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I'm in the process of designing a tiny embedded system, it has quite a bit of sensors and it is controlled by 2 MCUs.

On previous versions of the test boards, I used 2mm pitch size headers for connecting the main board to a programming board. For the new version of the board, we definitely can not put these headers anymore.

Figure

I had the idea of using tiny 0.35 ~ 0.4 mm pitch connectors to interface both boards. I never tried to deal with this type of connectors before and I was wondering if they would be a good option for repetitive use, which will happen when programming and testing the device.

I've found the processes of connector hunting quite hard as there is a HUGE selection of parts and I cannot find the wire that I'm looking for. I think I may have to custom order a FPC wire too?

I’m wondering if anyone had a similar experience or suggest a different method for interfacing the boards?

Thanks

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    \$\begingroup\$ "we definitely can not put these headers anymore". The reason for you saying this is probably the biggest factor in selecting a replacement. \$\endgroup\$
    – Finbarr
    Sep 22 '17 at 8:56
  • \$\begingroup\$ VTC - Questions seeking advice and recommendations on specific parts are off topic here. \$\endgroup\$ Sep 22 '17 at 10:08
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    \$\begingroup\$ @MichaelKaras I don't think this question quite matches that description. The OP is not looking for specific parts but instead is asking about different methods to mount boards together (i.e. card-edge, square headers, FFC, etc). \$\endgroup\$
    – DerStrom8
    Sep 22 '17 at 11:05
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    \$\begingroup\$ If you are just hooking and unhooking up a programming and debugging connection then look at a product called TagConnect. No connector at all.....just some pads. \$\endgroup\$ Sep 22 '17 at 11:45
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    \$\begingroup\$ Have you considered a card-edge connector? You'll have to extend the overall size of your board slightly so that you can turn it into contact tabs \$\endgroup\$
    – DerStrom8
    Sep 22 '17 at 17:03
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In order to know if connectors are good for repetitive use, look at its specification : it generally specifies how many mating cycles the connector can support.

Regarding an alternative solution, you can also consider to create your own "testbench" using a "bed of nails".

Personnaly I did so using "spring probes". I prepared the PCB with several test pads distributed on a 2.54mm grid. That allowed me to solder the "spring probes" on a downsized standard PCB card board with standard 2.54mm pitch. I wired the probes to a more regular connector fitted on the same "test PCB"

Further, I designed and 3D printed a bench in which I slide (and fix) this "test PCB". The board under test (design) is placed on the top. Guides help me place it at the appropriate distance and position easily and I have a method to keep it in place.

The spring probes that I used can support one million cycles - way beyond my needs. The test pads do not need to be through hole and do not need to be colocated - just at common distances if you want to build your test pcb by hand.

You can also draw your test PCB in a CAD tool and produce it like any other card - in that case you only need to make sure that the locations match.

By the way, the same system is used as a production bench where the PCB under test is kept into place by hand just for the time needed to produce the test report.

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  • \$\begingroup\$ "spring probes" aka: "pogo pins" \$\endgroup\$
    – Tut
    Sep 26 '17 at 12:42

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