2025-07-14
Ceramic substrate, also known as ceramic circuit board, consists of two parts: ceramic substrate and wiring metal layer. Metal wiring is prepared by sputtering, evaporation deposition or printing various metal materials on the ceramic substrate to prepare thin film and thick film circuits. In electronic ceramic packaging, in addition to providing structural support and electrical interconnection for circuits and chips, ceramic substrates must also provide good heat treatment to ensure normal operation.
Ceramic substrates mainly include planar ceramic substrates and multilayer ceramic substrates.
Ceramic substrates are divided into DPC, DBC, AMB, LTCC, HTCC and other substrates according to the process. At present, the commonly used ceramic substrate materials are mainly Al2O3, AlN and Si3N4.
In order to strengthen the communication and linkage between the upstream and downstream of the ceramic substrate and packaging industry, we participated in the "Fifth Ceramic Substrate and Packaging Industry Forum" held in Jiangsu on June 12, 2025. The theme of this seminar will focus on the latest research progress, future development trends and application prospects of high-performance ceramic substrates such as alumina, zirconia-toughened alumina, aluminum nitride, silicon nitride and packaging. We invited many friends from upstream and downstream of the industry chain to communicate together to contribute to the development of the industry.
1. Planar ceramic substrates
According to different processes, they are mainly divided into: thin film ceramic substrates, thick film printed ceramic substrates, ceramic copper clad substrates (direct bonded copper (DBC) ceramic substrates, active metal welding ceramic substrates (AMB), direct electroplated copper ceramic substrates (DPC) and laser activated metal ceramic substrates (LAM), etc.
(1) Thin film ceramic substrates
A metal layer is formed on the surface of the ceramic substrate by using processes such as magnetron sputtering, vacuum evaporation and electrochemical deposition, and then a specific metal pattern is formed by processes such as masking and etching. This process has the advantages of low operating temperature, high wiring accuracy, controllable metal layer thickness and high bonding strength between metal and ceramic. Commonly used ceramic substrate materials for thin film processes are mainly Al2O3, AlN and BeO. Thin film ceramic substrates are mainly used in device packaging with small current, small size, high heat dissipation requirements and high wiring accuracy requirements.
(2) Thick film ceramic substrates
The metal wiring layer is printed by screen printing, which is widely used in Preparation of co-fired ceramic substrates. Due to the limited precision of the screen printing process, the accuracy of the printed circuit graphics is limited. In addition, in order to reduce the sintering temperature and improve the bonding strength between the metal layer and the ceramic substrate, a small amount of glass phase is usually added to the metal paste, which will inevitably reduce the electrical conductivity and thermal conductivity of the metal wiring layer. Therefore, thick film printed ceramic substrates are only used in electronic device packaging that does not require high circuit accuracy.
(3) Ceramic copper clad substrates
Ceramic copper clad substrates are a composite metal ceramic substrate that combines the advantages of ceramic and metal copper by bonding copper plates and ceramic substrates through different processes on a ceramic substrate, thereby obtaining a composite metal ceramic substrate that has the advantages of both ceramic and metal copper, and has excellent thermal and electrical properties and easy assembly. Ceramic copper clad boards can be etched to form various wiring circuits and are widely used in power module packaging. The main ceramic copper clad substrate processes include DBC method, active metal welding (AMB) method, direct copper plating (DPC) method and laser activated metal (LAM) method.
① DBC ceramic substrate
DBC is heated in oxygen-containing nitrogen at a high temperature of more than 1000℃, so that the copper foil and the ceramic substrate are firmly bonded together by eutectic bonding. It has high bonding strength and good thermal conductivity and thermal stability.
② AMB ceramic substrate
AMB is a further development of the DBC process. This process uses solder containing a small amount of rare earth elements to achieve the connection between the ceramic substrate and the copper foil. It has high bonding strength and good reliability. Compared with the DBC process, this process has a low bonding temperature and is easy to operate.
③ DPC ceramic substrate
The laser is used to drill holes on the ceramic substrate, and the Cu seed layer is deposited on the ceramic substrate using a semiconductor process. Then the holes are filled by electroplating to thicken the metal layer. This process has the characteristics of high circuit accuracy and low preparation temperature. In addition, this process can also realize vertical interconnection of ceramic substrates to increase packaging density.
④ LAM ceramic substrate
The surface of the ceramic substrate that needs to be metallized is activated by laser beam heating, and then metallized wiring is formed by electroplating or chemical plating. This process can also be applied to three-dimensional ceramics. Laser activated ceramic technology is used, so it has higher wiring accuracy, and the metal layer and ceramic substrate have high bonding strength, and the circuit layer surface is flat. Currently, it is mainly used in the aerospace field.
2. Multilayer ceramic substrate
Electronic devices and circuits are developing towards high interconnection density and diversified application environments. Conventional planar ceramic substrates are beginning to face application limitations. In order to meet these requirements, electronic ceramic substrate technology is beginning to develop towards high interconnection density. High-density interconnection ceramic substrate technologies mainly include: thick film multilayer (TFM) technology, high-temperature co-fired ceramic (HTCC) technology and low-temperature co-fired ceramic (LTCC) technology.
① TFM
Ceramic substrate technology that realizes multi-layer interconnection through multiple thick film printing and sintering processes (or thin film sputtering and etching processes) on the surface of a single ceramic substrate. This process forms a cavity by printing ceramic slurry and metal slurry multiple times. However, due to the limited thickness of the ceramic slurry, the number of printing layers and the printing alignment accuracy each time, the thickness of the ceramic substrate cavity is inevitably limited. This process is suitable for electronic device packaging with small volume, low interconnection density and low precision requirements.
② HTCC
HTCC technology and LTCC technology are both multi-layer co-fired ceramic technologies. By punching holes, filling metal slurry and printing on each layer of raw ceramic sheets, and finally stacking them together to form a substrate with multi-layer conductor interconnection. The sintering temperature of HTCC ceramic substrate is 1400-1500℃, which has the advantages of high mechanical strength, high thermal conductivity, stable chemical properties and high wiring density. At present, the products with the highest market share in the HTCC field are mainly from companies such as Kyocera and NTK of Japan. The domestic companies mainly include China Ceramics Electronics, China Electronics Technology Group Corporation 55th Institute, China Electronics Technology Group Corporation 43rd Institute, Jiali Electronics, and China Aerospace Science and Technology Corporation.
③ LTCC
There are three types of LTCC ceramic substrate systems: microcrystalline glass system, glass-ceramic composite system and amorphous glass system. Due to the high electrical conductivity and excellent electrical properties of metal materials, passive components such as resistors, capacitors and inductors can be integrated into the three-dimensional ceramic substrate structure.
Currently, LTCC technology is widely used in high-density packaging, microwave/millimeter wave transceiver components, micro-electromechanical systems (MEMS), multi-chip module (MCM) and system-level packaging system integration (SIP). Major foreign companies include Murata, Kyocera, TDK, etc.; domestic companies include Jiali Electronics, 214 Institute, Chengdu Hongke, Fenghua High-Tech, Yanchuang Optoelectronics, etc.