66 SMT Magazine • November 2016
Test 2: 4-hour bake @ 150°C + 3X Pb-free
reflow:
Conclusion
All coupons within all three test groups
passed to 1,000 hours of IST testing. I was hop-
ing to make a big splash but unfortunately the
data doesn't support it. Effectively, boards built
to IPC Class 3 specifications seemingly do not
require pre-baking.
But what about boards built to Class 2 spec-
ifications? IPC Class 2 PCBs make up the vast
majority of PCB designs. Our next step will be
to duplicate this experiment using test vehicles
plated to IPC Class 2 standards. If you are inter-
ested in receiving the results of this next test,
please contact me.
SMT
Reference
1. Further information on IST testing can
be found here. I also found this nice write-up
by Polar Instruments.
Yash Sutariya holds
management positions at
Saturn Electronics Corporation
and Saturn Flex Systems Inc.
To contact the author, click here.
TO BAKE OR NOT TO BAKE
Test 3: As is, 3X Pb-free reflow after receipt:
