Thanks everyone. This information is very useful. Most of our boards are FR4 Tg 170 or higher. Most of the boards have LPI protective masking, with very few boards with unprotected FR4. Obviously the unprotected FR4 have a greater propensity to absorb than the protected, but is it true that not all FR4 is manufactured the same way? Meaning that one made by x manufacture has a different WVTR than another manufacturer? In the same respect, the masking material would have different WVTR as well. Question: do most EMS houses consider bare boards level 2 moisture sensitivity rating or better (polymide, Teflon, etc…)? Curious. Does anyone know when IPC-1601 will be released?



Thank again in advance for your feedback. Acquiring knowing is great!



Best Regards,



Chris Schaefer

Suntron Corporation

Process Engineer

800 N. Brutscher Street

Newberg, OR 97132

Work Phone: 503.554.6270

Cell Phone: 785.248.9016

Email: [log in to unmask]<mailto:[log in to unmask]>



From: [log in to unmask] [mailto:[log in to unmask]]

Sent: Saturday, September 12, 2009 9:38 AM

To: [log in to unmask]; Schaefer, Chris

Subject: Re: [TN] Bare Board Moisture Content Standard



Hi Chris,

The allowable moisture content depends primarily on the temperature your PCB will reach during the soldering process—the higher T the lower the allowable moisture content. some material suppliers make recommendations, see e.g. Isola Technical Belletin, “PCB Packaging for Lead-Free Assembly,” September 2007, 5 pages, available from www.isola-group.com.

Also, I developed a White Paper "Recommendations for PCB FAB Notes and Specifications in Printed Circuit Board Drawings for SnPb and Lead-Free Soldering Assemblies, the Qualification of PCB Shops and Activities to Assure Continued Quality" that among many other things contains an extensive discussion on PCB moisture content.

Werner





-----Original Message-----

From: Chris Schaefer <[log in to unmask]>

To: [log in to unmask]

Sent: Fri, Sep 11, 2009 4:51 pm

Subject: [TN] Bare Board Moisture Content Standard



Hello fellow techies,





















My question today concerns allowable moisture content by percentage and if











there is a standard that applies to the varying materials used to make fabs.











We are in the process of creating a flow down document to our board houses











to ensure boards are stored, packaged and20handling appropriately prior to











delivery to us. I have been unable to find a standard that has any information











in regards to this, but have been told there is one. I'm hoping you all couls











shed some light on the subject.





















Thanks in advance and have a great weekend.





















Ciao!





















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