(1) Direct marking method: Use the letters and numbers to directly mark the model and specifications on the shell. (2) Letter symbol method: Use a regular combination of numbers and letter symbols to represent capacity. The text symbol indicates the unit of its capacitance: P, N, u, m, F, etc. The method is the same as that of resistance. The nominal allowable deviation is also the same as that of resistance. For capacitors less than 10pF, the allowable deviation is replaced by letters: B-- ± 0.1pF, C-- ± 0.2pF, D-- ± 0.5pF, F-- ± 1pF. (3) Color scale method: It is the same as the resistance expression, and the unit is generally pF. The withstand voltage of small electrolytic capacitors is also color-coded, and is located near the root of the positive lead. The meaning is shown in the following table: Color Black Brown Red Orange Yellow Green Blue Purple Grey Withstand voltage 4V 6.3V 10V 16V 25V 32V 40V 50V 63V (4) Identification method of imported capacitors: Generally, imported capacitors are composed of 6 items. First item: Letters for categories: The second item: use two digits to indicate its shape, structure, packaging method, lead start and relationship with the shaft. The third item: the temperature characteristics of temperature-compensated capacitors, with letters and colors, the meaning is shown in the following table: No. Letter Color Temperature Coefficient Allowed Deviation Letter Color Temperature Coefficient Allowed Deviation 1 A gold +100 R yellow -220 2 B gray +30 S green -330 11 P Orange -150 YN -800 ~ -5800 Note: The unit of temperature coefficient is 10e -6 / ℃; the allowable deviation is%. The fourth term: use the numbers and letters to indicate the withstand voltage, the letters represent valid values, and the numbers represent the power of 10 of the multiplicand. The fifth item: Nominal capacity, expressed by three digits, the first two are valid values, and the third is a power of ten. When there is a decimal, it is represented by R or P. The unit of ordinary capacitor is pF, and the unit of electrolytic capacitor is uF. The sixth item: allowable deviation. Expressed by a letter, the meaning is the same as domestic capacitors. The color coding method is also used, the meaning is the same as that of domestic capacitors. For imports, take 477 A71N13 as an example, the next six digits respectively correspond to the above six items  

1. Bypass (decoupling) This is a low impedance path for some paralleled components in AC circuits. In electronic circuits, decoupling capacitors and bypass capacitors both play a role in anti-interference. Capacitors are in different positions and have different names. For the same circuit, the bypass capacitor takes the high-frequency noise in the input signal as the filtering object, and filters the high-frequency clutter carried by the previous stage. The decoupling capacitor is also called decoupling. Capacitors are designed to filter out interference from output signals. We can often see that a decoupling capacitor is connected between the power supply and ground. It has three functions: one is to serve as an energy storage capacitor for the integrated circuit; the other is to filter out high-frequency noise generated by the device and cut off The propagation path through the power supply circuit; the third is to prevent the noise carried by the power supply from interfering with the circuit. 2. Coupling The ceramic capacitor used in the coupling circuit is called a coupling capacitor. It is used extensively in RC-Coupled Amplifiers and other capacitive coupling circuits. It acts as a DC-to-AC barrier. It acts as a connection between two circuits and allows AC. The signal passes and is transmitted to the next stage circuit. 3. Filtering The ceramic capacitor used in the filter circuit is called a filter capacitor. The filter capacitor removes the signal in a certain frequency band from the total signal. Therefore, in the power circuit, the rectifier circuit changes the AC to a pulsating DC, and After that, a large-capacity ceramic capacitor is connected, and its charging and discharging characteristics are used to make the rectified pulsating DC voltage into a relatively stable DC voltage. 4. Resonance The safety capacitors used in LC resonant circuits are called resonance capacitors. This type of capacitor circuit is required in both LC parallel and series resonance circuits. 5. Temperature compensation Compensate for the effects of the insufficient temperature adaptability of other components to improve the stability of the circuit. 6. Tuning Is a system tuning for frequency-related circuits, such as mobile phones, radios, and televisions. 7. Energy storage Energy storage is the storage of electrical energy for release when necessary. Such as camera flash, heating equipment and so on. (The energy storage level of many capacitors can now approach the level of lithium batteries, and the energy stored in a capacitor can be used by a mobile phone for a day).    

In the usual circuit design and practical application of high-voltage ceramic chip capacitors, the biggest advantage is that this high-voltage capacitor has a very high current climb rate, which is especially suitable for high-current loop non-inductive structures. This advantage makes it particularly suitable for the selection and use of high-voltage substations. At the same time, the high-voltage capacitor of this material also has high stability, and its own capacity loss changes with temperature and frequency, and its own special series structure also makes it very suitable for long-term stable in high-voltage environment  jobs.

