Low profile (<3mm) board to board connector.

[DTJ]

I've got two boards one above the other that I want to run some signals between via a pluggable connector pair.

Their mounting is fixed and can't be changed, the space between the boards is 3mm.


I've got 8 or so signals that need to got between the boards:
SPI x 3 signals
Power 3v @ <100mA
Ground
A couple of digital status lines.


I'd prefer to use 2mm or 2.54mm pitch SIL connectors but the I've only found these Samtec ones with a mated gap of 3.89mm. I need 3mm max.

http://au.element14.com/samtec/sl-108-t-10/receptacle-2-54mm-pcb-8way/dp/1668062
http://www.farnell.com/datasheets/1927698.pdf?_ga=2.37384996.569325269.1503285096-1413671594.1503025027


Have you got a favorite pluggable low profile board interconnect you can suggest?



Cheers.

[Rerouter]

Do they have to be vertically mated?

If so, look into PCB pin sockets. e.g. https://www.mill-max.com/new_products/detail/2

If not, horizontal mating would have less than 3mm gap.

[ovnr]

To be honest, pin headers aren't really meant for tight spaces.

If 1.27mm pitch is fine, these would work:
https://www.digikey.com/product-detail/en/harwin-inc/M50-3130845/952-3587-ND/7044003
https://www.digikey.com/product-detail/en/harwin-inc/M50-3630842/952-3611-ND/7044026

The receptacle is a bottom-entry model so the excess pin length will be taken up inside the board - you'd put clearance holes for every pin. Total height is 3.0 mm.

Otherwise, if having tall components on one (outer) side of the board stack is fine, using bottom-entry connectors (like this 2.54mm x8 model) means you don't have to worry about anything but the insulation height of the header.

[ajb]

I'll second the bottom-entry header idea.  You can get bottom entry headers in 2.54mm pitch as well if you're more comfortable with that. 

[Neilm]

I have used Molex mezzanine connectors in this sort of application. THey are surface mount connectors that go down less than 3mm

[DTJ]

@Rerouter - thanks for the Mill-Max link. They look interesting but for my application may be a bit fiddly.
I've saved them away for another day.

@ovnr (& ajb) - ahhh! That's the solution. Using bottom entry connectors I can do what I want. Thanks very much for the idea. I've found some suitable connectors and are going with it.


@Neilm - the Molex Mezzanine look good, a bit pricy for my application but book marked for the future.