This is a first for us.  Our customer has specified

"Capacitance between layers 4 and 5, and layers 6 and 7, shall be greater
than 250pf per square inch, assuming unperforated planes".

Layers 4 5 6 and 7 are all plane layers (ground/voltage pairs each).

Now, I understand the concept of capacitance but I have not come across, nor
can I seem to source any info telling me how to ensure that we are
manufacturing to this specification.  I have the IPC-2141 which makes
reference to controlled capacitance lines (not planes) but does not seem to
provide any useful info from a manufacturing perspective.

Can anyone help?

Regards
John Parsons


---------------------------------------------------
Technet Mail List provided as a free 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/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
-----------------------------------------------------