Bill, Thanks for your response. I didn't state the actual issue very well. So I shall start with that. We observed two 0603 resistors cracked on several boards. The resistors are placed near a swaged standoff, but not within the 0.75mm per IPC-2221 page 55. The line voltages and potentials per your response are not remarkable enough to warrant a greater clearance. The standoffs in question are garden variety Keystone 1589-2 #2-56 x 0.156 O.D. Keystone on its website specifies a recommended staking tool, TL-19, which consists of a punch and anvil. Keystone does not specify a particular tooling clearance or staking force. We may need to add a note on the assembly drawing about maximum swaging force, in order to prevent the installer from damaging components due to excessive force while swaging. But in my experience, the caveat when adding such notes is, first you have to pay someone to set up the secondary op step, then you have to pay someone else to inspect the first few articles, then you have to pay for a jig, yada yada. All these costs get passed on to the customer, whereby at the end of the day you may have created a cost increase which could be overkill. For next build I moved the resistors to the other side of the board, and further away from the standoff area. That's fine, but I want to understand the root cause for future edification. I would like to understand whether I had to do this because I violated a rule of thumb, or whether I was victimized by manufacturing ham-handedness, or a little of both, so I can build the proper keepouts into the footprints for these swaged standoffs. I don't know if some of the older specs such as IPC-CM-770 would give me the rule of thumb that I need, or if I will need to email Keystone specifically. Thanks, Gary M. Koven, C.I.D. Engineering Services Manager Dynazign, Inc. 806 Tyvola Road, Suite 100 Charlotte, NC 28217 P: 704.405.1234 x210 F: 704.405.1402 http://www.dynazign.com/ better rendering of this issue. -----Original Message----- From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Brooks,Bill Sent: Monday, March 28, 2005 1:44 PM To: [log in to unmask] Subject: Re: [DC] Conductive pattern to mechanical hardware clearance I don't believe there is a specific spec for what you are looking for...someone please correct me if I am wrong... The IPC-2221 page 55 has an example requirement that says for UNCOATED (no soldermask or conformal coating) boards, you need .75mm minimum but not less than allowed by the electrical clearance requirements... The things that would govern the amount of spacing from any mounting hardware would be voltage on the line in question relative to any voltage or ground potential on the hardware, tooling clearance to swage or mount the standoff, and installation tool (screwdriver?) and hardware clearance from any screws and washers used in mounting the standoff to a chassis or bracket. Also be concerned about clearance to any nearby component body as well as the conductive pattern or any conductive non-insulated lead(s) from the component involved. If you are doing UL or TUV certification, there are more stringent requirements to be concerned about... The ability to prevent shock hazard by not allowing the end user to get their finger or a tool into an area that will get them electrocuted across the line or from the line to ground, spacing between the primary line voltages and SELV or Safety Extra Low Voltage requirements at 48VDC or lower... secondary voltages... Distances from Ground to the line voltages, line to line voltages, and on and on... They are also concerned with Fire hazard... a failure shall not cause a fire hazard... etc... It's a little more complicated... Best regards, Bill Brooks - KG6VVP PCB Design Engineer , C.I.D.+, C.I.I. Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510 e-mail:[log in to unmask] http://www.dtwc.com http://pcbwizards.com -----Original Message----- From: Gary M. Koven [mailto:[log in to unmask]] Sent: Monday, March 28, 2005 10:11 AM To: [log in to unmask] Subject: [DC] Conductive pattern to mechanical hardware clearance Which IPC specification will show the minimum clearance from conductive pattern to mechanical hardware such as swage standoffs? Right now I have approximately 0.025in (0.635mm) from via pad edge to standoff lip edge, and want to make certain that distance will be sufficiently robust for production. The manufacturers' datasheets don't specify a recommended clearance, and neither do the IPC-222X series specs. Thanks, ====================== Gary M. Koven Engineering Services Manager Dynazign, Inc. 806 Tyvola Road, Suite 100 Charlotte, NC 28217 P: 704.405.1234 x210 F: 704.405.1402 http://www.dynazign.com/ ---------------------------------------------------------------------------- ----- DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF DesignerCouncil. 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