Brad,
Thank you for clarifying.

Always interesting to learn what others are experiencing.  We aren't 
using no-clean paste.  I imagine that's the biggest process 
difference between us.

Live and learn.

Thanks again,
Steve


At 11:02 AM 1/12/2006, you wrote:
>Steve,
>         My pads are similarly oriented. Typically my pad width 
> matches the chip width.
>
>         We are homeplating because of excess solderball generation. 
> It is something that became more prevalent recently with current 
> formulations of no-clean (leaded) solder pastes that we were 
> getting. Our screens are anywhere from 5mil to 7 mil thickness 
> depending on the assemblies. We are homeplating all chip components 
> that do not have some form of relief (i.e. SMB or SMC devices, some 
> molded devices have relief areas, troughs, around the contact where 
> the solderpaste is not squished between the contact and the part 
> body) around the pads/contacts. Our SMT people tried a lot of other 
> solutions and consulted with the paste supplier extensively, the 
> only workable solution we found was the homeplating. Of course 
> being a SMT production issue it could have contributing factors 
> from many sources during processing.
>
>Sincerely,
>Brad Velander
>Senior PCB Designer
>Northern Airborne Technology
>#14 - 1925 Kirschner Road,
>Kelowna, BC, V1Y 4N7.
>tel (250) 763-2329 ext. 225
>fax (250) 762-3374
>



 
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