For electronic packaging, ceramic substrates play a key role in connecting the internal and external heat dissipation channels, as well as both electrical interconnection and mechanical support. Ceramic substrates have the advantages of high thermal conductivity, good heat resistance, high mechanical strength, and low coefficient of thermal expansion, and they are the common substrate materials for power semiconductor device packaging.
In terms of structure and manufacturing process, ceramic substrates are classified into 5 types.
High-Temperature Co-fired Multilayer Ceramic Substrates (HTCC)
Low-Temperature Co-fired Ceramic Substrates (LTCC)
Thick Film Ceramic Substrates (TFC)
Direct Bonded Copper Ceramic Substrates (DBC)
Direct Plated Copper Ceramic Substrates (DPC)
Different Production Processes
Direct Bonded Copper (DBC) ceramic substrate is produced by adding oxygen between copper and ceramic to obtain Cu-O eutectic solution between 1065~1083℃, followed by the reaction to obtain intermediate phase (CuAlO2 or CuAl2O4), thus realizing the chemical metallurgical combination of Cu plate and ceramic substrate, and then finally realizing the graphic preparation by lithography technology to form the circuit.
The thermal expansion coefficient of the DBC substrate is very close to that of LED epitaxial materials, which can significantly reduce the thermal stress generated between the chip and the substrate.
Direct Plated Copper (DPC) ceramic substrate is made by sputtering a copper layer on the ceramic substrate, then exposing, etched, de-filmed, and finally increasing the thickness of the copper line by electroplating or chemical plating, after removing the photoresist, the metalized line is completed.
Different Advantages and Disadvantages
Advantages of DBC Ceramic Substrate
Since copper foil has good electrical and thermal conductivity, DBC has the advantages of good thermal conductivity, good insulation, high reliability, and has been widely used in IGBT, LD, and CPV packages. Especially due to the thicker copper foil (100~600μm), it has obvious advantages in the field of IGBT and LD packaging.
Disadvantages of DBC Ceramic Substrate
The production process employs a eutectic reaction between Cu and Al2O3 at high temperatures, which requires a high level of production equipment and process control, thus making the cost high.
Due to the easy generation of microporosity between the Al2O3 and Cu layer, which reduces the thermal shock resistance of the product, these disadvantages become the bottleneck of DBC substrate promotion.
Advantages of DPC Ceramic Substrate
The low-temperature process (below 300°C) is used, which completely avoids the adverse effects of high temperature on the material or line structure, and also reduces the cost of the manufacturing process.
The use of thin film and photolithography technology, so that the substrate on the metal line finer, so the DPC substrate is ideal for the alignment of high precision requirements for the packaging of electronic devices.
Disadvantages of DPC Ceramic Substrate
Limited thickness of the electroplated deposited copper layer and high pollution of electroplating waste solution.
The bonding strength between the metal layer and the ceramic is low, and the reliability of the product is low when applied.
