TECHNET Archives

March 2010

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Hernefjord Ingemar <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Hernefjord Ingemar <[log in to unmask]>
Date:
Mon, 15 Mar 2010 10:28:30 +0100
Content-Type:
text/plain
Parts/Attachments:
text/plain (47 lines)
Wayne,

it's not easy to make a reference, because all is about surface energy. Microscopically seen, two boards (non coated)may seem exactly the same, but one board can have a nanometer film of e.g. a oil, which will result in quite different surface energy. There may be numbers of reasons for the surface energy to vary, even if it's all about FR-4 or about solder mask or whatever. The cohersive forces that makes droplets to form is also depending on the microstructure, and even here, I think there are large variations. Moreover, the polar water molecules (that will make a droplet)are  depending on the polarity of the object, which means the board can be more or less repellent. I'm afraid I can't help you, but there is a TN guy with endless knowledge. He may develop this topic.. if he got time. Brian Ellis.

/Inge

 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Thayer, Wayne - IIW
Sent: torsdag 11 mars 2010 15:36
To: [log in to unmask]
Subject: [TN] condensation

Anyone know of a reference for RH thresholds for moisture condensation on an uncoated assembled PCB?  My intuition tells me to expect that condensation will initiate in tiny cracks at RH levels below 100%.  I found some references for this effect with some ceramics, but nothing on PCB assemblies.  I'm trying to advise my customer to conformal coat if he really wants to pass a test at 95%.

Thanks,

Wayne Thayer

________________________________
This e-mail and any files transmitted with it may be proprietary and are intended solely for the use of the individual or entity to whom they are addressed. If you have received this e-mail in error please notify the sender.
Please note that any views or opinions presented in this e-mail are solely those of the author and do not necessarily represent those of ITT Corporation. The recipient should check this e-mail and any attachments for the presence of viruses. ITT accepts no liability for any damage caused by any virus transmitted by this e-mail.

______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------

______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------

ATOM RSS1 RSS2