Rick,

The dimensions you called out are well within achievable limits. Some of our customers
(we're a fabricator) send in work with little or no solder mask dam, we usually 'beef'
it up to compensate for our processes.

If they expose at correct levels, then develop it properly they really should have no
problems meet those requirements.

...and afterthought...when we have ran into extremely dense pitch we have added cure
time or included UV exposure to ensure the dam does not become compromised...

Good luck

Franklin D Asbell
Network Circuits, Inc.
Irving, Texas 75061

Rick Thompson wrote:

> Hi,
>
> We have a customer who has a board with 20 mil pitch QFP's on it.  The
> actual pad size is 11.8 mils wide and there is a 2 mil gap in the soldermask
> around the pads leaving 4.2 mils of solder mask between the pads.  The board
> house that is building these says they can't maintain the soldermask between
> the pads and is asking for a window around all leads in the group or a
> tightening of the soldermask openings around the pads.  Before I go to our
> customer with this, I'd like to get some feedback on whether or not this is
> unreasonable?  Are these dimensions acheivable or should I ask our customer
> for a deviation?
>
> Thanks in advance,
>
> Rick Thompson
> Ventura Electronics Assembly
> 2665A Park Center Dr.
> Simi Valley, CA 93065
>
> +1 (805) 584-9858 voice
> +1 (805) 584-1529 fax
> [log in to unmask]
>
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