Hi Kate!

I've been using a "Ramp" or "Tent" profile for the last couple of years. The
reasons are because:

1.) Sometimes (depending on the board), it's kinda' difficult to acheive the
"soak" profiles in a convection oven, not that it can't be done, but you
don't see the same kind of distinct zone separations in a convection oven
like you might see in a I/R oven back when these type of profiles were being
recommended...the air moves around.

2.) With a "Ramp" profile it's much easier to stay within 1-2-degrees per
second temperature ramp rates throughout the profile (including the reflow
spike at the end) which is much more gentle on the parts...less "popcorning"
or heat shock...

3.) The "Ramp" or "Tent" profile will ensure pretty much that all parts will
be at the same temperature when entering the "spike" or liquidous zone. Belt
speeds will be a bit slower, but that's what allows everything to come-up to
temperature slowly and evenly...be it a 0402, or a PLCC-68...

BTW, there are a few solder paste vendors that are recommending "Ramp"
profiles, Alpha Metals with their WS-609 paste are one...

My 2-cents...

-Steve Gregory-

<< Hello,

 I will be performing a study on the temperature profile design in the
 reflow ovens (forced convection) of our SMT lines.  Currently they are
 set up in the traditional 4 zone profile (soak zone included.)

 Has anyone switched to a 'ramp profile' (eliminated the soak zone) ?
 What were the benefits seen with this new profile design?

 What is the general opinion in regard to using a ramp profile?

 Thanks!

 Kate Bishop
 Process Engineering
 Leitch Technology Int.
 [log in to unmask] <mailto:[log in to unmask]>
 (416) 445-9640  x. 3395 >>

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