In the past I've tried to use 10nF (0.01uF) and/or 100nF (0.1uF) capacitors for decoupling ICs and micro-controllers.
However, I've heard that when using physically small capacitors (for example 0402), the capacitance of the capacitor doesn't affect the frequency response, and therefore it's best to just use the largest value you can get.
Therefore, I was wondering if it's a good idea for me to just buy a lot of 1uF capacitors in 0402 packaging and always use one of these going forwards (is 1uF too high?).
Specifically I was thinking about this one:
http://datasheet.octopart.com/CL05A105KP5NNNC-Samsung-datasheet-26589000.pdf
It's 1uF, 10V and 0402, it also works up to 85 degrees celsius and is made by a brand I've heard of. It's also pretty cheap at 0.5 cents each.
I'm interested if there's any reasons I'd need other values, or if this is a good idea. Additionally, should I stretch to 5uF in 0402 size? Is there a limit? (I can't solder smaller than 0402.)
Thank you.
Best Answer
High frequency behavior (ie, inductance or ESL) of MLCC caps depends on:
Capacitance influences the self-resonant frequency of course, but only has a very small influence on inductance, mostly through making the package bigger.
The real reason to stick lots of caps in parallel between power and ground planes is to lower the inductance. In this case, usually small values are used like 10-100nF, because it's cheaper. This matters for a PC motherboard where you got hundreds of caps.
If you replace them with 1µF, it will cost a little more, but it will work just as well.
For DIY stuff, it does make sense to do what you suggest. Just get a hundred 1µF caps with quantity pricing, and off you go. Please note that the "1µF" is only with 0V bias though, and smaller packages tend to lose more capacitance under bias than larger ones like 0805.
Note: I am not covering the case where the capacitor self resonant frequency is used in the design.