capacitorpackages
I'm looking at a capacitor that will be used as an output cap on a buck regulator. Looking at what I think is the same exact cap from TDK (10uF, 16V, X5R) but in an 0603 and an 0805 package.
Beyond those parameters, is there something else I should be paying attention to that's likely to change as package sizes change? I can't find ESR or ESL values in either, other than a nominal "low ESx" statement in the description.
In general, what starts to give as package sizes decrease for capacitors?
It looks like SON and DFN refer to the same package. JEDEC documents like this one talk about "SON/QFN", but on the whole JEDEC site I couldn't find one reference to "DFN".
On the other hand, among its dozens of packages Linear Technology lists DFN and QFN, but there's no trace of SON.
JEDEC describes the USON as:
The Plastic Ultra-Thin Small Outline No-lead Package(USON) is a rectangular semiconductor package with metal terminals along two sides of the bottom of the package. The terminals are either flush with bottom or protruding slightly below bottom of package. The main body of the component is generally a molded plastic.
So a SON package, having its terminals on two sides, is much like a DFN. So 4 pins on 2 sides would be SON/DFN. A QFN-12 may have 4\$\times\$3 terminals, but other configurations like 2 \$\times\$ (5 + 1) are also possible.
This may cause some confusion if we look at the following package:
which appears to be a DFN-16 and not a QFN-18.
Common tolerance codes for capacitors: J = ± 5%; K = ± 10%; M = ± 20%.
Common value code for capacitors: Two numbers, and a third number c, where c tells you the number of zeroes behind the first and second number. Usually, the result is to be read in pF.
Sometimes, there's also a value expressed in pF or µF, and you have to guess which is right. Some examples:
A ceramic capacitor with the number "470" on it likely has 470 pF, because ceramic caps are still mostly used for small-ish values.
"0.47" doesn't make sense in pF, because 0.47 pF would be too small for almost any practical use, so pretty much all capacitors labeled "0.47" will have a value of 0.47 µF = 470 nF.
"470" on a large-ish film or electrolytic capacitor will likely mean the cap's value is 470 µF.
(And even more strange markings do exist...)
Now, let's use your capacitors' markings as examples for this - here's what I guess:
capacitor #1:
103M Z5U 2-3KV ARC GAP KAP CHINA
10 * 103 pF = 10 000 pF = 10 nF. M: ± 20%
Z5U is the type of dielectric. This is a pretty creepy type of ceramic with huge tolerances over voltage and temperature.
capacitor #2:
NPO 7.5D IKV
7.5 is a fairly uncommon value for a capacitor. Mostly, you find values from the E6 or E12 series, hardly anything else. However, 7.5 is part of the E24 series, so it is not entirely alien, and according to this source, D would mean you have a tolerance of ± 0.5 pF. NP0 is a very good type of ceramic mostly used for values below 10...100 pF (that 0 in NP0 is a zero; I remember to have read that NP0 means negative-positive-zero, i.e. nearly zero tolerance over temperature and voltage changes). I guess your cap has 7.5 pF. That I is likely a 1, meaning the maximum voltage for this cap is 1 kV.
Capacitor #3:
CM 1000M 125L
Maybe 1000 pF = 1 nF, with a tolerance of ± 20 % (M).
Capacitor #4:
271 2KV
27 * 101 pF = 270 pF. Maximum Voltage: 2 kV.
Capacitor #5:
Z5U 4700M IKV
Another one with a cheap type of ceramic (Z5U), probably 4 700 pF = 4.7 nF. Tolerance: ± 20 % (M). Max. Voltage: 1 kV.
Again, this is guess-work. Unfortunately, there is no standard that all manufacturers adhere to, so to be exactly sure, you would have to measure your devices and find the original data sheets with the device marking specifications, which can be very, very annoying.
Even more examples from similar questions: Identifying Capacitors, https://electronics.stackexchange.com/questions/10474/what-kind-of-capacitor-is-this
Best Answer
What gives? Cost, availability are non-technical factors. The smaller ones cost about triple the price in 1000's. You can check and see what other sources you have available if the TDK ones are not in stock.
The voltage coefficient also tends to be higher for smaller parts, meaning you'll typically see less capacitance at operating voltage for the smaller part.
Edit: You'll have to dig pretty deep to find the voltage coefficient specifications, on the manufacturer's websites. Here's some representative performance of similar Japanese-made parts (Murata), thanks to a Maxim article.
Edit2: I really suggest you go to http://www2.tdk.co.jp/ccv/step3.asp. It's an online tool that will show you the typical characteristics of a TDK component directly from the part number. Most of the characteristics of the smaller part are worse including tempco and voltage coefficient (the 0603 almost does a disappearing act at 10V bias).
For what it's worth, I went through this selection process a few weeks ago and chose 0805 parts for two new products.