Hi Toby,
Sure there is a difference. It needs to be measured in situ.
Your ideals:
"The 'ideal's' I'm working with are,
max temp between 210-200 degC
45-75s above 183 deg C
ramp up no more than 4 deg/s
ramp down no more than 6 deg/s"
are less than ideal. The max T of 210-200 degC is inadequate to assure proper
reflow of eutectic Sn/Pb and "45-75s above 183 deg C" is irrelevant for
solder reflow. To assure proper reflow every solder joint [that means the SJ
heating the slowest] needs to reach Liquidus +20 degC wich for  eutectic
Sn/Pb means 203degC for about 5 sec. Also your ramps are much too high by
about a factor of 2.

Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL  32174  USA
Phone: 904-437-8747, Fax: 904-437-8737
E-mail: [log in to unmask], Website: www.engelmaier.com

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