Custom PCB and enclosure options?

I almost have my breadboard project complete, and am looking forward to how I’m going to “productize” this. It will be a pretty simple PCB about 3 x 5 inches, and I’d like to have a hard plastic enclosure for it. It will need cutouts for a wall wort to plug in for power, and a DB25 connector.

So my questions have to do with getting the custom PCB built and the enclosure. I’ve googled the site, and see what the options are for getting custom PCBs printed, but I’m not clear on whether or not you can have someone populate the PCBs with your components for you. Also, what if I want the Ardunio on the PCB? The cleanest design would be if the Ardunio itself and all my circuitry were on the same PCB. If I have to solder my stuff onto the PCB it wouldn’t be the end of the world, but I couldn’t build an Ardunio with all those surface mount components!

So is it possible to have an Ardunio clone board build (I’m using the Yun), populated with the Ardunio stuff, and include my custom circuitry?

Regarding enclosures, who could I have build an enclosure as described above?

And is there anyone that will do all this for me - print and populate the PCB and put it in an enclosure?

  • Dave

Firstly well done for taking something to construction.

How many units do you want to make?

And why are you using a Yun? Does your board really need all that power?

The best approach would be to work out what minimum size you could make your board, them find a case that is large enough.... preferably with some of the holes you need.

I work in the electronics enclosure industry, and my advice is to select a suitable enclosure BEFORE you design the PCB. We see so many PCB designs that are all very nice, but sometimes almost impossible to supply an enclosure for.

Consider where the connectors are placed, and avoid putting them on all sides of the PCB. One edge is usually fine, as is opposite edges, but as soon as you have connectors on say the front edge and one of the sides, you're going to struggle a bit.

Most plastic boxes have some sort of internal mounting points for a PCB. Try to design the PCB with matching holes.

If you look at extruded aluminium enclosures, the PCB generally slides into slots inside the box. Avoid components and circuit traces along the edges of the PCB, or risk shorting on the case.

It's amazing how many electronics engineers design the PCB with no thought about putting it inside an enclosure. They usually end up paying for an expensive custom solution.

Ian

My thoughts were, work out how big a case you are going to need, find some alternatives, then make the PCB fit the case, but you do need a ball park figure of how big a case you need to start with.

Thanks for the replies. As I said above, the case needs to be about 3 inches by 5 inches, maybe 1 inch thick. The important cutout is for the DB25 connector. And I might want a cutout for some kind of reset button, and one for an optional power connection (normally power will come over the DB25).

I am willing to build my PCB around a case, but where do I find options for cases? As for materials, I'm thinking plastic. The case won't get any abuse, and lighter is better. Cheaper is better too - which leads me to plastic.

And yes - I do need a Yun. I need to talk to the board over WiFi.

And once I do have a PCB designed around a case (hopefully I can find one pre-made), any suggestions about how to get the PCB populated? Can I incorporate all the Yun circuitry into a custom PCB and have someone build it for me?

Thanks everyone!

Could you build your non-arduino circuitry onto a protoshield or a custom shield? Then all you would need to do is drop it on top of your Yun. There are cases available for an Arduino with one or two shields on top.

Look at cases here, might be overkill for your needs, who knows. www.polycase.com Then you can design your PCB with mounting holes to match, or add a simple adapter plate to interface the box holes to your card holes.

DB25 takes a lot inside the box, you may have to let it layer over the boards, or go with a bigger box dimension.

Poly case looks awesome - thanks!

My board controls 6 motors, so there’s a lot of stuff going on. Plenty of room to fit in a db25 connector.

Any suggestions on how I can get a custom PCB populated with the Yun circuitry and my stuff?

I am new to this, and am not clear on whether or not that’s a thing. I’m actually not too far from you - Bob (I’m in Manchester). Is that a service you offer?

