Surface mount passive component value marking

Surface mount components ( resistors, capacitors, inductors) are harder to identify than their through – hole counterparts.. In addition they are very small ( the smallest in practical use is the 0402 size ( 40 mils by 20 mils). Almost impossible to see with the naked eye. If you find a SMD component what are its markings indicating? Here is some information about this which may be useful ( specially if you do a lot of surface mount assembly by hand). (1) Resistors: These will have either 3 or four digits on them. The last digit is simply the number of zeros after the first few digits. For example 473 is 47 followed by three zeros or 47k. Another example is 5673. Same old rule. This is a 567k resistor

(2) Capacitors are more difficult: Sometimes there may not even be any labeling If there is labeling, it is the same as SMD resistors, but in pF. Polarized capacitors have a stripe on the positive end of the package. Some electrolytic SMT capacitors may be marked on the negative end of the package. They are rectangular, and often black or tan colored. The black capacitors can be easily mistaken for diodes because of the white stripe on one end.

(3) Inductors: An inductor may use the color code system. If so the value represented is in µH. There may be a wide silver or gold band before the normal colored bands. A thin tolerance band at the end may also be there.

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