You can use test coupon or cut off edge of the pwb that has no copper for test (TGA). If it is HDI (most likely, not in NASA case), you need to develop your own criteria and risk assessment (or risk tolerance) analysis. Not "as dry as bone" is the best. My 2 cents.
--------------------------
Sent using BlackBerry
----- Original Message -----
From: Garcia, Rigo (GSFC-300.0)[MANTECH SRS TECHNOLOGIES] [mailto:[log in to unmask]]
Sent: Friday, October 21, 2011 02:31 PM
To: [log in to unmask] <[log in to unmask]>
Subject: [TN] How do we determine the Maximum Acceptable Moisture Content (MAMC) for a board?
Hi everybody,
Does anybody know how do we determine the Maximum Acceptable Moisture Content (MAMC) for a board?
I understand that IPC-1601 states that for most designs a MAMC between 0.1% and 0.5% of moisture weight to resin weight is adequate. However, it does not describe the basis to establish the range. I can think of many variables that can affect this number like minimum pitch, voltage across, component clearance, whether the board gets conformal coating or not, etc. I would like to know if anybody knows of a safe method to determine the MAMC for a given board.
Paul... I can already see your "it depends" coming... :)!
Thanks for the help!
Rigo Garcia
Sr. Quality Assurance Engineer
Workmanship Standards, Code 300
NASA, Goddard Space Flight Center
Greenbelt, MD 20771
Phone. (301) 286-6129
Fax. (301) 286-6576
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