The issue is not Tg but Td. Some higher Tg materials actually perform
worse than lower Tg materials. It is important develop a test program
to validate your lead free process with specific base materials.
Laminate manufactures offer some variety of thermally stable materials
targeting lead-free, but these are used at a premium. If your lead-free
process can be supported by existing base materials, than that is best
economic solution. The test program will provide the feedback needed.
Please contact me off-line if you need specific information on alternate
base materials and Td for lead-free.
Jeffrey Bush
Director, Quality Assurance and Technical Support
VERMONT CIRCUITS INCORPORATED
76 Technology Drive - POB 1890
Brattleboro, Vermont 05302
Voice: 802.257.4571.21 Fax: 802.257.0011
http://www.vtcircuits.com
-----Original Message-----
From: Black, Paul [mailto:[log in to unmask]]
Sent: Wednesday, November 24, 2004 3:08 PM
To: [log in to unmask]
Subject: [TN] FR4 and Lead free
Hi Tech Gurus,
As people talk more and more about Lead free, I keep hearing that
standard FR boards might not be able to take the extra heat required for
a reliable Lead free solder joint. The problem is that I keep hearing
the word MIGHT. I have not heard that this is definitely true and, if it
is true, I have not heard anyone offer a cost effective solution. So, I
am asking the many experts on this forum, will standard FR4 be able to
handle the higher excursions (particularly, let's say, for a 7" X 9", 8
layer, double-sided SMT, .062" 5/5 board) associated with Lead free
solder paste? If not, what would be the most cost-effective offering
(i.e. high Tg FR4)?
Thank you,
Paul Black
Manufacturing Engineer
Kronos
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