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Best contrast for Fiducials

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GEB

#39284

Best contrast for Fiducials | 24 January, 2006

Hi, We are starting to have supplied to us by customers different colour PCBs, which affects the ability of our MPM AP-27 stencil printer to see the fiducials. Has anyone tried and found out what the best and worst colours/ materials are for the fiducial and resist around the fid. We are not always able to choose what materials the boards are made from but this may help us reach a happy medium with the customer.

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RDR

#39285

Best contrast for Fiducials | 24 January, 2006

We utilize a "keepout zone" around the fiducial that is free of resist, silkscreen, vias, and any other feature.

e.g. fiducial diameter of 1mm- we use a 3mm diameter keepout zone. This works very well for us.

If the surface finish changes the light lever may require adjustment but usually not.

Russ

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Chunks

#39286

Best contrast for Fiducials | 24 January, 2006

Tell your board house/customers you want "non-smobc". hich stands for non-solder maske over bare copper. MPMs love exposed fids in just about any finish. You can always use pads on an MPM too.

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PWH

#39287

Best contrast for Fiducials | 24 January, 2006

Although I can't say I've had much trouble at all with MpM's reading fids, I will say that most of the P&P equipment I have run can be picky on fids. The fid surface needs to be pretty flat in order to be trouble free on some P&P equipment. I don't know much about surface finishes - I just know flat is good. Rubbing a fid with a pencil eraser helps dull an uneven, shiny surface to help your machine read it.

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