Hey Doug,
 I have seen people use Kapton tape on the four corners of the device
as type of mechanical stop or visual indicator of ball collapse. We
would use 1 mil thick Kapton and make a grid from 4 mil to 10 mil thick
stack ups. We would then cut smaller grids out of each section and place
the smaller pieces in the 4 corners of the BGA. Depending on the size of
the ball and package we would determine the preferred amount of collapse
and use the appropriate tape thickness from the grid.
 I wish I could say we developed this method but a local company (STI)
trained some of our operators to perform BGA rework and used this
method. We have had very good success with it.

>>> [log in to unmask] 07/22/03 01:42PM >>>
BGA collapsing we also have 3 Air Vac DRS24. I was reading the article
dated on 22JULY in regards to placing  non-solderable material under the
corners of the BGA. My question is what kind of material is being used?



        NOKIA Connecting People
         Douglas L, Trimble
      Training Instructor: Rework / uBGA
      After Market Services Training Americas Region
      Nokia, Inc.
      795 W. Nasa Blvd., Melbourne, FL 32901
      Office: (321) 726-4545
      Email: [log in to unmask]

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