Why are there two unused spots in the room for SMD Quad pack

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EDALearner

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PCB Design Rules

Sometime there are two big special spot in the two corner of the mounting room for SMD Quad package. These spot always left alone and does not connected to any net, what is the use of them? Any helpful sugesstion?
 

automatic targets

They could be optical alignment targets for automatic assembly machines to use.
 

Re: PCB Design Rules

flatulent,
It was a metal spot! not a colored one! Also it was so big for photo alignment process.
 

Re: PCB Design Rules

I would agree that they are vision targets for the QFP, they would reside on the copper layer with the soldermask removed and no silkscreen anywhere near.

pd



EDALearner said:
Sometime there are two big special spot in the two corner of the mounting room for SMD Quad package. These spot always left alone and does not connected to any net, what is the use of them? Any helpful sugesstion?
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