The rated voltage range of chip tantalum capacitor is 4 ~ 50V, the capacitance range is 0.047 ~ 330 uf, and the working temperature range is -80°C～ + 155 ℃. Packaging is divided into three types: non packaging type, molding packaging type and resin packaging type. It has the characteristics of good high frequency characteristics, large capacity, small volume, low impedance and small leakage current, widely used in computers, mobile phones, pagers, program-controlled exchanges, fax machines and military equipment.   International market development Due to the wide range of tantalum electrolytic capacitor capacity and the high maturity of chip technology and product structure, the total production and chip rate are increasing year by year. According to relevant reports, the output of tantalum electrolytic capacitors in the world increased from 11 billion in 1995 (market demand of US $2.165 billion) to 18 billion in 1998, 21 billion in 1999, 24 billion in 2000, 27 billion in 2001 and 31 billion in 2002. The average annual growth rate of tantalum electrolytic capacitors was 16.9% from 1995 to 2000 and 13.6% from 2000 to 2002.   The market demand of traditional lead tantalum electrolytic capacitor is decreasing year by year, while that of chip tantalum electrolytic capacitor is increasing year by year. The global output of chip tantalum electrolytic capacitors has increased from 7.9 billion in 1995 with chip rate of 71% to 19 billion in 2000 with chip rate of 80%. At present, the chip rate has exceeded 90%. Its development direction is as follows:   (1) High reliability with the chip tantalum electrolytic capacitor is widely used, in order to ensure the normal operation of electronic equipment, and suitable for all kinds of harsh environment, its reliability is put forward higher and higher requirements. Led by the United States, in order to meet the needs of military equipment and constantly improve its reliability, such as satellites, space shuttles, etc. have reached the level of eight or more reliabilities.   (2) With the continuous improvement of the specific capacitance of tantalum powder, the large capacity chip tantalum electrolytic capacitor is developing continuously: first, under the condition of the same size, volume and voltage resistance, the capacitance of chip tantalum electrolytic capacitor is increasing; The second is to develop chip tantalum electrolytic capacitors with high voltage and larger capacity to meet the needs of the development of electronic machines.   (3) Small volume is represented by Japan, small volume chip tantalum electrolytic capacitor is developing continuously, in addition to large-scale production and large-scale put on the market 0805, 0402 has been successfully developed in the laboratory.   (4) High frequency and low equivalent series resistance (ESR) at the end of 1980s, the United States first developed chip tantalum electrolytic capacitor with low ESR, which was widely used in military electronics. Such as T494 andT495 of KEMET, TPS of AVX, 595Dof Sprague, etc. It is reported that KEMET has developed an ESR of less than 20 m Ω Products.   At present, AVX, NEC, Hitachi, Matsushita and KEMET are the main manufacturers of tantalum electrolytic capacitors in the world, with an annual capacity of 2-7 billion. Among them, AVX company of the United States accounts for 25% of the market share of chip tantalum electrolytic capacitors in the world, and the quotation of AVX and KEMET is very low, which makes domestic enterprises unable to compete with them.   China market development The domestic market of chip tantalum electrolytic capacitors has two characteristics: one is that 90% of the market share is occupied by imported products; the other is that the average price of domestic products is about twice that of imported products. These means that domestic enterprises have encountered serious resistance in developing chip tantalum electrolytic capacitors, and the products have been defeated by the price war before entering the market.   In 2000, 3.324 billion tantalum electrolytic capacitors were imported, with a year-on-year growth of 306.4%, and foreign exchange consumption of 624.833 million US dollars, with a year-on-year growth of 273.7%; Domestic production is 1.265 billion, export is 1.069 billion, with a year-on-year growth of 58.4%, and foreign exchange earning is 526.63 million US dollars, with a year-on-year growth of 95.3%; The total demand of domestic market is 3.52 billion pieces and 77 million US dollars; The market share of domestic chip tantalum electrolytic capacitors is 5.6% and 16.2% respectively. The gap is due to the fact that the average domestic price of domestic chip tantalum electrolytic capacitors is three times that of imported products. The low market share makes us see the big gap.   In 2001, domestic production of chip tantalum electrolytic capacitors was 1.92 billion, with a year-on-year growth of 51.5%. Although it was the low tide year of world economic development, the export still increased by 52.4% year-on-year to 1.63 billion, but because the average export price decreased by 51.0%, the foreign exchange earning was only 422.32 million US dollars, with a year-on-year decline of 25.3%; Due to the great development of domestic mobile phone production, the import volume doubled to 7.576 billion over the same period of last year. As the average import price also dropped by 35.6%, the foreign exchange consumption was 925.2367 million US dollars, up only 46.9% over the same period of last year; The total demand of domestic market was 7.86 billion pieces and 108 million US dollars, with a year-on-year growth of 123.3% and 40.3% respectively; The total demand of domestic market was 7.86 billion pieces and 108 million US dollars, with a year-on-year growth of 123.3% and 40.3% respectively; The market share of domestic chip tantalum electrolytic capacitors is 3.7% and 11.9% respectively, and the market share continues to decrease.   In 2002, the average export price of domestic chip tantalum electrolytic capacitors increased by 43.1% instead of decreasing, so the export volume decreased by 25.5% to 1.214 billion, and the foreign exchange earned was 425135000 US dollars, up 6.7% year on year; The average import price rose more year-on-year, reaching 69.4%. However, due to the strong demand in the domestic market, the import volume still increased by 20.2% year-on-year, reaching 9.108 billion, and the amount of foreign exchange increased by 103.7% year-on-year to 194 million US dollars; It is estimated that the annual output of chip tantalum electrolytic capacitors in China will be 1.52 billion, with a year-on-year decrease of 20.8%; The total demand of the domestic market was 9.4 billion pieces and 213 million US dollars, with a year-on-year growth of 19.7% and 97.2% respectively; The market share of domestic chip tantalum electrolytic capacitors is 3.2% and 9.1% respectively, which is still declining.   The mainland of China has become one of the largest consumers and main producers of chip tantalum electrolytic capacitors in the world. However, due to the low level of domestic production technology, especially the high production cost and average export price of domestic enterprises, not only the export is reduced, but also the products are difficult to enter the domestic mobile phone production market. The domestic market share is getting lower and lower, and the domestic market demand is met by a large number of imports. The development of chip tantalum electrolytic capacitors in China is facing serious challenges, and domestic enterprises have a long way to go.   In the face of the reality of the rapid development of chip tantalum electrolytic capacitor domestic market, it is only a drop in the bucket, and it is beyond expectation. I don't know when the situation of organic meeting but not challenging will come to an end.    

