For LF assembly and loss performance I would look at IS415.  We have
done some work with getting IS620 to work well with LF assembly and some
new information is released from Isola to prevent delam issues.  Both
415 and 620 fabricate fairly well. 

Jeffrey Bush
Director, Quality Assurance and Technical Support
VERMONT CIRCUITS INCORPORATED 
           76 Technology Drive - POB 1890 
              Brattleboro, Vermont 05302
                Voice - 802.257.4571 ext 37 
                    Fax - 802.257.0011
                       <http://www.vtcircuits.com/> 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dale Ritzen
Sent: Monday, March 12, 2007 12:22 PM
To: [log in to unmask]
Subject: [TN] FR408 vs. FR-4 in RoHS Compliant SMT Process

We have a customer that is experiencing delamination issues with the
FR408
material they have specified for use on one of their circuit boards.
They
have recently gone RoHS compliant with Pb-free solders and the
associated
rise in reflow temperatures seems to have created this problem. Does
anyone
have any experience with mitigating this problem, or can you suggest a
better PCB platform instead of FR408 for high frequency signal
resolution/internal impedance control applications at higher reflow
temperatures?

Thanks,
Dale Ritzen
Quality Manager
Austin Manufacturing Services

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