Kim, Screw/Washer choice: - should a washer be used or not? ONE COMPANY I WORKED FOR USED SCREWS WITH INTEGRAL STAR WASHERS. WE NEVER HAD ONE WORK LOOSE EVEN IN MOBILE APPLICATIONS.
- Is an adhesive like Loctite a reasonable alternative to lock washers in this case? I WOULD THINK LOCKTITE WOULD BE GOOD BUT I WOULD DESIGN IT TO MAKE SURE THE SCREW IS NOT REQUIRED AS A FAULT CURRENT PATH. - should the screw be zinc plated? or some other plating? I FAVOR USING THE SAME PLATING THAT THE PEM NUT USES. PCB layout: - Should we use a plated through-hole with ground planes connected inside the hole? WE USED PLATED THRU BUT THE CONNECTION TO THE NTERNAL LAYERS CAN FAIL SO I WOULD NOT RELY ON THEM. - or a non-plated hole with vias in the surface layer pad connecting to the ground plane? YES VIAS, OUTSIDE THE SCREW HEAD AREA ARE PREFERRED. THE PAD SHOULD BE ON THE PEM NUT SIDE SO THAT THE SCREW IS NOT A PART OF THE FAULT CURRENT PATH. I WOULD DEVELOP A TORQUE SPEC, USE A TORQUE WRENCH, AND PUT THIS IN THE ASSEMBLY DOCUMENTATION. Dave Cuthbert Micron Technology This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
