Sender: |
|
X-To: |
|
Date: |
Wed, 24 Nov 2004 11:10:56 -0800 |
Reply-To: |
|
Subject: |
|
From: |
|
Content-Transfer-Encoding: |
7bit |
In-Reply-To: |
|
Content-Type: |
text/plain; charset="iso-8859-1" |
MIME-Version: |
1.0 |
Parts/Attachments: |
|
|
Hmmm, tricked again! So much for trying to get all my ducks in a row before
contacting the customer. His reply to my questions relating to his
impedance controls design was this;
"The board is not really an controlled impedance design. It is an IS
(Intrinsic Safety) design. We require the 1mm clearance from the copper on
layer 4 to the copper on the bottom layer."
Thanks for all your input.
Now, how to make this puppy FLAT?
John
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of John Parsons
> Sent: November 24, 2004 9:19 AM
> To: [log in to unmask]
> Subject: [TN] Controlled Impedance Design
>
>
> This is one for the experts. I have been under the general
> assumption that
> with controlled impedance designs (single ended microstrip) that the
> reference plane is typically the first adjacent plane layer encountered in
> the stack-up. We are quoting a 6 layer build for a customer which has the
> following stack-up (cap construction specified)
> L1 Signal Layer (2oz)
> 8mil core
> L2 Split Plane Layer (2oz)
> 5mil preg
> L3 Split Plane Layer (2oz)
> 5mil core
> L4 Split Plane Layer (2oz)
> 22mil preg
> L5 Split Plane Layer (2oz)
> 22mil core
> L6 Signal Layer (2oz)
> We have not built this before but they have indicated that previous
> prototypes suffered from warping (you don't say!) and the doc's
> state "This
> is a controlled impedance PCB. Spacing between L4 and L6 must be 44mil.
>
> My question, from a controlled impedance perspective does it seem to make
> sense to spec the distance between the outer layer 6 and layer 4 (2 plane
> layers away) as having a critical spacing requirement? We have not been
> provided with the impedance requirement nor the critical traces.
>
> Educate me please!
>
> Regards
> John Parsons
>
> ---------------------------------------------------
> Technet Mail List provided as a service by IPC using LISTSERV 1.8e
> 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 or (re-start) delivery of Technet send e-mail
> to [log in to unmask]: SET Technet NOMAIL or (MAIL)
> To receive ONE mailing per day of all the posts: send e-mail to
> [log in to unmask]: SET Technet Digest
> Search the archives of previous posts at: http://listserv.ipc.org/archives
> Please visit IPC web site
> http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional
> information, or contact Keach Sasamori at [log in to unmask] or
> 847-615-7100 ext.2815
> -----------------------------------------------------
>
>
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------
|
|
|