Reflow Oven Selection

Thanks for the replies.

Interesting white paper. Didn't quite answer my concerns but still a good read. I was actually surprised that to test temperature uniformity across the zone, they attached T/C's to the substrate rather than measure the air temperature. By reading the temperature values on the board, it seems that they are getting closer tolerances than if they were reading the air temperature of the zone. I think they advertise/d temperature uniformity within 2 degrees. Always thought that's the air temperature tolerance within the zone . . . guess not.

As far as them placing aluminum plates before and after the test board . . . main purpose was to show that the heaters have enough power/wattage to ramp up in a short period of time when the air temperature begins to drop. Hence, maintain the set temperature within 2 degrees. The heavier the load the longer heaters must be in the ramp up mode to maintain temperature.

What I am concerned about is the actual temperature of the aluminum plate. Can a reflow temperature (210 C) be achieved of the aluminum plate itself in 5-6 minutes of being inside the oven? I am thinking that to achieve approx. 210 C on the aluminum part would certainly take longer than a typical reflow cycle time. Alternatively, if the air temperature of the zone is set to 500 C for example, it will heat up faster. So that's my dilemma . . . to figure out whether a reflow oven rated to say 350 C can be used or if I need an oven capable of much higher temperatures.

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Have not researched vapor phase reflow ovens. Thought they were no longer manufactured (outside of Europe). Can you recommend a manufacturer based out of US? Never seen one in production, only heard of these ovens being widely used up to early 90's then, like dinosaurs they died out.

thanks

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I respectfully disagree with vapor phase or reflow oven being the technology of choice here. Have you considered straight conduction heating? (ie: hot plate) If you have a lot of these to do you can purchase in-line conduction ovens like the Sikama or equivalent that work by conduction.

If there are no active electronic components which could be damaged from strong magnetic fields, I think that you could also treat this as a straight-forward brazing operation. From my experience in high mass reflow of heatsinks and heat exchangers, induction heating will work far better (no to mention) faster and probably be less expensive to procure and operate than condensation heating systems.

If your not familliar with induction systems you might want to look into them. Your parts would be heated in open air on a flat plate in the proximity of a water cooled induction coil. Due the intrinsic nature of the metals you are joining with the materials conduction; heat is evenly generated within the substrates and assure a good all around bonding.

The newer systems allow you to program reflow profiles, but I'm inclined to beleive thay you won't need a process that sophisticated.

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