Kenny: The rationale for the part stand-off requirement is two-fold. First to assure sufficient standoff to allow cleaning systems to remove process residuals, second to assure that a component with a conductive body is not mounted directly on conductive traces. - Paragraph 4.17 of Mil-Std-2000A states: "Devices mounted over circuitry. Parts mounted over protected surfaces, insulated parts over circuitry, or surfaces without exposed circuitry, may be mounted flush. Parts mounted over exposed circuitry shall have their leads formed to allow a minimum of 0.25 mm (0.010 inch) between the bottom of the component body and the exposed circuitry. The clearance between the bottom of the component body and the printed wiring surface shall not exceed 1.0 mm (0.040 inch)." - By way of additional explanation. The allowance for mounting parts flush to the pwb surface is predicated on the assumption that both the pwb surface and the lower surface of the component do not contain contaminates. With a component such as you described, there should (ideally) be minimal residue trapped beneath the component during soldering and the cleaning system used should be capable of extracting/removing process residuals from the lead/pwb interface area. The allowance for mounting insulated parts flush over in circuitry is worded in a manner to require that the parts be separately insulated from the surface circuitry. A separate insulator is required because, as far as DOD has always been concerned, solder mask does not constitute a dielectric barrier since dielectric withstanding is neither a design attribute or a measured characteristic of ALL solder maskant materials. The 0.040 maximum height limitation is imposed to assure nominal resistance to X & Y axis vibration and shock by minimizing Z axis arm. During the DOD/EPA/IPC tests conducted to identify alternative cleaning technologies (eliminate CFC's) it was found that most all cleaning systems were capable of extracting process residuals if a component standoff of 0.2 mm (0.008 inch) existed, hence the present requirement of ANSI/J-STD-001. - Bottom line. You should be able to maintain 0.010 inch standoff with little or no problem. The proof of the pudding however will be the results of your cleanliness testing, not the dimensional measurement of standoff. Hope this has helped some. If additional information is needed e-mail me direct. Regards, Jim Moffitt ############################################################## TechNet Mail List 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 web site (http://www.ipc.org/html/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ##############################################################