Dan,

Assuming your aspect ratio is right, a good -325 mesh solder paste is capable and consistent to 0.4mm apertures so a smaller mesh should not be necessary.  The benefit vs cost comparison is poor.  Below 0.4mm a -400 or -500 mesh (depending upon aperture size) gives a marked improvement in depoist consistency due to the ball size to aperture size ratio.  If your paste has trouble with 0.5mm apertures in general, then a -400 is probably in order for the 0201 process.

John Vivari
Technical Service Engineer
EFD Inc.
www.efd-inc.com
<mailto:[log in to unmask]> 
Ph: 401-333-3800 x2204
Fx: 401-333-4954

Date:    Wed, 19 Dec 2001 14:49:39 -0800
From:    "Dan R. Johnson" <[log in to unmask]>
Subject: mesh size

I am currently using a -325 mesh solder paste, we just started using 0201 components. Will a finer mesh solder give me more uniform solder application with the smaller apertures?

Dan