Four Japanese Electrolytic Capacitor Makers on Hybrids, AI Servers, and Miniaturization: The Ichiken Lounge at Techno Frontier 2025
イチケン / ICHIKEN
At Techno Frontier 2025, held July 23–25, 2025, the electronics YouTuber Ichiken ran the "Ichiken Lounge" again after doing it the year before. The format pairs Ichiken one-on-one with representatives from component manufacturers so viewers can compare each company's strengths and product focus in one sitting. The second day was devoted to aluminum electrolytic capacitors, which Ichiken framed as a key power-electronics component for electrification, renewable energy, and server power supplies. Four domestic makers took part, in this order: Nippon Chemi-Con, Rubycon, AIC Tech, and Nichicon.
Ichiken asked each company to walk through its slides and then answered the same closing question: what is the best feature of your products? The companies overlapped on several themes, especially hybrid capacitors and AI servers. Each still pitched a distinct technical story: foil technology and immersion-cooling seals, in-house manufacturing equipment and a new film technology, heat dissipation and through-hole foil, and high-voltage polymer capacitors.
Nippon Chemi-Con: Three Capacitor Types and a New Hybrid Factory
The first guest was Chisai (as transcribed) from Nippon Chemi-Con's Product Development Department. Ichiken has worked with the company before and once visited its facility in Kanagawa, where he hand-wound an electrolytic capacitor himself. He said that seeing how the parts are actually made was very interesting, and that the video is on YouTube.
The representative described Nippon Chemi-Con as a company founded in 1931 that develops, manufactures, and sells aluminum electrolytic capacitors worldwide. Its lineup runs from very small to very large parts. Although electrolytic capacitors are its core, it also makes coils, large ceramic capacitors, varistors, and electric double-layer capacitors.
He divided aluminum electrolytic capacitors into three types:
- the conventional type, which uses liquid electrolyte;
- the conductive polymer type;
- the hybrid type, which uses both liquid and conductive polymer.
He singled out the hybrid type as having very good characteristics and said the company is currently selling it mainly for automotive applications and AI servers. Against that demand, Nippon Chemi-Con has built a dedicated hybrid building at its factory in Osaki City, Miyagi Prefecture. He said it would roughly double current production volume, bringing capacity to 100 million units per month.
To explain why hybrids perform well, he pointed to a graph of ESR (equivalent series resistance) against temperature. Down in the low-temperature region, around -40°C, the conventional liquid-electrolyte capacitor shows clearly higher resistance than the conductive polymer and hybrid types. Ichiken asked where the output of a new factory would go. The representative named servers and in-vehicle equipment, which he described as places where parts must never fail. He said the company's long market track record and high reliability suit those uses.
Immersion Cooling and the Sealing Rubber Problem
One slide showed a capacitor board submerged in a bottle of liquid. The representative explained that as server power output rises, fan cooling has become insufficient, so some systems now immerse the entire board in coolant. He cited a figure that has been reported for this approach: the electricity used for cooling can be cut by about half. He presented this as part of the company's environmental efforts.
Ichiken asked what matters when a capacitor sits in that liquid. The answer was the sealing rubber. The capacitor's exterior is an aluminum can closed with a rubber seal. The seal keeps the internal electrolyte from evaporating and keeps outside impurities from getting in. In a coolant bath, that rubber can swell. On an X-ray image, circled in red, the seal bulged outward until the representative said the parts end up "looking like gummy bears." Once that happens, coolant can penetrate the capacitor and cause failure. He said Nippon Chemi-Con develops its own sealing rubbers in-house and was able to bring an immersion-compatible part to market among the first.
Where Each Type Goes in an AI Server
A simplified AI-server power-supply diagram ran from commercial power on the left to the GPU on the right. The representative said Nippon Chemi-Con can supply electrolytic capacitors for every stage of it.
On the high-voltage input side, large board-mount aluminum electrolytic capacitors are used, because servers need high capacitance to ride through momentary power outages or brownouts by holding power for a short time. Toward the low-voltage side near the GPU, the output involves very high frequencies, so the company supplies conductive polymer and hybrid capacitors with very low resistance.
Ichiken asked about voltage ratings. The representative said conductive polymer products are usually available only up to about 16V and are not easy to push higher. Hybrids can go up to about 100V. The intermediate stage of the server supply runs at roughly 48V, so he recommends hybrids there.
Foil Technology and a Tenfold Volume Reduction
The next slide explained capacitance at the foil level. An aluminum electrolytic capacitor has an anode foil and a cathode foil, and the product's capacitance is their combined capacitance in series. If the cathode foil's capacitance is made very large, the product capacitance approaches that of the anode foil alone.
Nippon Chemi-Con has developed high-capacitance anode foil with proprietary technology. Ichiken was shown "past" and "present" cross-sections and asked to spot the difference. He identified them as anode foils and noted that the black central band was ragged in the old one and a clean straight line in the new one. The representative explained that the black band is the remaining aluminum core. Etching deeper into the aluminum raises capacitance, but digging too far erodes the core and weakens the foil. A high-capacitance foil that is too weak cannot be turned into a product. The company's technology aims for high capacitance while leaving the core clean.
The company also makes its own cathode foil, which is very thin and high in capacitance. A thinner cathode leaves room for more anode foil, which also aids miniaturization.
He then showed a physical comparison. A capacitor made in 1980 and a current product with the same rating differ in volume by a factor of about ten. Ichiken remarked that smaller parts are welcome when designing equipment, and the representative said the company wants to keep shrinking them.
Nippon Chemi-Con's Closing Pitch
For future focus, the representative named the hybrid KHU series for AI applications. Asked for the company's best feature, he cited its integrated in-house production system, which covers materials and equipment. He said this lets the company be first to market with new products and helps make power supplies smaller, higher in output, and more environmentally friendly.
Rubycon: The "Rubycon Triangle" and In-House Equipment
The second guest was Mukaiyama from Rubycon's Electrolytic Design Department in the Engineering Division. Rubycon is based in Ina City, Nagano Prefecture. He gave annual sales of roughly 60–70 billion yen, of which about 80% comes from aluminum electrolytic capacitors. The remaining 20% or so comes from custom power supplies, film capacitors, PMLCAP, and polymer capacitors. By market, he cited power supplies at 30%, automotive at 23%, industrial at 20%, and consumer at 15%.
