Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Pcb Drill Hole as Fiducial

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#79833

Pcb Drill Hole as Fiducial | 20 February, 2018

Is it good practice to use a PCB mechanical drill hole as local fiducial? Would it increase my placement accuracy? Or should I stick to my panel fiducials? We're using a panel with 4 boards and we're trying to reach a 50 microns accuracy.

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dwl

#79834

Pcb Drill Hole as Fiducial | 20 February, 2018

Proper fiducials are going to be more accurate than drill holes. Since drilling is a separate step in the PCB fab process, the registration to the PCB isn't as accurate as the copper etching process which forms the fiducials.

In a pinch, it can be used, but its no substitute for a copper fiducial.

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#79838

Pcb Drill Hole as Fiducial | 21 February, 2018

Depends a lot of PCB manufacturer and how good is the registration of the films to drills and what is drill precision etc. General rule is that components are placed on the copper layer pads, so copper fiducial is aligned with same accuracy as the pads where components are placed. Using drills as fiducials will add drill alignment inaccuracy to your placement machine error

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#79897

Pcb Drill Hole as Fiducial | 5 March, 2018

If it's a plated hole though, you can use the ring around it, which should be as accurate as a copper fiducial. just know that any plated hole with a trace coming off of it will have a "tail" and it might throw the computer off when scanning.

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