PSUs 101: A Detailed Look Into Power Supplies

Capacitors Manufacturer Tier List

In the case of polymer caps, all types are considered good for PSU usage due to their ability to withstand higher operating temperatures than their electrolytic counterparts. When it comes to electrolytic caps, since they are hugely affected by increased temperatures caused by heat build-up at the PSU’s internals (but mostly by current ripple), the caps made by Japanese manufacturers are the safest and highest-quality choice. This is also why Japanese capacitors are always preferred.

However, there are two problems with using Japanese-made caps: their cost is higher and sometimes there are availability problems. Most PSU factories are located in China, so they have to import the capacitors from Japan, requiring additional time and shipping costs. However, we believe enough Japanese companies have manufacturing facilities in China (along with many Taiwanese manufacturers), so the problem might not be as significant in some cases. Of course, it is still much easier for Chinese PSU companies to acquire caps made by a Chinese factory. Chinese cap companies can offer larger quantities, and if we take into account that in most high-end PSUs only Japanese caps are used, then it is more likely for availability problems to occur with Japanese caps.

The situation becomes even worse when you consider that you cannot order huge quantities of Japanese caps, store them for a prolonged period and then use them, since their performance will be greatly affected. Electrolytic caps should be stored under specific conditions in order to retain their electrolytes, and especially for use in SMPS units, their storage period cannot exceed a specific threshold. If the recommended storage period is exceeded, the capacitors need to be checked one-by-one (including ESR and capacity measurements). In many cases, they need reforming before use in order to avoid operating problems. And since the reforming process takes time and equipment, production costs are further affected.

After some serious reading and gathering of information from various PSU manufacturers and engineers, we would like to note that besides the cap’s manufacturing origin, it is crucial to choose the right cap for the specific task you have in mind. For example, if you install a cap with only a 380V rating in the APFC stage, then it will fail much sooner, even if it is of very high quality, since its max voltage is too close to the DC bus voltage of this converter. In addition, as with most products, all cap manufacturers have a portfolio that includes products with differences in performance and expected lifetime. So besides a good manufacturer, you also have to choose caps from the suitable product family with the desired technical specifications for the corresponding application. This, of course, applies not only to caps but to all components used in every electronics device. However, inside a PSU, poor component choices can bring undesired results much faster.

First-Tier Caps

Even the Japanese manufacturers include some mainstream lines in their portfolios, which aren’t as good as their top-of-the-line products. So, in addition to the brand, we always take a closer look at the product family and its specifications to better judge capacitor quality and to make a rough estimation of their lifetime. 

All Japanese caps are considered of high quality, and we like to see the following cap brands:

• Rubycon
• United Chemi-Con (or Nippon Chemi-Con)
• Nichicon
• Sanyo/Suncon
• Panasonic
• Hitachi
• FPCAP or Functional Polymer Capacitor (ex-Fujitsu caps segment, which was bought by Nichicon)
• ELNA

Besides Japanese manufacturers there are also several US and European vendors that make high-quality capacitors. Probably we won’t meet any of the below cap brands inside a consumer grade PSU, at least their electrolytic offerings, but we decided that it still worth mentioning them.

• Cornell Dubilier (USA)
• Illinois Capacitor (Currently owned my Cornell Dubilier)
• Kemet Corporation (USA)
• Vishay (USA)
• EPCOS (TDK company, Germany)
• Würth Elektronik (Germany)

Second-Tier Caps

On this list you will find capacitors made by some of the Taiwanese manufacturers, which often use factories in China. These caps perform well, so they are usually used in mid-level PSUs and sometimes even in high-end units, and they strike a balance between good performance and affordable prices.

• Taicon (belongs to Nichicon)
• Teapo
• SamXon (except GF series which belongs to a lower Tier)
• OST
• Toshin Kogyo
• Elite

Third-Tier Caps

These third-tier capacitors, according to information from various PSU manufacturers and people with knowledge of RMA statistics, along with our own experiences with caps, might not be among the best choices, but are still a grade above the caps that belong to the last category.

• Jamicon
• CapXon

Fourth-Tier Caps

This group includes the rest of the capacitor brands. When you see one of these brands in a contemporary PSU, you’ll know that the manufacturer set lower-cost production as a priority instead of reliability over time. We are listing only the popular cap brands that are usually found in low-cost PSUs, but we are well aware that many other low-cost cap brands exist and there is a good chance that you’ll find them in non-branded PSU, and even in some branded units.

• G-Luxon
• Su’scon
• Lelon
• Ltec
• Jun Fu
• Fuhjyyu
• Evercon