Circuit Boards

I started out my 'maker' journey using whatever I could find to provide a starting point for my initial project (see LoRa Gateway). Pretty quickly, I got to a point where I needed some sort of enclosure for my creations. I initially considered buying a 3D printer to address this issue but after doing my first custom PCB, discovering how easy and relatively inexpensive that was, and having noted the existence of a whole range of relatively inexpensive off-the-shelf enclosures, I turned my attention to creating a PCB that would both support my application and mount directly into one of these enclosures.

The boards described below represent my efforts to date in this direction. Initially, they were all just 'prototyping' boards that fit into common 100 mm × 68 mm and 85 mm × 58 mm (more recently being advertised as 83 mm × 58 mm—I've not purchsed any of these, so I don't know for sure that they're exactly the same) enclosures. If you need them, M2.6 × 6 mm phillips pan head cutting tail self tapping screws, used to fix the boards into these enclosures, can be sourced from any number of on-line suppliers (I used to include a link to a supplier, but as with many components, suppliers come and go, so it's more reliable to just use a good description to search for a current source).

These efforts then led to the development of more specific layouts that also fit these enclosures and, more recently, both smaller and larger enclosures.

I mucked around for ages, trying to finalise a circuit design before fabricating a PCB. When I 'did' my first PCB and discovered how cheap it was to fabricate (~A$6 for 5 boards, plus freight, which, admittedly, was the larger component, ~A$25, of the ultimate cost), I decided to follow a different route and simply refine a very general board design as I went along. This also provided the benefit that I would have a base for any project that I wanted to fit within one of the enclosures with which I was working.

The boards generally start with a standard 100 mil (0.1" or 2.54mm) pad matrix overlaid on a board base that fits neatly into the relevant enclosure. From there, pads are moved, removed or linked to provide the required functionality. Because the cost to fabricate a board is based purely on its size, not the complexity of the underlying design, there is no downside to packing as much 'functional flexibility' into one of these prototyping boards as is possible. Because you can also include additional boards on any fabrication order for just another ~A$6 (for 5)—the basic freight charge covers the cost of shipping up to (about) five different boards (i.e. 5 × 5 = 25 PCBs)—I am also tending to make several variants each time around, sometimes just including features that look like they might be of interest. It's an iterative approach that may seem wasteful on the surface, but it's a bit like instruction caching (if you're familiar with computer architecture)—sometimes you blow it, but most of the time you're a step or two ahead, and most of the basic boards end up being useful for general prototyping in any case.

I pretty much exclusively use JLCPCB for fabrication services because, for me, they are the most economical and their board quality is at least the equal of anything else I've seen. The board price is way lower than anywhere else I've looked, although the shipping costs were often far more significant than the price of the boards. This situation has improved of late, with the fabricator now allowing shipment by 'standard post', rather than insisting that shipment be by courier, originally DHL. For me, this has often more than halved the cost of shipping and resulted in little more than a couple of days extra shipping time.

Gerber File Names

There was a minor problem with some of the boards I had fabricated by PCBs.io (who no longer appear to be in business, but I leave this note here in case anyone encounters a similar problem with other fabricators). I had trouble uploading the CAM outputs produced by Eagle, with PCBs.io complaining about duplicated Board Outlines. As a result, I was only able to upload the Eagle .brd file.

The issue here is that in processing an Eagle .brd file, fabricators do not seem to include the Values layer by default, so that the boards ultimately don't have the Values layer on the silkscreen. This is only a minor issue in that the values of the individual components are not printed on the board (apparently this is 'normal')—this is entirely irrelevant for many of the prototyping boards because in most cases there are effectively no components and hence no values to print.

I ultimately discovered that my problem was that PCBs.io required that individual Gerber files have distinct file extensions. Eagle, however, by default, produces Gerber files with descriptive names, but all with the same .gbr extension. This is all configurable within Eagle and all of my CAM file archives should contain files named in a format that is more universally acceptable to fabricators. I have tested the listed Fabrication Filenames with JLCPCB, PCBs.io and OHSPARK.

The only problems I have encountered in uploading CAM files for fabrication have been with the naming of the individual Gerber files so, if you are using a fabricator other than those I have listed and you're having problems, the first thing I would suggest doing is to check the fabricator's file naming requirements. The content of the files has always been fine, it has only ever been the respective names that have required modification.