Hi,
I'm Eric - application engr, for wafer saw process. Recently I came
across a type of wafer known as the 'clipper wafer' whereby both top and
bottomside of this wafer is identical in order to enable contact to be
made via miniture clips thus eliminating the need for wire bonding .
Current process to ensure 99% yield , they have to do a first cut 30%
thru' with a porous chuck separated by a silk screen , flip the wfr over
then mounted onto blue tape then sawn thru 1 mil into the tape. This
process take almost 3hrs to complete. Attempt to do a single pass is
disasterous almost 99% backside crack die .Street width is 3mil.
thickness is 6mils . Currently we are using a soft nickel blade, 2 -6 um
diamond size,low concentration ,thickness 0.8mil blade with exposure of
20mils . Tape used Nitto 224 , bake temp . 70deg. for 30min. prior to
saw .
Wonder if you can offer any recommendation/info/article to handle thin
wafer with backside cracks issues . Any form of advise wil be greatly
appreciated
Thanks
Have a nice day.
Eric See