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I want to buy some 0402 SMD capacitors (well some is about 1 to 10k).

I always use the method of use the cheapest part for the given specs approach. But today I noticed something odd:

I was comparing these two parts on digikey:

Partno.         Price/piece   Price for 10k
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490-10777-2-ND  0,00317€      31,68€
399-8942-2-ND   0,08236€      823,63€

The top one is from a company called murata (never heard of them) and the bottom one is from KEMET (which I know of). But looking at the specs given, there is absolutely no justification for the much higher price:

enter image description here

I know there might be some other parameters which might come in to play which are not listed by digikey.

But really 10 times the price for some capacitors? What is the justification ? Is it because of the brand-name? If so, why should I care?

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    \$\begingroup\$ Some companies charge strange things to make profits off of runs. However, there are still things like ESR, ESL, frequency variation of capacitance, RF certification, and a myriad other things that you'd only find in the data sheet. These can make a difference. Or it could be that these are a reference part for something (or several things) and people just buy them without thinking (or wanting to re-certify the design). Demand goes up and so does the price. I've seen that second scenario a few times. \$\endgroup\$
    – Dave
    Commented Dec 31, 2015 at 8:57
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    \$\begingroup\$ Murata is a massive company. If it's anything to do with brand, then my guess is that Murata can make more caps, keep their costs lower and therefore sell it cheaper. \$\endgroup\$
    – Armandas
    Commented Dec 31, 2015 at 8:58
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    \$\begingroup\$ It would not be surprising to hear that Murata loses 1 to 10k capacitors under their equipment each day. \$\endgroup\$
    – Ignacio Vazquez-Abrams
    Commented Dec 31, 2015 at 9:12
  • \$\begingroup\$ hrm.. I looked at both datasheets and both do not specify a ESR/ESL value :( what would you suggest doing / buying ? How important is the ESR/ESL value for decoupling logic ICs? I never have seen an ESR/ESL value given for a bypass cap in a datasheet :S \$\endgroup\$
    – Marco
    Commented Dec 31, 2015 at 9:17
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    \$\begingroup\$ ESR and ESL can be very important in bypass applications, depending on the specifics of the circuit. A decent ceramic from a reputable manufacturer (and both above meet that criteria) will have an ESR measured in milliohms. ESL is dominated by the package. I posted an answer about ESL at electronics.stackexchange.com/questions/193608/… \$\endgroup\$
    – Peter Smith
    Commented Dec 31, 2015 at 9:49

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Making an 100nF/10V X7R in a tiny 0402 for $0.002-0.003 is close to bleeding edge. My take is that Kemet is an older U.S.-based company and they simply have not mastered it yet. They do have competitive prices on 0603 parts.

Since you have the choice of many well established Asian companies you're probably fairly safe with that size - Samsung (Korea), Taiyo Yuden (Japan), Murata (Japan) and Yageo (Taiwan) all have competitive prices in your one-off quantity (one lone reel is not reely a large quantity). If you're not buying for mass machine production, 0402 is not pleasant for hand assembly- 0603 is worth the small difference IMHO.

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  • \$\begingroup\$ what about 0201 components? \$\endgroup\$
    – Marco
    Commented Dec 31, 2015 at 16:19
  • \$\begingroup\$ 0201 components, while great for high density designs, are not what I would choose for hand assembly; a microscope and a very steady hand are required. Due to the smaller size, the voltage ratings for 0201 are substantially lower than for 0402 devices. 0201 devices have to be handled carefully due to the increased risk of shorts beneath the device due to the small pad spacing. \$\endgroup\$
    – Peter Smith
    Commented Dec 31, 2015 at 16:40
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    \$\begingroup\$ @d3l If you really need that kind of density, 0201 and 01005 (0.4 x 0.2mm) (and even metric 03015 - 0.3 x 0.15mm) parts are available, sure. I'm sure I could assemble them (for a prototype) under my Leica microscope too, but for a low density design it's silly. I was even getting occasional problems (tombstoning) from the contract assembler with 0402 parts only a few years ago. \$\endgroup\$
    – Spehro 'speff' Pefhany
    Commented Dec 31, 2015 at 19:55
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    \$\begingroup\$ @d3l You might also want to check the voltage coefficient- with very small parts it can be shockingly large. In the case of 0201 parts you may have to settle for poor tempco as well (X5R). Also a reel of 0201 is usually 15,000 parts (at a premium price) so you may be looking at 4x the outlay of 0603 or 0402 parts. \$\endgroup\$
    – Spehro 'speff' Pefhany
    Commented Dec 31, 2015 at 20:05
  • \$\begingroup\$ @SpehroPefhany I saw that with the poor temp coefficients for the 0201 parts. I mainly want to use them because I need to decouple some BGA-Devices. Probably I don't get a reel of 15k parts (too expensive). Thanks for your advice :) \$\endgroup\$
    – Marco
    Commented Jan 1, 2016 at 6:01

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