You might want to give Cash Olsen's embossing gun technique a try. His site has gone down now, but the basic idea is to use the hot plate to preheat the components to only 212 (100C) and then blast the leads with an embossing hot air gun for just a few seconds. Long enough for the solder paste to reflow.
I've had an 0805 cap or two pop up on one end while doing this technique and have actually been able to push them back down via the air pressure of the gun. An IC would be forced towards the PCB even more owing to its greater package surface area to lead surface area ratio.
Just a thought.
Regards,
Royce
--- In Homebrew_PCBs@yahoogroups.com, "Jim Lewis" <jim.lewis@...> wrote:
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> I have a problem with SMT chips jumping off the board during reflow. I preheat for 2.5 minutes 1/4" above the hot plate and then reflow 1.5 minutes directly on the hot plate at 375F with a cover. Paste is from Stencils Unlimited. Any solutions?
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