Torch MLCC Production Process
Nov 21, 2024
MLCC industrial chain can be divided into three parts: upstream materials, midstream manufacturing and downstream applications. The raw materials mainly include ceramic powder, electrode metal and so on. Ceramic powder is the most important raw material, which determines the performance of MLCC. The core requirements are purity, particle size and shape. The manufacturing technology and process of high purity, ultra-fine and high performance ceramic powder is the bottleneck restricting the development of MLCC industry in China. Due to the difficulty of preparation, most of the market share is occupied by Japanese and Korean suppliers, while the electrode metals such as silver and nickel are mainly supplied by domestic manufacturers.The manufacturing links in the middle reaches are mainly concentrated in Japan and South Korea, Taiwan and Mainland China. MLCC downstream applications are divided into civil and military fields. Consumer electronics and automobile are the biggest components of civil field. Military field includes aerospace, aviation, ships, weapons and other important national defense fields. Military products have more stringent requirements for reliability.
Wet printing and ceramic adhesive transfer technology become the development direction. At present, the mainstream MLCC production processes include dry tape casting process, wet printing process and ceramic adhesive film transfer process. With the increasing demand for products and the demand for high end multilayer ceramic capacitors, wet printing process and transfer process of ceramic adhesive have attracted much attention due to the advanced technology of manufacturing, and have gradually become the development trend of multilayer ceramic capacitor manufacturing technology. From the perspective of the complete manufacturing process of MLCC, the order is batching (sizing), tape casting (film stripping), electrode printing, stacking, pressure balancing, cutting, debonding, sintering, polishing, chamfering, silver staining, electroplating, testing, taping and packaging.
Pulp mixing, molding, printing, stacking and sintering are the core processes, and also the technical barriers of manufacturers.
1) Preparation technology of dielectric ceramic powder paste: MLCC requires dielectric ceramic powder to have no defect, good compactness, fine and uniform grain. The quality of adhesive, the amount of various components, the order and time of preparation, the choice of dispersant and the application of dispersion equipment directly affect the viscosity, dispersibility, plasticity and wettability of porcelain powder slurry. This technical link is the core know-how of each manufacturer, which is derived from the continuous debugging and accumulation of many years of production experience.
2) Thin medium film forming technology: the quality of ceramic medium is one of the main factors affecting the performance of MLCC. The main factors affecting the quality of ceramic film are: bubbles, pinholes, impurities, tape casting equipment and dispersion of ceramic powder slurry (preparation technology of dielectric ceramic powder slurry). Therefore, the film casting equipment with high precision and full automation is generally used, and then the film thickness is controlled by the film thickness monitor with high precision and full automation, which can produce the film with moderate strength and elasticity, compactness and uniformity .High quality ceramic film with good properties, dust-free and impurity free.
3) Screen overprint Technology: the formation of inner electrode is a crucial process of MLCC. The position, shape and flatness of inner electrode are related to the electrical performance of MLCC. At the same time, in order to realize the miniaturization and large volume of MLCC, the precision of its printing graphics is one level higher than that of the general thick film printing, so there are very high requirements for the speed of the printing press, the angle of the scraper, the type of the screen, the wire diameter, the thickness, the area and the opening rate of the screen.
4) Lamination technology: high level MLCC has a very high requirement for lamination technology. Low lamination pressure will lead to a decrease in the density of capacitor chip, which is easy to cause delamination of chip lamination. High tech lamination technology can eliminate the above defects, and control the thickness of dielectric film through lamination technology to improve the yield of MLCC.
5) Sintering technology: sintering has a crucial impact on the electrical performance of MLCC. In addition to the problem of metal oxidation, the difference of sintering shrinkage curve between electrode and medium should be considered during sintering, and the ideal sintering curve should be selected. If the sintering time is too short, the temperature is too low, and the atmosphere in the furnace is not enough, the grain growth is poor, the ceramic body is not dense enough, and the electrical properties are reduced. On the contrary, if the sintering time is too long, the temperature is too high, and the atmosphere is too thick, the grain will grow abnormally, and the additional crystal phase will be produced, which will make the electrical performance worse. Only when the sintering parameters are strictly controlled, can uniform and dense ceramic dielectric structure be formed.
Thin medium and high layer number are the development direction of technology. Increasing capacitance is the trend of MLCC. The capacitance of MLCC is proportional to the overlap area of inner electrode, the number of layers of dielectric ceramic materials and the relative dielectric constant of the dielectric ceramic materials used, and inversely with the thickness of single layer medium. Therefore, there are two ways to increase the capacitance in a certain volume. One is to reduce the thickness of the medium, the lower the thickness of the medium, the higher the capacity of MLCC; the second is to increase the number of layers inside the MLCC, the more the number of layers, the higher the capacity of MLCC.
LEER MÁS