Re: [PEDA] New Question.. Best Practices...
I have library parts for mounting holes and other hardware (i.e. all PCB features exist on the schematic). A consequence of this is that I can define an M3 mounting hole component that includes a keepout definition. This definition is usually a 360 degree arc on the keepout layer with an appropriate clearance to the hole, plus additional keepout arcs on the top and bottom layers (with a larger radius) to keep a sufficiently large zone clear of traces and components so that a lock washer can't do damage. John Haddy > -Original Message- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] > Sent: Thursday, 21 February 2002 10:48 PM > To: Protel EDA Forum > Subject: Re: [PEDA] New Question.. Best Practices... > > > Stephen, > > My line manager has just been to a one day seminar on DFM, and I'll > review the notes next week - so going on a short course might answer > some of your questions. > > When I do 3mm mounting holes, I leave 6mm clear of components. I do this > by temporarly enlarging the pad while routing/placing and shrink when > I'm nearly finished. We had a similar problem here when we accidently > used crinkle washers which shorted our board to chassis. > >[...] > * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] New Question.. Best Practices...
Steven or others, here is a good article on the topic of holes, mounting holes and plane clearances, etc.. Some of it is a bit basic but good reveiw for most. http://www.speedingedge.com/docs/platedholeanatomy.pdf Sincerely, Brad Velander. Lead PCB Designer Norsat International Inc. Microwave Products Tel (604) 292-9089 (direct line) Fax (604) 292-9010 email: [EMAIL PROTECTED] http://www.norsat.com See us at Booth 323 at Satellite 2002 in Washington, DC March 6-8. -Original Message- From: Stephen Casey [mailto:[EMAIL PROTECTED]] Sent: Thursday, February 21, 2002 1:17 AM To: Protel EDA Forum Subject: Re: [PEDA] New Question.. Best Practices... Sam, Another (related) issue is the clearance on inner plane layers. I had 100 boards manufactured once with a slight misalignment on the power plane. All the connections were ok, but the power plane was almost breaking through the wall of the mounting holes on one side. One or two screws cut sufficiently deeply into the side wall to cause a short to the chassis. Now I leave about 30 thou (as an aside - most PCB houses I speak to here in the UK always assume that I mean 'mm' if I say 'such and such mil', so I always say 'thou' - what's the convention?) Hope this helps Steve. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] New Question.. Best Practices...
Apologies for responding to my own post, but a tip that might be useful if you encounter the same problem that I described is to use the plastic bushes that are supplied with TO3 mounting kits. The sleeve successfully isolates the screw from the copper, and the wall thickness is such that they fit without opening the hole up (for M3, anyway!). Hope this helps somebody someday. Steve. > -Original Message- > From: Stephen Casey [mailto:[EMAIL PROTECTED]] > Sent: 21 February 2002 09:17 > To: Protel EDA Forum > Subject: Re: [PEDA] New Question.. Best Practices... > > > Another (related) issue is the clearance on inner plane layers. I had 100 > boards manufactured once with a slight misalignment on the power > plane. All > the connections were ok, but the power plane was almost breaking > through the > wall of the mounting holes on one side. One or two screws cut sufficiently > deeply into the side wall to cause a short to the chassis. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] New Question.. Best Practices...
Sam, One of the issues that's bitten me more often than I'm prepared to admit - Clearance around mounting holes. It's amazing how unfeasibly huge an M3 screw head looks when zoomed in on a PCB. Almost every time I'm doing a board I do a print to check that I really do need that much dead space, and every time it's true. Another (related) issue is the clearance on inner plane layers. I had 100 boards manufactured once with a slight misalignment on the power plane. All the connections were ok, but the power plane was almost breaking through the wall of the mounting holes on one side. One or two screws cut sufficiently deeply into the side wall to cause a short to the chassis. Now I leave about 30 thou (as an aside - most PCB houses I speak to here in the UK always assume that I mean 'mm' if I say 'such and such mil', so I always say 'thou' - what's the convention?) Hope this helps Steve. P.S. Are you supposed to be using Protel with an email address like that? ;o) > -Original Message- > From: Samuel Cox "Sam" [mailto:[EMAIL PROTECTED]] > Hello everyone.. > What are the top Ten or twenty(now a days) DFM "Best Practices" process > steps, or checks or suggestions you might look for > to ensure a design is right the first time you send it to manufacturing.. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] New Question.. Best Practices...
Hello everyone.. We have pretty much beaten to death the definition of PWA, PWB, PCA, PCB. Now that we know what we are talking or not talking about.. The question I have is What are the top Ten or twenty(now a days) DFM "Best Practices" process steps, or checks or suggestions you might look for to ensure a design is right the first time you send it to manufacturing.. When I say manufacturing I mean fabrication, assembly and test. I am trying to put together a checklist that will address 80-95% of the problems that seem to come back from manufacturing causing delay or a respin.. increased cost etc... Thank you in advance. Sam Cox... * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
