I have an enclosure and want to add some protoboards inside it. I can place two next to each other, but since I'm a bit out of space I think it's best to stack 3 of them with PCB spacers.

However, I will have some (not many) connections from one board to another (and second to third board).

I can use either pin headers without soldering, with soldering or using terminal blocks. Terminal blocks cost some more space, but when soldering pin headers, I can never replace anything without desoldering, even when I use for the necessary ICs DIP8 sockets. And I wonder if using nonsoldered pin headers would be rigid enough for a device that will be moved around all the time and not handled always softly (except while in use).

What would be best:

  • Soldering pin headers and when something is broken to desolder the pin headers?
  • Not soldering the pin headers at all?
  • Using terminal blocks?

In my case I will use only a few terminal blocks from one board to another, but it's more a generic question for in future use.

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    \$\begingroup\$ Is there any reason you couldn't do something commonly seen in small dev-board applications (Arduino "shields" for example)? \$\endgroup\$ – Shamtam Sep 6 '18 at 13:09
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    \$\begingroup\$ Why not solder male headers on one board, and female headers on the next? \$\endgroup\$ – Bort Sep 6 '18 at 13:09
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    \$\begingroup\$ What Shamtam and I are saying is the same thing. Once mated with each other, they should be quite rigid. \$\endgroup\$ – Bort Sep 6 '18 at 13:14
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    \$\begingroup\$ I don't understand the distinction you're making between "dev board" and "proto board". Mechanically, they're essentially identical. \$\endgroup\$ – Dave Tweed Sep 6 '18 at 13:16
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    \$\begingroup\$ Just to clarify: you are using PCB spacers (with screws I guess) and now are thinking about the stability of the connectors? The connectors won't be there to handle the mechanical stresses as that will be covered by the PCB spacers? \$\endgroup\$ – Arsenal Sep 6 '18 at 13:26

Use male and female headers.

Female header with short pins:
female pin header
(Image from grobotronics.com)

"Stackable" female header with long pins that go through to the next board (or can be simply cut to length).
stackable female header
(Image from sparkfun.com)

Observe that the stackable pins are sort of "flat", and due to their length, have some bend to them.

Male header:
male header
(Image from solarbotics.com)

These headers are more "square" than the stackable variety, which makes them stay mated better, and they are less bendable.

Note that male headers can but cut or snapped-off to the exact pin count desired. Female headers can be cut, though it is not nearly as convenient (and will probably look bad).

When the headers are mated (the boards stacked), there should be some rigidity, depending on how many pins. Double-row headers will have even more rigidity. Having headers in two places on the same board offer even more rigidity (removing the possibility of the header bending/acting like a hinge).

Typically, they do not fall-out on their own, even with vibration, though if put in a vehicle for years, you may want to secure them further (See below).

The end result when using the long-pinned stackable headers:

Stacked PCBs
(Image from adafruit.com)

If that's not enough, you can combine the headers with standoffs between boards:

stacked PCBs with standoffs and headers
(Image from robotroom.com)

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    \$\begingroup\$ Just make sure you have DFT in mind when assembled with access to test points. Shields are so untestable for Analog interior signals. The extra mechanical pins can be test points as long as EMC is kept in mind. At a penny per pin, they are popular. \$\endgroup\$ – Tony Stewart EE75 Sep 6 '18 at 13:44
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    \$\begingroup\$ BTW cut header pins expose non-gold-plated steel pins prone to rust and scraping the receptacle plating too. \$\endgroup\$ – Tony Stewart EE75 Sep 6 '18 at 13:50
  • \$\begingroup\$ @TonyEErocketscientist Thanks, yes that's a good one (DFT). I am used to it for software, but for electronics it's also a good idea. \$\endgroup\$ – Michel Keijzers Sep 6 '18 at 22:00

One approach is to use ribbon cable and IDC connectors between boards. This has the advantage that you can 'open' your stack like a book and debug both boards while still keeping them electrically connected.

You can get pre-fabbed cables or invest in an IDC crimping tool and buy the ribbon cable and connectors separately to make cables of nearly any length and width you need, from 2x3 pins up to 2x64. The connectors plug into standard 2.54mm male pin headers and for your application right-angle pin headers will help keep a lower profile.

  • \$\begingroup\$ A ribbon cable is how me and some other students solved it on a robot course where we had to stack some PCBs. I can vouch for this. \$\endgroup\$ – Harry Svensson Sep 6 '18 at 14:41
  • \$\begingroup\$ I like this too, except that in my case the cables would be so small that pin headers are a better solution. Also in my solution I have 5 different parts split quite well so debugging is hopefully not a problem when something is broken. \$\endgroup\$ – Michel Keijzers Sep 6 '18 at 14:43

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