Physics is a science that we must learn to go to school, in the world of physics, we can learn a lot of materials that we usually see but do not know, such as capacitors, capacitors are a substance commonly used in our lives, but many people do not quite understand him. Ceramic capacitors are the most widely used, but it is sometimes due to the influence of some factors and lead to failure. We want to use the normal use of ceramic capacitors, you can only first understand the factors that lead to its failure and its characteristics, the following small make up for your specific introduction.
Introduction of ceramic capacitors:
It is shaped in the form of a chip, but also tube, round and other shapes. Ceramic capacitor is a general term for capacitors with ceramic material as the dielectric. There are many varieties of ceramic capacitors, and their dimensions vary greatly. According to the use of voltage can be divided into high-voltage, medium-voltage and low-voltage ceramic capacitors. According to the temperature coefficient, dielectric constant can be divided into negative temperature coefficient, positive temperature coefficient, zero temperature coefficient, high dielectric constant, low dielectric constant. In addition, there are type I, type II, type III classification method. General ceramic capacitors and other capacitors, compared with the use of higher temperature, large specific capacity, good moisture resistance, dielectric loss is small, capacitance temperature coefficient can be selected within a wide range of advantages. Widely used in electronic circuits, the amount is very considerable.
Ceramic capacitor failure of the intrinsic factors are mainly the following:
1. Ceramic dielectric cavity
The main factors that lead to the emergence of voids for the ceramic powder within the organic or inorganic pollution, improper control of the sintering process. The generation of voids is very easy to lead to leakage, and leakage leads to localized heating inside the device, further reducing the insulation properties of the ceramic medium and thus leading to increased leakage. The process occurs cyclically, worsening, leading to serious consequences such as multilayer ceramic capacitor cracking, explosion, and even burning.
2. Sintering cracks
Sintering cracks often originate at one end of the electrode, along the vertical direction of expansion. The main reason is related to the cooling rate in the sintering process, cracks and hazards are similar to voids.
3. Delamination
Multilayer ceramic capacitor sintering for multilayer material stack **** burning. Sintering temperature can be as high as 1000 ℃ or more. Interlayer bonding is not strong, volatilization of internal pollutants in the sintering process, improper control of the sintering process may lead to the occurrence of delamination. Delamination and voids, cracks, similar to the harm, for the important multilayer ceramic capacitors inherent defects.
Ceramic capacitor failure of the external factors are:
1. Temperature shock crack
Mainly due to the device in the welding, especially wave soldering to withstand the temperature shock caused by the improper repair is also an important cause of temperature shock cracks.
2. Mechanical stress cracks
Multilayer ceramic capacitors are characterized by:
is able to withstand greater compressive stress, but resistance to bending ability is relatively poor. Any operation that may produce bending deformation during device assembly may result in device cracking. Common sources of stress are: patch alignment, process board operation; flow process of people, equipment, gravity and other factors; through-hole component insertion; circuit testing, veneer segmentation; circuit board mounting; circuit board positioning riveting; screws mounting and so on. This type of crack generally originates from the upper and lower metallization end of the device, along the 45 ℃ angle to the device internal expansion. This type of defect is also a type of defect that actually occurs the most.
After understanding the characteristics of ceramic capacitors, in order to better use, ceramic capacitors are usually very small, the cost is relatively low, so people live in a lot of places to use it. In addition, we should pay more attention to the failure of ceramic capacitors in several areas, if you do not pay attention to, it may lead to our family so will not be able to use electrical appliances, the most direct is the failure of ceramic capacitors. In our study of physics, we will learn the factors affecting the change of capacitance, we should learn to use, to learn to apply to life.
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