Reverse aspect ratio capacitors

[Joel Kolstad]

(I didn't get any response to this over on sci.electronics.components so I'm
trying it here...)

Could someone who's used 0508 and/or 0306 sized capacitors comment on whether
or not you had any particular difficulties in manufacturing relative to the
use of 0805s and 0603s? Our contact at our current contract manufacturer
initially said he'd never _heard_ of 0306's and, after talking to some of his
guys, said that, yes, they had used them, but sometimes ended up having to
laser trim the footprints (presumably so as to avoid solder bridging between
the pads or part misalignment or somesuch). I'm curious as to whether this is
a real problem with reverseaspect ratio parts, or if it's a lot of FUD on
their part... I'm really surprised that there's been so much resistance to
using the things!

Thanks,
---Joel Kolstad

 

[PeteS]

I used 0306 parts a year or two ago and I had no problem at all with
them. My board manufacturer was somewhat higher end (Tyco Santa Clara,
I seem to recall), but with the proliferation of smaller parts (0201
come to mind) no PCB manufacturer that does fine pitch should really
have any issues with them.

Note that the stuff/reflow people need to take care with the solder
stencil, but there's plenty of knowledge out there to deal with this
stuff.

Cheers

PeteS

 

[[email protected]]

Could someone who's used 0508 and/or 0306 sized capacitors comment on whether
or not you had any particular difficulties in manufacturing relative to the
use of 0805s and 0603s?

What advantage do these components offer over the incumbent types?

I'm sure there are some, just not thinking of them, only the
disadvantages, such as not being able to route as many traces through
the middle.

 

[PeteS]

These components have lower ESL (because they are physically shorter in
the signal path).

Cheers

PeteS

 

[Joel Kolstad]

What advantage do these components offer over the incumbent types?

Roughly one quarter the equivalent series inductance, which results in a
self-resonant frequency that's roughly doubled. Additionally, they more
closely match the width of a 50 ohm microstrip trace (on a regularly spaced
four layer .0625" board, this is usually in the ballpark of 25 mils wide), so
there's a small but measuable improvement in transmission flatness.

---Joel

 

[Jasen Betts]

What advantage do these components offer over the incumbent types?

Lower inductance


Bye.
Jasen