We are required to run the Hygroscopic Dust Test (part of NEBS testing). The test is performed to simulate 30 years of environmental exposure. The hygroscopic dust is applied as a liquid spray and is then dried for 24 hours. After the liquid is dried the board is powered up at humidity levels between 70% and 80% and is required to be 100% operational. Sensitive circuitry could fail due to low impedances paths created at high humidity. In fact I have seen an intermittent failure on some of the more sensitive clock circuitry during these tests. I need to specify a sealant to apply around the BGA devices with sensitive circuitry. This bead of sealant around the BGA should prevent the liquid spray from entering the pin field under the BGA. I know that conformal coating the entire board is out of the question here so please only suggest solutions that seal around a specific BGA device. Does anyone have a recommendation on the type of sealant that should be used or you have used in the past? Obviously, I will be calling my CM to discuss this issue but I wanted some feedback from the forum also. Thanks Tony Cosentino Tekelec [log in to unmask] 919-460-3656 --------------------------------------------------------------------------------- DesignerCouncil 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 DesignerCouncil. To temporarily stop/(restart) delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL/(MAIL) Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 ---------------------------------------------------------------------------------