long ago, we made an investigation on 'warpage' during soldering, and we found, that the 'warpage' was more or less the result of Isac Newton and his apple, and to a less extent warpage due to thermal forces.
So, the boards 'warped'(middle hanging down)in the oven, but went back to original status after oven exposure.
Any more with this experience?
Inge 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Guy Ramsey
Sent: den 8 januari 2008 13:36
To: [log in to unmask]
Subject: Re: [TN] Warpage of components


Richard's recommendations, prebake them always, and very slow ramp rate 1°C per second (again) Richard's advice for soaking type reflow are prerequisite. 

The trick is to use two zones for reflow, one zone to control ramp up and one zone to control ramp down. Exiting the convention controlled zones while the part is in reflow produced unacceptable warp.

We had better results in an oven with very well controlled convention pressure and even heat distribution within the reflow zones. 

It was not possible to do this part in a short oven or malfunctioning oven.
During the process of optimizing the oven for this part we discovered that our OmniFlo 7 was malfunctioning. Once corrected we achieved good results with both the Paragon 98 and OmniFlo.

It was not possible to rework this part in any of our BGA rework stations, and we had many brands and types, Nothing had enough control to heat it without warping.
 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier /*
Sent: Monday, January 07, 2008 4:07 PM
To: [log in to unmask]
Subject: Re: [TN] Warpage of components

Hi Guy,
What could you do to that profile to prevent the warpage of the Altera Flex484?



Werner

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