Mount PCBs together in a 90° angle

[DomesticHacks]

I'm planning a project with two PCBs.
The second PCB has to be mounted on the first one in a 90° angle.
I haven't that much space so I don't think i could use some kind of connector like a pinheader.

Is there a best practice for doing this?

[ajb]

If your PCB fabricator supports internal routing (most (all?) of the inexpensive ones don't, at least not officially), then you could route a slot in one board that the other slots into.  Careful alignment of copper pads on the edge of each will allow you to solder them together, preferably on both sides, which should be pretty sturdy if your slot is sized to a close fit. 

[gregallenwarner]

Depends on how the PCB's are gonna be used. Are there going to be any stresses on one or both of them? In which direction will the forces be applied? Will it be under constant stress, i.e., buttons on one of the boards routinely being pressed? What about separation of the boards? Do you want them to be easily separable for working on them?

I'd recommend you build your chassis/mounting hardware such that it takes most of the stress away from the electrical connections.

[PointyOintment]

If your PCB fabricator supports internal routing (most (all?) of the inexpensive ones don't, at least not officially), then you could route a slot in one board that the other slots into.  Careful alignment of copper pads on the edge of each will allow you to solder them together, preferably on both sides, which should be pretty sturdy if your slot is sized to a close fit.

OSH Park allows it:

Internal cutouts are allowed and supported. Draw them on your board outline layer.

[daqq]

There are several options that come to mind:

REALLY small board-board connectors
Flexible hybrid PCB ( http://www.pcdandf.com/cms/magazine/95/2948 ) - you can do really amazing assemblies with this
Just solder one on the other as though it was an SMD device
What you said

The last two options are mechanically somewhat risky, and should be used with care - repeated stress can cause delamination of your PCB.

[DomesticHacks]

Depends on how the PCB's are gonna be used. Are there going to be any stresses on one or both of them? In which direction will the forces be applied? Will it be under constant stress, i.e., buttons on one of the boards routinely being pressed? What about separation of the boards? Do you want them to be easily separable for working on them?

I'd recommend you build your chassis/mounting hardware such that it takes most of the stress away from the electrical connections.

They are not under heavy stress like preasure but there are two relatively heavy parts mounted to them.
So only thing I'm concerned about is that the device will be not stationary so vibrations could be a issue.

It shouldn't be detachable.

[mikeselectricstuff]

If your PCB fabricator supports internal routing (most (all?) of the inexpensive ones don't, at least not officially), then you could route a slot in one board that the other slots into.  Careful alignment of copper pads on the edge of each will allow you to solder them together, preferably on both sides, which should be pretty sturdy if your slot is sized to a close fit.

Or use plated holes in one PCB and rout some pegs on the edge of the other - using a plated hole should give better strength than butt-soldering a PCB through a slot.

[SeanB]

If subject to vibration you really need a screw through the board and a block with tapped holes, or a small metal angle and either nuts or hank nuts in the plate. Vibration will fatigue the solder joints quite fast and they will crack. If the board is big then you need 2 or more mounting blocks at the ends, otherwise for a small one one nearest the heavy components or where you have switches or external connections direct on the board.

[Pack34]

Is there a reason they have to be directly connected? If there heavy components and possible vibration issues, what about mounting them in your chassis independently and using a ribbon cable to connect them? I've personally had reliability issues using card slot connectors in robot applications (even with mechanical retention) a more flexible connection like a ribbon cable may improve reliability.

[gregallenwarner]

Is there a reason they have to be directly connected? If there heavy components and possible vibration issues, what about mounting them in your chassis independently and using a ribbon cable to connect them? I've personally had reliability issues using card slot connectors in robot applications (even with mechanical retention) a more flexible connection like a ribbon cable may improve reliability.

I second this idea. Even though your project requires a permanent connection, a ribbon cable will be the most tolerant of vibration, and you can secure the PCB's at a 90 degree angle using purely mechanical connections, and not have to worry about the electrical connections.

[michaelym]

You can use PCB slot connectors (like PCI) and still have some mechanical freedom (with the correct connectors and PCB thickness)

[DomesticHacks]

Thanks for all of your suggestions. I think I will use the smallest pin header I can find or maybe a slot (have to figure out the best way to do it in Eagle).

[fcb]

Might be a tad big.  But have a look at DIN41612 connectors.

[EEVblog]

Put a plated through slot on the main board, and routed fingers with pads on the other board <1.6mm (PCB thickness) in length, insert and solder both sides for rigidity. This is quite a common technique for mounting (small) boards at right angles.

[Psi]

i've used 90deg 2.54mm header blocks (2row by 8 ) to mount boards at 90deg without any problems. 

You need to decide on the best way to use the connector, rotation wise.
This is the way i found worked the best for me. But you do have to make sure the holes in the vertical PCB (V) are not too close to the edge.
Not all headers are created equal in terms of plastic height, (the bit that rests on the H PCB).

         V
         V
     ---V-----||-\
     ---V-----||\ |
HHHHHHHHH | |HHHH
                    '  '

(The V board would obviously be soldered hard right, up against the plastic, i just drew it in the middle to make it clearer)

[SL4P]

Simple trick from the old days.
prepare the two boards (with 90-degree support if needed)
solder the 90-degree meeting point as shown

[David Hess]

Put a plated through slot on the main board, and routed fingers with pads on the other board <1.6mm (PCB thickness) in length, insert and solder both sides for rigidity. This is quite a common technique for mounting (small) boards at right angles.

I have worked on test instruments that used this construction method.  Invariably one of the solder joints will have a crack.

They make right angle pin headers which are perfect for this.

[DomesticHacks]

I will go with SL4Ps method, since it is easier to manufacture. When there will be problems with cracked solder joints I will try something else.

[DomesticHacks]

Doesn't that look very nice? 

[Vgkid]

That looks ood, what is it?

[DomesticHacks]

That looks ood, what is it?

My new wristwatch with Numitrons

[Precipice]

And is a monumental pain to desolder, so do it right!

[NivagSwerdna]

It's almost Halloween so resurecting this thread doesn't seem too frivolous...
I have a similar situation where I need to connect two PCBs at 90 degrees with 8 connections between them... but in my situation I need to be able to plug/unplug them, for maintenance/repair without de-soldering.
Given my PCBs are FR4 is there a suitable card connector I could put on one board into which fingers on the other board would insert?  (Like in the old S-100/Eurocard days)
(I looked at 2.54mm female headers on one and  right angle male on the other but the geometry seems a bit variable?)

[Gyro]

For so few connections, single row r/a 2.54mm headers and sockets would probably be the most appropriate and economical solution. You can get r/a connectors 2.54mm double row connectors with housings on the male part if you're worried about alignment though.

You will almost certainly end up with spare pins though - I don't think you will find anything as small as 2x4 pin.

[KL27x]

If you want them to meet at a corner, flush, you could use a castellated finger/box joint.