Hi Todd - Most of the engineering data for threaded fastener torque values deals with joining two or more plies of metal, which is for the most part considered incompressible under these loads. The principle of torquing is to stress the fastener material to about 60% of the yield point of the fastener metal involved. When a composite material, such as a circuit card, comes into play, the torque values are no longer applicable or appropriate. First, the composite will generally change form and size (thickness) under sustained load, resulting in a loose fastener. The composite, may also undergo compressive fracture, if enough force is applied over a small enough area. Split washers and the like, are generally dependent on being able to penetrate the surfaces being joined, slightly. They are also not always shakeproof and may loosen in vibration, such as shipment. A more reliable solution may be to use either: a locking nut; a screw with preapplied locking compound or nylon insert; or use a thread sealant at time of assembly. Dependent on design, you may also want to consider a screw with a dual lead, or deformed thread. Good luck - Kelly ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################