Dear all,

I am fabricating a focal plane array for imaging.  For
this process, I flip-chip bond a focal plane array to a
readout circuit, apply underfill epoxy, and then remove
the substrate.  I remove the substrate using a selective
wet etching chemistry.  After the substrate is removed,
there is a solid ridge of excess epoxy on all four sides
of the focal plane array.  This ridge is formed because
underfill epoxy wets the edges of the substrate during
application.

I am writing because I want to know of alternative methods
for bonding a focal plane array to a readout circuit
without the issue of excess epoxy at the edges. Please let
me know your suggestions.  Thank you.

Best regards,
John