Matt, In my earlier response, I should also have mentioned that we underfill BGA's before coating with a reworkable epoxy. This completely fills the air gap underneath and helps support the BGA solder joints as well. It softens at soldering temperature so you can remove a BGA as normal (well almost - it needs a bit more lifting power to detatch it from the board than does a BGA with no compounds underneath). Underfilling is not necessary though if your product is not going to be temperature cycled much. If your coating is thin enough to penetrate beneath components well and is applied properly, it will protect all surfaces well enough. If you use very thin coating, you will require several coats to build up the necessary thickness (anywhere between about 1 mil and 5 mils), since the solids content that forms the coating is a relatively low percentage of the native coating volume. Humiseal supplies quite good appliation notes for the various methods of applying their coatings. Peter joyce <[log in to unmask]> 22/05/2003 10:32 PM Sent by: TechNet <[log in to unmask]> Please respond to joyce.koo To: [log in to unmask] cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group) Subject: Re: [TN] Conformal Coating Application Method for BGA Use CVD. jk >-----Original Message----- >From: TechNet [mailto:[log in to unmask]] On Behalf Of >Gray, Matthew D HS-SNS >Sent: Thursday, May 22, 2003 9:54 AM >To: [log in to unmask] >Subject: [TN] Conformal Coating Application Method for BGA > > >Hello - > >I am requesting feedback to material and processes that have >provided environmental performance protection for BGAs and >other large array packages. The performance environment of >consideration is corrosion and humidity. > >Can users provide particular details regarding application >process spray (inclusion of steps used for flood/fill/etc), >dip, other, and material that has provided a high amount of >coverage and ability to protect electrical connections and >components in humidity and salt fog environments. Ideally, >these materials are below the parylene step. All feedback is >appreciated. > >Regards - Matt > >--------------------------------------------------- >Technet Mail List provided as a free service by IPC using >LISTSERV 1.8e 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/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 1.8e 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ----------------------------------------------------- [This e-mail is confidential and may also be privileged. If you are not the intended recipient, please delete it and notify us immediately; you should not copy or use it for any purpose, nor disclose its contents to any other person. Thank you.] --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------