The srew terminal type high voltage ceramic capacitor also called "Doorknob Capacitor" in English or  High Voltage Screw Terminal Ceramic Capacitor. The renowned Japanese company TDK (Tokyo Denkikagaku Kogyo) refers to it as "Ultra High Voltage Ceramic capacitor." Since Japanese electronics giant Murata announced the discontinuation of high voltage screw terminal capacitors in autumn 2018, the highest market share in China is held by Japanese brand TDK . TDK has over 40 years of experience in manufacturing and marketing of ultra-high voltage ceramic capacitors, which are widely used in Chinese domestic power transformers, circuit breakers, high-end medical CT machines, industrial NDT non-destructive testing, high-power laser weapons, high-voltage electrostatic precipitators, etc. TDK's sales focus is primarily in Japan, South Korea, Russia, and the Asia-Pacific region, with relatively less presence in European and American markets.

 

Since period of former U.S. President Trump, restrictions have been imposed on Chinese companies regarding high-tech components such as high-end chips and electronic parts. Many listed companies, state-owned enterprises, and large-scale equipment manufacturers in China have begun to consider domestic alternatives for key components. The alternative and  replacement of TDK's ultra-high voltage ceramic capacitors has also been put on agenda.

 

In fact, some excellent Chinese high-voltage ceramic capacitor manufacturer such as HVC Capacitor have successfully replaced high voltage screw terminal ceramic capacitors from well-known Japanese brand MURATA and American brand Vishay. HVC capacitors have gained long-term testing recognition from numerous European and American listed companies and Fortune 500 companies. Due to material and ingredient limitations, TDK products do not provide the same level of experience for European and American customers as MURATA from Japan and Vishay from the United States. Recently, there have been feedback from European and Chinese research institutes and end customers indicating that TDK products are inferior in quality and certain parameters compared to HVC capacitors. As a result, customers have opted to use HVC capacitors instead of Japanese TDK products. 

1) Applicable Voltage and Capacitance Range: TDK ultra-high voltage ceramic capacitors: 20KV-50KV (Z5T, Y5P, Y5S materials); HVC doorknob type high-voltage ceramic capacitors: 10KV to 150KV (main materials are N4700, Y5U, Y5T, etc.). The highest voltage capacitance model currently offered by TDK is FHV-12AN 50KV 2100PF, Y5S material. HVC provides standard products to customers such as 50KV 8000PF N4700, 60KV 2000PF N4700, 150KV 1000PF N4700, and more. When customers require a working voltage higher than 50KV, HVC capacitors can offer a rich variety of higher voltages and even very large capacitances.



2) How good technical level of TDK's Z5T, Y5P, Y5S dielectric material capacitors?

HVC's engineers actually measured TDK's 30KV 2700PF and 50KV 2100PF screw capacitors and found that although TDK uses Class 2 ceramics Y5S, Z5T, and lead-containing materials (claimed to be under the ROHS exemption program on their website), the D.F. (dissipation factor) values reach the level of Class 1 ceramic N4700. This surpasses the products of Chinese counterparts in this aspect.
 

 

3) Internal structure of the capacitors: TDK's ultra-high voltage ceramic capacitors use a traditional single ceramic chip structure, and the epoxy resin encapsulation mold has a standard size of only 60mm, as mentioned above, which limits the design to a maximum of 50KV 2100PF Y5S capacitor. HVC employs an innovative internal structure with dual-chip series or parallel connection, enabling the production of capacitor specifications far exceeding those of well-known manufacturers. Capacitors with high voltages such as 80KV, 100KV, and 150KV are derived from dual-chip series connections, while capacitance values of Class 1 ceramic 5000PF and even 8000PF are achieved through dual-chip parallel connections.


4)Disc coating and other detail: TDK ceramic chip surfaces traditionally coating capacitance through "silver plating." Silver ions are excellent conductors but are also prone to migration. In contrast, HVC screw capacitors internally coat the ceramic chip with copper electrodes, providing better resistance to high voltage and high current capabilities compared to conventional silver plating. (The picha hapo juu shows TDK capacitors without epoxy resin layer, removed to reveal ceramic chips with silver plating and metal terminals, and the picha hapa chini display the unique copper plating technology on the surface of HVC capacitors.)






