Anybody, First, How many classes of materials are called out in IPC 4101? Second, If a board is called out to be built to class 2 should the material be class 2 also? What other things are specified by building to class 2? Chris Robertson Designer Lockheed - Martin Services, Inc. 4912 Research Dr. Huntsville, AL 35805 [log in to unmask] Ph/Fax (256) 722-2626 ICQ# 13541566