Ideas on how to mount electronics within a project box

Hi,

I am in the process of mounting my first project in a project box, and could really use some inspiration as to how this can be done. The project consists of:

  • Some buttons and leds
  • A handful of breakout boards (SD, GPS, Accelerometer, OBD)
  • LiPO charger and battery

The plan was to include a solder breadboard with the buttons, leds and the small breakout boards. While the larger breakout boards are fixed to the box and connected to the main board with cables. But I could really use some recommendations as to how breakout boards are normally handled/fixed in a project box, and perhaps some pictures of how others have done it.

Some boxes have slots along the walls, you are meant to cut your board to fit between them. Then just slide the board in. http://www.circuitspecialists.com/15-1.html

A rather extreme number of slots, usually they are a cm or so apart.

Or you might mount the board on standoffs with bolts.

Many project cases come with plastic posts and screws to use in mounting PCBs inside.

This project box has both slots along the walls, and plastic posts on the bottom:

Here you can see the built-in plastic posts being used:

The person making this project used standoffs in the box, as his PCB didn't align with the posts: http://benryves.com/journal/3689399

You can even buy project boxes with soldered PCBs already made for them:

Sometimes parts are affixed to the board so that when things like potentiometers and jacks are screwed into the case, they are all at the proper height and all LEDs and displays are in the proper place and height. In that case, the parts are the board mount. It can be a bit tricky to get that correct.

Something similar can be done using short wires between the things mounted in the front panel and the board. Not nearly as critical, and you are simply relying on the very short wires to make up for any inaccuracies but be short and stiff enough to hold the board.

Obviously, not good for anything heavy on the board, like a large heat sink.

Sometimes, boards are held in by parts being mounted on a heatsink, and the heatsink is bolted down. Again, nothing heavy on the board like large electrolytic capacitors or large toroids, or you should also be using standoffs and mounting the board properly.

Having the board hanging by stiff wires or component leads isn't good if this is something exposed to a lot of vibration. In cases like that, for instance automotive use, use only stranded flexible wire and mount the board on standoffs, possibly even using rubber standoffs.

I have found that it is a good idea to use a bit of ribbon cable between LCD displays and the main board. Otherwise, normal knocking around can flex the LCD board from the weight and torque of the main board pulling on its connector, and there is only a conductive silicone ribbon between the LCD glass itself and the LCD driver board. Flexing that can make it unreliable.

Thanks polymorph, that was a very extensive reply with a lot of good ideas. I already got this case https://www.sparkfun.com/products/8601 so that will be used for my first attempt :)

I am not too keen on have bolts/screws through the case to hold the boards within, so I am contemplating either just gluing the bolts to the inside of the case, or use some kind of strong double sided tape.

I would avoid the glue or tape as they won't last What's so bad about holes and bolts?

bomadsen: Hi,

I am in the process of mounting my first project in a project box, and could really use some inspiration as to how this can be done. The project consists of:

  • Some buttons and leds
  • A handful of breakout boards (SD, GPS, Accelerometer, OBD)
  • LiPO charger and battery

The plan was to include a solder breadboard with the buttons, leds and the small breakout boards. While the larger breakout boards are fixed to the box and connected to the main board with cables. But I could really use some recommendations as to how breakout boards are normally handled/fixed in a project box, and perhaps some pictures of how others have done it.

What I always do is build the entire project on a "sub plate", then when it's finished I attach the subplate to the bottom of the project box.

Round-headed bolts look pretty awful, but if you use countersink bits and compatible screws, you can put the mounts on one side (like the bottom) and it's really unobtrusive.

If you have access to a place that has a large inventory of fasteners (check for a Fastenal in your town -- there's one here in Anchorage, AK, if you can believe that...), go there and see what they have. I picked up a few boxes of small (#6, plus or minus a few sizes) machine screws and compatible lock-nuts, in black, with countersink Allen heads. I think they look sharp.

mmcp42: I would avoid the glue or tape as they won't last

That is also my main concern, however I think roughing up the plastic and using epoxy would give it a fighting chance to hold :) Also, don't underestimate double sided tape, if you get the right stuff (3M VHB for example http://solutions.3m.com/wps/portal/3M/en_US/Adhesives/Tapes/Products/~?N=6105&rt=r3) it WILL hold.

mmcp42: What's so bad about holes and bolts?

As it is now, I need to mount breakout boards/breadboards to both the bottom and the lid of the box. If I have bolts/screws popping out all over that would look quite messy. Also I risk scratching whatever I put the box on (my car for example :) ).

SirNickity: Round-headed bolts look pretty awful, but if you use countersink bits and compatible screws, you can put the mounts on one side (like the bottom) and it's really unobtrusive.

I had not considered countersunk screws, that was an excellent idea! Thanks.

SirNickity: If you have access to a place that has a large inventory of fasteners (check for a Fastenal in your town -- there's one here in Anchorage, AK, if you can believe that...), go there and see what they have. I picked up a few boxes of small (#6, plus or minus a few sizes) machine screws and compatible lock-nuts, in black, with countersink Allen heads. I think they look sharp.

I live in Denmark, so the nearest Fastenal may be a bit far away. But we have comparable shops, so I will go hunting tomorrow :)

Krupski:
What I always do is build the entire project on a “sub plate”, then when it’s finished I attach the subplate to the bottom of the project box.

That would make for a very clean installation, much cleaner than what I am planning. Hmmm, I would need a “two story” sub plate to fit all the stuff, but that might actually be doable.

Lots of great suggestions in this thread, thanks.

I've even seen small projects mounted inside battery holders.