My experience is that it depends. For one
thing a 25KV ESD discharge happily jumps over an 0402 but not a 1206 and
sometimes not an 0805. As nice as small parts are they don't always fit
the bill, especially for ESD,EMI,RFI etc.
Another thing I have seen happen is when a
product gets bombarded with an external radiation source, the smaller caps
don't even look like a cap electrically.
The test I am talking about is a 0-10 GHz sweep
at 1v/1M. This is what I like to call the UFO test, because when tested
on vehicle applications, the lights on the dash glow without vehicle power,
but you'll be in trouble if your electronics fail.
Also on power applications for UL requirements a
1206 might fit the bill for trace and or pad spacing at 120Volts, but a 0603
certainly will not.
Also on applications where board layers are
restricted i.e. double or even worse single layer boards, on a 1206 you can
jam between 3 and five traces under a 1206 where a 0402 you won't get 1 or
maybe 1 if you're lucky.
I still laugh at those who said through hole
technology is dead years ago. Hmmm seems to still be real active to
me. Not to mention all that darn machinery for making through hole parts
was paid for long ago. Of course when it breaks down, you might have to
dig up the guy (literally) that knew how it was designed and how to fix it,
but hey, with that cloning thing maybe.....oh never mind.
Mark Ross
----- Original Message -----
Sent: Thursday, August 09, 2001 11:41
AM
Subject: Re: [TN] Capacitor 0603 vs
0402...why not networks and arrays?
Hi
Steve and everyone,
Thanks for the inputs. You
guessed it...real estate is at a premium. Individual caps are used
here for electrical performance and placing them at specific locations is
critical. Still, arrays arrays are something to keep in mind in the
right application.
Thanks again,
Glenn
Hi Glenn!
I've read the
responses you've received to your question (they've all been
good),
and want to ask another question...
I assume the reason to use
smaller passive components, is to reduce the real
estate needed by
these components. My question is; why isn't there more use
of chip
resistor networks and capacitor arrays?
To me, it seems obvious
that the use of these components will reduce real
estate, but I don't
see them being used as often as they could be...maybe I'm
not aware of
the electrical characteristics or something else, but I wonder
why
they aren't used more often in designs that are tight for space than what
I've seen so far...
Can anybody shed some light on this?
-Steve Gregory-