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.

With the increasing global concern for environmental issues, new energy vehicles have become an important direction in the automotive industry. In the power supply system of new energy vehicles, the application of high-temperature capacitors is gradually attracting attention and recognition. This article explores the application and technological characteristics of high-temperature capacitors in the power supply systems of new energy vehicles. Overview of Power Supply Systems for New Energy Vehicles The power supply system of new energy vehicles is one of its key components, and its performance directly affects the vehicle's dynamics, range, and safety. Traditional internal combustion engine vehicles rely on fossil fuel engines for power generation, while new energy vehicles use electric motors as their power source, typically including components such as battery packs, motor controllers, and charging systems. The Role of High-Temperature Capacitors In the power supply system of new energy vehicles, capacitors are important electronic components mainly used for energy storage and voltage filtering. However, in high-temperature environments, traditional capacitors often experience performance degradation and shortened lifespans, thereby affecting the stability and reliability of the entire system. Therefore, the adoption of high-temperature capacitors has become an effective way to enhance the performance of power supply systems for new energy vehicles. Technological Characteristics of High-Temperature Capacitors   High-Temperature Resistance: High-temperature capacitors are designed with special materials and structures that can maintain good performance in high-temperature environments, minimizing issues such as leakage and breakdown.   Long Lifespan: High-temperature capacitors have a longer lifespan, maintaining stable electrical characteristics under high-temperature conditions, thus reducing replacement and maintenance costs.   Low Losses: High-temperature capacitors exhibit low losses, effectively improving energy utilization and reducing energy losses during the energy conversion process.   Efficient Energy Storage: High-temperature capacitors have high energy density and power density, allowing for rapid charge and discharge, meeting the requirements for quick acceleration and high-power output in electric vehicles.   Application of High-Temperature Capacitors in Power Supply Systems for New Energy Vehicles Battery Management System: High-temperature capacitors can be used for DC bus voltage smoothing and short-term peak power compensation in battery management systems, improving system stability and dynamic performance.   Motor Controllers: High-temperature capacitors can be employed for DC bus voltage filtering and power factor correction in motor controllers, enhancing motor drive efficiency and response speed.   Fast Charging Systems: High-temperature capacitors can be utilized for DC bus voltage smoothing and short-term peak power support in fast charging systems, reducing charging time and improving charging efficiency.   In-Vehicle Electronic Devices: High-temperature capacitors can also be used for power filtering and regulation in in-vehicle electronic devices, ensuring the normal operation of various electronic devices inside the vehicle.   Conclusion   With the rapid development of new energy vehicles, high-temperature capacitors, as important electronic components, have broad prospects in the power supply systems of new energy vehicles. In the future, with the continuous progress and improvement of high-temperature capacitor technology, it is believed that they will play an increasingly important role in the field of new energy vehicles, providing strong support for the popularization and development of new energy vehicles.  

