Surface Mount Capacitors and their Markings

[AaronRollens]

Decoding Capacitor Part Markings

This guide is intended to take the mystery out of identifying part markings on the various styles of capacitors.

All capacitors are measured in Farads. The scale of which they are measured can sometimes be different. If they are measured in Farads, Microfarads, Nanofarads, or Picofarads can be determined by the physical size and type of the capacitor.

Click here for a refresher on the Metric System and how to convert between the metric scales.

Larger parts might spell this outright as the product has the space to do it. When they do there are a couple of things to be careful of.

• You may see the units of millifarad referenced as MF instead of mF like the convention tells us it should be. with that said, millifarad is rarely used.

• Even though the proper way to call out microfarads would be µF, there will be times that is specified using an “MFD”

As the parts get smaller, the specifications tend to be conveyed by a code. The type of capacitor and the convention of the code used on it will play a part in decoding what it actually means.

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Aluminum Electolytic Capacitors

These are usually large enough that their specifications will be printed on them but there are expections to this. The most notable example would be the surface mount version.

To learn more about the voltage

SMT Electrolytic Capacitor with no Voltage Rating

One questions that comes through our department is from customers who are trying to identify a surface mount Aluminum Electrolytic Cap and there is no Voltage listed. Once we start looking at the cap we often find that the voltage is listed, however as a letter and not the actual voltage value. Here is a marking chart from Rubycon’s TZV series of Capacitors. [image][image] Cornell Dubilier has a similar chart with their AFK Series [image] This however is not standard as some of the capacito…

will have markings two to four characters is length.

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Three-Digit EIA

Standard-tolerance SMD capacitors use a 3-digit code to mark the capacitance value on the part. The first two numbers will indicate the significant digits, and the third will be the multiplier. ‘R’ is used to indicate the position of a decimal point.

10	Significant Digits
7	Multiplier

To get our value we multiply our significant digits against our multiplier. We simply add that number of zeros on to the end. This value is in picofarads. To change to to microfarads, simply move the decimal point to the left six spaces.

10 + 0,000,000 = 100,000,000pf
100,000,000 pf = 100µF

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Four-Digit EIA

Similar to the three digit EIA, the four digit format uses the beginning values to indicate the significant digits, the last digit as the multiplier and a letter designating a tolerance. ‘R’ is used to indicate the position of a decimal point. The four digit format allows for higher precision.

Tolerance code

Code	Tolerance Value in %
B	0.1
C	0.25
D	0.5
F	1
G	2
J	5
K	10
M	20
Z	+80/-20

The Tolerance code D = 0.5%

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Two-Digit EIA ( EIA-198)

Sometimes there is so little room on the part that even the standards are not practical. The EIA-198 system of part marking uses two characters (one number and one letter) in which the letter represents the value and number represents the multiplier. There are a couple of things to know.

• *This system is case sensitive.
  You will notice that by using some of the lower-case versions of letters they could eliminate many of the troublesome numbers such as I and O. They too easily get confused for 1 and 0.

• The capacitance codes are not based upon the capacitance value like the others
  The first digit is used for capacitance and correlate to the following tables.

• Please be aware, While this system is still measured in picofarads, The multiplier code is one more than what we are used to in the other two methods.

Code	pF
A	1
B	1.1
C	1.2
D	1.3
E	1.5
F	1.6
G	1.8
H	2
J	2.2
K	2.4
a	2.6

Code	pF
L	2.7
M	3
N	3.3
b	3.5
P	3.6
Q	3.9
d	4
R	4.3
e	4.5
S	4.7
f	5

Code	pF
T	5.1
U	5.6
m	6
V	6.2
W	6.8
n	7
X	7.5
t	8
Y	8.2
y	9
Z	9.1

Multiplier Code	Value
0	1
1	10
2	100
3	1,000
4	10,000
5	100,000
6	1,000,000
7	10,000,000
8	100,000,000
9	0.1

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Comparison

Three-Digit EIA	Four-Digit EIA	Two-Digit EIA ( EIA-198)
107	107D	A8
100µF	100µF	100µF
-	0.5%	-

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Voltage Ratings

Some capacitors also have a voltage rating that is indicated by a two character code begining with a number and ending with a letter.

Code	Voltage		Code	Voltage		Code	Voltage
0E	2.5VDC		2A	100VDC		3L	1.2KVDC
0G	4.0VDC		2Q	110VDC		3B	1.25KVDC
0L	5.5VDC		2B	125VDC		3N	1.5KVDC
0J	6.3VDC		2C	160VDC		3C	1.6KVDC
1A	10VDC		2Z	180VDC		3D	2KVDC
1C	16VDC		2D	200VDC		3E	2.5KVDC
1D	20VDC		2P	220VDC		3F	3KVDC
1E	25VDC		2E	250VDC		3G	4KVDC
1V	35VDC		2F	315VDC		3H	5KVDC
1G	40VDC		2V	350VDC		3I	6KVDC
1H	50VDC		2G	400VDC		3J	6.3KVDC
1J	63VDC		2W	450VDC		3U	7.5KVDC
1M	70VDC		2J	630VDC		3K	8KVDC
1U	75VDC		2K	800VDC		4A	10KVDC
0K	80VDC

Resources

If you would rather do some pointing and clicking to find your value I recommend you check out our SMD Capacitor Code Calculator.

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[reallybadguy]

I haven’t been able to find an answer to this question, so maybe you’ve got it.

I’m trying to identify SMD caps on an existing assembly, and they’re marked with what appears to be the two-character EIA-198 code, but followed by a caret (^), e.g. A5^ . Any idea what that might indicate? Voltage, manufacturer, tolerance, etc.?

[Verna_1353]

Welcome to the Technical Forum. Can you post pictures with the part markings clearly shown? We can then try to see if we can identify them with the pictures. If you can give dimensions that would be useful also.

[reallybadguy]

No pictures available. It’s just as I described, three characters, that’s all. The one marked A5^ (previously mentioned, and presumably a .1uF) is a 1210. This board is from the late 1980s.

[Verna_1353]

I am not sure what the A5 is. You can look through the .1uf 1210 options we have on the website:

Capacitors | Ceramic Capacitors | Digi-Key Electronics

I would try to figure out with the circuit how much voltage this needs to handle. You can narrow the search by the voltage to get less options. If you are unsure you can just choose the highest voltage. Though doing this could make the tolerance worse. I am not sure with the information provided what the voltage would be.

[reallybadguy]

@Verna_1353

I am not sure what the A5 is.

Then why are you replying to a question about “Surface Mount Capacitors and their Markings”?

Please have someone reply who understands the subject.

[Ryan_2724]

Hi reallybadguy ,

I notified all our technical staff, to see if anyone can identify what this vintage caret symbol ^ would be. Hopefully someone will have knowledge on the importance of what this vintage symbol means. I am hoping we get a response today, but possibly this week sometime as we may have some currently out of office.

Thanks for your patience and look forward to one of our employees to hopefully have more knowledge on this.

@DigiKey_Internal

[Brian_2933]

I searched alot and will look some more but did notice that AVX uses ^ as a logo sometimes it is filled in like an arrow head and sometimes it is a sharp ^ however it always is on the left of the part but I do not know how they did it in the 80’s … I will keep looking and update If I find more.