Why are Ceramic Substrates Made by DPC Technology More Expensive than Those Made by DBC Technology

DPC(Direct Plating Copper) technology and DBC(Direct Bond Copper) technology are two commonly used ceramic substrate manufacturing technologies. While they are both method for manufacturing ceramic substrate, there are some important differences between them that make the DPC technology more expensive than the DBC technology.

1. Definition

DPC Technology: It refers to a technology of plating copper directly on the ceramic surface. It can be achieved by electroplating or hot plating.

DBC Technology: It refers to a technology that directly combines copper and ceramics. It is usually made by adding oxygen element between copper and ceramics, followed by chemical metallurgical bonding.

2. Advantages

DPC Technology:

1) The temperature of magnetron sputtering technology is below 300°C, completely avoiding the adverse effects of high temperatures on materials or circuit structures, and also reducing manufacturing technology costs.

2) Thin film and photolithography development technology are used to make the metal circuits on substrate more refined, so DPC substrates are very suitable for electronic component packaging that requires high alignment accuracy.

3) The surface roughness is less than 0.5um, which is more suitable for wiring, precision refrigeration chip packaging and other requirements.

DBC Technology:

1) Because copper foil has good electrical and thermal conductivity, and alumina can effectively control the expansion of the Cu-Al₂O₂-Cu composite, the DBC substrate has a thermal expansion system similar to that of alumina. Therefore, DBC has the advantages of good thermal conductivity, strong insulation, and high reliability.

2) Compared with the DPC technology, the DBC technology flow is simpler and the cost is lower.

3. Disadvantages

DPC Technology:

1) The thickness of the copper layer deposited by electroplating is limited. 

2) The bonding strength between the metal layer and the ceramic of the DPC technology is lower than that of the DBC technology, and the reliability of the product application is also lower.

3) The technology flow is complex and the cost is high.

DBC Technology:

1) During the preparation process, the DBC technology utilizes the eutectic reaction between Cu and Al₂O₂ at high temperature (1065°C), which requires high equipment and technology control, making the substrate cost relatively high.

2) Since micropores are easily generated between the Al₂O₂ and Cu layers, the thermal shock resistance of the product is reduced. These shortcomings have become a bottleneck in the promotion of DBC substrates.

3) Only single sided PCB can be produced, and through-hole connections cannot be made.

4. Different key technologies

DPC Technology:

1) The bonding strength between the circuit layer and the ceramic substrate is the key to the reliability of the DPC ceramic substrate. Due to the large difference in thermal expansion coefficient between metal and ceramic, in order to reduce interface stress, a transition layer needs to be added between the copper layer and ceramic, thereby improving the interface bonding strength. Since the bonding force between the transition layer and ceramics is mainly based on diffusion adhesion and chemical bonding, metals with higher activity and good diffusivity such as Ti, Cr and Ni are often selected as the transition layer and also as the electroplating seed layer.

2) Electroplating hole filling is also a key technology in the preparation of DPC ceramic substrates. At present, most DPC substrate electroplating holes are filled using pulse power supply. Its technical advantages include: ①It easily fills through holes and reduces plating defects within the holes; ②The surface coating structure is dense and the coating is uniform; ③Higher current density can be used for electroplating to improve deposition efficiency.

DBC Technology:

During the preparation process of DBC substrate, the eutectic temperature and oxygen content need to be strictly controlled. Oxidation time and oxidation temperature are the two most important parameters. After the copper foil is pre-oxidized, the bonding interface can form enough CuxOy phase to wet the Al₂O₂ ceramic and copper foil, and has a high bonding strength. If the copper foil has not been pre-oxidized, CuxOy will have poor wettability, a large number of voids and defects will remain at the bonding interface, and the bonding strength and thermal conductivity will also be reduced. For the preparation of DBC substrates using AIN ceramics, the ceramic substrate needs to be pre-oxidized to first form an Al₂O₂ film, and then react with the copper foil to produce a eutectic reaction.

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