He explained the company's structure with a diagram called the "Rubycon Triangle":
- the Ina headquarters handles product development and new-product R&D;
- about ten minutes away by car is a foil joint venture (the transcript's rendering of its name is unclear);
- about ten minutes further is a manufacturing-equipment company that also sells machines to outside customers.
Mukaiyama called that ability to build its own equipment one of Rubycon's main features. Ichiken asked whether it shortens the feedback loop between product and production, and Mukaiyama agreed. He tied this back to Nippon Chemi-Con's point about foil. As anode foil is etched for ever-higher capacitance gain, it becomes more brittle, and winding it neatly is a difficult technique. Rubycon develops its own winding technology, and he said that as a result it has long held a high share in miniaturized capacitors.
Strobe Capacitors, Water-Based Electrolytes, and a Long-Life Hybrid
Mukaiyama touched on company history. Rubycon supplied a large share of capacitors for camera strobes in the era of disposable cameras; the transcript gives a figure of about 80%. He also said Rubycon developed water-based electrolyte capacitors as a world first. These are now used on the secondary side of flyback power supplies as smoothing capacitors that handle large ripple current. The product line is the ZL series, with ZLR as the latest, and he described them as the most reliable products of that kind.
Rubycon's hybrid capacitor differs from its competitors' in what it pairs with the polymer. Instead of a conventional electrolyte, it uses what Mukaiyama called a "functional liquid" with a high molecular weight. Liquid-electrolyte capacitors suffer "dry-up," in which solvent slowly escapes through the seal, and lower-molecular-weight liquids escape faster. He said a high-molecular-weight liquid hardly escapes at all, which gives very long life and high heat resistance.
He showed an experiment. A capacitor was mounted on a PCB with a heatsink on its top and run at 14A for 4,000 hours, and it failed in open mode. He said heat resistance at that level would be almost unthinkable for an electrolytic capacitor, and that the part is already used in automotive applications. Ichiken asked whether the functional liquid is the key, and Mukaiyama agreed. He added that although electrical engineers see capacitor makers as parts manufacturers, the companies actually employ many chemistry graduates.
PMLCAP: A Film Capacitor Made by Vapor Deposition
Mukaiyama then turned to PMLCAP, a film-type capacitor that is not an electrolytic. Ordinary film capacitors use plastic film that is heat-stretched down to about 2 microns. PMLCAP is made in a vacuum chamber by a different process:
- Liquid plastic monomer is deposited.
- The monomer is hardened with an electron beam.
- The plastic is patterned.
- Metallic aluminum is deposited.
All of this happens continuously on a large rotating drum, building up layers "like making baumkuchen." Ichiken asked whether it behaves like a film capacitor, and Mukaiyama confirmed that its characteristics are similar.
According to Mukaiyama, Rubycon has mass-produced PMLCAP as SMD chips for 17 years, about 400 million units in total. Its main uses so far are audio and visual equipment, in low-pass filters where its filtering performance improves sound quality. He said high-end amplifiers now generally contain PMLCAP. Ichiken said he sometimes sees the name online in high-end audio discussions. He asked whether the in-house equipment capability connects to PMLCAP, and Mukaiyama said the deposition step is a very special technique, with post-processing also done in-house. He also noted that the seismometer on NASA's InSight lander, which contains PMLCAP, detected a "marsquake," and that Rubycon received a commendation for it.
Heat Resistance, Permittivity, and Layered Structure
Mukaiyama explained several technical advantages of PMLCAP.
Heat resistance. The dielectric is a thermosetting resin with no melting point, unlike ordinary films that soften when heated. He said PMLCAP allows a 40°C temperature rise at a 125°C maximum, compared with a 30°C rise at 100°C for general films.
Permittivity. He put the relative permittivity at about 3.0–3.2, compared with about 2.0 for ordinary polypropylene. That roughly 40% higher permittivity alone allows about 33% miniaturization.
Layered structure. Because the process can make sub-micron plastic layers, a 2 µm dielectric can be built from five 0.4 µm layers in series. This gives the same breakdown voltage and roughly the same capacitance as a single 2 µm film. The five internal metal electrode layers reduce resistance to one-fifth and roughly double heat conduction.
Pushing PMLCAP into Power Electronics, and the Moisture Problem
Mukaiyama brought a 500V/10µF PMLCAP and said Rubycon is expanding into high-voltage parts for power electronics. Ichiken had assumed from the audio examples that the technology was limited to low voltages. Mukaiyama then showed an electric compressor whose smoothing capacitor needs roughly 10A of ripple current. The PMLCAP handles the same 10A, and he said Rubycon is developing products to replace such capacitors in automotive systems.
Ichiken noted that inverters contain film capacitors about the size of "a big lunch box" and asked whether PMLCAP could shrink them. Mukaiyama said the permittivity advantage alone gives about 30%, and adding the series-parallel layering technology brings the reduction to about 40%. At lower voltages the advantage grows. Below about 500V, conventional film cannot get thinner than its 2-micron limit, but PMLCAP can. Below 400V, he said the size could be about one-quarter.
Ichiken asked what the difficulties and future challenges are. Mukaiyama said the plastic is an acrylic resin that absorbs water easily, so improving moisture resistance is an urgent issue, and Rubycon is developing monomers in-house to address it. Ichiken asked whether humidity is a real concern in automotive use. Mukaiyama acknowledged that in the same package, PMLCAP still falls short of Rubycon's own polypropylene film capacitors, and that a breakthrough there remains an open issue. Looking further ahead, he mentioned supplying elements including the package for integration with SiC devices, all done within the company.
For the best feature, Mukaiyama cited in-house winding equipment and the miniaturization technology that comes from it, which he said stands out in the industry. He also named the highly heat-resistant polymer hybrid as a main product, and PMLCAP as a pillar Rubycon wants to grow.
AIC Tech: Hitachi Heritage and Large Capacitors
The third company was AIC Tech. Ichiken has worked with them several times; his very first job with them was a visit to their factory in Moka City, Tochigi Prefecture, where he wound an electrolytic capacitor and learned how it is impregnated with electrolyte. That video is also on YouTube.
