Electrolytics are here to stay

This article originally appeared in the Dec'23 magazine issue of Electronic Specifier Design – see ES's Magazine Archives for more featured publications.

Advances in performance and lifetime combined with low cost, mean that electrolytic capacitors are often the preferred choice of designers, yet sources of supply are becoming limited, since some manufacturers are issuing EOL (end of life) notices on certain styles, namely through-hole technology (THT – also called plated through-hole, radial lead, or leaded) parts. 

Aluminium electrolytic capacitors can deliver significantly more capacitance in a given volume than ceramic capacitors, therefore high value electrolytic capacitors can be relatively small – a significant advantage in many instances. Electrolytic capacitors are commonly used to reduce voltage fluctuations, for example in smoothing rectified AC, noise-filtering, and in audio frequency amplifiers. In the last ten years, polymer and hybrid polymer capacitors have emerged offering certain benefits over ordinary electrolytic capacitors, including longer lifetime, higher maximum working temperature, better stability, lower equivalent series resistance (ESR), and a safer failure mode.

However, many design engineers still prefer to use simple electrolytics. This is probably because they are very inexpensive, especially if there are no space restrictions. Also, many applications – for example in power supplies – can still use leaded parts, again saving cost. While it is tempting to believe that SMT (Surface Mount Technology) is ubiquitous, continuing the example of power supplies, very often the PCB will contain magnetic components that require through-hole mounting technology for mechanical stability. This means that the board will be populated both by SMT and THT parts, so unless there is pressure on PCB real-estate, the choice of whether to use a leaded or surface mount capacitor can be reduced to component price (assuming equivalent performance).

End of life notices?

So, despite numerous advances, there is still room for the humble electrolytic capacitor – even the older-style leaded device. Here, however, is where we hit a concern. Some manufacturers are issuing EOL notices on leaded electrolytic capacitors in certain case sizes. An exception to this is Panasonic Industry, which regards electrolytic capacitors as a core technology, and continues to invest both in R&D and in new manufacturing capacity. Specifically for leaded through-hole (THT/PTH) devices, Panasonic has made a commitment to its customers that it will continue to supply all case sizes and capacitance values in its portfolio for the foreseeable future.

Series FR and FS are two examples of leaded electrolytic capacitors from Panasonic that perform extremely well. Rated from 6.3 to 100 VDC, EEU-FR series radial leaded aluminum electrolytic capacitors are high-quality, competitive products that deliver 4.7 to 8200µF in case sizes from Ø5x11 to Ø16x25mm, and offer 10,000 hours lifetime, elevated temperature operation up to 105˚C, low ESR and high ripple-current capabilities. Series EEU-FS devices are rated for 6.3 to 100 VDC use and deliver 27µF to 10000µF offering higher capacitance within same case size, reducing space and, potentially, the number of capacitors required. 

New SMT developments: long life; high temperature; low ESR

Although as we have said, there is still a strong demand for through-hole electrolytic capacitors, most new designs utilise surface mount (SMT) devices which are smaller and easier to mount using automated production equipment. Therefore, most R&D investment is targeted at SMT parts.

One major trend is increased lifetime. There is a growing global movement towards sustainability and Panasonic is fully onboard with its GREEN IMPACT initiatives. Panasonic Corporation has made a commitment to achieving net zero CO2 emissions at all its operating companies by 2030. Looking to 2050, the company has shared its goals for contributing to society-wide reductions in CO2 emissions by switching customers to energy-saving products and supplying energy-saving solutions and green energy technologies to B2B/B2G customers. Of course, components that have a longer life need replacing less often and therefore make a contribution to sustainable operation.

Looking more closely at applications, we find that many indoor and outdoor applications like remote metering and small cell base stations require components with extended lifetimes, not only to reduce the need for frequent replacement, but also because installations may be difficult to access, and downtime is expensive.

Panasonic’s FH series devices provide a good example, delivering the longest lifetime for surface mount electrolytic capacitors of their type. Devices are available rated from 6.3 to 100V, providing capacitance values ranging from 10 to 680µF, in case sizes measuring Ø6x7.7 to Ø10x10mm. They have a lifetime of 10,000 hours at 105°C, 3,000 hours (>40%) higher than most competitors. Manufacturers who can match the lifetime cannot provide the same capacitance – as an example, Panasonic delivers 390µF whereas the competitor offers just 220µF – or temperature rating. In common with Panasonic’s entire range of electrolytic capacitors, FH series devices also minimise ESR and offer high ripple-current ratings. For the ultimate in low-ESR, SMT electrolytic capacitors, Panasonic’s FT series devices provide values down to 60mohm.

Here to stay

Thanks to significant and ongoing investment, Panasonic Industry has increased its electrolytic capacitor production capacity by 10% and reduced lead times. The company is also continuously improving the performance of its products, especially with respect to lifetime, capacitance/size, temperature rating, and ESR. And while some competitors are leaving the industry – especially concerning through-hole parts – Panasonic is committed to remaining in the market with wide availability of performance parts. Electrolytics, certainly as far as Panasonic is concerned, are definitely here to stay.