Dan,

The rule of thumb that I had heard from a solder paste application engineer
was that you should be able to fit 8 solder balls across your smallest
aperture width.

I am not sure your 0201 solder paste aperture will work very well (unless
you made a typo).  .13mm x .26mm is really, really small.  If your foil size
is .076mm
(.003") or greater, your aspect ratio is below .6

You really need to be around .3mm x .35mm or .34mm square if your foil size
is .13mm.  This puts your AAR over .66

Steve A

> -----Original Message-----
> From: Dan R. Johnson [SMTP:[log in to unmask]]
> Sent: Thursday,December 20,2001 8:19 AM
> To:   [log in to unmask]
> Subject:      Re: [TN] mesh size
>
> Thanks John, this confirms what I thought. I don't know if you could say
> the aspect ratio is "right" but I am using a .13X.26mm paste pad. This is
> an Rf application and the design engineer is adamant that all component
> pads be as small as possible.
> You mentioned the ball size to aperture size ratio, is there a "rule of
> thumb" for this?
> Dan

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