Have you considered using micro vias? You can place them in the pads and
solder right over them, you will never see them on the top layer. Also laser
drilling is less expensive than mechanical drilling.

Regards,

Ted

-----Original Message-----
From: Jeff Stout [mailto:[EMAIL PROTECTED]]
Sent: Thursday, November 29, 2001 5:17 PM
To: Protel EDA Forum
Subject: Re: [PEDA] Blind and buried via's Mayhem


[snip]

> At 03:53 PM 11/29/2001 -0600, Jeff Stout wrote:
> >1. Can I use a hole pair that goes through the prepreg, but
> >does not go through the core material above or below that
> >level?  I just don't see how it can be manufactured.
>
> No.  At least not to my knowledge.  My understanding of the process is
that
> basically you can only use blind vias on cores.  You may not connect cores
> to one another except with full through-hole vias.
> Exception:  If you have 2 internal cores you can prepreg these together
and
> then drill through them... plate to connect these cores together, and then
> prepreg more cores to the outside of that unit, through-hole drill the
> whole thing and plate again, etc, etc, etc.
>

So if you want to connect two layers across a layer of prepreg, your
stuck with having holes on the outside of the two cores surounding
the prepreg.  Well t'aint that shitty.

So in a PCB, with a stack up like:

T
--C--
1
--P--
2
--C--
3
--P--
4
--C--
B

It's only possible to manufacturer:

T -> 1
T -> 3
T -> B
2 -> 3
2 -> B
4 -> B

Without having some extra "through holes" somewhere,
of course.

I think I'm beginning to understand this.

Jeff Stout

[snip]


* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* To post a message: mailto:[EMAIL PROTECTED]
*
* To leave this list visit:
* http://www.techservinc.com/protelusers/leave.html
*
* Contact the list manager:
* mailto:[EMAIL PROTECTED]
*
* Forum Guidelines Rules:
* http://www.techservinc.com/protelusers/forumrules.html
*
* Browse or Search previous postings:
* http://www.mail-archive.com/proteledaforum@techservinc.com
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

Reply via email to