The solution to your MLCCs shortage problems

The MLCC shortage

Multilayer ceramic capacitors, or MLCCs, have been a staple in electronics manufacturing for many years. These capacitors constructed of alternating layers of ceramic and metal layering have a wide range of uses, amongst them incorporation as bypass capacitors, in op-amp circuits, filters and more.

The market is facing hard times with the ongoing global shortage of MLCCs. With no end in sight, there are many reasons contributing to the supply shortage.

Firstly, the electronics industry is advancing at a rapid pace. New technologies are being developed and consumer products are being replaced at faster rates, living a much shorter product lifecycle. Many products, such as cars, are being built with smarter technology, which always leads to more electronic components being used, and ultimately, more capacitors being used within each device.

As a result, the big suppliers of MLCC are at their capacity limit, and can’t produce the amount of MLCCs needed. The larger corporations are investing in the development of higher quality capacitors, which means they could be reducing or discontinuing production of standard-range MLCC. These products being discontinued or supplied in reduced capacity are the ones that are so important for smaller companies that primarily focus on small-batch production.

However, when one door closes, another one opens. Suppliers like KEMET and Panasonic have been developing polymer capacitors as alternatives to MLCC to match the market needs. And who would have thought, these tiny devices can now not only replace MLCCs but also improve the performance of your application!

Polymer capacitors the MLCC alternative

When looking at polymer capacitors as an alternative to MLCC, there are four common types with which we can cover most use cases:

• Round polymer aluminium capacitors
• Polymer tantalum capacitors
• Polymer hybrid aluminium capacitors
• Layered polymer aluminium capacitors

The product line is completed with film capacitors.

The following overview shows the different designs of the polymer capacitors.

Stable, small and safe

All four capacitors have some advantages in common:

• Stability: consistent temperature during performance, stable DC bias, overall stable characteristics
• Size: 1 polymer capacitor can replace multiple MLCCs
• Safety: with its short circuit failure mode, a polymer capacitor adds safety to your PCBs

Shahrokh Kananizadeh, European Capacitor Product Manager at Panasonic has commented on the products stating:

The dielectric constant does not change when the voltage is changed – this is the major benefit of Polymer Capacitors (SP-Caps). MLCC on the other hand, are susceptible to structural distortion when DC voltage is applied, reducing overall reliability.

So, why haven’t polymer capacitors already replaced MLCCs?

First of all, MLCCs are truly a one-for-all product. They are very versatile and are suitable for most use cases. Polymer capacitors, on the other hand, are not a ‘drop in’ product, their use case has to be carefully defined. However, once the suitable polymer capacitor is found, it often leads to a better, long lasting, consistent performance.

The main disadvantage for polymer capacitors is that they are polarised. This instantly rules out the use in any circuits where they may experience a reverse-bias or an AC-signal.

Switching to polymer capacitors

If you are considering switching to polymer capacitors, define your requirements within the following criteria:

Voltage;

MLCC capacitors are specified at 0/1V – actual capacitance decreases with applied voltage. Polymer Capacitors are stable over applied voltage, but a 10-20% derating needs to be considered.

Required capacitance;

You need to know the capacitance of 1 MLCC capacitor under application conditions (applied voltage, frequency and aging), and the number of capacitors parallel to calculate the total net capacity.

Ripple current;

Polymer capacitors can easily handle ripple currents up to 2 to 3 arms (higher ripple requirements with single digit ESR products or stacked construction).

Operating frequency, Operating temperature, Maximum height;

Polymer capacitors are slightly bigger than MLCCs but replace multiple MLCCs.

Total solution cost;

If only a few MLCCs are used, the polymer capacitor might be more expensive, but due to the fact that it replaces multiple MLCCs, you can usually save some money.

Shahrokh Kananizadeh at Panasonic tried to simplify the topic of the ESR for us with a general guideline for impedance and ESR frequency:

The lower the impedance or ESR value of your capacitor, the more useful it is for smoothing when it is used in a circuit. MLCCs have the lowest ESR and impedance but SP-Caps are pretty close to that. For the capacitors you are considering it is important to evaluate the frequency response and, in particular, the self-resonate frequency.

Major guideline here, make sure that the caps are being used at a lower frequency than the self-resonate frequency. 1MHz is in this context, roughly speaking, the critical threshold and you need to look carefully at your capacitor’s differences in frequency response.

With this use case in mind, along various types of polymer capacitors such as layered polymer aluminium capacitors, mentioned here by Panasonic, SP-Caps, let’s have a closer look at a few different polymer capacitors and their strengths:

Q&A with the experts of KEMET and Panasonic

Matthias Harder, Director Business Management TBG EMEA at KEMET and Shahrokh Kananizadeh, European Capacitor Product Manager at Panasonic gave us some insights on this article and even took the time to answer some of our questions.

Distrelec: How can we convince an engineer who is prototyping, and has MLCC requirements, to think about an alternative solution, like polymer capacitors, and to incorporate them into his/her new design? Is there a tool/cheat sheet to help in a decision making process?

Matthias: Alternative products are available now. But not only that, looking at the total cost of the targeted capacitance, the desired net capacitance, alternative solutions will be cost saving and space saving. Polymer capacitors can offer a more stable capacitance over the applied DC voltage and a stable capacitance over lifetime. For more information, we have created a webinar on exactly this topic.

Shahrokh: An excellent point of reference is our S.O.S Polymer Capacitors Flyer: https://eu.industrial.panasonic.com/download/sos-short-mlccs-choose-panasonic-polymer-series

Distrelec: Is it a like for like replacement or do I need to rethink / redesign my application?

Matthias: We do have products that can replace 0805 and 1206 MLCC´s 1:1. However, we do not recommend to do so, because the benefits of the polymer technology is not being efficiently used with a 1:1 replacement. In general, it makes sense to consider polymers for the following use cases:

• A net capacitance >= 10 μF (for application voltages up to 14.4V)
• 0.68-10 μF (at application voltages of 45V and higher)
• Application Voltages up to 67.5V (60V for Harsh Conditions)
• Frequencies of up to 1MHz

But other use cases are possible as well.

Shahrokh: Due to the case sizes and Polymer advantages over MLCCs, the redesigning would be necessary. This redesign though happens to be the advantage of your design considering the fact that it carries the advantage of space saving on PCB and cost reduction.

Distrelec: How are the global resources for polymer capacitors? How are the production facilities? If we start using them globally, are we running into a shortage soon?

Matthias: KEMET is planning to increase the tantalum polymer production capacity by March 2020 by more than 50% compared to March 2018. The current annual demand lies at around 1100 tons worldwide with reserves of more than 100 000 tons.

Shahrokh: Panasonic has for each Polymer capacitor its own factory and R&D in Japan. There is a second source for SP-Cap and POSCAP outside Japan in case of natural disasters and delivery issues, meaning we have no current anticipation for shortages. Having second source of supply for OSCON and Hybrid is under consideration but we currently have plenty of capacity in anticipation for growth.

Distrelec: Tantalum is considered a conflict resource. Which countries is KEMET getting its tantalum from?

Matthias: KEMET is the only fully conflict-free manufacturer of tantalum polymer and MnO2 capacitors according to the SEC Final Rule on the Conflict Minerals, Section 1502 of the Dodd-Frank Act.

We are sourcing only certified conflict-free material, due to a “closed-pipe-system” we are also able to source from the Democratic Republic of Congo (DRC), but also any other Tantalum Ore (Coltan), K-Salt (intermediate product) or Tantalum Powder or Wire which is certified as conflict-free from other countries. In depth information can be found at http://www.kemet.com/conflictfree