How does everyone do right angle board mounting?

[NorthernWing]

Just throwing this one out there for opinions.  I've got a project that's going to consist of a 12"x9.6" board, basically a 2-layer backplane, which is eventually going to have about a dozen smaller 4x3" daughterboards mounted at a right angle to it on a bus.  Reason for the size is that I can just toss it in a standard ATX PC case and boom, enclosure with power and USB ports.

The question is, does anyone around here have any off-the-shelf connectors or hardware (Digikey/Mouser/LCSC) they like to retain a board and keep it from flopping around?

I only have about 40 signals that need broken out, plus power.  Bitrates are only around 10-20MHz so pretty much anything that makes contact is fine.  I've considered:

• Using DDR4 DIMM sockets, but 288 pins is a little overkill considering I have to assemble this thing. 
• Using two of these on the backplane and two right angle mates with jackscrews, currently what I think is the best option.
• These seem nice but I'm not sure how secure I trust a snap-in card guide to be.
• These are awesome and we use them in test equipment at work but they're way too expensive for one connector.

I'm not going to throw this thing down a flight of stairs, but I'd like to be able to move it around without having everything fall out the side every time.  I'm sure someone around here has had to rigidly mount a free-standing right angle board to another PCB at some point, what'd you use?

Pretty easy problem to solve but I'm not making custom metalwork/hardware just for a personal project and finding board mounting hardware with the Digikey/Mouser parametric search has been a crapshoot because it's just scattered everywhere.

[Ian.M]

What's wrong with 'old-skool' 0.1" pitch card slots like PC ISA bus?  One end can be secured with an ISA or PCI card bracket with board mounting tabs.  If extreme retention is required, add some sort of retaining latch for the other end, which could be as simple as a bent spring steel clip that engages with a slot in the motherboard and the top edge of, or a hole in the daughterboard.

[fcb]

https://www.toby.co.uk/pcb-hardware/card-guides-and-pulls/

[John B]

2.54mm dual row bent male pin headers plugged into female headers has always worked for me.

[ajb]

There are lots of options depending on what your other specific requirements are.  How often are you swapping the smaller boards out? do they have ports that need to support external cable connections? Are they heavy? Are you willing to get an edge beveled for a card slot connector that requires that? 

There area few manufacturers that I've run across for things like card slot guides and that, I think Keystone do some of those, but for things like that it's often easier to google for what you want, see who makes it, and then see if they're distributed somewhere.  As you've seen finding those sorts of bits and pieces on a distributer's site is often a huge pain. 

There are also some enclosure manufacturers that do card cages, I think OKW is one?  Would be more expensive than an ATX computer case, but if it just solves all of your mechanical concerns and comes with a nice outline drawing for a backplane PCB might be worth it?

[David Hess]

I like your second idea of using d-connectors because of low cost but access to the screws may be difficult.  Otherwise my first choice is what Ian.M suggests, printed circuit board edge connector.

[jonpaul]

Normally either right angle headers or a connector and header are used eg most 1970s..1990s TEK scopes, many HP, Fluke, Kiethley instruiments.

We use SAMTEC parts, very good quality.

The connectors allow easy servie and assembly.

https://www.samtec.com/connectors/standard-board-to-board

The 0.1" dual row are most common

A right angle header is used if separation of boards is not needed.

Finally the 1960s ..1970 used PCB board edge connectors, like the TEK TM500/TM5000, 7000 etc.

https://www.samtec.com/connectors/edge-card

Bon chance '


Jon

[Mark]

Got this in my email this morning:

https://www.digikey.com/en/product-highlight/j/jae/ma01-series-floating-board-to-board-connectors
https://www.jae.com/en/connectors/series/?search_ext_col_25[]=T1020

[david77]

I like the DIN41612 type of connectors, use them a quite a bit.

[Nominal Animal]

I'm just a hobbyist, but...

How about a known and time-tested straight 64-pin PCIe connector?  Say, UMAX 3183-10201P1T (C404114 from LCSC)?  (It is also in JLCPCB parts library, minimum order 60 for $23.91.)
In this particular one, the board seats 7mm deep into the through-hole connector.  The pitch is 1mm.  (Or perhaps UMAX 3183-10211P1T (C444349 from LCSC); very similar.)

The logic behind this suggestion is that PCIe connectors are absolutely ubiquitous in AMD/Intel-compatible motherboards, and are manufactured and used in massive quantities.  The pitch is 1mm, and the current rating is 1.1A per pin.  The plastic used in the connector body should be glass-filled polyamide/nylon (as used by e.g. Amphenol).  (UMAX does not specify, just calls its "high-temperature thermoplastic".)

If you look at the quality connectors, say Amphenol 10018783-10201TLF or 10018783-10211TLF (that you can find at e.g. Mouser/Digikey/etc.), you'll find you can find physically interchangeable connectors from many different manufacturers.  I do not know if the UMAX connectors are any good, but those are obvious Amphenol clones LCSC keeps in stock.

[Ian.M]

If you do that, to make it reasonably idiot resistant, use an ISA card bracket not a PCIe one (the board mounting tabs are on opposite edges), and fit the PCIe socket further from the backplane edge than the PCIe standard calls for, so a PCIe card *WONT* line up with your backplane's slots or even go in if misaligned.

However I'm reasonably confidant that a 0.1" pitch ENIG finish contact pad ending the minimum clearance from a V-grooved board edge (lightly sanded after snapping to remove loose fibers), will stand up to light use and a reasonable number of insertions into a PC/XT bus card socket, whereas for a PCIe compatible card edge at 1mm pitch you are probably going to need to go to hard gold and a properly machined bevel on the edge to get reliability.