Sal,

In a previous job I worked with D-shaped solder pads with via's in them. Compensation for the volume of the via was achieved by 10 mil overprinting of the solderpaste, the shape of the aperture was the same as the pad. 
We used 8 mil stencil to get the necessary extra volume. I doubt if you will be succesfull with 5 mil foils.

Kind regards,

Daan Terstegge
Unclassified mail
Personal Website: http://www.smtinfo.net


>>> Salim Yusuf <[log in to unmask]> 10/30 5:25 pm >>>
Does anyone out there have experience in designing apertures for D type
pads that incorporates a via within it. The pads are for a 1206 resistor.
Our current design is a circle which is offset from the front of the pad to
eliminate solder balls, he foil thickness is 0.005" ( due to other fine
pitch devices on the assembly . The solder fillet resulting from our
current aperture design is just passable, but is definately bordering
insufficient, due to the solder running down the via. Any help or advice on
the following questions would be greatly appreciated:

1. How do I calculate how much solder volume ie required for a type of pad
that incorporates a via hole within it ?

2. Can I over-print onto the solder mask ?

3. What other aperture designs are available for this type of pad ?

Sal.

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