The
IPC spec states to handle the boards by the edges or with
gloves.
Of
course you would think this is not open to interpretation, but, it
is.
If you
have a board that's panelized and you handle the board on the surface but only
touching the
breakaways....is THAT OK?
So,
one might ask -- what's the intent.
The
intent is to keep contaminants off the board that will affect solderability
and....end product performance and reliability.
Rather
than go into a long speech about cleanliness (I believe Doug P. at Rockwell may
have opened my eyes to this issue), I'll give my 2 cents on what we think
is best for the products we provide to our customers
Handle
the boards by the edges (especially after the last clean
cycle).
If its
a class 3 medical device and requires extra special cleanliness, then, handle
the boards with new clean gloves after the last clean cycle and make sure your
totes are clean as well. Finger cots, gloves, even your freshly washed
hands will get "dirty" very quickly depending on how fast you sweat, what you
pick up (ex: pens, eyeglasses, eye Loup). So, you never know what you are
transferring to the board.
You
can also try some experiments -- Handle some boards with your sweaty, dirty,
food laden paws all over the board. Run it through an omega meter and
compare the results to a board handled by the edges. Just remember, the
omega test does not test for all contaminants.
Bottom
line -- common sense.
-Carrie
Advice requested,
I'm sure
this topic has been broached before, but I would like to solicit your opinions
on the subject of using fingercots or gloves verses using bare hands when
handling components or PCB's before soldering or conformal coating (IPC Class
II). I tried to do a TechNet search on this, but it failed to go through
for some reason.
I am of
the opinion that careful handling of components or PCB's by their
non-soldering surfaces with clean bare hands is the way to go. Of
course, it is up to manufacturing personnel to keep their hands in a clean
condition. From what I have seen, gloves just tend to soak up and
disperse multiple contaminants on soldering surfaces and they give personnel a
false sense of security. Any thoughts? Thanks in advance for the
advice.
Howard Watson
SMT
Manufacturing Engineer
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