How to code SMD Capacitors?

SMD Capacitors

Capacitors find use in many electronics applications. It is marked in a variety of ways and its actual format or way of marking depends upon the capacitor type. The format or codes used depends upon whether the capacitor used is surface mount, a simple component, a capacitor dielectric or technology. In coding, size also plays a role which determines the space required for marking. The capacitor marking systems are standardized by the EIA - the Electronic Industry Alliance, and these provide commonality across the industry.

SMD Capacitor

SMD devices or Surface Mount Capacitors are capacitors which are robust, small and easy to place making them ideal for today’s environment. SMD capacitors are the next common type which comes after the SMD resistors.

Basics

Surface Mount Capacitors have metallized connections at either ends.  The size, ease of use in manufacturing and lower spurious inductance are the basic features that makes SMD capacitors the popular.

• Size:   SMD capacitors can be made very much smaller than their leaded relations.

• Ease of use in manufacturing:   SMD capacitors are easier to place using automated equipment.

• Lower spurious inductance:  Levels of spurious inductance are much smaller and these capacitors are much nearer the ideal component that their leaded relations.

These capacitors form the majority of capacitors that are being used and manufactured. They are normally contained in the same type of packages used for resistors. The different types of SMD capacitors are Multi-layer ceramic SMD capacitors, tantalum SMD capacitors, Electrolytic SMD capacitors etc.

A multilayer ceramic SMD capacitor consists of many rectangular block of dielectric in which a number of electrodes are contained. Some dimensions and measurements of SMD capacitors are listed in the table below

Tantalum SMD capacitors provide levels of capacitance that are higher than those that can be achieved when using ceramic capacitors.

Electrolytic SMD capacitors

Nowadays, electrolytic SMD capacitors are widely used in many SMD designs. These designs have high level of capacitance with low cost and are widely used in many areas. The electrolytic SMD designs are marked using value and working voltage.

• In one method, the value is included in microfarads. For example, if the capacitor comes up with a marking of 33.6V. It means that it has 33microfarad capacitance and 6volt working voltage.
• In the second method, a letter is followed by three figures. Here the letter indicates the working voltage and the three figures indicate the capacitance in pico farads. For example, G106; here G means a working voltage of 4 volts and a capacitance of 10^6 pF.

SMD capacitor codes

In most of the SMD capacitors, values are marked on the cases. While some come up with codes. These codes are easy to decode and are also simple to learn.

One example for SMD type of coding is given below.

• In the example, a SMD capacitor code 472 with first two figures indicates the significant figures and the third indicates the multiplier.