# Advice needed: comparing two parts

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
-------------------------------------------
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:

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?

• 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. – Dave Dec 31 '15 at 8:57
• 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. – Armandas Dec 31 '15 at 8:58
• It would not be surprising to hear that Murata loses 1 to 10k capacitors under their equipment each day. – Ignacio Vazquez-Abrams Dec 31 '15 at 9:12
• 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 – marco-a Dec 31 '15 at 9:17
• 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/… – Peter Smith Dec 31 '15 at 9:49