Thank you all for your feedback. I'd like to clarify a couple of things.
First, I did not approve this change in stackup, nor do I have authority
to do so. That's up to the responsible engineer (who chose not approve it).
Second, I don't work in the phone division. I work in the Networks division
(been here a couple of months). I raised the question to this forum because
I wanted to hear about the experiences of others with respect to EMI considerations
as they relate to stackup. I have worked with many engineers who have approved
stackup changes such as this one. In those cases, the boards must have passed
EMI with a very wide margin so that a change in thickness would not affect that
particular test. Clearly, this is not the case with this particular board.
Thanks again for the feedback; I appreciate it.
-----Original Message-----
From: ext Tom Garman [mailto:[log in to unmask]]
Sent: 09 June, 2003 09:53 AM
To: [log in to unmask]
Subject: Re: [DC] Core thickness/emissions
Matthias;
I guess I didn't clarify myself. A good designer will ask for the
engineer's requirements before the first part is placed on the board.
Sometimes the engineer doesn't know, then it is up to the designer to
either get what he needs or point the engineer in the right direction.
Some large companies have experts with EE/ME degrees on staff to
determine what the stackup and other constraints should be. They perform
a valuable service to both the EEs and designers. The EE is doing work
he was trained to do instead of hooking up non-critical signals and the
designer is not wandering in the wilderness and routing a clock under
the power supply.
More companies should have these people. But a lot of these positions
have been cut for "cost savings".
As for your "ugly wired chaos prototype", I have seen some of those in
production. A lot of them came from companies at did not have the
resources for a PCB expert. A lot more of them came from "let the
autorouter hook it up, then no cleanup afterwards.
Bottom line is, a good designer will rely on people like you and if that
resource isn't available then do best he can with what he knows.
Tom Garman
PCB Designer
330-575-1636
[log in to unmask]
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On
Behalf Of Matthias Mansfeld
Sent: Monday, June 09, 2003 12:04 PM
To: [log in to unmask]
Subject: Re: [DC] Core thickness/emissions
Might get a bit off-topic...
[...]
> In my viewpoint it is a waste of an engineer's time to be laying
> out boards. The engineer should be reviewing the layout but unless
> he is at the low end of the salary scale it is not cost effective
> for him to do layout.
[...]
You assume the circuit design engineer always knows what he does an
what he has to specify. Especially which freedoms or constraints for
bare board mfg and assembly.
I am engineer and PWB layout is my main business. Often I have to
tell the customer which stackup he needs or whether it doesn't
matter. Often it is totally up to me to make a ugly wired chaos
prototype which ran more or less well on the engineer's desk to an
EMI compliant, manufacturable product.
Regards
Matthias Mansfeld
--
Matthias Mansfeld Elektronik
* Printed Circuit Board Design and Assembly
Am Langhoelzl 11, D-85540 Haar, GERMANY
Phone: +49-89-4620 0937, Fax: +49-89-4620 0938
E-Mail: [log in to unmask]
Internet: http://www.mansfeld-elektronik.de
------------------------------------------------------------------------
---------
DesignerCouncil 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 DesignerCouncil.
To set a vacation stop for delivery of DesignerCouncil send: SET
DesignerCouncil 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
------------------------------------------------------------------------
---------
---------------------------------------------------------------------------------
DesignerCouncil 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 DesignerCouncil.
To set a vacation stop for delivery of DesignerCouncil send: SET DesignerCouncil 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
---------------------------------------------------------------------------------
---------------------------------------------------------------------------------
DesignerCouncil 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 DesignerCouncil.
To set a vacation stop for delivery of DesignerCouncil send: SET DesignerCouncil 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
---------------------------------------------------------------------------------
|
