Missing paste mask for exposed pad ground on processor, please update gerbers

[cmcjames]

Hello, We are manufacturing KickStat and the manufacturer informed us of the missing paste mask for the processor's exposed pad. Without the exposed pad soldered to the board, it would leave ground pins 5 and 18 floating. For this particular package, there is no mention in the datasheet of all the digital and analog grounds being connected internally to compensate for the missing paste mask. Please update the gerber files for others. Thank you.

[hoilett]

Hi, Which manufacturer are you using? These are the exact Gerber files I sent my manufacturer (PCB Way) without any issue. https://github.com/LinnesLab/KickStat-Paper-Firmware/blob/master/KickStat/Hardware/Button-Cell/RevB/MiniStat-Button-RevB-Gerbers-2019-07-29-1030.zip

Though I do admit PCB Way may have filled in any missing files for me without mentioning it.

[cmcjames]

Hi,

Yes, I just downloaded those files.

In the gerber file with extension GTS, I can see the soldermask opening for the pins and exposed ground pad. In the file with the extension GTP, I can see the pastemask missing for the exposed ground pad. Comparing the schematic with the gerber file with extension GTL, pins 5 & 18 attach to the exposed ground pad, and without that connection, they would be floating because the only connection to actual ground is through pin 42, also connected to the exposed ground pad.

Thank you,

-James

From: Orlando Hoilett @.> Sent: Thursday, February 24, 2022 12:15 PM To: LinnesLab/KickStat-Paper-Firmware @.> Cc: James Millar @.>; Author @.> Subject: Re: [LinnesLab/KickStat-Paper-Firmware] Missing paste mask for exposed pad ground on processor, please update gerbers (Issue #2)

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Hi, Which manufacturer are you using? These are the exact Gerber files I sent my manufacturer (PCB Way) without any issue. https://github.com/LinnesLab/KickStat-Paper-Firmware/blob/master/KickStat/Hardware/Button-Cell/RevB/MiniStat-Button-RevB-Gerbers-2019-07-29-1030.zip

Though I do admit PCB Way may have filled in any missing files for me without mentioning it.

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[cmcjames]

And thank you for building the KickStat. We’re looking forward to giving it a whirl!

[cmcjames]

I missed taking a closer look at the GTL layer (traces!). In the GTL board layer, pins 5 & 18 are connected through the exposed pad on the layer then to pin 42 and off to ground, so they won’t be left floating. The datasheet doesn’t mention the exposed pad must be connected to ground for this particular package and the recommendations seems to differ depending on the package type. It would however be good practice to connect the exposed pad to ground with vias in the pad so as not to leave too much inductance in the ground circuit by forcing current from pins 5 and 18 though the sole ground connection off pin 42. If you have had any feedback on digital & analog ground layout for noise reduction, I would be interested to learn more about it.