Hi Ted,
you hit the very essence of RoHS. There have been extensive discussions on Technet regarding this issue and things are not clear at all yet. You could go to IPC-4101B and reference one of the RoHS related slash sheets, 99, 101, 124 and a couple of others, but it seems that this is not enough. You might also want to request speciffic testing of the PCBs using either T288 time to delamination or IST.
There is a white paper written by Werner Engelmaier (reliability guru) that proposes an impact index. You can contact him at [log in to unmask]
Good luck,
Ioan Tempea, P.Eng.
Sr. Manufacturing Engineer
Positron Technologies Inc.
18107 Transcanada Hwy,
Kirkland, QC H9J 3K1
Canada
Tel: (514) 782-3100 ext. 4145
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]]On Behalf Of
Klefisch, Ted J
Sent: Monday, August 27, 2007 2:19 PM
To: [log in to unmask]
Subject: [DC] base materials for lead-free PCB's
Hello Designers,
I work for a medical OEM. We will soon be producing RoHS-compliant
PCBA's. I am not sure what exactly to include in the fab notes to
specify the PCB base materials for compatibility with lead-free assembly
temperatures.
For pre-RoHS boards I have included a note on the fab drawing that
specifies "FR4, copper-clad laminates" plus board thickness and UL
rating requirements. Our boards are generally .062" thick and 8-layers
or less. As far as I know, we've always used conventional FR4.
What would you suggest I include in a fab drawing note to assure that
the boards survive the higher assembly temperatures? Is it enough to
specify decomposition temperature alone or should glass transition
temperature also be called out? Td=330C? Tg=150C?
I really appreciate your suggestions and advice.
Thank you.
Ted Klefisch, CID
Covidien
444 McDonnell Blvd.
Hazelwood, MO 63042
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