Trimmer capacitors: The trend setters - Components

Electronic News, July 29, 2002 by Kozo Kagawa

Trimmer capacitors are the frequency adjusters of the components world, and as a result they are on the leading edge of component trends that are reshaping the electronics industry.

Today trimmer capacitors are used to aid advancements in the cell phone and wireless markets and fuel the production of more sophisticated applications, such as remote keyless entry (RKE) systems for the automotive electronics industry. These new applications rely on key trends in the trimmer capacitor market including advancements in materials, miniaturization and integrated devices.

Currently, there are six main types of trimmer capacitors that are manufactured using varying dielectric resources. However, more than 90 percent of trimmer capacitors used in the market today are made from ceramics. By contrast, only 9 percent use polyethylene or film, while the remaining 1 percent are made from other materials.

Ceramic's popularity is due in large part to its ability to achieve small sizes. Unlike air-based products that are limited to larger sizes because of a small dielectric constant, ceramic material has a simple construction and high dielectric constant so engineers can create simpler designs. Efficient printed circuit board (PCB), mount-ability and a good capacitance linearity curve also add to ceramic's attractiveness.

Further, ceramics, including classical ceramics (bricks, pottery and porcelain.), have four main attributes that the other materials with plastic or metal bases do not posses, including rust resistance, non-flammability, resilience/hardness and malleability. Also, ceramic has the characteristics of an insulator, like most stones, but it can function as a conductor and semiconductor as well. This is particularly important for trimmer capacitors because it provides them with stable characteristics to protect against environmental stresses. In the meantime, ceramics are currently being tested to improve their response to high-frequency and high-voltage use, which will further increase their potential.

In addition to material advancements, trimmer capacitors are downsizing to meet the smaller size demands of cell phones and other consumer products such as personal digital assistants (PDAs). Because of the ceramic properties of trimmer capacitors, the miniaturization trend from 4mm to 1mm has had little effect on the quality of the product.

These attributes, including small size, small and consistent capacitance value, and the stability of both the ceramic and metal parts, present a unique process for substrates. In addition, lead-free construction meets environmental requirements while providing high-heat resistance during the soldering process.

Trimmer capacitors, because they are used in most wireless devices and in new automotive applications, are an ideal candidate for determining the next big trend in electronic components.

Kozo Kagawa is Murata Electronics North America (MENA) group product manager for thermistors, potentiometers and trimmer capacitors.