I'm sure you will get a lot of input from the experts (Iconic
Contamination) on this subject and there are varying views on the
validity of the established cleanliness values, but it's all a wash.
Cleanliness, like luck is the residue of design. Your job is to decide
whether the values/requirements are adequate/acceptable given the
design/performance parameters you are dealing with.
IPC-5702 has just been released. It will give you some insight on
acceptance criteria for unpopulated Printed Boards. You can build on
that to establish adequate pass/fail criteria for final assembly
requirements.
Dewey

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Chafin, Ken G.
Sent: Monday, October 01, 2007 12:47 PM
To: [log in to unmask]
Subject: [TN] Ionic Cleanliness

Does any IPC Standard recommend a minimal level of  PC Board, or PC
Assembly ionic cleanliness in terms of material per square unit of board
or assembly area?

E.g.   0.2 micrograms of sodium chloride equivalent per square
centimeter.

In IPC-A-600D, section 19.1 a solvent resistively value for an
IPC-TM-650 test is given (greater than 2 X 10 to power 6 ohm per
centimeter is recommended).

Even if an appropriate response to this question is complex can the
question itself be answered yes or no?

Thanks for any guidance. 



Kenneth Chafin


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