Nope .... those vias are filled with prepreg from the lamination cycle. It
had nowhere to go ... it melts and floods up the hole, capillary action.
The fabricator should have planed the surfaces to bring the prepreg back
down level to the copper layer.

Valerie





stephen gregory <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
09/12/2005 07:02 PM
Please respond to TechNet E-Mail Forum; Please respond to stephen gregory


        To:     [log in to unmask]
        cc:
        Subject:        Re: [TN] raised vias...


Hi Everyone!

I'm home now, but I can answer some of the questions.

The picture of the board is as it was given to us. It hasn't been through
reflow...this is how the bare board looks.

The vias aren't filled.This is a 10-layer board that is made from
IPC-4101/26
(GF) material. BUT, there is 5-layers on one side of a .045" thick copper
core,
and on the other side of the core is the other 5-layers. There is
double-sided
SMT on the board, and both sides have the "anthills" like you see in the
picture.

Pretty strange, huh?

-Steve Gregory-


"Brooks,Bill" <[log in to unmask]> wrote:
I'm just passing the message on... it's Steve's board...

Thanks,

Bill Brooks





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