TECHNET Archives

April 2001

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Ray Humphrey <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 4 Apr 2001 08:26:14 -0700
Content-Type:
text/plain
Parts/Attachments:
text/plain (95 lines)
Thanks, Jack, for your input.  (Long time, no talk to!)  Designing with B/B
vias is not the problem; getting a reasonable, standard cost differential
from PCB fabricators is the problem.  IMO, designers are reluctant to use
B/B vias and some fabricators charge excessive prices for them, especially,
laser drilled blind vias.  Everyone continues to consider the use and
fabrication of B/B vias as 'new technology'.  Anything that's been around
this industry for over a decade is not new.  I am very frustrated with PCB
fabricators for not keeping up with the industry they are a part of and
support.

We are starting to design with .5mm pitch, .3mm pad CSPs.  This doesn't
leave room on the inner pads for anything except in-pad, micro vias.  This
is especially true for PCBs in the 2 to 6 GHz range.

I have asked several vendors for a cost factor to consider when using blind
vias, getting less than satisfactory responses.  I have posted my question
to both the DC (640 subscribers) and TN (1242 subscribers) forums, getting
the same results.  It goes beyond interesting, Jack.

Ray


-----Original Message-----
From: Olson, Jack [mailto:[log in to unmask]]
Sent: Tuesday, April 03, 2001 10:45 AM
To: 'DesignerCouncil E-Mail Forum.'; 'Ray Humphrey'
Cc: [log in to unmask] ORG (E-mail)
Subject: RE: [DC] Blind and Buried Vias

I would like to contribute Ray, but I have only had to use blind/buried vias
once in my life.
I can tell you from a design point of view in Veribest it is effortless, you
just state the range of layers for each via type, use vias wherever you want
(whatever type you need) and the computer takes care of the rest (multiple
drill files, fab dwg layers, etc)

Its not that I am reluctant to use them, I just rarely see a need (yet).
We are using 1mm BGAs on .093 thick boards with no problems with regular ol'
vias

But I have absolutely no idea how to evaluate the cost difference, since
there is no way to get a "multiple quote" on a design that would prove
anything. Can't you just ask a couple of fab vendors what to use as a rule
of thumb for cost-adders?

It IS interesting that absolutely no one knows this,
or is willing to share anything about it, hmmm?

Good Luck,
(onward thru the fog)

Jack

-----Original Message-----
From: Ray Humphrey [mailto:[log in to unmask]]
Sent: Saturday, March 31, 2001 11:47 AM
To: [log in to unmask]
Subject: [DC] Blind and Buried Vias


In a recent posting, Your Opinoin Needed - Designers Learning Symposium, I
notice that blind and buried vias were included in the 'newer technologies'
category.  I also find that most designers are reluctant to use blind and/or
buried vias, for various reasons.  Blind and buried vias have been around
for over a decade, they are not new.  I have a great article from the March
1988 issue of PCD magazine talking about the use of blind and buried vias
down to 2 mils in size!  I am frustrated that PCB fabricators are failing to
keep up with the industry they support and continue to charge excessive
prices for such an old process.  Much of today's technology require the use
of blind and/or buried vias - I say it is time for designers to get over
their paranoia and for fabricators to stop taking advantage of it!

Several days ago, I posted this question to the DC forum, "Could someone
please give me a general guideline concerning the additional cost of using
blind vias on a PCB?  Perhaps there is someone out there in the PCB
fabrication business or a fellow designer that has done some extensive
research into this?"  To date, I have not received a single response.

Isn't it time we stopped considering blind and buried vias as a 'new
technology'?

Just my rant - I feel better, now.  :)

Ray

---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------

ATOM RSS1 RSS2