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Question on EVMAM1808 component footprints

Anonymous
Anonymous

Hi,

 

I would like to ask a question on EVMAM1808 board component footprints.

 

 

In EVMAM1808 board BOM, I see lots of footprint sizes like "C402-25", which are not EIA standards.

 

In addition, heading entries of Google search of "c402-25" are within SpectrumDigital site. There are only a very limited number of results from other sites, and from this it seems clearly that "c402-25" or alike {r402-25} are not industry standards, but are instead SpectrumDigital's internal naming conventions.

 

Besides the above, there are also inconsistencies between the schematic and PCB layout. As shown in the screenshot attached:

 

 

footprint in PCB

footprint in schematic

C136

C402-25

0603

C146

C402-25

1206

 

Of course, the actual footprint used on PCB should be the standard since the final board is accordingly manufactured. Then this indicates that the footprints specified in schematics are already out of date.

 

And what is the correspondence between you SpectrumDigital's convention {c402-25, r402-25} and industry standard such as EIA?

 

 

Zheng

 

  • 0
    TI__Mastermind 27585 points

    Here's the response from the board manufacturer:

    Every part has a unique footprint for manufacturing and pwb layout. We typically use suggest footprints from manufacturers and do not use EIA standards as there are inconsistent items between standards ( EIA, IPC ), and many footprints we used are optimized for spacing. This should not cause any issue as they are all verified footprints.

  • Anonymous
    0 Anonymous in reply to jc-ti

    jc-ti,

    Thanks for asking SpectrumDigital for this. I will measure the footprints more precisely in the later phase of board design.

     

    Zheng