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Why are SMD resistors marked with their value, but SMD ceramic (and similar) capacitors are not? Most SMD resistors, even the very small 0402 and 0603 ones, have their values written on them. Most SMD ceramic caps are not, I haven't to date seen a single one. The only possible reason I can think of is that resistors are far more likely to fail than capacitors as they natively dissipate heat. Supporting this theory is the fact that tantalum and aluminium electrolytic capacitors generally have a value written on them, because they are less reliable than ceramics.

Out of curiosity.

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    \$\begingroup\$ I've never seen a value on an 0402 resistor. \$\endgroup\$
    – markrages
    Commented Mar 18, 2011 at 2:20
  • \$\begingroup\$ @markrages On some older 0402's, I have. Perhaps they have stopped doing it. I use 0603 in most of my designs. \$\endgroup\$
    – Thomas O
    Commented Mar 18, 2011 at 8:02
  • \$\begingroup\$ Many capacitors have tolerances that are very bad, so the number that you want to see is almost meaningless in the first place. Even if they had 0% tolerances, the value of many capacitors is all over the place based on temperature and voltage. \$\endgroup\$
    – doug65536
    Commented Nov 8, 2022 at 1:42

3 Answers 3

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The reason is that 'default' surface material used in resistors is suitable for printing, while on caps(ceramic dielectric) it's not. Extra coating would increase price & reduce cap quality, that's why they don't do it usually. When caps are big enough & plastic, they usually have markings.

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    \$\begingroup\$ Also, SMT resistors have a top and a bottom (e.g. resistive film is on only one side), while caps do not (top and bottom are interchangeable) \$\endgroup\$
    – Connor Wolf
    Commented Mar 18, 2011 at 2:26
  • \$\begingroup\$ I've seen an example of ceramic SMD caps with printing - 0805 size or so. As I recall it wasn't readily decodable. \$\endgroup\$
    – John Lopez
    Commented Mar 18, 2011 at 2:51
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    \$\begingroup\$ +1 can you provide a link to the reference(s) you found? \$\endgroup\$
    – kenny
    Commented Mar 18, 2011 at 15:05
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    \$\begingroup\$ So why are tantalums frequently printed with useless nonsense ? \$\endgroup\$
    – Rocketmagnet
    Commented Mar 19, 2011 at 11:49
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I disagree with the others on the statement that caps are easy to troubleshoot. I do QC for living and when the wrong cap value is installed, it is an absolute hell to figure out the problem. Caps have the same exterior coating as most microchips. There's no real excuse for why they aren't labeled.

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    \$\begingroup\$ MIL-spec caps have to be marked for inspection. Of course they cost more :D \$\endgroup\$
    – Lorenzo Marcantonio
    Commented Apr 1, 2021 at 7:32
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I think it's simply a case that the material is harder to mark economically. Also there are typically far fewer different value caps than resistors, so the mark being there for inspection purposes is less necessary.

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