Tuesday, February 12, 2013

Applications of multilayer chip capacitors

I had the pleasure of interacting many times with Norman CM Lui, CEO, Skymos back in 2006. Established 1983, Skymos Electronics Ltd is one of the foremost designers and manufacturers of chip components, specializing in multilayer chip inductors, ferrite chip beads, multilayer chip ceramic capacitors, chip resistors and resistor networks. Ithas been awarded ISO 9001 and 9002 approval.

It was among the few suppliers offering multilayer chip inductors, ferrite chip beads, chip resistors, low-temperature co-fired ceramic capacitors (LTCC), etc.

Back then, he spoke of the applications of MLCCs that were generally in Bluetooth, GPS, cable TV equipment, satellite, etc. For example, taxis plying with GPS would need high Q (quality) MLCCs. New applications include converged handsets, MP4 players, PS3, digital cameras and video cameras; flat-panel high-definition TVs; dual-core multiprocessors (for motherboards, notebooks, desktop PCs and scanners); and automotive electronics.

Lui said most suppliers were more concerned about the 3H – high capacitance, high voltage and high frequency – for MLCCs, as well as high Q (quality factor). The frequency of MLCCs had become much higher as the termination is done on the top, instead of the sides.

Various types of dielectric were being used for MLCCs – such as the BaTiO3, NP0/C0G, XSR/X7R and Y5V/Z5U, respectively. The X5R allowed more capacitance for MLCCs and dielectric constant (K) was higher. The NP0/C0G group supported capacitance ranging from 1pF to 1µF and up to 10nF.

As for the electrodes, Pd/Ag was being used and Ni was also being used currently. For Pd/Ag electrode, the termination was in Ag/Ni/Sn. For Ni electrode, termination was mainly in Cu/Ni/Sn. Skymos is currently focusing on the Pd/Ag electrodes for MLCCs.

One major development was the use of BME (base metal electrode). Lui said that moving from the current electrode to BME would require lot of investment of about $50 million. For using BME, suppliers would need to install all new equipment, especially for the furnace, which would be used to oxidize the Ni element.

Another development has been the improvement in capacitance. Using BME for 0402, suppliers can produce MLCCs with high capacitance, such as 2.2µF, 3.3µF/6.3V, etc. Earlier, capacitance was 0.47µF using Pd/Ag electrode. The BME could enable higher capacitance due to an increase in the number of active layers.

For instance, the dielectric was 8-10 microns when using Pd/Ag electrodes. Using BME, the dielectric became 2-3 microns. The corresponding values for 0603 type is 10µF/6.3V using BME, 47µF for 0805, and 220µF for 1206. MLCCs have replaced those applications that previously required tantalum capacitors.

Another development has been the advent of the MLCC array, which has more applications in the PC industry. This array can reduce the EMI. Skymos is offering this MLCC array. It also improves the high Q, voltage and capacitance.

On the issue of MLCCs vs. ultracapacitors, Lui said, suppliers could already reach up to 220µF capacitance via MLCC, which were replacing tantalum capacitors. The tantalum capacitors were now being used for applications requiring 220µF-330µF capacitance. As a result, all other types of capacitors were dropping in demand, as compared to MLCCs. Ultracapacitors were intended to replace the Ni battery. However, there has also been a shift to oxide batteries.

The supplier’s R&D strategy includes focusing on 3H and possibly, BME. It also reduced the insulation loss and noise by grounding. The MLCC combined a capacitor and a filter. I hope Skymos has produced 20KV MLCCs. It was already offering 10KV MLCCs.

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