Hi Geoff,

The following is a copy of the conversation Leonard and I had offline concerning the impact of via in pads on the assembly process. The technology is not what you would consider mainstream but is practiced by most of the leading edge fabricators and contract manufacturers. The
scenarios below have all been accomplished in real applications.

Any questions, please call.

Keith Larson
Circuit Technology Inc.
817-481-7281

_________________________________________________________

Hi Leonard,

The assembly issue that has to be overcome is solder pulling down into the
hole from the joint during reflow. We have handled this in three ways:

1) Apply PPT Solid Solder Deposit to the bare board (adds about 5.00 to each
assembly)
2) Selectively apply extra solder paste to the pads with vias in them
(additional cost is based upon the number of vias affected)
3) Reduce the via size to the smallest available from your fabricator or go
to a blind via technology (bare board price increases and is again dependent
upon number of vias)

If you need additional info on the above or pricing impact on a specific design
just let me know.

Regards,

Keith



Leonard Toohey wrote:

> Are you seeing any through vias in SMT pads?
> We are wanting to put a .010" (+.003/-.010) through hole in
> 0603, 0805 and 1206 parts. The board is .062".
>
> I know from a bare board fab perspective this is not a problem.
> What I am wanting to find out are any assembly issues...
>
> Thanks
>
> LT
>
>
>



Kishpaugh Geoff wrote:

> All,
>  I have been watching this discussion with interest and unless I missed some posts have found only 2 answers to the original question. Can I assume that not many companies are using "via in pad"? Is there a reliability issue with this design practice? Any responses are welcome.
>
> Thanks,
>
> Geoff Kishpaugh
> Motorola Inc.
> 1900 Winchester Rd, IL-46
> Libertyville, IL, 60048
> Phone: 847-523-0067
> Fax:   847-523-0078
> email: [log in to unmask]
>