On 22 January, Gary Shoemaker wrote:
> Does anyone know the IEC spec (or any other document) that shows the value
> code used in the industry for resistors and capacitors (ei: 5R6=5.6pF,
> 103=10K)? Our documentation dept. wants published proof of this before
> accepting the code as our standard.
> Thanks,
> Gary Shoemaker
> [log in to unmask]
Hi Gary,
Pretty much most component manufacturers all mark components the same way
nowdays, but there are a few vendors out there that deviate from what the rest
of the world does, so my suggestion to you is to get a data book or catalog from
the vendor that you buy your components from...there normally is a section in
the catalog that describes the coding scheme that a particular vendor uses, and
use that for your reference.
But here is everything I know about SMT capacitor and resistor markings:
EIA Single-Character Marking:
The EIA has a standard for the marking of a single character on a resistor or a
capacitor to identify it's value. The color of the marking identifies the column
and the character itself will define the row for locating the value. The value
for resistors is in ohms and for capacitors the values are in picofarads. For
instance a Violet "A" is marked on top of a resistor, the value is 10K or 10,000
ohms.
----------------------Color----------------------------
Significant Orange Black Green Blue Violet Red
Character Digits X 0.1 X 1 X 10 X 100 X 1K X 10K
A 10 1.0 10 100 1000 10K 100K
B 11 1.1 11 110 1100 11k 110K
C 12 1.2 12 120 1200 12K 120K
D 13 1.3 13 130 1300 13K 130K
E 15 1.5 15 150 1500 15K 150K
H 16 1.6 16 160 1600 16K 160K
I 18 1.8 18 180 1800 18K 180K
J 20 2.0 20 200 2000 20K 200K
K 22 2.2 22 220 2200 22K 220K
L 24 2.4 24 240 2400 24K 240K
N 27 2.7 27 270 2700 27K 270K
O 30 3.0 30 300 3000 30K 300K
R 33 3.3 33 330 3300 33K 330K
S 36 3.6 36 360 3600 36K 360K
T 39 3.9 39 390 3900 39K 390K
V 43 4.3 43 430 4300 43K 430K
W 47 4.7 47 470 4700 47K 470K
X 51 5.1 51 510 5100 51K 510K
Y 56 5.6 56 560 5600 56K 560K
Z 62 6.2 62 620 6200 62K 620K
3 68 6.8 68 680 6800 68K 680K
4 75 7.5 75 750 7500 75K 750K
7 82 8.2 82 820 8200 82K 820K
9 91 9.1 91 910 9100 91K 910K
EIAJ Double-Character Marking
The EIAJ has a standard for the marking of two characters on a resistor or
capacitor to identify it's value. The first character identifies the row and the
second character defines the column for the value. There is no dependence on
color for the marking. The value for resitors is in ohms and for capacitors the
values are in picofarads. For instance a resistor with a "A4" marked on it would
be 10K or 10,000 ohms.
Significant
Character Digits 0 1 2 3 4 5
A 10 1.0 10 100 1000 10K 100K
B 11 1.1 11 110 1100 11k 110K
C 12 1.2 12 120 1200 12K 120K
D 13 1.3 13 130 1300 13K 130K
E 15 1.5 15 150 1500 15K 150K
F 16 1.6 16 160 1600 16K 160K
G 18 1.8 18 180 1800 18K 180K
H 20 2.0 20 200 2000 20K 200K
J 22 2.2 22 220 2200 22K 220K
K 24 2.4 24 240 2400 24K 240K
L 27 2.7 27 270 2700 27K 270K
M 30 3.0 30 300 3000 30K 300K
N 33 3.3 33 330 3300 33K 330K
P 36 3.6 36 360 3600 36K 360K
Q 39 3.9 39 390 3900 39K 390K
R 43 4.3 43 430 4300 43K 430K
S 47 4.7 47 470 4700 47K 470K
T 51 5.1 51 510 5100 51K 510K
U 56 5.6 56 560 5600 56K 560K
V 62 6.2 62 620 6200 62K 620K
W 68 6.8 68 680 6800 68K 680K
X 75 7.5 75 750 7500 75K 750K
Y 82 8.2 82 820 8200 82K 820K
Z 91 9.1 91 910 9100 91K 910K
a 25 2.5 25 250 2500 25K 250K
b 35 3.5 35 350 3500 35K 350K
d 40 4.0 40 400 4000 40K 400K
e 45 4.5 45 450 4500 45K 450K
f 50 5.0 50 500 5000 50K 500K
m 60 6.0 60 600 6000 60K 600K
n 70 7.0 70 700 7000 70K 700K
t 80 8.0 80 800 8000 80K 800K
y 90 9.0 90 900 9000 90K 900K
Three-Character Marking
Traditionally, most SMT passives use a 3-Character marking. The first two digits
are integers (0-9) of the value. The third digit is the number of zeros after
the integers, or otherwise known as the multiplier. For instance a 10K ohm
(10,000) resistor would be marked as 103.
Four-Character Marking
There are what's known as "Precision Resistors". Precision resistors will be
within a tight tolerance of it's marked value...mostly 1%. The first two digits
(0-9) are the integers, the third character is the tolerance range, and the last
character is the number of zeros or multiplier. For instance a 10K ohm (10,000),
1% resistor would be marked 1013.
Now, for a little rhyme that we used to use to remember how to tell the values
for PTH passives; "Our Bad Boys..."
NAW, I'd better not...I might kicked offa' the list...(GRIN ;^D)
Some of ya'll know what I'm talking' about, huh?
__\/__
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#------.OOOo----oo----oOOO.-----#
# Steve Gregory #
# SMT Process Engineer #
# The SMT Centre Incorporated #
# [log in to unmask] #
#________________Oooo.__________#
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