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Reflow Oven Selection

Views: 5132

Mark

#36328

Reflow Oven Selection | 25 August, 2005

I have an application that requires soldering pieces of metal (copper plate and copper fins to make a heatsink). Each piece is about 1 lb. I cannot test it in our reflow oven (5 zone) since the piece is about 3" in height. Has anyone attempted to reflow parts with so much thermal mass in reflow ovens intended for board assembly. It seems that all conveyer ovens have a clearance of no more than 2". Does anyone know if manufacturers can customize the tunnel clearance?

BTU has an oven on their website that may fit my application http://www.btu.com/tca.asp though, I am afraid to know the price for one of those units.

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Dave

#36330

Reflow Oven Selection | 25 August, 2005

Hi Mark,

Check out Heller's white paper link for a study done with a PCB in line with thick and thin aluminum plates to measure repeatability and delta T with loads of large mass materials. The result was less than 1 degree with their oven due to it's efficient reflow zones. It's also priced way lower than BTU or Vitronics.

www.hellerindustries.com/docs/wpload.doc

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GS

#36344

Reflow Oven Selection | 26 August, 2005

Have you considered to use Vapor Phase Reflow(Condensation) ? Regards

GS

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SuMoTe

#36345

Reflow Oven Selection | 26 August, 2005

^^ Agree with above. vapor reflow.

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#36346

Reflow Oven Selection | 26 August, 2005

Heller did a tall tunnel for a customer in Florida a few years ago for a very similar application. As I recall, it was 3". Marc Peo or Don DeAngelo at Heller shold remember the details.

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Mark

#36357

Reflow Oven Selection | 27 August, 2005

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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Mark

#36358

Reflow Oven Selection | 27 August, 2005

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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Leo

#36359

Reflow Oven Selection | 28 August, 2005

We have had this experience in China. Some of our customer produce aluminium radiator. They always ask us to design this type reflow oven for it.Because the large desire of the heat,we have to design the oven at a higher temperature.It's almost meet 350 degree.

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GS

#36366

Reflow Oven Selection | 29 August, 2005

Just few brand names of VP reflow machines:

- ASSCOM http://www.asscom.de

- epmIBL http://www.epm.ch

One of the the Heat Transfer Fluid used with today Vapor Phase Reflow(condensation) technology is the GALDEN that you can select according to the reflow temperature required by your process. See details of this product at sito: - Solvay http://www.solvaysolexis.com

Regards

GS

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#36368

Reflow Oven Selection | 29 August, 2005

Carmichael

#36429

Reflow Oven Selection | 31 August, 2005

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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Brian

#36497

Reflow Oven Selection | 2 September, 2005

We (ETS) are a manufacturer of reflow, curing and preheat systems and have had similar requests from customers in the past. One in particular required soldering onto an aluminum heat sink weighing approx 5 lbs. You might consider selective/robotic soldering for this. Preheat followed by robotic soldering. Tyco has pretty good robot solder systems and we manufacture preheaters designed for large thermal mass products. Clearance of 3.5" above and below passline. Adjustable throat opening if required (closer to the heater the faster it heats). The preheaters are convection with optional IR Boosters to accellerate preheat times. Conveyor can park to maintain product temp until downstream equipment requests it.

If you'd like process testing done on your assembly email me at bstumm@energytechnologysystems.com or visit our website http://energytechnologysystems.com

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