Board-to-board connector recommendations

From circuitbending to homebrew stompboxes & synths, keep the DIY spirit alive!

Moderators: Kent, luketeaford, lisa, Joe.

Post Reply
giszo
Learning to Wiggle
Posts: 14
Joined: Sun Jul 22, 2018 9:18 am
Location: Hungary

Board-to-board connector recommendations

Post by giszo » Mon Sep 16, 2019 7:16 am

As a part of one of my DIY projects, I would like to connect small(er) PCBs to a bigger host board, in a 90 degree manner.

Looking for recommendations what kind of connector should I use that is fairly small (need to fit 70-80 pins within 20cm of PCB length), and more-or-less tolerates mechanical shock, so PCBs will not fall out of the host board by accident.

What kind of connector would you recommend to try it?

At first I though about going with something like this, but I am not sure how it will hold up.
Image

ixtern
Common Wiggler
Posts: 229
Joined: Mon Jan 22, 2018 4:34 am

Post by ixtern » Mon Sep 16, 2019 7:29 am

Maybe you should consider angled IDC40 (2x20) sockets with ejection latch.

User avatar
SyndieBot2000XL
Common Wiggler
Posts: 219
Joined: Sat Feb 16, 2019 2:45 pm
Location: Owe Hi-O

Post by SyndieBot2000XL » Mon Sep 16, 2019 7:34 am

I’ve built a couple modules that use these 90-degree pin headers for board to board connections. They form a pretty strong joint. You wouldn’t want to bang on it but it’s reasonably shock proof. You can use female headers on one side as well, but then the two sides will tend to wiggle apart inside the case after a while.

User avatar
mskala
Super Deluxe Wiggler
Posts: 2654
Joined: Thu Mar 27, 2014 7:33 am
Location: Toronto
Contact:

Post by mskala » Mon Sep 16, 2019 7:47 am

SyndieBot2000XL wrote:I’ve built a couple modules that use these 90-degree pin headers for board to board connections. They form a pretty strong joint. You wouldn’t want to bang on it but it’s reasonably shock proof. You can use female headers on one side as well, but then the two sides will tend to wiggle apart inside the case after a while.
How do you use them without female headers - by soldering both sides?

That brings up an important question for the original poster, which is how often these will or won't be unplugged and changed. A connection that's meant to be interchangeable is quite different from one that's meant to be permanent. For a solid interchangeable connection the traditional thing is what PC expansion cards do: turn the edge of the daughter board into a connector by adding gold-plated fingers to the PCB design, and then plug it into a card-edge slot connector. But that requires special manufacturing of the PCB, with different gold plating from the ENIG used for solderability. Card edge connectors can be made with clips to help hold the card in place (like DIMM memory mounting) and that may be good enough for a really small daughter board, but the really "pro" technique is to do the mechanical mounting separately from the electrical connection and not place all the strain on the connector, whatever kind of connector it is.
North Coast Synthesis Ltd.
Latest Web log posting: Genome Jazz

giszo
Learning to Wiggle
Posts: 14
Joined: Sun Jul 22, 2018 9:18 am
Location: Hungary

Post by giszo » Mon Sep 16, 2019 8:00 am

mskala wrote:That brings up an important question for the original poster, which is how often these will or won't be unplugged and changed.
I'd like to connect voice cards into a carrier PCB, so definitely looking for a solution that can be disconnected later on. For the prototyping phase, it might happen more often, but still needs something disconnectable later on for servicing and such.
mskala wrote:For a solid interchangeable connection the traditional thing is what PC expansion cards do: turn the edge of the daughter board into a connector by adding gold-plated fingers to the PCB design, and then plug it into a card-edge slot connector. But that requires special manufacturing of the PCB, with different gold plating from the ENIG used for solderability. Card edge connectors can be made with clips to help hold the card in place (like DIMM memory mounting) and that may be good enough for a really small daughter board, but the really "pro" technique is to do the mechanical mounting separately from the electrical connection and not place all the strain on the connector, whatever kind of connector it is.
I have seen something similar inside the Prophet 6, for example. However, I don't think that is suitable for the average DIY people. :-)

User avatar
search64
Ultra Wiggler
Posts: 999
Joined: Sun Feb 15, 2015 4:48 pm

Post by search64 » Mon Sep 16, 2019 8:03 am

The Buchla Music Easel (clone) uses almost this setup (slightly lower density than you require though):

These pins:
https://nl.mouser.com/ProductDetail/538-26-48-1061

With these connectors
https://nl.mouser.com/ProductDetail/538-09-48-3065

The connection is very secure, but the cards can be removed for problem solving and such. These pins are quite big, bigger than you might think based on the picture. I'm sure there's a smaller sized equivalent that you could use instead.

User avatar
SyndieBot2000XL
Common Wiggler
Posts: 219
Joined: Sat Feb 16, 2019 2:45 pm
Location: Owe Hi-O

Post by SyndieBot2000XL » Mon Sep 16, 2019 7:29 pm

mskala wrote:How do you use them without female headers - by soldering both sides?
Yup, exactly. Although the projects I’ve done that way were only single row headers. Also, they were slim modules with the right angle header joining a component pcb to a jack pcb, where there is no parallel pcb like you would have with several voice cards - so there’s plenty of clearance if one needs to swap out a front panel component. Sounds like it could be a possibly fatal shortcut for OP.

giszo
Learning to Wiggle
Posts: 14
Joined: Sun Jul 22, 2018 9:18 am
Location: Hungary

Post by giszo » Wed Sep 18, 2019 9:07 am

Thanks for all the suggestions.

For the first prototype I am going to try something like this: https://eu.mouser.com/ProductDetail/571-5104340-1
After I have some impression how those hold up, I might add some proper mechanical support to the cards, as mskala suggested.

Post Reply

Return to “Music Tech DIY”