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January 1997

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Subject:
From:
"Max Bernhardt "<[log in to unmask]>
Date:
Thu, 23 Jan 1997 08:58:00 -0600
Content-Type:
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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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