Hello Sal,

One solution is to use Microvias, if you are ready for them.  If you can use
small blind microvias in your design, they will not take enough solder to
create problems in assembly. The amount of solder paste you put down can
require only a slight increase and sometimes not even necessary.

Larry Burgess


-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Salim Yusuf
Sent: Monday, October 30, 2000 8:26 AM
To: [log in to unmask]
Subject: [TN] Via in Pad (VIP) Technology

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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