What is DBC Ceramic PCB?

What is DBC ceramic PCB?

A DBC ceramic PCB, full name is Direct Bonded Cooper ceramic boards, as its name implies, it is a technology process that bond the copper conductor on the ceramic substrate directly under appropriate temperature. For numerous years, DBC ceramic substrates have consistently demonstrated their effectiveness in providing outstanding solutions for the electrical isolation and thermal management requirements of high-power semiconductor modules.

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.

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.

Benefits of DBC ceramic PCB

In fact, all the ceramic circuit boards feature a very good thermal conductivity and low CTE (coefficient thermal expansion) because the ceramic substrate itself has such properties. But ceramic board manufactured with different technology process has different advantages:

1. The thicker copper layer permits ceramic board has higher current loading for the same conductor width. Assuming the same copper cross-section the conductor needs to be only 12 % of that of a normal printed circuit board.

2. DCB ceramic PCB is gradually become the base materials of construction and interconnection technology of high-power semiconductor electronic circuits and also have been the basis for the "Chip-On-Board" (COB) technology which represent the packaging trend in the future.

3. Excellent electric insulation voltage means it can greatly improve the safety for the user.

4. Good thermal conductivity and heat-transfer provides the possibility of small packaging of the chips, result in increasing of power per unit of volume, improving reliability of systems and equipment.

5. The super-thin (0.25mm) DBC substrate can be an alternative material for beryllium oxide (BeO), it eliminates the unfriendly of environmental protection and toxicity; but seldom be used, as it is extreme expensive!

6. Superb thermal stability and power cycling capabilities (up to 50,000 cycles) makes it well-suited for applications that require in high temperature and high voltage environments, such as aerospace.

Where Can I Use the DBC ceramic PCB?

With the rapid development of the electronics and semi-conductors, there is no doubt that the era of big data is here. In the next couple years, DBC ceramic substrates will be sure to replace and serve as the fundamental materials for constructing and connecting electronic circuits, surpassing conventional printed circuit boards. These substrates will be utilized in electronic components with high power dissipation and stringent demands for thermal shock resistance and low failure rates, as showcased in the following examples:

A: Insulated Gate Bipolar Transistor (IGBT chips)

B: Power supply for telecommunication

C: Power semiconductor modules

D: High frequency switch mode power supplies (SMPS)

E: Solar cell component

F: Automotive system

G: Aerospace

DBC Ceramic PCB Manufacturing Capability from BSTCeramicPCB

BSTCeramicPCB has fabricated and supplied DBC ceramic board for many years, our full set of high-tech machines and a series of test equipment such for AOI, resistance measurement, two-dimensional testers support us to make high quality and defective-free products for our customers. Below are the manufacturing capabilities for DBC ceramic PCB:

Item	DCB/DBC Capabilities
Layer Count	2 Layers
Max Board Dimension	138*178mm
Min Board Thickness	0.30mm.0.40mm
Max Board Thickness	1L: 1.3mm; 2L 1.6mm
Conductor Thickness	3.90Z-8.60z
Min Line Width/Line Space	12/12mil (0.30/0.30mm)
Substrate Type	AI203,ALN, Zro2
Substrate Thickness	0.25, 0.38, 0.50, 0.635, 0.76,1.0mm
Min Hole Diameter	4mil (0.1mm)
Min Hole Spacing	NPTH: 16mil (0.30mm); PTH: 20mil (0.5mm)
Min PAD Ring(Single)	N/A
PTH Wall Thickness	N/A
Min Solder PAD Dia	8mil (0.20mm)
Min Soldermask Bridge	8mil(0.20mm)
Min BAG PAD Margin	8mil (0.20mm)
PTH/NPTH Dia Tolerance	PTH: ±4mil (0.1mm) ; NPTH: ±2mil (0.05mm)
Hole Position Deviation	± 4mil (0.1mm)
Outline Tolerance	Laser: +0.2/0.05mm
Line Width/Spac Tolerance	+5mil (0.125mm)
Surface Treatment	OSP/Ni Plating, ENIG
Thermal Stress	3 x 10 Sec @ 280C