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January 1997

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Wed, 22 Jan 97 20:38:20
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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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