High-Q Microwave Capacitors

Excellent temperature resistance, high volume/capacitance ratio, electrical properties and reliability make Exxelia's ceramic capacitors ideal for a wide range of fields of application including medical implants, aircraft flight controls, switched-mode power supply in harsh environments, core samplers for petroleum exploration, and space vehicles. Exxelia also offers Hyper Frequency ceramic capacitors with optimized size and very low ESR. 

These HiQ capacitors offer excellent performance levels for RF applications requiring functional reliability. Typically these applications include civil and military telecommunications (cellular base station equipment, wireless broadband service, Point to-Point or Multipoint radios, radio broadcasting equipment), and MRI coils.

Our multilayer ceramic capacitor (MLCC) is a chip capacitor manufactured with layers of ceramic material and metal. The alternating layers can be built up to the desired capacitance range. The dielectric thickness determines the voltage rating. The capacitance is determined by multiplying the number of layers by the amount of active area and then the dielectric constant for the material. This number is then divided by the dielectric thickness. The active area is the overlap between the electrodes.

A capacitor with a thicker dielectric layer handles higher voltages than one with a thinner layer. Inversely, the thinner dielectric will have a higher capacitance rating. The MLCC design provides a significant space-saving advantage over other capacitor styles.

High temperature ceramic capacitors and high temperature mica capacitors are often used in situations that require a higher voltage or a higher power than normal. Because of the ways in which they are built, they can offer low ESR and excellent inrush current and ripple capabilities that other types of capacitors cannot. The only downside is that they tend to be physically larger than other types of capacitors.

The automotive industry is another area where high temperature capacitors are required. The temperature conditions can vary dramatically depending on what area of a car you’re talking about. The brake systems, the engine and the transmission are often the most temperature intensive areas.

Ceramic chips are created with binders and solvents added to a specified ceramic powder. The slurry created is dried, forming a sheet or tape of ceramic material. Metal powder is mixed with solvents and additional ceramic material to create a liquid electrode. The liquid is then printed onto the ceramic layer. Layers of the ceramic sheets are stacked and laminated to form a solid structure.

The solid structure is cut into the desired size. Once cutting is complete, the assembly must be kiln fired. The temperature used in the firing process is critical in determining the capacitor’s characteristics. The process is similar for disc and chip styles. Disc capacitors use long leads to mount through circuit boards. Chips use surface mount technology.

A Class 1 ceramic capacitor is the best choice for applications that demand low losses and high stability. This style provides a reliable capacitance within the designated range of frequency, temperature and voltage. Class 2 series offer higher capacitance, but have wider fluctuations. The thermal stability varies by +/- 15 percent; these should be used in applications that do not require a continual exact capacitance. Exxelia uses NPO and P100 as Class 1 dielectrics ; and BX, 2C1 and X7R as Class 2 dielectrics.

Class 1 feedthrough capacitors offer high frequency noise reduction, and are excellent for use in microwave transmission, medical applications and DC supply and signal lines. Feedthrough design uses an axial-style lead for connections.