Hi
Jenny,
Your
horrified expressions are not without merit. Since the flux hasn't been
heated, it hasn't had a chance to go through its full chemical reaction cycle
that allows the activators to get bound by the residue. That means the
flux is still active as you ship it out the door. Add a mix of moisture to
mobilize the activators and you will be able to charge your customers for the
"Chia Pet" that is on the board :-)
Its a
classic problem. Don't worry, you're not the first company to do this, and
you won't be the last. (You might even get to revisit this in a few years
after everyone forgets why un-reacted no-clean flux can't remain on the
board).
Ryan
Grant
Consider a hand
rework situation.
We had a revelation
from our production floor that occasionally a certain product is cleaned
using a no-clean flux pen. We have a product that the customer is very
stringent that if we use no-clean solder on their product, we must not
clean any residue off the board with our standard board
wash.
However, if a
component is removed and replaced during a rework situation, often there is a
lot of excess flux residue left on the board. It came to light that in
order to make this look better, they were applying a small amount of no-clean
flux to the area with a flux pen, and then scrubbing the area with a
brush.
There were several
horrified expressions around the table when this came to light.
What would be the
dangers of doing this? The board is not heated like a reflow situation, or
anything like that, after the 'cleaning' operation, so does this mean the
flux may not be 'inert'? I thought that it is no-clean flux used in the
rework in the first place - why do they need to clean it off? They said
that it looked awful, and the inspectors wouldn't let the product thru if
it wasn't cleaned up.
Thoughts,
suggestions? Should we be horrified, or just let them
continue?
Genny Gibbard (mailto:[log in to unmask])
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