Manish,
     I ran into the same problem not long ago. The Zymet underfill I was
trying to remove was X6-82-5.
I contacted Zymet.Their advice was to try Dynasolve 165.It is a formulated
solvent made by Dynaloy Inc.(1910 South State Ave, Indianapolis,phone
1-800-669-5709 fax
1-800-671-9583). The stuff is mostly Methylene Chloride, and some acid
additives. If you have straight Methylene Chloride this may work.

     We didn't have any methylene Chloride, or time enought to buy in the
Dynasolve. Instead we used fuming Nitric acid. This destroyed enough of the
Zymet structure and it's adhesion to the chip that it could be lifted off
the die. The board was first ground away from back to reveal the chip and
underfill. Not a very nice method, but Methylene Chloride isn't a pleasant
chemical either. The Zymet materials seem to be particularly resistant to
chemical attack.

regards, Jeremy Drake
Celestica.

>>
Hi Everybody

Is anyone aware of any solvents that may be used to dissolve the cured
encapsulants.  We often receive field failures (flip chip on flex) and for
some FA purposes we intend to dissolve the encapsulant.  We tried a
solvent J100 which works good with most of the encapsulants except for
Zymet.

Has anyone ever had any luck with zymet.  Any responses would be highly
appreciated.

Regards
Manish<<

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