Basic information for Electronics
Capacitor Basics Guide
by Leif Erickson (Copyright 1//02/04)
Nano, Pico, Micro?
We first start out with nomenclature. These are the basic measures of Capacitance,
Inductance, Resistance, and any type of electronic measurement.
You can replace Farad with Ohms or Henry, Hertz, etc.
1 mF (milli) = 10-3 farad,
1 uF (micro) = 10-6 farad.
1 nF (nano) = 10-9 farad,
1 pF (pico) = 10-12 farad.
1 pF = 10-3 nF =10-6 uF.
Nano is used almost as much as micro and pico, mostly in European designs. 100 nanofarads = 0.1uF.
"Femto farad " (fF) is used as a very small capacitor value, usually an "On Chip" capacitor,
as there are no discrete capacitors available in that size range.
On a 0.1 uF cap you will see the numbers "104", means it is a 0.1uF, a "105" is a 1 uF,
"103" is a 0.01uF,
"102" is a 0.001 uF/1000pF,
"101" is a 100pF,
"100" is a 10 pF part.
Caps smaller than 10 pF usually have an R between digits, like 4R7, for 4.7 pF.
BIG Thing, parts markings, and sizes:
1206 stands for the size of a part. 0.120" x 0.060" for 1206.
1210 is 0.012" x 0.010".
0805 is 0.080" x 0.050" in size.
0603 is 0.060" x 0.030".
Very important concept for the novices and others!! This goes for all passive devices.
Check out the links below for more in depth information. Cross References, Markings, and applications and Data sheets.
How to decipher Capacitor markings
It would be nice if there was a little more consistency to capacitor markings.
When the manufacturer has a lot of room, like big electrolytics, they usually print Capacitance, Working Voltage, and Temperature range,
series, and even country of manufacture.
As the part gets smaller, the less information you get until, the Code Marking begins.
On small through-hole ceramics, a two-number-plus-exponent system is often (but not always) used.
Like most marking systems, this is based on the picofarad, the lowest value of capacitance.
330 may be 33 (33 x 100) or 330 pF but 331 is almost certainly 330 (33 x 101).
333 will probably be 0.0033. However, 335 will probably mean 3.3 (33 x 10-5)or 3.3 uF.
Values below 10 pF may use "R" for a decimal point, 4R7 = 4.7 pF for example.
You may also find the material (C0G, X7R, Z5U, etc.) and voltage rating.
The tolerance may be next to the value.
Don't expect to find every possible combination of values, tolerances, and dielectrics.
The tighter tolerances mostly apply to small C0G capacitors and the looser tolerances(more variance in capacitance) to larger Class 2-4 ceramics.
COG, or NPO is the best, tightest tolerance, then X7R, then Z5U.
Markings are not consistently used by manufacturers, suggesting they may not be EIA sanctioned.
For example, if you see .033K, the value is .033 uF 10%.
Some ceramic disks have a color "skull cap" to indicate the type of dielectric. These will also use a XXM format to indicate value (where the M is the multiplier), and a tolerance letter.
For example, 102J with a black cap would a 1000 pF 5% C0G. There is a similar system for Class 2 and 3 ceramics.
With European parts, you may also see capacitors marked with a two-digit system with the "multiplier" letter used as a decimal point. For example, 4700 pF would be written as 4n7, which is 4.7 nanofarads.
Some film capacitor manufacturers use a code that indicates the capacitor type. I have seen it referred to as "European". A few manufacturers seem to follow this system exactly, while some others sometimes use it with variations.
More info is available at :
Murata caps codes
Kemet capacitor company-More good info
Also check out these manufacturers Application notes and Specifications - Panasonic, Murata, Vishay, CDE, Nichicon, and Xicon.
CDE capacitor company-good info
Tecate Group caps and more
listing of cap companies
Vishay Surface mount caps
KOA-Speer Surface mount caps
The technician or hobbyist using surplus parts (or someone doing repairs) should consider investing in a cheap capacitance meter (or build one). See the Links Page for sources of Test Equipment circuits.
SMD ceramics will often be marked with a two-digit EIA code (letter plus number) to indicate value. You may also see a one-digit-plus-color-code.
Manufacturers usually offer volume buyers three marking options, EIA standard, custom, and none. What you usually get is NONE.
For example, A5 = 1.0 x 105 = 100,000 pF = 0.1 uF, and f9 = 5.0 x 10-1 = 0.5 pF.
SMD tantalums usually have enough room to have the value and voltage spelled out (sometimes without telling you which is which), some use the two-digit EIA code above, and some are marked in other ways.
Tantalums can also be found with a voltage code (instead of the tolerance code normally seen on ceramics).
At least one company sometimes uses the letter part of the EIA code, without the exponent, to indicate uF instead of pF (J would be 2.2 uF).
When it comes to polarity identification, tantalum manufacturers are totally fixated on the anode, either with a stripe (either white on black body or black on light body), a "+", a sharp bevel, or some combination.
However, some SMD tantalums are so small they have no markings at all. In that case, the anode end is identified by allowing a nib of anode wire to stick through the anode termination. I donīt know of any manufacturer who marks the cathode, but who knows?
Military capacitors use a long-winded code that gives dielectric, temperature drift, value, tolerance, temperature range, voltage, and failure rate.
See http://fcim.csdc.com for that and some other marking codes.
Obsolete Mica Codes
Molded micas (sometimes called "stamp" micas) came in cases with molded-in "pockets" for colored paint dots that identified some combination of value, tolerance, voltage rating, vibration rating, temperature rating, and temperature drift.
MIL-C-5 used a 6 and 9 dot system to show value, tolerance, voltage, vibration rating, and temperature drift. The voltage rating was determined by case dimentions when 6 dots were used.
EIA RS-153 was a 5, 6, or 9 dot system very similar to MIL-C-5. The EIA system covered "button" micas as well as stamp micas. Manufacturers have used a variety of proprietary 3, 4, 5, and 6 dot systems to show value, tolerance and voltage. Eventually, some manufacturers gave up the paint dots and just printed the numbers on the case, especially if the part didnīt fit the system (a 1/2% tolerance part for example).
Click here for the color codes for most of the manufacturerīs systems.
Click here for the Mica color codes.
Other Obsolete Codes
Someday, this may be of interest to people repairing antique electronics. Molded paper capacitors once used a color dot system of the sort used by molded micas.
Additional sites with capacitor marking information. Be sure to search for Application Notes, and Specifications on capacitors. Be amazed at how much you can find in the manufacturer's sites.
Click Here for a Cross reference to ceramic caps from 18 manufacturers.
Go to the main page http://www.avxcorp.com for more info.
Click here for a small but informative SMD code table.
Click here for a collection of capacitor marking standards for older mica, ceramic, and paper capacitors.