Don - Take a look at IPC-2221, section 5.2. This provides a pretty good set of guidelines for the designer. Realize that the decision to fasten or secure a component must lie with the designer of the board or assembly, based on the intended system usage. These are no longer fixed rules served up on a "one size fits all" basis. Regards - 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 ################################################################