The representative explained that AIC Tech is only in its fifth year as a company but has a long lineage. It was formerly Hitachi AIC and, before that, Hitachi Capacitor, and research on aluminum electrolytic capacitors began at Hitachi, Ltd. 80 years ago. The skills and experience from that period have been passed on, and the company is confident in its technical capabilities.
AIC Tech's products were historically centered on capacitors for motor starters and camera strobes. As demand for efficiency spread inverters, screw-terminal board-mount aluminum electrolytic capacitors used as DC-link capacitors became its flagship. The representative said the company is very good at large products for industrial equipment, including wind and solar power, general-purpose inverters, and power supplies.
The company also makes film capacitors for power electronics. DC-link applications originally used aluminum electrolytic capacitors, but demand grew for longer life, maintenance-free operation, and withstand voltages above 1,000V. AIC Tech already produced film capacitors for power applications and partially applied that technology to develop film capacitors for power electronics.
Moving the Pressure Valve to the Side for Better Cooling
The representative said customers strongly request two improvements: higher ripple current capability and miniaturization.
Higher ripple generally means lowering internal resistance to suppress self-heating. AIC Tech has instead focused on improving heat dissipation. The hottest spot in a capacitor under ripple is its center. AIC Tech's structure presses the cathode foil against the bottom of the aluminum case, so heat travels from the core through the cathode foil and the case to the outside.
The catch is the pressure valve. Conventional designs put it on the top face, and space must be left around it so gas can escape unimpeded. AIC Tech moved the valve to the side of the can, a "side valve" structure, which makes the top flat. A heatsink can then contact the capacitor directly, raising ripple capability beyond what the capacitor achieves alone.
The representative said side valves are not very popular in Japan, because customers worry that venting gas sideways could hit neighboring parts and have given feedback that it is not easy to use. The design is becoming more common in other countries. AIC Tech hopes Japanese companies will adopt it too.
Multi-Anode Technology and a Live Foil Demonstration
For miniaturization, the representative explained that capacitance rises with the surface area of the internal anode foil, so the goal is to fit more anode area in a limited space. AIC Tech combines two approaches: raising foil capacitance and a "multi-anode" technique that stores more anode foil.
In the multi-anode structure, two anode foils are stacked. With ordinary foil, the overlapping faces cannot exchange charge because an aluminum core remains in the middle, so the stack behaves like one thick foil. AIC Tech uses foil with through-holes so charge can move through it.
They demonstrated this on the spot. Ichiken wrote "AIC" in red marker on a conventional non-penetrating foil, and the ink stayed on the surface. Writing the same letters on the through-hole foil showed the ink coming through to the other side. The representative said this confirms the foil is penetrated.
Ichiken asked whether a penetrated foil would be too weak. The representative agreed that it is very brittle and folded both samples to show the difference. The through-hole foil crumbled and cracked. The non-penetrating foil broke too, but retained the suppleness of aluminum from its metal core. Ichiken said such a brittle foil must be quite difficult to wind. The representative agreed it is challenging: winding speed and tension must be set to suit the foil, and that condition setting is an important point. Ichiken summarized that the company has cleared that hurdle, and the representative confirmed it.
AIC Tech's Handbook and Closing Pitch
AIC Tech was also exhibiting a booth nearby. This year it produced a comprehensive handbook on aluminum electrolytic capacitors, offered free to visitors who filled out a short questionnaire. Ichiken said he had received one and that it contains knowledge that isn't in textbooks but is taken for granted in the field, and he encouraged viewers to pick one up.
For the best feature, the representative cited the company's high-impact products. These include ultra-miniaturized parts using the side valve and through-hole foil, and a φ120 capacitor that he called the largest product in the industry.
Nichicon: Capacitors Plus an Energy-Storage Business
The final company was Nichicon, founded in 1950 in Kyoto and marking 75 years this year. The representative said it runs two businesses. The capacitor business centers on aluminum electrolytic capacitors but includes various other capacitors. The NECST business develops, produces, and sells products such as energy storage systems. For aluminum electrolytic capacitors, Nichicon is vertically integrated: it produces and processes its own electrode foil, assembles products, and handles sales.
Ichiken noted that Nichicon's website shows it sells to general consumers as well as businesses and asked about the background. The representative said capacitors have always been sold to companies and set manufacturers. Demand for energy surged after the Great East Japan Earthquake, and Nichicon, which had long had a circuit business, used that expertise to commercialize products like energy storage systems.
Nichicon's aluminum-capacitor lineup includes:
- hybrid capacitors;
- solid (conductive polymer) electrolytic capacitors;
- surface-mount chip types;
- through-hole leaded types;
- board-mount types.
Requirements vary with input voltage, so each family covers low to high voltages. Asked which genre is strongest, the representative said conventional aluminum electrolytic capacitors, where Nichicon has a long history and large market share. He added that hybrid and solid polymer types are now in high demand, and Nichicon has invested in equipment for them.
Growth Markets: Automotive and AI
Nichicon has been strategically strengthening its business in growth markets, which the representative identified as automotive and information and communication equipment. Electric vehicles and automated driving are electrifying vehicle systems, and requirements on capacitors are becoming more demanding and more diverse. The trend at the equipment level is toward higher output and power. For capacitors that means high capacitance, high ripple, and continued miniaturization.
In automotive power systems, capacitance is needed, but ripple current must also be considered. As AIC Tech explained, ripple produces heat, so capacitors must withstand that. The representative said AI is in the same situation: the field is booming, processing very large amounts of data at high speed, and power levels are rising.
High-Voltage Polymer Capacitors
The representative then introduced conductive polymer aluminum solid electrolytic capacitors. In a conventional aluminum electrolytic capacitor, electrolytic paper sits between the anode and cathode foils, and the wound element is impregnated with liquid electrolyte, which is what yields large capacitance. A polymer capacitor replaces that liquid with a solid conductive polymer.
Nichicon uses PEDOT. Liquid electrolyte conducts ionically, while PEDOT conducts electronically. The representative said its conductivity is about 10,000 times higher, giving very low specific resistance and very good capacitor characteristics. He said the key is the proprietary additives combined with PEDOT, which he called each company's know-how. Nichicon's additives aim for a more stable polymer over the long term and higher reliability.
