1) Yes there are different grades/types of FR-4. What is best depends on
your application. Without seeing your design I wouldn't even hazard a
guess.

2) If you spec the material per IPC-4101 they had better be.

3) You don't even have to change grades to see a change in Er/Dk the
real driver is the glass to epoxy ratio.

4) If impedance is a real concern then no you need to do much more to
control it. The best way is to specify which lines are critical, what
the target impedance is, the tolerance, and the tool used to calculate
the design criteria. Then a reputable fabricator should be able to
set-up a "recipe" that will produce the desired results.  I have done
designs in the 2+Ghz range this way.   


Jeffrey A McGlaughlin, CID
Engineering Designer
Battelle Memorial Institute
Columbus Ohio
http://www.battelle.org
[log in to unmask]

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David Harman
Sent: Tuesday, February 22, 2005 1:30 PM
To: [log in to unmask]
Subject: [TN] FR4 board material

Hello technet group,
 
    Thanks for all the help with previous questions. My question today
is regarding  grade of FR4.FR4 ( Flame retardant) type 4 indicates woven
glass reinforced epoxy resin.  
 
1. Are there different grades of FR4 used? IF so what are the best
grades to control impedance for RF?
2. Are material specifications the same overseas as it is domestically?
3. Will the different grades give you different impedance levels?
4.  We have no control on our impedance specification,  we are expecting
the grade of FR4 and the process of fabrication to control this,  is
this the right approach? 
 
 
    
 
 
David Harman

 

 

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