I made a custom PCB which I would like to charge through a (2pin) pogo pin connector. Do I only need to place two SMD pads and glue two magnets on the PCB for it to work?
I only need the USB's 5V and GND. There are some premade charging cables (2pin to USB) I would like to use something like this: 
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\$\begingroup\$ You would need to attach the magnets to the opposite side of the PCB from the looks of that connector, otherwise the pogo pins won't be able to reach. Does the circuit have polarity reversal protection? If not, perhaps a connector with three pins would work better - if the connections are symmetric then it won't matter which way round it is attached. \$\endgroup\$– Andrew MortonCommented Dec 20, 2023 at 15:28
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\$\begingroup\$ You may find this post of interest: electronics.stackexchange.com/questions/694745/… \$\endgroup\$– Tim WilliamsCommented Dec 20, 2023 at 15:30
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3 Answers
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It can be. But a bare PCB pad would have to be gold-plated to be suitable; cheap HASL finish will oxidize over time and the contact will degrade. Your cheaper gold finishes (ENIG, ENEPIG) will also degrade over connect/disconnect cycles, as the gold is extremely thin and soft; it'll wear off.
While you could spend a lot of money to have your board plated with hard gold, a better option would probably be to use a small gold-plated brass pogo pin target, like these. These are soldered onto the board and provide a more durable contact surface than ENIG as the gold is several times thicker (10 μ" compared to ENIG's typical 1 to 3 μ").
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\$\begingroup\$ Thank you for suggesting and linking a better solution I think I will go with those. \$\endgroup\$ Commented Dec 20, 2023 at 15:26
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It depends on the expected cycle count (mating and unmating).
On a standard PCB your SMD pad has ~35µm copper + surface finish. Assuming you PCB uses ENIG finish that makes another ~5µm nickel and <0.5µm of soft gold.
For a few tens of cycles this will very likely be good enough. At a few thousand cycles I would assume wear of the pad to be a real problem.
At a few hundred I'm not sure, might work, might not.
Hard gold surface will last longer than ENIG, but will also be more expensive in production.
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\$\begingroup\$ Thank you for your answer, I didnt think about the durability. \$\endgroup\$ Commented Dec 20, 2023 at 15:25
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Use an SMD pad for pogo pins pushing directly on a PCB. Gold plating is recommended. A reputable manufacturer will provide footprint dimensions in the cable's datasheet.
More likely, though, the cable will probably also have a specific female connector to mate with, with the proper magnets already built in. You may find it easier or more reliable to use these connectors in your design rather than try to properly align and mount magnets into a PCB. The part number for the connector should also be found in the cable's datasheet.
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\$\begingroup\$ The premade female connecters are not good for me becasue they are too tall and I couldnt find any low profile ones. I also have an SPO2 sensor on the bottom (where the pogo pins go) and that should be the tallest for good contact with the human skin. The SPO2 sensor is on an another PCB that is soldered to the main PCB so it sticks out only as much as the standard PCB thickness which is 1,6mm. \$\endgroup\$ Commented Dec 20, 2023 at 15:23