Hi Bruce! We are routinely putting acrylic conformal coating over plastic BGA components without using underfill for avionics use environments. We did a fair amount of testing looking both at paraylene and acrylic prior implementation. This work was published at the IPC APEX 2000 Conference in Long Beach (the paper title was "An Investigation of the Effects of Printed Wiring Board Surface Finish and Conformal Coating for Ball Grid Array Assembly"). Can you expand on your concern of "entrapped air"? We have not seen any issues for that topic after 2 years of production experience. Dave Hillman Rockwell Collins [log in to unmask] "Misner, Bruce" <[log in to unmask]>@ipc.org> on 03/19/2002 01:48:38 PM Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond to "Misner, Bruce" <[log in to unmask]> Sent by: TechNet <[log in to unmask]> To: [log in to unmask] cc: Subject: [TN] Conformal Coating BGA's My question of the day: Is anyone conformal coating (not parylene) plastic BGA's on FR-4 in Hi-Rel applications (aircraft; -20 to +71C ambient operating temperature requirement) without benefit of an underfil? If yes, has entrapped air been a major issue? Anyone care to comment on this approach? Regards, Bruce Misner --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 --------------------------------------------------------------------------------- --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------