  For supercapacitors, there are different classification methods based on different contents. First, according to different energy storage mechanisms, supercapacitors can be divided into two categories: electric double layer capacitors and Faraday quasi capacitors. Among them, electric double-layer capacitors generate storage energy mainly through the adsorption of pure electrostatic charges on the electrode surface. Faraday quasi-capacitors mainly generate Faraday quasi-capacitance through reversible redox reactions on and near the surface of Faraday quasi-capacitive active electrode materials (such as transition metal oxides and polymer polymers), thereby achieving energy storage and conversion. Secondly, according to the type of electrolyte, it can be divided into two categories: aqueous supercapacitors and organic supercapacitors. In addition, according to whether the types of active materials are the same, they can be divided into symmetric supercapacitors and asymmetric supercapacitors. Finally, according to the state of the electrolyte, supercapacitors can be divided into two categories: solid electrolyte supercapacitors and liquid electrolyte supercapacitors.

  1) Lifetime: If the internal resistance of the supercapacitor increases, the capacity will decrease if it is within the specified parameter range, and its effective use time can be extended, which is generally related to its characteristics as specified in Article 4. What affects the life is the active drying up, the internal resistance increases, and the ability to store electrical energy drops to 63.2% is called the end of life. 2) Voltage: Super capacitors have a recommended voltage and an optimal working voltage. If the used voltage is higher than the recommended voltage, the life of the capacitor will be shortened, but the capacitor can work continuously for a long time in an over-voltage state. The activated carbon inside the capacitor will decompose to form a gas It is beneficial to store electrical energy, but it cannot exceed 1.3 times the recommended voltage, otherwise the super capacitor will be damaged due to the excessive voltage. 3) Temperature: The normal operating temperature of the super capacitor is -40 ~ 70 ℃. Temperature and voltage are important factors affecting the life of supercapacitors. Every 5 ° C increase in temperature will reduce the life of the capacitor by 10%. At low temperatures, increasing the working voltage of the capacitor will not increase the internal resistance of the capacitor, which can improve the efficiency of the capacitor.   4) Discharge: In the pulse charging technology, the internal resistance of the capacitor is an important factor; in the small current discharge, the capacity is an important factor. 5) Charging: There are many ways to charge capacitors, such as constant current charging, constant voltage charging, and pulse charging. During the charging process, connecting a resistor in series with the capacitor circuit will reduce the charging current and increase the battery life.

  1) Super capacitors have a fixed polarity. Before use, confirm the polarity. 2) Super capacitors should be used at nominal voltage. When the capacitor voltage exceeds the nominal voltage, it will cause the electrolyte to decompose, at the same time the capacitor will heat up, the capacity will decrease, and the internal resistance will increase, and the life will be shortened. 3) Super capacitors should not be used in high-frequency charging and discharging circuits. High-frequency fast charging and discharging will cause the capacitor to heat up, the capacity will decrease, and the internal resistance will increase. 4) The ambient temperature has an important effect on the life of the supercapacitor. Therefore, super capacitors should be kept as far away from heat sources as possible. 5) When a supercapacitor is used as a backup power supply, because the supercapacitor has a large internal resistance, there is a voltage drop at the moment of discharge. 6) Super capacitors should not be placed in an environment with relative humidity greater than 85% or containing toxic gases. Under these circumstances, the leads and the capacitor case will be corroded, causing disconnection. 7) Super capacitors should not be placed in high temperature and high humidity environments. They should be stored in an environment with a temperature of -30 to 50 ° C and a relative humidity of less than 60% as much as possible. Avoid sudden temperature rises and falls, as this will cause product damage .   8) When a super capacitor is used on a double-sided circuit board, it should be noted that the connection cannot pass through the capacitor's reach. Due to the way the super capacitor is installed, it will cause a short circuit. 9) When the capacitor is soldered on the circuit board, the capacitor case must not be contacted with the circuit board, otherwise the solder will penetrate into the capacitor through hole and affect the performance of the capacitor. 10) After installing a super capacitor, do not forcibly tilt or twist the capacitor. This will cause the capacitor leads to loosen and cause performance degradation. 11) Avoid overheating capacitors during soldering. If the capacitor is overheated during welding, it will reduce the service life of the capacitor. 12) After the capacitor is soldered, the circuit board and the capacitor need to be cleaned, because some impurities may cause the capacitor to short circuit. 13) When supercapacitors are used in series, there is a problem of voltage balance between the cells. A simple series connection will cause one or more individual capacitors to overvoltage, which will damage these capacitors and affect the overall performance. Therefore, when the capacitors are used in series, , Need technical support from the manufacturer. 14) When other application problems occur during the use of supercapacitors, you should consult the manufacturer or refer to the relevant technical data of the supercapacitor's instructions.

