Answers:

1. You compensate by varying the line width of the trace. You need an
impedance calculator to get the values.

2. I'm familiar with designs with the laminate thickness as low as 3 mils.
I'm sure the fabricators on this forum have a better answer.
David Ricketts

Pertek Engineering
Voice: 949-475-4485
Fax:   949-475-4493

----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Sefika Ozkal
Sent: Friday, October 11, 2002 5:35 AM
To: [log in to unmask]
Subject: [TN] Thickness Problem



Hi,



If we have a PCB with signal layers whose thicknesses are 6, 8, 10,12 mils,
how can compansate the impedance differences? To achieve the impedance
requirements of a design can you offer some solutions?



What can be the minimum thickness of the laminate between the VCC and GND
planes where the laminate can be FR4 or?





Sefika Ozkal

Electronics Engineer





----------------------------------------------------------------------------
----- 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 -------------------------------------------------------------------
--------------

---------------------------------------------------------------------------------
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
---------------------------------------------------------------------------------