A chart mapped rated-voltage ranges across the industry, including hybrids, by temperature range and lifetime. The representative said Nichicon's lineup covers very high voltage bands that other makers do not. Its highest-rated polymer product is 125V, and it has 63V and 80V products for 125°C and 135°C that he described as the only ones in the industry.
Ichiken asked whether others don't make them because they are difficult. The representative explained that polymer capacitors were traditionally used at low voltages such as 2.5V and 6.3V. As equipment output rises, demand has shifted toward higher withstand voltage, and customers want non-liquid capacitors even in high voltage bands, so Nichicon expanded its lineup. Asked whether high-voltage polymers compete with hybrids, he said yes: customers choose between them based on both cost and characteristics.
He also stressed lifetime. A table estimated service life at actual operating temperatures and showed polymer capacitors guaranteeing a much longer life than aluminum electrolytic or hybrid types. Because there is no liquid inside, they do not suffer the dry-up and evaporation-driven degradation of liquid types, which makes them suited to long-life requirements.
Hybrids, and Offering Both
Nichicon's last slide covered hybrid capacitors, which the representative said are in a very busy period of business. By combining liquid electrolyte and conductive polymer, a hybrid pairs the high capacitance and low leakage current of an aluminum electrolytic capacitor with the low ESR and high ripple current capability of a polymer capacitor. He said this makes it greatly superior to conventional aluminum electrolytics in characteristics.
Ichiken asked how Nichicon thinks about choosing between hybrid and solid. The representative said there is demand for both, so Nichicon offers both. Handling both also lets it share technical know-how and incorporate the best of each into its development.
For the best feature, he repeated two points: high-voltage polymer capacitors that other companies lack, and hybrids with what he called the industry's highest specifications. He added that Nichicon is developing products for even higher ripple and capacitance requirements.
Ichiken's Takeaway
In a brief wrap-up, Ichiken said the overall impression from all four companies was that automotive and AI are where much of the demand lies. The requirements placed on capacitors are trending toward larger capacitance and higher ripple, and every company is focusing development on products that meet them.
In this video, here's a look at the special conversation that took place in the Ichiken Lounge at Techno Frontier 2025, July 23–25, 2025. In this conversation about the future of electronic components, I, Ichiken, meet face to face, one-on-one, with representatives of manufacturers at the forefront of the industry. We take an in-depth look at each company's strengths and product features.
The theme of this issue is electrolytic capacitors. For electrification, renewable energy, power supplies for servers, and more, electrolytic capacitors are a key component for power electronics. We draw out each company's latest lineup, technical features, and focus applications. Here you go.
Ichiken. Thank you all for being here today. Continuing from last year, we are inviting manufacturers and related companies to Ichiken Lounge. What are the characteristics of each company? What are the differences between them? We are planning to have you see it all at once.
This time, we're talking about electrolytic capacitors. We have invited four electrolytic capacitor companies: Nippon Chemi-Con, Rubycon, AIC tech, and Nichicon. I would like to start with Nippon Chemi-Con. I look forward to working with you.
I look forward to working with you. My name is Chisai from Nippon Chemi-Con's Product Development Department. Good day to you.
We have worked with Nippon Chemi-Con several times before, and I went myself to the institute in Kanagawa. We actually hand-wound electrolytic capacitors there. When you actually wind them and learn how they are made, it's very interesting. We have a video on YouTube, so everyone, please take a look!
Let's start with this slide. Could you please explain briefly?
First of all, what kind of company is Nippon Chemi-Con? The company was founded in 1931. We operate globally, focusing on the development, manufacturing, and sales of aluminum electrolytic capacitors. For the product lineup, you can see the picture in the middle. We offer a variety of products, from very small to very large.
Thank you. Is it correct to say that electrolytic capacitors are your main business?
That's right. Since today we are talking about electrolytic capacitors, we haven't listed much else here. As you can see in the upper right corner, we also produce coils, large ceramic capacitors, varistors, and electric double-layer capacitors.
I see. In addition to electrolytic capacitors, you offer a lot of other capacitor-related products. Next slide, please. How about this one?
There are three types of aluminum electrolytic capacitors: the type that uses electrolyte inside, the conductive polymer type, and a capacitor called a hybrid that uses both liquid electrolyte and conductive polymer. The hybrid type has very good characteristics, and we are currently selling products especially for automotive applications and AI servers.
Against this background, we built a dedicated hybrid capacitor factory in Osaki City, Miyagi Prefecture. This would approximately double the current production volume, allowing us to make 100 million units per month. I urge everyone to purchase them!
You mentioned that hybrid capacitors have good characteristics. How good are they?
There's a graph around the middle. The horizontal axis is temperature, and the vertical axis is ESR, or resistance. Conductive polymer and hybrid capacitors have very low resistance compared with general aluminum electrolytic capacitors. As you can see in the −40°C and −60°C areas, the resistance of aluminum electrolytic capacitors is higher.
You are building a new factory. That probably means you have somewhere to sell the products. Do you have any expectations in that area?
Our products have a long track record in the market and high reliability. They are often used in servers and automotive applications. We would like to sell them for applications where you never want them to break.
I see. Thank you very much. You can see immersion cooling on the right side of this slide. Please explain this.
There's liquid in the bottle, and the entire board with capacitors is immersed in it. As servers and similar equipment operate at higher power, cooling them with a fan is no longer enough. Immersion cooling cools the entire board.
By using something like this, the electricity used for cooling is said to be cut by about half. We would like to pursue this as part of our company's environmental efforts.
What are the key points when dealing with immersion cooling?
The capacitor's exterior is an aluminum can, and a rubber seal is used there. In addition to preventing the electrolyte inside from evaporating, the rubber prevents external impurities from entering.
If you put it in this liquid, the sealing rubber can swell a little, as shown in the area circled in red on the radiograph. It ends up looking like a gummy bear. If that happens, coolant gets inside, and the capacitor fails. To prevent this, we also develop sealing rubber in-house. That has allowed us to be among the first to bring something like this to market.
So the sealing rubber is the key. Next slide. What does this show?
This has commercial power on the left and GPU on the right. It is a simplified schematic of an AI server's power supply. On the left, fairly large board-mount types are used. In the middle are the hybrids I mentioned earlier, and on the right are conductive polymer types. We offer various sizes and voltage ratings, so we can provide electrolytic capacitors for all these locations.
