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I have a question regarding local fiducials so as to achieve proper alignment of the board, during the soldering of a 0.4mm pitch chip. As I have seen the best practice for local fiducials is to place 2 of them, one on the upper right corner of the chip and one down and left. Due to lack of space I can only place one fiducial at the down left corner. Is this going to be helpful or useless? I have also placed 3 global fiducials for general board alignment.

Thank you

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    \$\begingroup\$ The only person who can answer definitively is your fabricator, but to me it seems like one local and 3 more should be fine. \$\endgroup\$ – Scott Seidman Dec 6 '19 at 14:57
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    \$\begingroup\$ Where I worked we had in-house SMT fab. We used three global fiducials out near the corners, and one local one dead center in the footprint of the occasional fine-pitch part (TQFP, etc.). The robots had cameras and AOI to check the rotation and offset after picking, and make adjustments before placement. \$\endgroup\$ – AnalogKid Dec 6 '19 at 15:13
  • \$\begingroup\$ A single local fiducial will not really gain you anything more than only relying on the three global fiducials. \$\endgroup\$ – DerStrom8 Dec 6 '19 at 16:31

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