Dave,

Please reference IPC-J-STD 001A. I THINK it suggests a level of less than
1.5 micrograms / centimetre square i.e. less than 10 mg / inch square.

Max Min levels? Depends. Consider that this level of 1.5mg/cm2 also means
the maximum level - but if you are making fine line, fine pitch and BGA
etc., then this level will almost certainly be too high - although that does
also depend upon the nature of the operating environment. Many therefore
apply an empirical level of around 0.2mg/cm2

Another issue is that checking this contamination underneath low stand-off
components is often incomplete unless the component is removed for the test.
This is because the alcohol/water mix simply does not adequately get under
and remove whatever is beneath the component.

Hope this helps.

Regards, Graham Naisbitt

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-----Original Message-----
From: D. LOAN <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: 22 March 1999 15:20
Subject: [TN] Circuit Card Cleanliness


>IPC,
>
>
>I am using IPC - CH - 65 Guide for cleaning PCB's.
>
>I am using an Ionograph Contaminometer to check contamination levels
>on populated boards.
>Is there a standard max level for the surface area of a board, such
>as 1.5ug / SQ CM.
>
>The Ionograph does not quote a standard max level.
>I will be greateful for any help you can give.
>
>Best Regards,
>
>Dave,   Quality  Control  Technician.
>
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