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Fudical, where, size, etc

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#37527

Fudical, where, size, etc | 1 November, 2005

I am forced to use fine pitch parts in a new design. Board alignment in production has to be addressed. Fudicals, where to place, shape, size. I'm assuming they must be in the copper to represent the pad positions.

Are they placement machine dependent or generic?

Someone send me a sample graphic please.

Dave

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RDR

#37545

Fudical, where, size, etc | 2 November, 2005

Don't have any graphics but they are relatively simple.

1. They do need to be put into the copper. 2. We usually use a 1mm circle but many other shapes and sizes are useable but I know that all machine will take a circle. 3. Maintain a keepout area around the copper circle of at least 1mm (1mm circle surrounded by a 3mm free area) this area should be free of solder mask as well. 4. use a minimum of 3 global fiducials located at the corners of the PCB. Do not make them symmetrical to prevent placement on PCBs that have been loaded backwards into a machine. 5. You may want to place local fiducials at the finepitch locations with two fids located diagonally symmetrical from center location of part, or one located at the center. 6. Make sure that the fiducials are located at least 5mm away from the edge of PCB to allow for edge clamping in the placement machine, breakoff rails may need to be added. 7. Ensure that their location is present in the centroid data for programming

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#37571

Fudical, where, size, etc | 2 November, 2005

Why stop at fids: * IPC-2221 - Generic Standard On Printed Board Design * IPC-2222 - Sectional Design Standard For Printed Board For Organic Printed Boards

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#37572

Fudical, where, size, etc | 2 November, 2005

Russ, thanks for the explination. Makes sense now. DaveF, where do I get the documents you listed?

Why is me username (erokc) for login showing as Author instead of my display name? I've checked my preferences, it's still shows Dave??? Is there an administrator for this forum. I should report to him/her.

I just checked that and on this computer it shows correct "Dave". The other computer I use it does not. Nevermind.

Dave

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#37588

Fudical, where, size, etc | 3 November, 2005

Get the documents from IPC.

Roland Girouard [rgirouard at smtnet.com] is an system admin

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#37613

Fudical, where, size, etc | 3 November, 2005

Davef, pardon my ignorance. Where is and who is IPC. http://www.ipc.com is a financial institute.

Please lead the way

Dave

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RDR

#37639

Fudical, where, size, etc | 4 November, 2005

www.IPC.ORG will get you there

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#37660

Fudical, where, size, etc | 4 November, 2005

Have some mercy with my english. Russ is correct. We do simular things. The differents we do and this must be applied to who it concerns: We do ourself/or we often have requirements to the customer to layout the fid's to 1.5mm diameter. We have some pcb:s with a lot of via:s with a surrounding copper ring that is almost 1mm dia. Theese vias if they are near the search are of the fiducial camera, can cause the vision system to call out the wrong mark, despite that mark is Not a filled curcular spot instead of a ring.

Depending on the board layot; i.e if the board need to be build with components mostly on one side; then the pcb manufactory very often put a pattern of copper marks on the rest of the pcb. The reason for this is to even out the "unbalancing" of that pcb during the manufactoring process of the pcb (this is complicated and I will not go to deep, as I do not fully understand it myself).

Anyhow; theese extra pattern marks should be made diamond shapes; so that the fiducial recognition system don't take them for fids. They are videlicet very often rounded and with a dia. between 1.0 - 1.5mm. /Sincererly

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#37661

Fudical, where, size, etc | 4 November, 2005

I forgot to mention something about the local fiducial marks: In the "old days" where board stretch was a factor to count with; the use of local fid's around a fine pitch component was sometimes necessary; not to forget that the pick & place machines was not to accuracy. But I have Not seen the need for this for many years now. We place components down to 0.4mm pitch QFP:s and micro BGA:s with "only" 3 fid's witout any placement issues. The reason for using 3 fiducials; one in each corner of the pcb; is just that the third fiducial will pick up the eventually board strech (this is how the the logaritm of the visionsystem on the majority of the pick&place machine works). It is enough to do "centering & squaring" with only 2 fid's but most of us I think; program the placement machines to use these 3 board corner fid's. Which is perfect. /Sincerely

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#37673

Fudical, where, size, etc | 5 November, 2005

Here is a tip: Always try the excellent SMT.NET forum search... If You do Not find what You are searching for, and we are unable to help You out; well... we did the best we could, ..or... http://www.smtnet.com//forums/index.cfm?fuseaction=view_thread&CFApp=1&Thread_ID=3101&#Message12584 /Sincererly

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#37794

Fudical, where, size, etc | 10 November, 2005

SMT in-printer dispensing

Hioki Flying Probe Tester