Normal process is to use a very experienced engineer.

However the approach I am taking with mature products is to run the reflow samples back through the oven after weighing them.

I then take the output from the data logger and fit a mathematical equation to it using a cubic spline approach which allows me to calculate area under the curve at critical points such as time above liquidus.

By these experiments I am working on compiling a data base of complexity, mass size etc which should allow the set up to be more predictive.

The aim is to predict the oven zone temps for both top and bottom of the board at the prototype first run stage.

John Burke

Sent from my iPhone

> On Feb 4, 2016, at 2:49 PM, Tom Gervascio <[log in to unmask]> wrote:
> 
> Many times we have to create an oven profile but only have a bare board. Many times the boards are complex and have many bottom terminated components on them and wanted to avoid having to guestimate how a profile for a bare board would actually perform on a populated board. Can't imagine that we are the only persons to face this problem. Wondered how other users have worked around this problem?

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