Mini-Cap® - Comet’s first Vacuum Capacitor for the semiconductor industry

September 20, 2023

Comet PCT originally provided Vacuum Capacitors for high-power broadcast applications. The emerging semiconductor market, however, required a completely new range of products.

Back in the 1990s, the dot-com era was in full swing, and Silicon Valley’s semiconductor industry was expanding tremendously. Comet had some experience as a vacuum capacitor supplier to the Japanese semiconductor industry already and was eager to join the booming U.S. market.

Comet had been manufacturing mainly for the broadcast industry – which required large, powerful capacitors. The semiconductor industry, however, demanded vacuum capacitors with a small form factor that could be built into the RF matching networks that steer the impedance of the plasma chambers during semiconductor production.

Breaking in to Silicon Valley and the U.S. market

During a roadshow in 1996 Comet presented its vacuum capacitors to potential U.S. users. Their high quality with regard to execution and lifetime sparked the interest of one of the largest OEMs, but the vacuum capacitors were simply too big.


The Comet reps went back to headquarters in Switzerland and started working on the development of a new product range specifically for semiconductors. In 1997 the Mini-Cap® product series was born. Soon the new partners in Silicon Valley successfully tested them against established products from competitors around the world.

What is a Mini-Cap® Vacuum Capacitor?

As the name suggests, the Mini-Cap® is a fixed Vacuum Capacitor in a compact size. It quickly gained market recognition as a reliable, cost-effective, high-quality capacitor for both high- and low-current applications (from 2 – 175 ARMS) and not only became a preferred component for designers of matching networks but also helped Comet Plasma Control Technologies to successfully gain a foothold in the semiconductor market. Over the years, the Mini-Cap® product series has grown enormously with the addition of complementary products.

Mini-Cap® series

Features, technical specifications,
product range


Close, trusted collaboration with customers

Comet developed the Mini-Cap® series in response to specific customer requirements and pain points. That customer-centric focus continues to this day as Comet works closely with the semiconductor OEMs to provide tailored, uniquely effective products. Each technology node presents new challenges which can often be solved only if all involved parties work together and innovate.

Taking on customers' challenges and developing unbeatable solutions is the core of Comet’s business. One great example of this is the development of Trimmer Vacuum Capacitors, a derivative of the Mini-Cap® product family.

When small adjustments are necessary

Around 2010, one of Comet’s OEM partners in Silicon Valley needed specific fixed vacuum capacitors for a project. To determine the correct capacitance, their head engineer asked for a large test range of Mini-Cap® capacitors that differed by small intervals. Comet’s R&D team was willing but knew that many sizes would need to be developed, with only one ultimately matching the customer’s needs.

To facilitate the adjustment process, the Comet engineers came up with a great idea: They gave the fixed Mini-Cap® a variable feature to provide a slight adaption of +/– 5 pF in order to meet an individual circuit tolerance. The new solution kept the small geometry of the Mini-Cap® vacuum capacitors but also provided some flexibility.

With that, the prototype of the Trimmer vacuum capacitor was born. The new feature proved useful to many customers, and the Mini-Tune series was permanently added to Comet’s product range.

What is a Mini-Tune (Trimmer)
Vacuum Capacitor?

A Trimmer is a vacuum capacitor that’s a hybrid of fixed and variable. It’s used when small adjustments are needed to meet an individual circuit tolerance or to compensate for slight differences per tool, or tool “drift” over time. Mini-Tune capacitors are also helpful during the design and development phase to discover the exact capacitance needed.

The Mini-Tune series have the same body sizes as the Mini-Cap® C, D, and E geometries.

Mini-Tune series

Features, technical specifications,
product range


Adaption according customer’s needs

Customer relationships are key to advancing Comet’s stated goal of empowering new technologies, and the Mini-Cap® and Mini-Tune vacuum capacitors are a great example of this. They were developed in response to specific customer needs and remain essential components of many impedance matching networks.

Comet’s initially small product portfolio has grown tremendously over the years through close collaboration with customers and focused attention on their requirements – including additional frequencies, other gases, more cycles, and more accurate processes. We always welcome the opportunity to solve demanding technical challenges.

Product recommendations


Compact, covering wide range of capacitance and voltages test test test



When small adjustments are necessary


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Comet Plasma Control Technologies


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