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Microvias, Blind and Buried Vias

In a few previous posts, here,
here
and here,
for starters, I've discussed the dreaded via in pad and hopefully, given some
useful information about what to do if you must put vias in pads.

In the image, (A) shows an open via which we don't recommend at all. If you
must do this, give us a call first to see if we can help you out. We have built
boards like this, but we can't guarantee the work when we do and there are
things you can do to make it better or worse.

(B) shows one of our favorite options; the copper capped via, also called a
blind via by some. You can have the via hole filled with a variety of materials
at the boards house for mechanical durability. If this is done properly, we
can't even tell that a via exists.

(C) shows a micro via. This usually works pretty good, but you should still
call us first to talk about it. Sometimes the solder paste or the BGA solder
ball can flow down into the microvia leaving insufficient solder to make a good
mechanical or electrical connection. Call us first.

(D) shows the buried and blind via. In this case, the via is completely
isolated from the BGA pad so, as with (B), we don't really care.

Duane Benson
Bury that viaspec, Bury that viaspec , bury it, bury it, bury
it

Posted on May 24, 2007 in QFN
and DFN , Via
in Pad

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Comments

Im not sure exactly what you're asking, but the technique for putting the
vias in the layout would be different for each different CAD system. You might
have to get some help from an expert in the package that you use.

Posted by: Duane
Benson | May 24, 2011 at 11:22 AM

i am not understand the theory i would like to know that if i want to place
a via from top top to last layer then how can place a vias

Posted by: sai krishna | May 20, 2011 at 09:00 AM

The comments to this entry are closed.

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