You may mean the top side of the board and not the bottom?

Typically a wave soldering system for tin/lead will be between 240-255C
depending on board type, component density, flux type and through put
requirements. Idealy the task is to keep topside joints below the reflow
temperature of the alloy 184C.

In the case of lead-free most of my trails have been run between 260-265C.
The key issue here is to avoid reflowing the top side reaflow joints again
just like with tin/lead refered top as secondary reflow. Again here we try
to keep the temperature on the top side below the alloy reflow temperature
of the lead-free paste alloy.

Here is the rub when you have lead/tin parts reflow with lead/free paste you
can get secondary reflow of termination interfaces at a lower temperature
than the lead-free alloy.

The NPL Team are starting a project on this issue shortly.

There is a paper from one of the IPC Lead Free Conferences I presented. I
will be covering this fun area in my Inspection and Quality Control Workshop
in San Jose with IPC in a couple of weeks. See the IPC web site for details.


Bob Willis
2 Fourth Ave, Chelmsford, Essex, CM1 4HA
Tel: 01245 351502
Fax: 01245 496123
Mobile: 07860 775858
Email: [log in to unmask]
Web: www.leadfreesoldering.com
Web: www.bobwillis.co.uk


-----Original Message-----
From: Leadfree [mailto:[log in to unmask]]On Behalf Of Laura J. Turbini
Sent: 27 February 2004 19:12
To: [log in to unmask]
Subject: [LF] Leadfree Wave Soldering


I have read in this forum that solder pot temperatures for leadfree wave
soldering are typcially 260 C.  Has anyone put thermocouples on the board
and determined the peak board temperature on the bottom side during wave
solder?
I have learned from colleagues that 201C to 205C are good numbers for SnPb
solder, but I need to know the correct numbers for leadfree.

Thanks, in advance, for your help.

Dr. Laura J. Turbini
Executive Director, CMAP
University of Toronto
184 College Street Rm 150B
Toronto, ON M5S 3E4
CANADA

416-946-7329
416-946-3628 FAX
[log in to unmask]
www.cmap.ca

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