I see. Within one AI server, you can use different types of electrolytic capacitors?
On the left, where the voltage is high, aluminum electrolytic capacitors are used. On the right, hybrid and conductive polymer types are often used.
In such cases, how do you use Chemi-Con's products differently?
High capacitance is needed. Servers need to handle momentary power outages and voltage dips, which means holding power for a little while. These large aluminum electrolytic capacitors are used where high capacitance is needed. On the right, on the low-voltage side, very high-frequency output power is required, so we offer conductive polymer and hybrid capacitors with very low resistance.
What about the voltage ratings of hybrid and conductive polymer capacitors?
Conductive polymer products are usually only available up to about 16 V. It isn't easy to raise that. Hybrid types can go up to about 100 V. The voltage in the middle is roughly 48 V, and since the line voltage is around that level, we recommend hybrid capacitors for those applications.
I see. So that's one use for them. Could you please explain the next slide?
In the upper right corner is the formula for calculating the combined capacitance of an aluminum electrolytic capacitor. There is an anode foil and a cathode foil, and the combined capacitance is the product of their capacitances divided by their sum. If the cathode foil's capacitance is very large, the product's capacitance is approximately equal to the anode foil's capacitance.
As shown in the upper left, we have developed high-capacitance foils using our proprietary technology. Using these contributes to higher capacitance and smaller size. On the left, it says past and present. Ichiken, do you see the difference in these photos?
The one on the left is probably the anode foil of an electrolytic capacitor.
That's right.
The black area in the middle is quite uneven in the older one. In the current one, it's a straight line. I think that's the difference.
That's right. The black part in the middle is aluminum. We etch into the aluminum in this area. If we etch too deeply, we lose the middle section, reducing the foil's strength. If it becomes uneven, that also reduces the strength. Even if we create a high-capacitance foil, we face the problem of being unable to commercialize it. With our technology, we can leave this area intact while aiming for high capacitance. We are continuing development.
So your core technology is mainly the production of anode foil and similar materials?
That's right, but there's also the cathode foil at the lower left. This is a cathode foil we developed ourselves. We also have very thin, high-capacitance cathode foils. Using these allows us to fit in more anode foil, which also enables miniaturization.
If the cathode foil's capacitance is made very large, the capacitance is determined by the anode foil. Thank you. I think this relates to what you just said, but what do we see in the lower right corner?
It shows the size of a capacitor from 1980. On the right is the most recent product, with one-tenth the volume. The sizes aren't the ones shown here, but I brought some today. Let's say the one on the left was made in 1980. Now, the same rating can be achieved in this smaller size. We are developing technology for this kind of miniaturization.
It's helpful to have smaller components when putting them into a device.
That's right. I don't think you'd want to put lots of these large ones in it. We would like to make them smaller and smaller.
I think it's time to close. Could you give a brief closing explanation of this slide?
As I mentioned earlier, we have built a hybrid capacitor factory, so we want to sell more hybrid capacitors. What we want to focus on in the future is the KHU series for AI. It's also used for many other things. We look forward to your consideration!
Thank you. I've decided on one final question to ask each company this time, and I'd like to ask Nippon Chemi-Con: What is the best feature of your product?
We have an integrated in-house production system covering materials and equipment. I think this lets us be the first to deliver such products to the market. It allows for smaller power supplies and higher power outputs. I believe we can also make environmentally friendly products. We hope to continue contributing to technologies that are friendly to the environment and people. Thank you for your continued support of Nippon Chemi-Con!
Thank you very much. The first company in our electrolytic capacitor dialogue was Nippon Chemi-Con. Thank you very much.
Thank you very much.
We are now on to the second company in our electrolytic capacitor dialogue. We have invited Rubycon to join us. I look forward to speaking with you.
I look forward to speaking with you. My name is Mukaiyama from Rubycon Corporation. I belong to the Electrolytic Design Department in the Engineering Division. I look forward to working with you today.
Please.
Today, I would like to explain our company and what makes us unique, our system called the Rubycon Triangle, and the main products we would like to promote in the future.
First of all, Rubycon Corporation is located in Ina City. We mainly make aluminum electrolytic capacitors. Annual sales are approximately 60 to 70 billion yen, and aluminum electrolytic capacitors account for 80%. Although they aren't shown here, we also make custom power supplies. Those, along with film capacitors and the polymer capacitor PMLCAP on the right, account for about 20% of sales.
Our major markets are automotive at 23%, power supplies at 30%, consumer at 15%, and industrial at 20%. This is our current sales structure.
Am I correct in understanding that electrolytic capacitors are your main products? Thank you.
Next is the Rubycon Triangle, a diagram explaining our company's features. Our headquarters are in Ina City, Nagano Prefecture, where we conduct product development and research and development of new products. About a 10-minute drive away is Shin-ei Capacitor Foil Co., Ltd., a joint venture with a company called JCC. Another 10 minutes away by car, we have a manufacturing equipment company that even sells equipment to external customers. We consider this one of our main features.
Since you can even make your own equipment, is feedback to product development and production quite fast?
That's right. As Nippon Chemi-Con explained earlier, anode foil becomes increasingly brittle as its surface-area enlargement ratio increases. Winding it neatly then becomes quite difficult. We continue developing our own technology in that area. As a result, we have long had a very high market share in miniaturized products.
In terms of miniaturization, the right side of this slide shows camera flashes and various other applications.
That's right. This is our company's history. In the past, we supplied about 80% of the capacitors for disposable cameras. Another feature is our water-based capacitors, which we were the first in the world to develop. They are now used on the secondary side of flyback power supplies as smoothing capacitors that handle large ripple currents. For those applications, we have our ZL series, with the ZLR series being the latest. We believe we are producing the most reliable water-based capacitors.
Next are hybrid aluminum electrolytic capacitors. Our hybrid aluminum electrolytic capacitors use a high-molecular-weight liquid called a functional liquid instead of an electrolyte. That's the difference. When electrolyte is used, solvent gradually escapes through the seal, causing what's called dry-up. The lower the molecular weight, the faster it escapes. This high-molecular-weight liquid is less likely to escape, giving extremely long life and high heat resistance.
Here's an example of an experiment at 14 A. We put a heat sink on the top of the capacitor, mount it on a PCB, and pass 14 A through it. It lasts 4,000 hours and then fails in open mode. This level of heat resistance is almost unthinkable for an electrolytic capacitor, but we can achieve it. This product is also currently used in automotive applications.
So the functional liquid is the key?
That's right. From an electrical engineer's point of view, electrolytic capacitor manufacturers are component manufacturers, but we actually have a very large number of people with chemistry backgrounds.
I wonder if chemistry is their strength.
The next component, PMLCAP, is not an electrolytic capacitor. I would like to explain it. This is a kind of film capacitor in which the plastic film is made by a vapor deposition process. Normally, film for film capacitors is made by stretching it with heat, producing very thin films of about 2 microns today.
This is deposition in a vacuum chamber. Liquid plastic monomers are deposited, and then I apply an electron beam to harden them. Plastic, patterning, and metallic aluminum deposition are repeated like making baumkuchen. Rotate the big drum and continuously produce the elements.
Is it like a film capacitor?
Characteristically, it is similar to a film capacitor.
What are the features of this PMLCAP? What is it used for?
As you can see in the picture here, we mass-produce this chip-type, SMD version. Over the past 17 years, we have produced about 400 million units. It is used in low-pass filters for audio and visual applications. Its very good filtering performance improves sound quality. Currently, high-end amplifiers generally contain PMLCAP.
I sometimes see the name PMLCAP on the internet in connection with high-end audio. On the previous slide, you mentioned making and developing your own manufacturing equipment. Can that also be applied to manufacturing equipment for PMLCAP?
That's right. The deposition part uses a very special technique, so that involves a specialized manufacturer, but we do all the post-processing in-house.
Also, in the upper right corner is NASA's InSight. Its seismograph used this to detect marsquakes. They aren't earthquakes because they're on Mars. We received a commendation for successfully detecting marsquakes.
Here's a brief introduction to this capacitor. On the left, this plastic material is a thermosetting resin. It has no melting point, so it does not melt. Ordinary films usually have a melting point and soften and stretch when heated, but this is a very heat-resistant plastic. For PMLCAP on the left, at a maximum of 125°C, a temperature rise of up to 40°C is acceptable. For general films at 100°C, a rise of up to 30°C is acceptable. It has very high heat resistance in this respect.
It has high heat resistance, and can the capacitance be made much larger?
That's right. Normal polypropylene has a relative permittivity of about 2.0. This has a relative permittivity of about 3.0 to 3.2. From the dielectric constant alone, about 40%—it can be miniaturized by 33%.
The figure on the right shows the structure. The way the PML layer is made allows plastic layers with submicron thickness. This is used internally: the one on the left has five sections in series. It's 0.4 μm × 5, so 2 μm. The right side is also 2 μm, so it has the same breakdown voltage, and the capacitance will be about the same. The one on the right is a normal film. As you can see, there are five metal electrode layers, which reduces the resistance to one-fifth. Heat conduction is roughly twice as large. That's the difference between the structures on the right and left.
I brought this high-voltage PMLCAP here with me. This is 500 V, 10 μF. We are making these high-voltage products for power electronics and are in the process of expanding our market.
Since the previous slides were about audio applications, I thought it might only work at relatively low voltages. Does this mean the voltage can be increased?
This is an electric compressor. The light blue part is a smoothing capacitor. It requires a ripple current of roughly 10 A, and this also handles the same 10 A ripple current. These are automotive applications. We are developing products with the aim of replacing those capacitors with these in the future.
When you disassemble inverters, there's a film capacitor inside that looks like a big lunch box. If we replace that with PMLCAP, does that mean it can be made much smaller?
The relative permittivity alone gives about a 30% reduction. If we add this series-parallel technology, it is possible to reduce the size by about 40%. At lower voltages, below 500 V, film capacitors reach a thickness limit of 2 microns. This can go beyond that. Below 400 V, it can be about one-quarter of the size.
I thought this was very interesting. I'm sorry if this is a bit rude, but I'm not sure how much voltage you're looking for. It isn't too difficult to make, but I imagine it gets harder as the voltage increases. What were the difficulties, and what challenges do you have for the future?
The plastic material itself is acrylic resin. Moisture resistance is a problem because it easily absorbs water. We are currently developing monomers and other products in-house. Improving moisture resistance is an urgent issue.
When it's used in an automotive system, is humidity still something you're very concerned about?
That's right. We also make film capacitors with regular polypropylene. Even with the same package, there is still a difference. Achieving a breakthrough there is one of our challenges.
I believe this is a capacitor we can expect to see quite a bit more of in the future.
That includes the package. When integrating with SiC, we can also supply the elements. We are pursuing those activities within the company for the future.
Thank you. We're getting close to the end of our time, so I'd like to move on to my last question. What is the best feature of your product?
For electrolytic capacitors, we have in-house technology for winding and manufacturing equipment. I think our miniaturization technology stands out in the industry. Our main products are polymer hybrid and highly heat-resistant electrolytic capacitors. Then there's the future-oriented PMLCAP, which we want to grow into a pillar of our business.
Thank you. The second company in our electrolytic capacitor dialogue was Rubycon. Thank you very much.
Thank you very much.
I'd like to move on to the third company in our electrolytic capacitor dialogue. The third company is AIC tech, Inc. Thank you for joining us.
Thank you for having us.
I've actually worked with AIC tech a number of times in the past. The very first job I did is shown in the image at the bottom left. I'm the one holding the electrolytic capacitors. We visited a factory in Moka City, Tochigi Prefecture, where we actually wound an electrolytic capacitor and impregnated it with electrolyte. It's a very interesting and educational video, available on YouTube. Please take a look.
I'd like to get started right away. First, please explain this slide.
We are a new company in our fifth year of business, so some of you may not be familiar with us. Previously, we were a member of the Hitachi Group, known as Hitachi AIC, and before that, Hitachi Capacitor. We have been developing and producing capacitors for many years. Eighty years have passed since Hitachi, Ltd. began researching aluminum electrolytic capacitors. We have accumulated skills and experience over that time, and we are confident in our technical capabilities.
Thank you. Looking at the product portfolio, there are two electrolytic capacitors on the left. Is it correct to say that electrolytic capacitors are your main business?
We mainly produced capacitors for motor starters and camera strobes. As demand for greater efficiency has driven the spread of inverters, aluminum electrolytic capacitors of the board-mounted and screw-terminal types for DC links have become our current flagship products.
