embedded passives market.

Thin Film Ceramic PCB

Thin film deposition system that combines film deposition technology using sputtering and vacuum evaporation with photo-etching technology, and a thick-film process using screen printing methods, and is capable of metallising, patterning and forming wiring of various metal films on ceramics and glass materials.By enabling extreme connection densities and precise conductor geometries, thin-film ceramic circuit has become the go-to solution for high-performance applications where intricate designs are paramount.

Thin-film technology’s potential for higher track resolution is one of its key assets, enabling engineers to achieve significantly increased interconnection density. This translates to better connectivity and improved signal performance compared to thick-film or LTCC (Low-Temperature Co-fired Ceramic) alternatives. Thin film ceramic PCB always be chosen for specialized applications where cheaper alternatives fall short. With higher track resolution, it excels in telecommunications and diverse industries, including extreme thermal and biomedical applications. Future prospects involve nanotechnology integration, three-dimensional circuits, and eco-friendly aspects.

 Various processed products, including ceramic substrates, are used in a wide range of fields to meet customer needs, such as space and defence applications, information and communications applications and industrial equipment applications.

Standard design rules (thin-film processes)