  1. Ceramic chip capacitor failure caused by external force (1) Because the ceramic chip capacitor is brittle and has no pin, it is greatly affected by the force. Once it is affected by the external force, the internal electrode is easy to break, resulting in the failure of the ceramic chip capacitor. As shown in Figures below, the capacitor end of ceramic patch is broken or damaged due to any external force. For example, in the process of mechanical assembly, the printed circuit board assembly is installed in the box, and the electric driver is used for assembly. At this time, the mechanical stress of the electric driver is easy to disconnect the capacitor.          (2) Due to the quality problem of poor bonding force of ceramic chip capacitor end (body and electrode), the metal electrode is easy to fall off through the process of welding, warm punching, debugging and other external forces, that is, the body and electrode are separated, as shown in Figure as below.    2. Failure caused by improper welding operation   (1) It is very common that the thermal shock of ceramic chip capacitor caused by improper manual welding or rework of electric iron. When welding, there will be thermal shock. If the operator contacts the tip of the soldering iron directly with the electrode of the capacitor, the thermal shock will cause the micro crack of the ceramic chip capacitor body, and the ceramic chip capacitor will fail after a period of time. In principle, the SMT should be welded by hand. Multiple welding, including rework, will also affect the solderability of the chip and the resistance to welding heat, and the effect is cumulative, so it is not suitable for the capacitor to be exposed to high temperature for many times   (2) The tin on both ends of the capacitor is asymmetric during welding.When welding, the tin on both ends of the capacitor is asymmetric, as shown in below figure. The tin on both ends of the capacitor is asymmetric. When the capacitor is subjected to external force or stress screening test, the ceramic patch will be seriously affected due to excessive soldering. The capacitor's ability to resist mechanical stress will lead to cracking of the body and electrode and failure.       (3) Too much solder The factors related to the degree of mechanical stress of multilayer ceramic chip capacitor on PCB include the material and thickness of PCB, the amount of solder and the position of solder. Especially, too much solder will seriously affect the ability of chip capacitor to resist mechanical stress, resulting in capacitor failure.   3. Capacitor failure caused by unreasonable pad design (1) The design of the pad is unreasonable, as shown in below Figure, when there is a hole in the pad. Solder will lose (there is such design phenomenon in the product), which causes welding defects due to the asymmetry of solder at both ends of capacitor. At this time, stress screening or external force will be conducted. The stress released at both ends of ceramic chip capacitor will easily cause cracking and failure.     (2) Another pad design is shown in below Figure. When using on-line welding, the size of pads at both ends of the capacitor is different or asymmetric (this design phenomenon exists in the product), the amount of solder paste printed is quite different. The small pad has a fast response to temperature, and the solder paste on it melts first. Under the action of solder paste tension, the component is straightened up, resulting in "upright" phenomenon or solder asymmetry, causing capacitor failure. One end of several ceramic chip capacitors share a large pad. If one capacitor at the common end needs to be repaired or one of the capacitors fails and needs to be replaced, one end of the other components will also experience a thermal shock, and the capacitor is prone to failure.       4. Failure caused by high and low temperature impact test During the test, the thermal expansion coefficient (CTE) of PCB, MLCC end electrode and ceramic dielectric is small, and the chip capacitor is subjected to certain thermal stress due to the rapid change of cold and hot. The body (ceramic) and electrode (metal) of SMC produce stress cracks, which lead to the failure of SMC.   5. Failure caused by mechanical stress Improper operation of the printing plate in the assembly process will cause mechanical stress, which will lead to capacitor rupture, and the pad is designed near the screw hole, which is easy to cause mechanical damage during assembly. This kind of damage makes the crack expand further in the temperature shock test, which leads to the capacitor failure. It can be seen from the structure that MLCC can withstand large compressive stress, but its bending resistance is poor. Any operation that may produce bending deformation during capacitor assembly will lead to component cracking.

