1. The required capacitor type depends on whether differential mode filtering or common mode filtering is performed
·Differential mode interference refers to the transmission of pulse signals along two wires (L-N) in opposite directions. When using differential mode filtering, an X capacitor needs to be connected between the wires to effectively return high-frequency interference to the sound source.
·Common mode interference refers to the transmission of pulse signals along two wires (L-N) in the same direction in the same device. When using common mode filtering, a Y capacitor needs to be connected between the two wires and the ground wire to bypass the pulse interference signal of the wires to the ground.
2. Safety requirements vary depending on the type of capacitor
·The noise levels of various electronic/electrical equipment must be maintained below a certain level defined by specific equipment standards.
·Filtering uses components such as capacitors or chokes, or a combination of these components.
·Due to the direct connection of the safety capacitor to the power supply, it must comply with the provisions of the IEC 60384-14 safety standard.
·The safety requirements for Y capacitors are more stringent, as short circuits/faults in these components can directly lead to electric shock hazards (see the following instructions).
Although capacitor short circuits in X1/X2/X3/X4 applications will not cause serious consequences, high surge currents can lead to electric shock in Y1/Y2/Y3 applications
·X or Y capacitor faults can cause equipment malfunction or damage.
·The surface mount component composed of two capacitors connected in series has an open circuit that leads to a decrease in capacity rather than a short circuit, as a short circuit in one part will not affect the other.
·Due to the connection between the live and neutral wires, a fault in the X capacitor does not pose a risk of electric shock, but it can cause an open circuit in the fuse or circuit breaker, and in extreme cases, it can cause a fire.
·The Y capacitor is located between the charged conductor and the metal shielding layer that humans can come into contact with, so a malfunction can cause electric shock.
4. Advantages and disadvantages of using thin film capacitors
Advantages:
·The capacity of thin film capacitors is higher than other technologies. For example, Vishay thin film capacitors reach the following rated capacities:
·Thin film capacitors have the ability to recover dielectric breakdown with minimal capacity reduction. This ability is called the "self-healing" effect. This is because the arc generated during the dielectric breakdown process vaporizes the metal layer, thereby eliminating the fault condition.
·What is the capacity and dissipation factor of thin film capacitors? Highly stable within the temperature range of 40 ° C to+110 ° C.
·The internal series connection structure of X2 thin film safety capacitors helps to maintain long-term stability of the device and maintain the capacity in series impedance or cross line application environments.
Disadvantages:
·Thin film safety capacitors are through hole devices, and if SMD components are used in applications, a different welding process from other components on the substrate is required.
·The price of thin film capacitors is generally higher than that of ceramic capacitors.
5. Advantages and disadvantages of using ceramic capacitors
Advantages
·Lead ceramic capacitors have the highest insulation and pulse strength among all technologies
·Lead ceramic capacitors are only available X1/Y1 safety capacitors
·Lead ceramic capacitor pulse processing capability up to 10 kV
·The capacity value of surface mounted ceramic capacitors is 1 nF, and the temperature coefficient of the capacitor is NP0
·The price of lead ceramic capacitors is generally lower than that of thin film capacitors
Disadvantages
·Compared to other technologies, ceramic capacitors have lower capacity and some applications cannot be used
6. Whether safety requirements can be met is affected by the arrangement of substrate components
·The market is developing towards miniaturized devices, but compliance with the IEC 60384-14 standard means compliance with regulations on creepage distance and electrical clearances
·The allowable ultra small creepage distance and electrical clearance for X1/Y1 capacitors are 8 mm
·Surface mounted capacitors also need to meet certain end-to-end creepage standards
·Vishay surface mounted capacitors meet strict 4mm testing requirements that cannot be achieved by similar devices
7. The total implementation cost of surface mounted capacitors is lower than that of through-hole capacitors
·Single piece cost of through-hole devices is low, but assembly cost is high
·According to rough estimates, the assembly cost for surface mount devices is less than $0.01, while the assembly cost for through-hole devices is $0.05
Not all single-layer capacitors are the same, no matter how described in the data manual. Three instances:
·Although the X1/Y1 capacitor is sufficient to withstand the 8 kV pulse specified in IEC 60384-14, Vishay guarantees that our VY1... C series pulse strength can reach 10 kV
·In terms of reliability, Vishay's AY2 and VY1... C series have passed the 85/85 1000 hour bias test certification, although the IEC standard does not have such a requirement (only requiring 40/95 500 hours)
·Our new VY1... C series replaces silver electrodes with copper electrodes to improve component service life and eliminate the negative impact of silver migration
9. Both thin film capacitors and lead ceramic capacitors can withstand harsh test conditions (rated voltage 85 ° C/85% relative humidity for 1000 hours)
10. It is important to pay attention to humidity
·The new version of IEC 60384-14 standard includes "humidity level" to ensure the performance of components in high humidity environments
·Certified using the 85/85 1000 hour testing procedure, Vishay's AY2 and VY1... C series have achieved ultra-high humidity levels (Grade III)
·The F340 family composed of VishayX1, X2, and Y2 devices complies with Grade III B standards. Under rated voltage of 85oC/85% relative humidity/1000 hours of testing conditions, the capacitance and dissipation coefficient decrease is limited.
11. Multiple capacitors can be used in one location to increase the total capacity
·The leakage regulation limits the capacity value of Y1 capacitor to 4.7 nF, but some applications require higher capacity. These applications can use two or more capacitors in parallel.
·When using parallel capacitors, it is necessary to reduce the rated voltage according to the number of capacitors used
·Vishay provides X1/Y1 capacitors with a capacity value of up to 20 nF through our 440LS20-R, saving substrate space and assembly costs while reducing the risk of failure
12. Y5V's excellent dielectric properties make it an ideal choice for low-cost single-layer capacitors
·The Y5V temperature coefficient is suitable for use as X1/Y1 and X1/Y2 capacitors
·Due to the high dielectric constant (reducing component volume), Y5V devices save space
·Y5V devices use fewer ceramic materials, thereby reducing costs
·In many applications, the operating temperature can reach the expected lower level - even at higher temperatures, specific ultra small capacity values are sufficient to support filtering