If the electronic component market is regarded as a big “Jianghu” with many sects, the small “Jianghu” in the capacitor field may be a relatively light class in the eyes of many people – capacitor products look similar, and upgrading iterations are not so frequent. But if you really think so, you are wrong!
The more seemingly “simple” things, the more they are in the pile of “homogeneous” products, the more they need to have characteristics different from others in order to stand out.
Especially when the capacitor is in a “dangerous” environment such as high temperature, high humidity and high vibration, it is particularly critical whether the capacitor product has the real Kung Fu of fearing challenges.
In this brand newLeading edge capacitance Series columnsIn, we will introduce some capacitor experts from Vishay one after another. Walk with them, and you will find:
River (ring) Lake (boundary) re insurance (harsh) evil (engraved)
Your development work can also be handy
Laugh proudly and freely
I don’t want to talk much about gossip. In this “frontier capacitor”, let’s start with a plate of hidden dragons and crouching tigers Vishay ceramic capacitor, look at the “experts” in it.
Ceramic capacitor, as the name suggests, is a capacitor with ceramic as the core component. This kind of product has the advantages of good heat resistance, excellent insulation, simple structure, low price and so on.According to different ceramic material formulations, ceramic capacitors can be divided into two categories:
Class 1 ceramic capacitor: this kind of ceramic capacitor has good temperature characteristics and small high-frequency loss. It is suitable for high-frequency resonance, filtering and temperature compensation circuits with high requirements for capacity and stability.
Class 2 ceramic capacitor: the dielectric constant of its ceramic material is large and the capacitance per unit volume is higher, but the accuracy and stability are worse than those of class 1 ceramic. It is suitable for low-frequency circuits with low requirements for capacity, loss and temperature characteristics, and plays the role of bypass, coupling and filtering.
Safety regulation Sanjie
An important use of ceramic capacitors is safety capacitors.The so-called safety regulation capacitor is the fixed capacitor used to suppress the electromagnetic interference of the power supply. This definition has two meanings: first, it should be able to eliminate the noise in the power line and filter the common mode and differential mode interference; The second is to meet the requirements of Safety specifications. Even after the capacitor fails, it will not cause electric shock, combustion and other hazards, and will not endanger personal safety. This special requirement gives birth to the special product category of safety regulated capacitor.
Safety capacitors are divided into two categories according to their use(see Figure 1):
Class X: This is a capacitor that spans between the live line and the zero line and is used to suppress differential mode interference. Polyester film capacitors with large ripple current resistance are mostly selected for this kind of capacitor, with small internal resistance, large instantaneous charge and discharge current, and the capacitance value is generally μ Class F.
Class Y: this kind of capacitance is used to suppress common mode interference between live line and ground and between zero line and ground. Its capacitance value is generally in the range of 2NF. However, such capacitors need to have high insulation characteristics and electrical strength. In order to withstand high voltage, it is often required to have sufficient safety margin in terms of electrical and mechanical properties. As can be seen from Figure 1, this is the main application field of ceramic capacitors, especially under electromagnetic interference filtering.
Figure 1: typical circuit and main types of safety capacitor
A qualified safety capacitor needs to meet the following requirements:
First, the rated voltage of the safety capacitor must meet the voltage requirements of the application.For example, different safety grades and insulation types of Class Y safety regulation capacitors correspond to different rated voltages, as shown in Table 1.
▲ rated voltage of Class Y safety capacitor
Secondly, the safety capacitor needs to have enough ability to withstand the impact of abnormal pulse voltage, so the peak pulse voltage is also a key performance parameterE.g. Y1 The peak pulse voltage of safety regulation capacitor needs to be more than 8Kv.
▲ characteristic requirements of safety regulation capacitor to withstand peak pulse voltage
In addition, it is also a very important point. In view of the particularity of safety regulation capacitor, it must have strong adaptability to harsh environment, which is particularly critical for many applications, such as automobile, industrial and consumer goods.The reliability characteristic of components can be defined through temperature humidity bias (THB) test. IEC 60384-14.4 standard defines the required conditions for THB test of safety capacitor (as shown in Figure 2).
Test condition B and test condition a are equivalent. Both tests prove that THB class IIIB test at 85 ° C / 85% RH / 1000 h means that the safety regulation capacitance meets and exceeds the requirements of the highest temperature and humidity tolerance level.
Figure 2: safety capacitor THB test conditions of IEC 60384-14.4 standard
If you screen according to the above criteria,
Three “experts” in Vishay’s ceramic capacitors should be on the list.