And I an also going to look into building a shield. I think I can get everything to fit except for the db25 connector. What I'd like is a shield protoboard PCB thst had a row of non interconnected pins alomg the long edge, outside the headers. I could connect a db25 there, and from there to the rest of the chips in my project.

Assuming that no such protoboard exists, is there an easy path to get the design of an existing one that I could modify and order to get built?

And I'm still wondering about having my own Yuns build. Is that doable? What would the cost be vs a retail Yun?

It's expensive to have boards assembled for you, particularly in small batches. How many are you getting made? 10? 100? 1000? Some of the larger PCB fab houses offer assembly as well, but the prices are eye-watering for small boards, because they have to make a stencil and all. A while ago I found a site that gave price quotes for that, though I forget what site it was. Basically, for small lots, the assembly will cost more than the parts. You look at the dirt cheap boards from china and think "look how cheap that HC-SR04 is, and all those parts, it can't be too expensive to have a board loaded for me" - but those are produced in lots of tens of thousands, using a design that's been in production for years.

Also, cloning the Yun is a lot more difficult than cloning a mundane arduino board - that WiFi section has fancy stuff under the hood, and since it does WiFi stuff, you might need to go through a certification process to sell it (not familiar with the applicable laws, but people on kickstarter always complain about the fcc certification). I wouldn't recommend that course of action - making a shield that you'd stack onto the yun would be much easier, and probably cheaper overall. Or, convert it to use ESP8266, and then roll your own arduino board and leave a header for plugging in an ESP8266. Either of those will be a much easier board to make.

Also - With boards, size is money, and 3x5 is huge, and in fact you won't even be able to design a 3x5" board in the free version of Eagle (that won't let you do any dimension larger than 4"). Do you ever wonder why all those chinese modules have everything crammed into a postage stamp sized board? For small run prototype, most of us use OSHPark, since they're usually the cheapest; from them, a 15 square inch board is $75 for three boards! ($5/square inch gets you three copies of the board).

I haven't seen any proto shields that would have a good spot for a DB25 connector on them, but that doesn't mean they don't exist. For first gen prototyping, I'd just solder wires onto the connector and run them into a 0.1" dupont connector that's real easy to connect to the proto shield.

In any event, your fear of SMD soldering will be a problem unless you have money to burn, because you'll need to solder up a prototype board to verify you didn't make any mistakes in the layout or design, before you send it off to make in quantity. But if you want to make it in quantity using throughhole parts, you'll take it in the wallet - assembly costs for throughhole parts are much higher. If you're not willing to do SMD soldering, you really limit yourself. All the best parts are SMD *, and they also take up so much less board space. Also SMD soldering really isn't that hard if you don't use the smallest sizes. The resistors and caps are by far the hardest part, though 805 and larger isn't that bad to do by hand.

*try to find a MOSFET that works at 3.3v gate voltage in through-hole, then try to find one that works at 1.5v in SMD, and you'll see what I mean. A lot of the good stuff is only in SMT now.

It's expensive to have boards assembled for you, particularly in small batches. How many are you getting made? 10? 100? 1000? Some of the larger PCB fab houses offer assembly as well, but the prices are eye-watering for small boards, because they have to make a stencil and all. A while ago I found a site that gave price quotes for that, though I forget what site it was. Basically, for small lots, the assembly will cost more than the parts. You look at the dirt cheap boards from china and think "look how cheap that HC-SR04 is, and all those parts, it can't be too expensive to have a board loaded for me" - but those are produced in lots of tens of thousands, using a design that's been in production for years.

Also, cloning the Yun is a lot more difficult than cloning a mundane arduino board - that WiFi section has fancy stuff under the hood, and since it does WiFi stuff, you might need to go through a certification process to sell it (not familiar with the applicable laws, but people on kickstarter always complain about the fcc certification). I wouldn't recommend that course of action - making a shield that you'd stack onto the yun would be much easier, and probably cheaper overall. Or, convert it to use ESP8266, and then roll your own arduino board and leave a header for plugging in an ESP8266. Either of those will be a much easier board to make.

