Andrew,

              A common problem in Polyimide curing is wafer warpage
caused by incorrect curing temperature rise.  papers have stated that a
temperature cure rate of greater than 4 degrees per minute can cause
wafer warpage due to the differences in Polyimide and wafer expansion
rates.  It is probably the epoxy curing causing the warpage.  Are you
using an accelerated temperature ramp to cure the epoxy.  Bill Moffat

________________________________

From: mems-talk-bounces@memsnet.org on behalf of ? ??
Sent: Fri 6/26/2009 5:29 PM
To: mems-talk@memsnet.org
Subject: [mems-talk] wafer bonding warpage


Hi all:

i am bonding one glass wafer and one silicon wafer with epoxy and their
TEC is the same. But why does it have near 500um warpage after bonding?

Thank you!

Andrew Du