When I read IPC Standards regarding conformal coating requirements for the different classes, all I can find is coating thickness on a board. **Mike, I feel your pain. You can find the materials requirements, the minimum that conformal coating materials must do, in IPC-CC-830. The B revision should be released in the next few months. That is primarily a materials procurement or qualification document. The two standards dealing with coating after it is put on are IPC-A-610 and J-STD-001. Both documents boil down to the same thing: put coating down where the drawing says, keep coating off where it ain't supposed to be, and make sure the coating film has a certain thickness and a certain quality, i.e. no pinholes, cracks wrinkles, etc. It is left to the user to determine what a coating needs to do for their hardware. You might find some more insight if you look at the latest draft of the Conformal Coating Handbook, which should be nearing publication. I'm trying to work to class 3 standards for conformal coating and am meeting those thickness requirements, however, I have to wonder how it works on a BGA for example, where the coating thickness is sufficient but doesn't completely cover and encapsulate the component. In other words, there is a gap between the top of the BGA and the PCB. **Thicknesses are measured on a flat unencumbered surface, not on just any surface on the board. You may have the minimum 2 mils of acrylic coating on the board, but it won't be that thick on sharp component edges, or tops of components, and certainly not on the underside of the components. The only coating that will get the bottom side of components is paralene/parylene/paralyne (I never can remember which one is right). Any thoughts on this would be appreciated. **If'n ya want, give me response off-line if there was something more specific you need. Doug Pauls Rockwell Collins "Conformal Coating - The Great Career Limiting Move" --------------------------------------------------------------------------------- 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 the following message: SET Technet NOMAIL 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 ---------------------------------------------------------------------------------