based on my knowledge, the conformal coat is not hermatic seal... what do
you mean contact with liquid? water resistance? how deep? pressure? etc.etc.
Water tide sealing at system level is got nothing to do with conformal coat.
please correct me if I am wrong.
                             jk (my 1.72 cents)

abcd

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Edward Mines
Sent: Tuesday, March 27, 2007 12:01 PM
To: [log in to unmask]
Subject: [TN] weather coatings


My e-mail to the author of the recent inquiry about "weather coatings" did
not go through.

  Conformal coatings protect PC boards from atmospheric moisture and hostile
chemical environments but are not waterproofing.

  Boards coated as directed in MIL-I-46058 and now IPC-CC-830 frequently
have incomplete coverage prone to fail when in contact with liquid water.

  Some engineers recognize this and apply thicker coating then is
recommended in the aforementioned documents and by some manufacturers. Some
coatings will not cure properly in overly thick cross sections.

  Encapsulation can provide the thicker layer necessary to provide complete
coverage.

  When I was in the conformal coatings industry I helped several customers
protect boards against rain and liquid sea water. Mr. Eckert, contact me off
list for  details.

  Edward Mines




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