EEVblog Electronics Community Forum
Electronics => PCB/EDA/CAD => Topic started by: cj7hawk on May 03, 2022, 11:09:51 am
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Hi All,
Is there a generally accepted optimal spacing for PCB edge connector pads, for 0.1" spacing type? Like the old XT ISA bus cards used.
I've seen everything from 0.4"pads to 0.9" pads in this, but wondered if there was an optimal spacing when it comes to avoiding shorts due to ill-fitting connectors and mechanical misalignment and other common bad things that afflict such connectors.
Thanks
David.
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Is there a recommendation in the datasheet for your chosen connector?
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If it's ISA card edge connectors you're specifically interested in, the EISA specification (which includes ISA) recommends the following pad dimensions:
(https://www.eevblog.com/forum/eda/optimal-dimensions-for-0-1-spacing-(eg-pcxt-type-)-edge-connector-pads/?action=dlattach;attach=1477399;image)
0.062" / 1.575mm pad width, 0.3" / 7.62mm height.
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Even though the pin spacing may be the same, that does not mean that the contacts for different connector should be the same.
Older type connectors usually have a quite big clearance to manage bigger production tolerances. Other connectors may have double contacts for each pin and require wider fingers on the PCB while yet others may be optimized for HF applications and low capacitance.
So the only right answer is to look it up in the datasheet of the connectors you are using.