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BGA Local Fiducials

jatins

Hi 

I was wondering at what point does it become necessary to add local fiducials to the BGA packages. 

Would a 0.8mm pitch package be placed correctly by machine if i do not use local fiducials or what if i go for 0.65/0.5mm pitch?

Would small packages with 24/48 pins don't require them as much as 324 pin packages?

  • Fiducials are only used if the machine is programmed to look for them during the alignment process every time a bare board is loaded.  If you have tons of extra room, why not?  Esp for 324 pins.

    We put two fiducials towards opposite corners on every board and 01005's yield ok.  But, our boards range from the size of a grape to a playing card. 

    To avoid going back and adding them, get ahead of any copper image-shift problems and locate a single fiducial in two areas on the board where extra accuracy will pay off in yield.  

    Talk to your assembly house if you're designing a rigid-flex assembly.  These have to be baked in an oven before assembly to drive moisture out as humidity causes flex expansion like crazy.

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