Bed of Nails design. Please, share your approach for DIY testing.

[kreutz]

Hello;

I want to make a (cheap but functional) DIY "Bed of nails" test fixture for my home shop, and wonder if any of you have the experience and want to share diagrams, photos and tips.

Thanks in advance and Best regards,

kreutz

[George]

Here's how I do it:

Sketch test points in solidworks & create a dimensioned drawing with the TP locations
Drill holes in a piece of 1/2" delrin
Attach delrin to an enclosure
Press fit pin sockets into holes
Solder ribbon cables to pin sockets, attach to test runner hardware
Add pins to sockets

[pickit2]

Same as posted by George.
If your making a test fixture for a pcb use a blank pcb and a probe on the pins you need to test.

[circuit77]

If you are laying out the PCB, I've had a lot of luck using the Tag Connect cables (http://www.tag-connect.com/) to do quick programming and serial communications without sacrificing board space.
The cables are a bit pricy ($40 USD) but they work well.

[Checksum8]

On top of what the other guys mentioned. Search "pogo pin" these are spring loaded contact pins that make a more reliable connections on the test board.

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2051541.m570.l1311.R2.TR10.TRC0.A0.H0.Xpogo+p.TRS0&_nkw=pogo+pins&_sacat=12576

[electrojit]

I was searching for esp8266 and seen the bed of nails board stuff on the link below - may be it can provide some inputs:

http://blog.electrodragon.com/design-a-simple-pcb-functional-test-board-envioronment/

Regards,
electrojit

[MrBojangles]

Pogo pins are the way to go. I think Adafruit has some tutorials on how to use them.


One trick is that you should put two test pads on your prototype shorted together. Preferably on either end of your board. That way you can just press your prototype into the pogo pins, and as soon as your dev board detects the short, it knows you're connected to the prototype.

[LabVIEWguru]

Purchase a sheet of Delrin about .250 inch thick and slightly oversize for your board or sheet of boards. The reason you want Delrin is that it has a high thermal expansion coefficient. Center your board on the Delrin and use (whatever number) of screws to secure your board(s) to the Delrin. Use small screws if these are the same place you are going to put the posts to align your board.

Measure the sockets for your pogo pins and find the holes in the board you want your test points at. Drill *very small* guide holes for your pogo pin sockets through the board. Remove the board and find a drill a few thousandths of an inch smaller than your pogo pin sockets and drill the Delrin on a drill press, using your guide holes. When finished, put the Delrin in the oven at (I think) 220 degrees F for a while (depends on the size of your board, thickness, etc.) When you remove the Delrin from the oven, drop the sockets in *from the top* (as they have a small ring on the sockets) and in a few minutes, when the board cools, the sockets will be tight. If you have some idiot destroy your test system, you can re-heat the Delrin and replace the sockets. You can make a really nice system this way.

The pogo pins used to be heavily plated and you could clean them with a brass brush when they became dirty. Don't do this - use an alcohol pad or purchase the chemicals they make to clean the probes. Since gold is so expensive they have a very thin plating on them and it's easy to ruin them by abrasion.