Sounds like too much heat for too long, with a long cooool down, have you put
a t/c in the area to run a local profile.

Mike Fenner

...........
In a message dated 29/04/99  09:52:33PM, you write:

>
>  TechNetters,
>
>  I would appreciate your help in deciphering a defect we are seeing
>  across one board after reflow.
>
>  The larger solder joints are exhibiting a ring-like structure - there
>  are a couple of lines in the joint ringed around the part (as if it
>  cooled at different rates depending on how close the solder was to the
>  part?).
>
>  Also, all of the parts (large and small) have many black "splotches" on
>  the joints.  Some of them, if you look closely, appear like snowflakes
>  or leaves of a fern tre

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