Hi All, Here is yet another opportunity for you to lend your wealth of knowledge as you have many times in the past. We build high voltage power supplies and some of our supplies require the multiplier and feedback boards run at voltages of 160keV or higher. For these applications we "submerge" the boards in Shell Diala AX oil used as a dielectric. Our manufacturing process currently has the boards (FR4) soldered using an OA flux and then washed in a Batch DI wash which dries for 20 minutes at up to 150°F. The boards are then routed to the next level of assembly, at which point they may be "sunk" in oil right away or could sit on the assembly shelf for some period of time before going into the oil. It is my understanding that FR4 will absorb some amount of moisture. Is FR4 the best choice for this application? Should the boards be baked to drive out any residual moisture right before "sinking" in oil? If so, for how long and at what temperature? While we are on this subject I have some questions about the cleanliness of the oil. Up until recently we weren't pushing our output voltages as high and the level of air, moisture and particulates in the dielectric oil didn't matter. Now with the higher voltages (and they are going to go higher) we see the need to monitor, process and control the "quality" of the oil. At the moment we are looking at heating the oil and storing it under a vacuum to remove the water and oil. Do any of you have experience with this type of application? I'd like to get some benchmarks so I have an idea just how nuts we have to go in processing the oil. One of my first places will be to call Shell oil and get their input, but I wanted to tap into the vast knowledge base of this esteemed group as well. Thanks in advance, Phil Nutting Manufacturing Engineer Kaiser Systems, Inc. --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------