I work for a small electronics manufacturing company, where we use strictly
thru-hole technology (old stick thru) and use CEM3 material for our PCA's.
We get our PCB's from China.

We are having problems for excessive Bow and Twist and poor solderablity on
out PCB's.

What is the possibility that the humidity in China and, across the ocean
during transit are causing the problems?  If the suppler increased the time
of the final bake will this help the problem.

Is CEM-3 more likely to have "Bow and Twist", and solderablity problems, if
so please explain?

When we receive the defective board for Bow and twist we send them off to a
machine shop to be baked. we are baking 200 panels (they are small panels,
about 8in by 8in) in a stack with 25inlbs of pressure in a clamping fixture
at 350 for 4 hour after PCB are at temperature.   It seems to work, but we
sometimes have a few panels that are not flattened.  Does any one have any
recommendations about this?

THANK YOU VERY MUCH!

Jon McDowell
208.395.8025
[log in to unmask]
Electroinc Controls Company (ECCO)
Boise ID 83705


THANK YOU
JCM