In conclusion, TDK and HVC's screw terminal type ceramic capacitors each have their own technological advantages, making them evenly matched competitors. In some aspects, HVC even outperforms the Japanese company TDK. However, considering factors such as delivery lead time and pricing which the buyers always take into consideration, the attractiveness of TDK's ultra-high voltage ceramic capacitors naturally falls short compared to HVC.

The world's number one brand for high-voltage screw-type ceramic capacitors is Japanese Murata. In 2018, after Murata announced its discontinuation of production, the American company VISHAY and Japanese company TDK respectively sought to fill the market vacuum left by Murata by issuing press releases and listing "cross-reference" information on TDK's official websites.



When comparing Japanese TDK and American Vishay, HVC Capacitor still  a better alternative option to Murata.

1) It can be observed that TDK's replacement for Murata is only a rough substitution. For example, Murata's DHS4E4C532KT2B 15KV 5300PF N4700 is matched by TDK with a corresponding substitute of 15KV 7000PF, Y5S. We know that although TDK's Y5S material exhibits limited low-loss performance, actual measurements show values similar to the N4700 level. However, Class 2 ceramics like Y5S are unable to perform as well as Class 1 ceramics in high-frequency environments. Additionally, the 7000PF capacity from TDK may be too large for customers accustomed to using Murata capacitors, and the component dimensions may not be consistent with the original Murata products. Considering that TDK is also a major international manufacturer, unless customers are extremely powerful buyers, TDK may not be willing to redesign molds and use the same level of ceramic material for Murata replacements.



If HVC were to provide a replacement for this Murata model, firstly HVC's standard doorknob capacitor product list is the most comprehensive in the market for high-voltage screw terminal products, encompassing all catalog models from top-tier and second-tier brands both domestically and internationally, such as Murata, TDK, Vishay, HVCA, etc. Essentially, any Murata model that has been publicly released on the internet has a ready-made solution from HVC. Even for Murata capacitors with customized dimensions and metal terminals for certain major clients that may not be seen online (for example, a 40KV 3000PF N4700 capacitor from a radiative enterprise under Japan's Sumitomo Electric), HVC would offer a 1:1 custom solution at very low mold cost. Furthermore, the capacitance, tolerance, material, etc., are essentially identical to the original Murata specifications, and in some cases, HVC even using Class 1 "N4700" ceramics material  to replace Murata's Class 2  "Z5U" ceramics material, very similar to Chinese ancient story of "The Race of the Swift Horse."（田忌赛马）
 

2) Furthermore, although TDK is a world-renowned Japanese electronic components manufacturer, the technical communication and service levels of TDK's branches and agents outside of Japan are not as strong as those of HVC's agents. There have been instances where a customer from a German electrical company reported that when testing with both TDK and HVC capacitors, TDK's agent did not provide adequate technical support. In contrast, HVC's German agent, AMEC, proactively visited key customers, ensured customer satisfaction through effective technical communication, and demonstrated flexibility in operations, leaving a positive impression on customers. In industries such as key equipment like power transformers, technical support is highly valued by end customers.

3) After years of effort, HVC Capacitor has gained recognition and achieved bulk shipments from high-voltage screw capacitor customers such as Nikon, Konica Minolta, GE Healthcare, Johnson & Johnson, Baker Hughes, and others. The business performance with Japanese clients and Fortune 500 companies demonstrates that HVC Capacitor meets the strict technical requirements of the most demanding end customers in the industry.




In summary, HVC Capacitor is a more suitable replacement for the high-voltage screw capacitors from the Japanese brand Murata compared to TDK. To some extent, HVC products can offer existing customers of TDK ultra-high voltage capacitors a different technological experience.

Below are the comparison models of the full range of high-voltage screw capacitors from TDK and HVC: