Great explanation Steve, However, the four digit marking is actually
the following: First 3 characters are significant digits. Fourth
character is multiplier. ex. 1013 = 10100 = 10.1 Kohm. With 1% or
tighter resistors, a person needs 3 digits to accurately describe the
resistor.
In addition, Electrolytic Aluminum caps, and many large films are given
in microfarads instead of picofarads. For example a KMH50VB332M25X35LL
is 3300 microfarads.
Hope this helps.
Max Bernhardt
Woodward Governor Co.
----------
From: [log in to unmask]
To: [log in to unmask]
Subject: Re: DOC:IEC Component value code
Date: Thursday, January 23, 1997 12:33AM
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?
__\/__
. / ^ _ \ .
|\| (o)(o) |/|
#------.OOOo----oo----oOOO.-----#
# Steve Gregory #
# SMT Process Engineer #
# The SMT Centre Incorporated #
# [log in to unmask] #
#________________Oooo.__________#
.oooO ( )
( ) ) /
\ ( (_/
\_)
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