  1. Avoid external force (1) During the assembly process, PCB must be avoided to meet too strong or too fast bending. (2) Ceramic chip capacitors are designed to avoid high mechanical stress when the circuit board is bent, as shown in below Figure. (3) The two solder joints of ceramic chip capacitor should be designed and mechanically bonded. The direction of stress is balanced and not at right angles, as shown in below Figure. (4) At the connector connection between the cable and PCBA, if the circuit board is not supported when the connector is pulled out or inserted, the circuit board will warp and damage the nearby components. When the area of circuit board is large (i.e. greater than 15 cm × 15 cm), special care should be taken to prevent damage to components.   2. Selection of materials In order to improve the thermal matching between the chip capacitor and the substrate material, it is necessary to select the appropriate substrate material and the capacitor with higher level and better resistance to thermal stress and mechanical stress to meet the requirements of product use.   3. Welding requirements When welding, the operator should strictly implement the process discipline and carry out welding according to the process documents and typical process requirements.   4. Design requirements The pad spacing should be reasonable. The design in below Figure(a) is easy to be damaged due to stress after the chip capacitor is welded. below Figure (b) design helps to improve resistance to mechanical stress.   (2) When designing PCB, designers should design pad according to enterprise standard to avoid unreasonable design.   5. Repair requirements When it is necessary to repair the capacitor, considering the effect of welding heat accumulation, the capacitor after welding should be discarded and new capacitor should be used.   6. Conclusion Correct operation method, reasonable material selection and correct pad design can play a very good role in reducing the failure of capacitor, improving product quality and reliability, and avoiding unnecessary rework.  

            i.   Storage Precautions Moisture sensitivity level(MSL)：MSL3 Storage Conditions: Temperature:-5~40°C， Humidity: ≤60%RH Free of corrosive gases. After removing the vacuum package, the capacitor should not be exposed to the air for more than 24 hours. Unused capacitors should be vacuum sealed again or stored in a dry cabinet.           ii.   Precautions before Soldering Tantalum capacitors can be attached by wave soldering, reflow soldering and hand soldering. Case A, B, C, D, D1, and E are recommended to use reflow soldering (if hand soldering is required, please see 2. Precautions for Hand Soldering Operations), and Case F and above are only suitable for hand soldering (large case tantalum capacitor is reflowing soldered, due to the expansion of the core, it is very easy to have cracks in case.). 1. Baking Treatment For CA55 capacitor that has been unpacked and exposed to the air for more than 24 hours, the user must remove tape before use and perform secondary baking at a humidity ≤ 60% RH to ensure that there is no excessive moisture absorbed inside the capacitor before soldering . The recommended baking temperature and time are: a. For CA55 capacitor that has been unpacked and exposed to the air for more than 24 hours, it is recommended to bake at 125°C for 12 hours before soldering. b. For CA55 capacitor that has been unpacked and exposed to the air for more than a week, Case A, B, C, D1, D, and E need to be baked at 125°C for 24 hours; Case F and above are only suitable for hand soldering, and no need to bake before soldering. 2. Hand Soldering capacitors that are hand soldered do not require baking before soldering, but the temperature of the soldering iron tip should be strictly controlled. It is recommended to use a soldering temperature of 280-350 ℃ (30W power soldering iron, anti-static ceramic electric soldering iron is recommended). At the same time, it should be noted that: a. It is prohibited to directly use a soldering iron tip to heat the element substrate. Because excessive temperature shock can cause damage to the internal microstructure of the component, leading to performance issues. b. The solder pad must be pre-printed with solder paste, and the thickness of the solder paste should be controlled between 0.15mm and 0.20mm. c. It is necessary to use a circuit board heater to preheat the bonded components at least 125 ℃~150 ℃/5 minutes, ensuring that the temperature of the component substrate is as close as possible to the melting point of the solder paste. d. The position of the soldering iron tip for soldering heating is the solder pad, not the component substrate. 3. Reflow soldering The reflow soldering curve is suitable for Case A, B, C, D, D1, E: Lead-free capacitors: the maximum soldering temperature is 250±5°C Leaded capacitors: the maximum soldering temperature is 235±5℃