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July 10, 2006

Can I upgrade my Long wave IR/convection oven for use with lead-free?

As a sequel to the question "Whether existing reflow ovens can be used for lead-free." My inline oven (11years old) has 4+4 zones and heats up by Long wave IR + convection. The oven manufacturer denies upgrade possibility of direct use for lead free citing "IR cannot be used for lead-free."

Can some body elaborate if this is true or another "sales talk."

Moghe Ajay

Experts Comments

Typically a statement like "IR cannot be used for Lead Free" will have some kernel of truth or a valid reason behind it so I would suggest you try to pin down the manufacturer as the exact reason(s) for such a statement. In general though, the proof is in the profile. So I advocate letting the board do the talking.

Put some Thermocouples on the board and run it through the oven. And if the profile meets the parameters set forth by the paste then you are done.

IR elements run much hotter than convection based systems so they can have a tendency to char the edge of the board depending on the size of the board and its complexity. So when you go to the higher temperatures associated with lead free you may see some brown edges and that may be the reason for your vendor's hesitation.

Additionally, the absorptivity of IR varies with the size and color of the components and with higher temperatures you may see a much higher Delta T on the board. This higher Delta T from your bare board to the highest thermal mass component may take you outside of the process window for Lead Free and that may be behind your vendor's reticence.

Or maybe he just hasn't seen a commission check in the 11+ years since you bought this machine and figures it's time. (Just kidding!) Seriously though, there may be real process issues so I would go with a process based solution and figure that your vendor has your best interests in mind.

Marc Peo
Heller Industries Inc.
Mr. Peo has been with Heller Industries for over 20 years and has been President for the past 8 years. Marc has authored several industry articles on Soldering, Flux collection, nitrogen use and Lead Free conversion.
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