Looking at these images, it seems you handle fairly large electrolytic capacitors.
We are very good at large products.
You mentioned that they're widely used in industrial equipment. More specifically, where are they used?
As noted here, they're mainly used in environmental fields such as wind and solar power, as well as general-purpose inverters and power supplies.
On the right, there are film capacitors for power electronics. What are these like?
We originally offered aluminum electrolytic capacitors for DC links. Demand has increased for longer service life, including maintenance-free operation, and high withstand voltages exceeding 1,000 V. We already developed and produced film capacitors for power applications, so we applied some of that technology to develop film capacitors for power electronics.
Could you please explain the next slide?
There is very strong demand for two capacitor performance improvements: higher ripple current capability and miniaturization. We prioritize these two areas in our development.
For higher ripple current capability, the general method is to lower internal resistance and suppress the heat generated by the capacitor. We have commercialized products that improve heat dissipation by using a structure with high heat dissipation.
As for miniaturization, capacitance increases in proportion to the surface area of the internal anode foil. Increasing the anode foil's surface area within a limited space is one key. In addition to that technology, we use multi-anode technology to increase the amount of anode foil that can be housed. We address these two points to achieve miniaturization.
Let's start on the left. Looking at the high-ripple diagram, there's the electrolytic capacitor's case. Does this mean the anode foil is pressed against the bottom of the aluminum case?
It's the cathode foil. We press the cathode foil against it. When ripple current is applied to a capacitor, the hotspot at its center becomes the hottest part. We improve heat dissipation by releasing that heat to the outside through the cathode foil and aluminum case.
You press it toward the aluminum case to let the heat escape there. Then the question is where the heat goes from the electrolytic capacitor. I think that's a rather difficult problem.
In the conventional structure, there is a pressure-relief valve on the top face of the capacitor. We ask users to leave space there so that the valve can release gas from inside without obstruction. For this type, we make that surface flat, allowing direct contact with a heat sink. The capacitor itself can handle higher ripple current, but a heat sink can further improve heat dissipation.
I see. The place where the gas escapes is shown in the image below.
That's right. This type has the valve on the side rather than the top surface.
Is the one with the valve on the side called a side-valve structure?
That's right.
From what I've heard, it doesn't seem to be very popular in Japan, but it's becoming more commonly used in other countries.
When the valve activates and releases gas sideways, it can hit other components. We have received feedback that this makes it difficult to use.
I see. It has gained some acceptance in other countries.
That's right.
We hope you'll sell it to Japanese companies!
We hope they'll use it!
I'd like to look at the multi-anode technology on the right. This has two layers of anode foil?
If you simply stack two sheets, an aluminum core remains in the middle. Since the overlapping foil surfaces cannot transfer charge, the structure simply becomes one thick piece of foil. For this double-anode structure, we use foil with through-holes. Those holes allow charge to transfer. We brought some foil this time, so I'd like to demonstrate it.
You're holding a gray sheet now. Is that anode foil?
This is conventional foil without through-holes.
That's the foil without through-holes.
I'll write on it with a marker.
You're writing the letters with a red marker now.
I wrote AIC like this. With foil without through-holes, the ink cannot pass through. Now I'll write on the foil with through-holes.
You're writing the same letters on the foil with through-holes now. Since the holes go through, let's see what happens.
I wrote on the foil with through-holes here. It hasn't passed through completely, but I think you can see that some has passed through.
It's showing through just a little. So charge transfers through it like this. Thank you. This is the foil without through-holes, and this is the foil with through-holes. I'd be quite concerned about the strength of foil with through-holes.
That's right. Because the holes go through, the foil itself is very brittle. You can see it when you fold it. This is the foil with through-holes. It crumbles and cracks like this. I'll handle the foil without through-holes in the same way. This is what it looks like. It breaks, but it retains the flexibility of aluminum and the metal core. I think you can see that it's very strong.
Winding that brittle foil seems quite difficult. Is that a particularly challenging area?
That's right. Winding control, including speed and tension, needs to be set according to the foil being used. Establishing those conditions is a very important point.
So you've addressed and overcome that?
That's right.
Thank you. Lastly, could you explain this slide? Does this mean you have a booth here?
That's right. This year, we created a comprehensive guidebook covering aluminum electrolytic capacitors. We're exhibiting here, just a few booths away. If you fill out a short questionnaire, we'll give you the guidebook free of charge. We hope you'll stop by afterwards!
I actually received this handbook too. It contains a substantial amount of knowledge that you don't find in textbooks but that is taken for granted in the field. I encourage everyone to visit the booth afterwards and get the handbook.
We're getting close to the end of our time, so I'd like to move on to my last question. What is the best feature of your product? Please go ahead.
I think one of our distinguishing features is that we develop high-impact products. As I explained earlier, we have developed and launched products with side valves, ultra-miniaturized products using foil with through-holes, and this 120 mm diameter product, which is the largest in the industry.
Thank you very much. The third company was AIC tech. Thank you very much.
Thank you very much.
Now for the fourth company in our electrolytic capacitor dialogue: Nichicon Corporation. I look forward to speaking with you today.
Thank you for having us.
First, I'd like to start with this slide, please.
First, I'd like to briefly introduce our company. Nichicon Corporation is based in Kyoto. Founded in 1950, this year marks our 75th year in business!
In terms of business, as written here, we are developing two areas: the capacitor business and the NECST business. As for the capacitor business, we deal in various capacitors, mainly aluminum electrolytic capacitors. In addition, the NECST business includes the development, production and sale of products such as energy storage systems.
And as for the production system, for aluminum electrolytic capacitors, we handle the production and processing of electrode foil, our main material, followed by product assembly, manufacturing and sales. We have an integrated production system, and this is one of our strengths. Also, in the lower right-hand corner are the priority markets we focus on.
Looking at the products and services on Nichicon's web page, it's actually not just electrolytic capacitors. There are products for general consumers, too. I thought doing B2C as well as B2B was a distinctive feature. Is this about developing new business with your own products?
That's right. We've been making capacitors for 75 years. Our main capacitor customers are companies and equipment manufacturers. During the Great East Japan Earthquake, demand for energy increased enormously. We had always had a circuit business as well, so we used that expertise to commercialize products such as energy storage systems to meet energy demand.
