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July 2014

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Subject:
From:
Bill Noel <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Thu, 17 Jul 2014 11:39:37 -0400
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In many of our designs there IS NOT enough room for local fiducials.  I've been told that today's high-tech pnp machines are accurate enough to be able to simply rely on global fiducials that are placed on the assembly rails.  Is this true?  If not where is the "pitch-limit"  In other words would anything under 1.0mm pitch require local fiducials? 0.5mm? 0.4mm?




---- Ahne Oosterhof <[log in to unmask]> wrote: 
> With 0.4 mm pitch you have about 0.2 mm room between pads. To be sure the part is landing on the pads you probably want a placement precision of close to 20 um. Question 1: can your pick-and-placement machine meet that criteria (all day long) and question 2: are the pads where they are supposed to be with respect to the board or panel fiducials.
> 
> Lots of opportunity for headaches especially when it comes to question #2!
> 
> Ahne.
> 
> 
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Bill Noel
> Sent: Thursday, July 17, 2014 3:31 AM
> To: [log in to unmask]
> Subject: [TN] Local Fiducials
> 
> Are local fiducials (those specifically associated with a single fine-pitch device) necessary anymore?  I've been told by a rep from our Assy CM that they're not necessary anymore with the advent of high-tech pick and place machines.  We've actually been designing some boards with .4mm pitch BGA's  Does this fine of pitch still not require fiducials?  Thanks in advance for the response.
> 


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