▉ MLCC的分类:
根据所采用陶瓷介质材料的类型, MLCC可划分为两大类:
1类陶瓷介质MLCC
具有极高的稳定性, 其电容量几乎不随时间、 交流信号、 外加直流偏压的变化而改变, 同时具有极低介质损耗, 即高Q值。适用于对容量精度和应用频率要求较高的谐振电路。根据电容量的温度系数又可分为温度稳定型与温度补偿型两种。、
Class 2
These capacitors have a very high capacitance per volume and non-linear temperature characteristics. They are used for by-passing, coupling, filter and de-coupling. For instance, they can be substituted for the Ta, Al electrolytic capacitors in DC-DC(AC) converters and switching power suppliers.
Manufacture process of MLCC
Ceramic powders, which formulation and crystal phase fitted the demand of designing, are carefully mixed with solvent and binder, and then finely milled as slurry.
The very thin green sheets can be obtained by casting or spraying the slurry. After this, electrode is printed on the sheets which then be stacked, pressed and cut into chips. The green chip is co-fired at temperatures between 1000 and1400℃to become a monolithic block.
They can be used in such applications as oscillators and filters where low losses, low capacitance drift or temperature compensation and high stability are required.
2类陶瓷介质MLCC
具有很高的比体积电容量, 适合用于旁路、 耦合、 滤波以及对容量稳定性要求不高的鉴频电路。在DC-DC(AC)变换器和开关电源滤波电路正逐步取代钽电解电容器、 铝电解电容器。
MLCC can be divided into two classes:
Class 1
Dielectrics are used with very high Q and linear temperature coefficient in these capacitors. They can be distinguished into temperature compensating type and temperature stable type.
The final product can be formed by metalizing the termination of the compact ceramic chip.
█ MLCC的结构
MLCC的电容量与内电极交叠面积A、 介质层数n和陶瓷介质材料的相对介电常数εr呈正比, 与单层介质厚度T呈反比关系。
MLCC片式多层陶瓷电容器工艺术模板
简介 Brief Introduction
▉ MLCC简介:
片式多层陶瓷电容器( MLCC) 是适合于表面贴装技术( SMT) 的小尺寸、 高比容、 高精度陶瓷介质电容器, 可贴装于印刷线路板( PCB) 、 混合集成电路( HIC) 基片, 有效地缩小电子信息终端产品( 特别是便携式产品) 的体积和重量, 提高产品可靠性。顺应了IT产业小型化、 轻量化、 高性能、 多功能的发展方向。
C = εr×ε0×A×n / T
额定工作电压主要依赖于介质材料抗电强度、 介质厚度以及电容器的结构设计。
如图1所示。
Structure of MLCC
The capacitance of a MLCC depends on the area of the electrodes(A),the thickness of the ceramic dielectric(T)and the dielectric constant of the ceramic material(εr),and the number of dielectric layers(n)with multi-layer ceramic capacitors:
█ MLCC的制造工艺
将化学组成和微观晶相结构符合设计要求的陶瓷原粉和有机粘合剂进行充分混合成为陶瓷料浆, 经过流延或喷涂等方式制得所需厚度的生坯膜片。在膜片上印刷内电极后进行叠压、 切割成为单个电容器生坯后于1000℃—1400℃之间进行多层共烧, 在所得瓷坯两端进行端电极金属化处理后即制成MLCC成品。最后经电性能测试和检验合格, 即可包装入库, 并交付使用。
General Introduction
Multi-layer ceramic chip capacitor is a kind of ceramic dielectric capacitor with small size, high capacitance per volume, high accuracy, suited surface mounted technology (SMT). It is widely used in electronic circuitry, mounted printed circuit board, and hybrid IC. These different functions require specific capacitor properties.