I had
the exact same question this week in the shop.....
1. A
low aspect ratio blind via is one that generally has a aspect ratio of 1 or
lower. That is to say that the thickness of the dielectric in
the blind via divided by the hole size is close to 1 or lower. The
key to the low aspect definition is the way the hole was produced. If the hole
was created from the external surface down to a capture pad it is a low aspect
blind via. I'm sure some shops produces blind holes with aspect ratio in the 2
range but in general, the capability of plating is limited to 1
or lower.
2.
"Blind Vias" on the other hand, are generally plated thru holes on a subassembly
that end on the external surface. Since these holes are fabricated
as std through holes when the subassembly is made, they have to met the
same requirement as std thru holes.
Mike
Hill
Hello Committe members, I have a question about
Copper thickness in Blind Vias. In the IPC-6012 ,provided two selection for it
in the table; one is blind vias and the
other is Low Aspect Ratio vias ,I wonder how to calculate the Aspect
and if any true data instead of the uncertainty word " low aspect" .Wish
get your advice !
Regards