Oops, I didn't read the original question very well, I thought you were
referring to QFP's instead of CSP, therefore my earlier answer doesn't make
much sense. Sorry.

Daan Terstegge

----- Original Message -----
From: "d. terstegge" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, December 15, 2003 4:34 PM
Subject: Re: [TN] .5 mm pitch components


> Hi Ted,
>
> Padsizes you can find in IPC-SM-782 or IPC's online footprint
> calculator. 12 mil width is standard, anything smaller than that may
> result in problems with paste printing. This leaves hardly any space for
> a good solder mask stripe, therefore it is quite common to have one
> large soldermask window around each row of pads, although some would
> argue that you need soldermask between each individual pad to get good
> gasketing of the stencil while printing solder paste. You may need the
> inner layers for the fan-out pattern, but that doesn't mean you need
> via-in-pad. When possible use ordinary via's for this.
> Hope this helps.
>
> Daan Terstegge
> Thales Communications
> Unclassified mail
> Personal Website: http://www.smtinfo.net
>
> >>> [log in to unmask] 12/14/03 02:59am >>>
> Hi all,
>
> Want to find out what pad size and solder mask opening
> are people using for .5 mm pitch components?  Since
> the pad size is so small, it is a must to use solder
> mask define pads?  Are people using via-in-pads to get
> traces out or just using the outer layers?  Thanks all
> in advance.
>
> Ted Kong.
>
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