Joining two PCB's at 90°

Thread Starter

dlad87

Joined Nov 9, 2020
25
Hi,

I'm looking to standoff a small PCB off of a larger main board at 90 degrees. What is the best way to do this with off- the shelf parts.

I was envisioning doing so with maybe a double row 90 degree header pins that would also provide the connections. The weight on the small board would not be an issue for something like these pins to support. Is there such a header pin? I was looking through Digikey and Mouser but the selection for headers is nearly infinite and looking for a starting point to look at.

Also, the boards would not have to disconnect meaning I would be ok to solder at both ends rather than one end being a connector.

Thanks
 

dl324

Joined Mar 30, 2015
12,790
From Jameco:
clipimage.jpg
Other sizes are available from other companies. I think I have some 34 pin.

Use a female header on one of the boards if you want to be able to disconnect them.
 

dl324

Joined Mar 30, 2015
12,790
Don’t know the exact number I need yet but probably around 12
The larger connectors have a lower per pin cost. You can cut them down with something like a Sears Handicutter.

Here's a picture of one listed on eBay (albeit in poor condition):
handicutter.jpg

Harbor Freight has a poor quality workalike.
 

AnalogKid

Joined Aug 1, 2013
9,175
There are single- and double-row pin headers and sockets in both straight and right-angle types. If you are going to go through a few, the low cost way is to buy them in long strips and snap off whatever you need. You can cut them apart with a box cutter. For the double-row type, you might have to sacrifice one section to get clean ends.

If you put the right-angle strip socket on the daughter board, the pins don't hang over the edge where they can get bent. I don't know the environment your boards will be in, but generally speaking, vertical pins on the main board are more robust than right-angle pins on the daughter board.

ak
 

ErnieM

Joined Apr 24, 2011
8,132
I was looking through Digikey and Mouser but the selection for headers is nearly infinite and looking for a starting point to look at.
Once upon a time dinosaurs when rulled the Earth Digi-Key (and most every other company too) shiped printed catalogs of the parts they sold for free. My wife (then fiance) would laugh at me as I was known to read the Digi-Key catalog. Mostly skimmed, but paid much close attention to the connector section.

I used these things called "bookmarks" which were small sticky pieces of paper one would stick onto pages of particular note.

One day when changing jobs I let my Digi-Key catalog behind to save me carrying it. Sadly that was just as sending free paper copies ended.
 

crutschow

Joined Mar 14, 2008
26,994
Sadly that was just as sending free paper copies ended.
I used to love the old Allied Radio Catalog that came every year (before they went totally commercial).
I learned a lot about different electronic parts from them (and built a Knight-Kit 20W/Channel Stereo Tube Amp}.
 

SamR

Joined Mar 19, 2019
3,246
can cut them down with something like a Sears Handicutter.
Use a pair of needle nosers. Line it up exactly at a right angle and twist them and then use a fingernail emery sanding board to smooth the broken edge. Usually breaks right at the next pin so you lose a pin count from the entire unbroken count. Keep an emery board in my pencil cup for things like this.
 

AnalogKid

Joined Aug 1, 2013
9,175
I used to love the old Allied Radio Catalog that came every year (before they went totally commercial).
I learned a lot about different electronic parts from them (and built a Knight-Kit 20W/Channel Stereo Tube Amp}.
Yes and yes.

a) Devoured the Allied catalog way before I knew what half of it meant.

b) I still have the Knight-Kit stereo amp I built for my parents.

Add to that the electrical section of the Sears catalog, another annual present from the geek godz.

ak
 

MrChips

Joined Oct 2, 2009
23,227
If you are mounting two PCBs at 90° via PCB connectors I would recommend not restraining the daughter board. It should be allowed to float freely in card guides. I have spent hours debugging systems with intermittent pin contacts.

I would recommend using ribbon cable instead. In this case you can restrain both boards rigidly.
 

MrChips

Joined Oct 2, 2009
23,227
There were two boards mounted at 90° with card edge connector as interconnect. Both boards were bolted down on their separate planes. This meant the edge pads on the daughter board were not allowed to align ("float") properly on the edge connector and some signals did not get through the interconnect.

For now, this is the only photo I can find.
This works because the board is held in place with one screw farthest away from the edge connector. The board edge still has some degree of freedom. With the faulty system, the daughter board was held down with screws at each of the four corners of the board, i.e zero degrees of freedom. And that is wrong.

1618632604235.png
 

MisterBill2

Joined Jan 23, 2018
8,443
Since you will not be removing the board you can solder the pins on both of them. BUT make sure that the holes are fairly close so that the square pins need to be pushed un a bit. That way you are not depending on the solder to keep the mount solid. It does require that the holes be precisely positioned, that is seldom an issue.
 

MrChips

Joined Oct 2, 2009
23,227
Boards in card cages are never restrained except for the card guides.

1618633731225.png

If the TS wants to solder 90° pin headers then that would be ok. Just be certain that you would not want to separate the two boards again.

1618634040564.png
 

SamR

Joined Mar 19, 2019
3,246
Remember removing EISA edge connector cards and rubbing the contact areas to burnish them with a No 2 pencil eraser back in the 80s. They improved since then as it wasn't needed in later decades. Even with soldered right-angle headers I would still try to support it if needed depending on size and weight.
 

Thread Starter

dlad87

Joined Nov 9, 2020
25
Yes, the header shown above was what I was looking for on Digi-Key. And yes, it is unlikely that I would want to separate the board in this case. I just need the item mounted on this board to be mounted at 90 to the main board due to its height, but otherwise could’ve been mounted to the main board
 

GetDeviceInfo

Joined Jun 7, 2009
1,844
You’ve not mentioned if it’s thru hole. Most connectors combine electrical and mechanical integrity. As mechanical needs reduce, so does the simplicity, all the way down to a simple soldered butt joint. A length of conductor is all I’ve used for prototyping. Beyond that, an identified need for manufactured connectors guides the choice.
 

Thread Starter

dlad87

Joined Nov 9, 2020
25
I was thinking I would do through hole for the 90 degree headers. I haven’t designed the boards yet but I could go either way. I’d imagine that through hole would be a little stronger because it could be soldered on both sides.
 
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