PMLCAP SMD Capacitors by RUBYCON
No Short-Circuit Risk With Snubber Capacitors With PMLCAP
Polymer Multi-Layer Capacitors (PMLCAP) from RUBYCON reach 500V 0.22μF in a size of 8.2x7.1mm with the new MH series. These SMD capacitors can be used in snubber circuits of inverter applications without the risk of short-circuit failure. In addition, PMLCAP offer an alternative solution to MLCC.
PMLCAP is a technology from RUBYCON that consists of a multilayer polymer with a uniform dielectric and no magnetic material. This achieves high signal fidelity and low distortion.
Technical Details and Advantages:
The technology is already widely used in high-end audio DC coupling or LPF (low pass filtering). It was even used for the seismometer in NASA's Mars lander "InSight". PMLCAP, like MLCC and film capacitors, are categorized as layer capacitors.
Advantages:
- No piezoelectric effect
- No change in DC bias capacitance
- No electrical distortion or very low Coulomb force causing squealing
- No risk of short-circuit, smoke or fire due to cracks or bending of the PCB
- Wide temperature range up to +125°C
In terms of size and electrical specification, PMLCAP are midway between MLCC and film capacitors. For the same capacitance, they are ten times smaller compared to metallized film capacitors. MLCC can be slightly smaller than PMLCAP. However, PMLCAP do not have undesirable characteristics like MLCC, such as DC bias characteristic or piezoelectric effect.
Apart from the size, there is no risk of short-circuit with PMLCAP due to its self-healing properties. Even if an overvoltage pulse is applied and a short circuit occurs, the current is concentrated on the shorted part. The resulting heat causes the metal electrode to vaporize, thus restoring the insulation.
A challenge for PMLCAP is the higher voltage. In the past, PMLCAP were only available up to a voltage of 100V, which was already sufficient for audio applications. However, the technology is also suitable for higher voltages, resulting in large film capacitors being replaced by smaller solutions. As the electronics market requires more and more high voltage and high current capacitors, RUBYCON has accelerated its PMLCAP development to extend the voltage range.
The new MH series is the first series suitable for higher voltages up to 500V. Currently, 250V 1.0μF and 500V 0.22μF are available for wider use. The MH series retains all the PMLCAP advantages mentioned above. By replacing film capacitors, the MH series certainly saves space and reduces the risk of smoke or fire from a short circuit. X7R MLCC may be smaller, but considering the capacitance drain due to DC voltage and the need to connect multiple MLCC in series or parallel, the space requirement could be larger compared to PMLCAP.
Your Contact Person
For more information, please contact Yasunobu Ikuno.