Safety gauge capacitorThis compact lead encapsulated disc ceramic capacitor has x1, 760 VAC / y1500 vac The rated voltage and withstand peak pulse voltage are up to 10 kV. What is worth mentioning is that it has passed the test of class IIIB with the highest reliability level in THB test (85 ° C / 85% RH / 1000 h)!Therefore, when you want to choose a product that hasHigh reliability performanceVy1… C safety capacitor is undoubtedly preferred when miniaturizing safety capacitor.
Figure 3: vy1… C series safety capacitor
2. AY1 series
If you need to find a safety capacitor with the same high temperature, high humidity and excellent high voltage pulse resistance for automotive applications, Vishay’s AY1 series ceramic capacitor is a wise choice。The capacitor has also passed the test of THB class IIIB test at 85 ° C / 85% RH / 1000 h, and has passed the aec-q200 vehicle regulation certification. Therefore, for high reliability EMI / RFI suppression applications in automotive applications, don’t hesitate to choose this material!
Figure 4: AY1 series safety capacitor
3. Smdy1 series
If the design is more sensitive to miniaturization (especially the height of the system) and requires SMD encapsulated safety capacitors, Vishay’s smdy1 series ceramic capacitors are highly recommended——The maximum body thickness is 4 mm, which is much lower than that of plug-in capacitor. At the same time, smdy1 series allows reflow soldering process, which can provide engineers with PCB Applications with low profile and compact spacing, and has similar functions to many traditional lead containing products.
Figure 5: smdy1 safety regulation capacitor this series of products have a maximum capacity of 4700 PF, the AC rated voltage also reaches x1760 VAC / y1500 VAC, and the DC rated voltage is 1500 VDC, which has an excellent performance in the industry.
In terms of reliability, smdy1 series has passed THB class IIB test (85 ° C / 85% RH / 500 h), which is an advanced representative among similar SMD safety capacitors.
In a brief summary, the three safety regulation capacitors mentioned above can be “listed” not only because of their excellent electrical performance, but also because of their outstanding performance in dealing with complex environmental applications, especially in THB high temperature and high humidity test。
Incidentally, these three are only representative products in Vishay’s rich safety regulated capacitor product portfolio. In Vishay’s extensive safety regulated capacitor product portfolio, selecting the right capacitor for a specific application may sometimes be a tedious task. Figure 6 shows a complete “Vishay safety capacitor selection guide”, which can help you quickly lock the appropriate safety capacitor products.
Figure 6: decision tree for selection of safety capacitor
In addition to safety regulated capacitors, Vishay’s ceramic capacitor product line also has a “master” who has to be mentioned. Different from the above three safety regulated capacitors, it is famous for its high temperature characteristics. This “master” is Vishay’s HOTcap ® capacitor。
1. High temperature resistance
In special applications, especially in automotive engine control unit, engine sensor protection, exhaust system, power converter and other applications, the requirements for high-temperature characteristics are particularly stringent, which requires that the capacitors that undertake filtering and other work in these systems should have excellent performance in this regard.
Generally speaking, for vehicle specification grade ceramic capacitors, the maximum operating temperature of 125 ℃ is quite good, and Vishay’s hotcap ® The capacitor is a ceramic capacitor that can support the working temperature up to 175 ℃ under normal working hours. It can even withstand the high temperature up to 200 ℃ within 500 hours! This is really valuable.
Figure 7: hotcap ® Superior high temperature characteristics of capacitors
In addition to high temperature characteristics, hotcap ® Other performances of capacitors are also commendable. Like instabilityAspect, hotcap ® Series c0g (NPO) capacitors (Class 1 capacitors) have high stability of ± 30 ppm / K in the temperature range of – 55 ℃ to 200 ℃; The change of capacitance value of x0u capacitor (Class 2 capacitor) of the same product series within the working temperature range is + 22% / – 56%, which can also meet the requirements of X7R and x9v standards for capacitance temperature coefficient.
Figure 8: hotcap ® Excellent stability of capacitors
3. High reliability
Again, due to hotcap ® The capacitor adopts the packaging form with lead. Compared with SMD components, it has stronger resistance to mechanical stress and vibration, and the capacitor can be directly welded (fusion welding or soldering) to the terminal. This feature is very beneficial to improve the reliability in some application environments without PCB board. Combined with these advantages, hotcap ® The characteristics of high temperature, high stability and high reliability of the capacitor are enough to meet or even exceed the needs of vehicle regulations and standards. It is on duty for key posts of automotive applications, and developers can rest assured.
In short, the Vishay ceramic capacitor product line can be described as crouching tiger, hidden dragon and a large number of experts. The four ceramic capacitors named on the “dragon and tiger list” today also have distinctive characteristics. Through this article, you must have got their true skills?