Ian, Jeffrey, et al,

A piece of supplementary information you might be interested in is the paper Scott Hinaga of Cisco presented at the IPC 2010 EXPO. Scott showed how temperature variations throughout a box could, by variation of material properties across a  circuit board, deskew, for example, a data bus.   Louis Hart

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Fox, Ian
Sent: Tuesday, October 04, 2011 8:40 AM
To: [log in to unmask]
Subject: Re: [TN] Dielectric Constant of FR-4 over temperature

Some figures I had, given me by a laminate manufacturer, suggests that at 1MHz for a typical FR4 you can expect the Dk to rise from about 4 at 20C to around 4.4 at 60C. Hope this helps

Regards
Ian Fox
Lead Materials and Process Engineer 
Aero Engine Controls
 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of McGlaughlin, Jeffrey A
Sent: 04 October 2011 13:26
To: [log in to unmask]
Subject: [TN] Dielectric Constant of FR-4 over temperature

We are trying to identify the root cause of an issue with the tuning of an RF circuit on FR-4 laminate. We are seeing a major shift in the attenuation of the received signal from room temperature (~20 deg. C) to high operating temperature (~60 deg. C).  I know that the volume and surface resistivity of FR-4 (GF/GFN) can change by a factor of up to 10^2 over the working temperature range of the laminate. Does this shift in performance also track with the dielectric constant and loss tangent of the material? If so does anyone have documentation as to how these properties change over working temperature?


______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 16.0
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
For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------