Also - With boards, size is money, and 3x5 is huge, and in fact you won't even be able to design a 3x5" board in the free version of Eagle (that won't let you do any dimension larger than 4"). Do you ever wonder why all those chinese modules have everything crammed into a postage stamp sized board? For small run prototype, most of us use OSHPark, since they're usually the cheapest; from them, a 15 square inch board is $75 for three boards! ($5/square inch gets you three copies of the board).

In any event, your fear of SMD soldering will be a problem unless you have money to burn, because you'll need to solder up a prototype board to verify you didn't make any mistakes in the layout or design, before you send it off to make in quantity. But if you want to make it in quantity using throughhole parts, you'll take it in the wallet - assembly costs for throughhole parts are much higher. If you're not willing to do SMD soldering, you really limit yourself. All the best parts are SMD *, and they also take up so much less board space. Also SMD soldering really isn't that hard if you don't use the smallest sizes. The resistors and caps are by far the hardest part, though 805 and larger isn't that bad to do by hand.

*try to find a MOSFET that works at 3.3v gate voltage in through-hole, then try to find one that works at 1.5v in SMD, and you'll see what I mean. A lot of the good stuff is only in SMT now.

Also - wow, polycase looks like the place to go for enclosures...

Wow - thanks for the great advice DrAzzy! I really don't know how many of these I'll make. Depends on interest. Right now, I only know of demand for 3 or 4. Eventually it could get up to a hundred or two, or maybe nobody will get one after those first 3 or 4.

So sounds like I should skip the custom fab for now, and do it myself, and put it on a shield. And although I keep figuring out better/cheaper/smaller ways to build my board, I'd really like to get the rev 1 design done so I can focus on writing the software, where the real value add is of this project. So right now I've got a prototype that uses some Pololu motor controllers. Rev 2 I might build my own motor controllers, perhaps even with SMD components. But even with the existing controllers, I think I can fit everything on a single shield except for the DB25 connector.

So, as per my question above - any thoughts on how to build a shield that has room on it for a DB25 connector along the outside? Is there a shield protoboard design, for example, that I can take and add some pins along the side and have made for me? Then I could do my prototype shield on that, and when it's all working have it reprinted as a custom PCB for me to populate.

Does that sound like a good path to take?

dptdpt:
So, as per my question above - any thoughts on how to build a shield that has room on it for a DB25 connector along the outside? Is there a shield protoboard design, for example, that I can take and add some pins along the side and have made for me? Then I could do my prototype shield on that, and when it’s all working have it reprinted as a custom PCB for me to populate.

Does that sound like a good path to take?

Makes sense to me.

You’ll probably want to design the board in Eagle when you start designing boards. Eagle definitely has a learning curve, but it didn’t take me that long to get the hang of it. To get started, I’d probably start with hacking up an existing design - you can get the files for the official one from http://arduino.cc/en/Main/ArduinoProtoShield

I just noticed, you could get away with a Mega shield (plugged into normal arduino) as a prototype as well, without modification. It provides holes for a double row of pin header along one edge, and you can just put male pin header in that, and plug a DB25-ribbon cable adapter (which can be had for $1.76 shipped on ebay: http://www.ebay.com/itm/161152338978 ).

Looks good! Would the mega fit on a Yun? And do you know if they make one without the stacking headers on top? I just want one shield on the Yun.

dptdpt: Looks good! Would the mega fit on a Yun? And do you know if they make one without the stacking headers on top? I just want one shield on the Yun.

Just don't use the included stacking headers, use regular header pin strips dropped through from the top of the shield (long ends down), enough hangs out the bottom to engage the main board's headers. Or put the strips in the bottom of the shield if it fits better with the plastic strips underneath.


Semi-related question, since the folks who know about enclosures are already here. Is there such a thing as a case that'll work with a 16x2 LCD-with-5-buttons shield?