Thank you. Now, please explain this slide.
This shows our development of aluminum electrolytic capacitor models for growing markets. Our lineup is shown in the upper part of the page. From left to right, there are hybrid capacitors and solid electrolytic capacitors. For aluminum electrolytic capacitors, we have small chip types for surface mounting on boards, as well as radial lead and snap-in types for insertion through holes. We have a very broad lineup of products.
Nichicon's electrolytic capacitors come in many different types and have various applications. What applications do you focus on?
There are a variety of applications listed here, and the required features change depending on each application. Depending on the input voltage range, we receive requests for everything from low-voltage to high-voltage types. Our lineup offers a wide range of products to meet those requests.
By the way, which is your strongest area?
We've been working on aluminum electrolytic capacitors for many years, and we have a large, strong market share. But as you can see on the left, hybrid and solid electrolytic capacitors are now in high demand. We've invested in equipment and have been focusing on this area. I'll explain more later.
Thank you. This slide, please. Here you've briefly summarized the major growth applications at the moment and their capacitor requirements.
We are focusing on growth markets and strategically strengthening and expanding our business base. Among those mentioned here are automobiles and information and communication equipment. With the move toward electric vehicles and automated driving, vehicles are becoming increasingly electrified. Accordingly, the requirements for capacitors are becoming more demanding. Equipment is becoming more functional and diverse, and higher output and power seem to be trends. For capacitors, that means increasing demand for high capacitance, high ripple current capability and the traditional requirement of miniaturization.
What do the requirements for automotive applications look like?
We're dealing with large amounts of power, so capacitance is naturally required, but ripple current and other factors must also be considered. As AIC tech and others explained earlier, heat is generated, so capacitors are required to withstand that heat.
Is the situation the same for AI?
That's right. Generative AI is a booming field, processing very large amounts of data at high speed. This is also becoming more powerful. As noted in the top right corner, the market trends are all toward higher output and power. We have a lineup of capacitors to match.
What does this slide show?
First, I'd like to introduce conductive polymer aluminum solid electrolytic capacitors, or polymer capacitors. Each company has already explained these, so I'll give a brief description. In normal aluminum electrolytic capacitors, electrolytic paper is placed between the anode and cathode foils, and these are wound together. The structure achieves high capacitance by impregnating it with electrolyte, a liquid that conducts electricity.
In a polymer capacitor, the liquid electrolyte is replaced by a conductive polymer, a solid that conducts electricity. The conductive polymer we use is called PEDOT. The electrolyte conducts through ions, whereas PEDOT is a solid electronic conductor. Its conductivity is approximately 10,000 times higher, with very low resistivity. This gives polymer capacitors very good characteristics.
This PEDOT and other proprietary additives are key to making the most of polymer capacitors' characteristics.
I think this is where each company's know-how comes in.
We combine our own additives to achieve a polymer that remains more stable over the long term, resulting in highly reliable capacitors.
I see. What does the part on the right show?
This table maps the rated voltage range of our polymer capacitors within the industry, including hybrids. It shows our rated voltage ranges for each temperature range and lifetime. As you can see, a distinctive feature of our lineup is polymer capacitors in very high voltage ranges that aren't available elsewhere in the industry. The highest is a 125 V product. Even at high temperatures of 125°C and 135°C, we have a lineup of high-voltage products, such as 63 V and 80 V, that are unique in the industry. As mentioned earlier, higher-output applications require high-voltage capacitors. We hope you'll consider using our capacitors in those applications.
Is the reason other companies don't make high-voltage polymer capacitors that they're difficult to manufacture?
That's right. Traditionally, polymer capacitors have mainly been used at low voltages, such as 2.5 V or 6.3 V. As mentioned earlier, higher output brings more demanding requirements, and there has been a shift toward higher voltage ratings. We've expanded our product lineup to meet requests for capacitors that don't use liquid, even in those higher voltage ranges.
At voltages this high, do they compete with hybrids?
That's right. Customers choose based on their application, considering both cost and characteristics.
I see. Thank you very much. What is this on the lower right?
As noted in the lower left corner of this page, one feature of polymer capacitors is their stable characteristics over a very long lifetime. Their basic lifetime is long to begin with, and the way lifetime is considered is a little different. As an example, the table below shows the estimated lifetime at actual operating temperatures. Compared with aluminum electrolytic and hybrid capacitors, polymer capacitors can guarantee a very long lifetime, making them an ideal product for long-life requirements.
Since there's no liquid in them to begin with, they aren't prone to drying out.
Aluminum electrolytic capacitors suffer characteristic degradation through drying out and evaporation. Since polymer capacitors are solid, they have an advantage in that respect.
This is the last slide. What does it show?
I'd like to introduce another type, hybrid capacitors, which the other companies have also explained. Business in this area is currently very strong for us as well. Hybrid capacitors combine liquid-type aluminum electrolytic capacitors and solid-type polymer capacitors, using both liquid and conductive polymers.
This combines the good characteristics of aluminum electrolytic capacitors, such as high capacitance and low leakage current, with those of polymer capacitors, such as low ESR and high ripple current capability. This type is in very high demand. Its characteristics also have significant advantages over aluminum electrolytic capacitors.
By the way, what are Nichicon's thoughts on choosing between hybrid and solid capacitors?
There is demand for both. We're expanding our lineup so we can offer either when requested. By handling both, we can incorporate the best aspects of each and share technical know-how to develop and produce superior products.
Thank you. We're getting close to time, so I'd like to move on to my last question: What is the best feature of your products?
To repeat what I said earlier, our strength in polymer capacitors is that we provide high-voltage capacitors that other companies don't have. For hybrid capacitors, we currently have a lineup with the industry's highest specifications. Another feature of our development is that we're working to meet even higher ripple current and capacitance requirements.
Thank you. The fourth and final company in our electrolytic capacitor discussion was Nichicon. Thank you very much.
Thank you very much.
I'd like to give my final summary. The overall trend is that there are many automotive and AI applications. The requirements for capacitors are still trending toward high capacitance and high ripple current capability. My impression is that everyone is focusing on developing and offering products to meet those requirements. With that, I'd like to bring this electrolytic capacitor discussion to a close. Thank you very much.
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