X5R and X7R are commonly used names of ceramic capacitors, well known for most electronic engineers, both professionals and amateurs. To clarify the knowledge about those components, let’s start with a short description to remind the meaning of a capacitor.
Ceramic capacitor has a fixed value. The aim of using the ceramic as a material of this component is to provide a dielectric layer (in number of two or more layers). The role of electrodes is played by a metal layer. Ceramic capacitors are one of the most common electrical components used widely all around the world, with their variety and available applications. They are divided into two classes, due to their features and thus the most adequate opportunities of application. The first class of ceramic capacitors include those components which have high stability and low losses for resonant circuit applications. The second class ceramic capacitors’ most important feature is high volumetric efficiency.
Both X5R and X7R capacitors are in the second class. There are some factor that differ them: temperature ratings, dielectric materials. All that have an impact on operation of a design.
To make it simpler, let’s take a closer look at the code used for naming the ceramic capacitors.
- X in both cases is used for determine the minimum temperature range -55 degrees Celsius
- the number describes the maximum temperature (for 5 it is +85 degrees Celsius and for 7 it is equal +125 degrees Celsius)
- R is for the percentage of capacitance change permitted (about 15%)
X5R is available for use in high capacitance values up to 100uF. It is well suited for decoupling and filtering.
X7R may be referred to as a temperature stable one, however, its capacitance change tends to be non-linear. It can be applied where such changes in capacitance under the circumstances of the applied voltage value or frequency, are allowed.