For the month of May, I won the CircuitMaker Circuit of the Month competition for my Gizmite Interface i.MX6 board. To celebrate I created a new ZigBee equipped board with a Cortex-M4 processor and JN5168 ZigBee MCU. The design is available here (accompanying documentation and software coming soon).

Background

In designing the board on a budget I put in a reasonable amount of effort in routing to make sure that I could keep the board on 2 layers. For the final version I do intend on moving to a 4 layer PCB, but when prototyping on a budget, if you can go 2 layer it may be worthwhile. I selected a black solder resist for no other reason than matching my existing prototype boards for the overall project. I do like the look of the black board, and it does give a nice brand recognisable signature on my boards if/when I move into production. The board is also a good test of the board houses quality as it includes USB and wireless connectivity, which can be difficult. The USB portion works perfectly after a bit of debugging discovered some code problems in initialising the port. The ZigBee wireless portion is still not running yet, but I've only had the required SDK from NXP for a few days and will need to do a bit more debugging on what the problem is.

Ordering

For the PCB manufacturing I decided to give PCBWay a try. PCBWay doesn't have CircuitMaker integration like OSHPark and CircutHub so you will need to first export your Gerbers through the outputs menu to use the service.
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The order process was fairly simple and cheap, the board dimensions are only 50.8 x 55.3mm so the overall dimensions of the board falls within their cheapest 100 x 100mm limit. The only problem I had with the upload is that after about an hour when their team reviewed the order they emailed me stating that the board was missing an outline on the keepout layer. CircuitMaker by default uses a separate outline layer that is created automatically, but that wasn't used.

The order process includes options to vary the substrate, number of layers, minimum clearance/trace width, and minimum hole size. There are also options for more superficial details like the colour of the silkscreen and solder resist.

I ordered late on a Sunday night Australian Eastern Standard Time, but after the email about the outline issues it was accepted and paid for on Monday morning. The order progressed quickly, and was dispatched 4 days later with DHL. Shenzhen to Australia is a fast postal route and I picked the package up from the local DHL office on Monday.

Arrival

The boards arrived packaged nicely in a DHL Satchel with a small PCBWay box inside with the PCBs inside, the box had some evidence of being crushed a little bit but the boards were packed securely in a sealed bubblewrap bag.

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Inside the sealed bubblewrap bags the 10 boards were held together with an elastic band.

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PCBs

When once I had opened the bag the first thing I did look across the board for were obvious defects. Something that is often warned about with these cheaper chinese board houses is that the quality is not always perfect.

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The first thing I looked at was the silkscreen and I noticed is off by a few mil to the left. This is not a big deal though as I always have a 2-3 mil allowance for where I place my silk objects. There are a few that are a bit close for comfort in my opinion but thats how the part comes by default in the CircuitMaker community library which I may eventually change. After looking at the silk, I found other than the small offset the quality is decent with the smallest details being a fraction of a milimeter. The silkscreen on all 10 boards was identical including the alignment issue, but there were no other reproduction errors across any of the boards.

I then looked at the HASL finish. I opted for HASL due to it being cheaper than the ENIG alternative, but I did opt for the lead free HASL finish which was about $7 extra, as I am using lead free solder, and lead free components. Across all 10 boards the finish was reasonably uniform with very little variation in thickness which was good due to the QFN component that did need to be placed, and despite what the front and back pictures of an individual board show they do have a nice silver colour to them.

While PCBWay do e-test the boards I did run over the whole board again with my multimeter just to make sure that there were no bridges as I did push it to the limit of the service in a few places at 6mil/6mil. It is not usually recommended to work at the minimum tolerance even on boards from the expensive board houses, and it is at a minimum, but there were a few places I had to. All traces tested perfect with no unintended bridges and there were no abnormal resistances from thin traces. Overall the quality of the etching on the board is to a level where I can find no obvious defects, if there are any they are in the millionths of an inch that I cannot visibly see with the black solder resist.

The solder resist is an area however that I did find isn't up to the same standard as some of the more expensive board houses. Looking around the QFN and LQFP parts you can see that the pads do extend to different lengths, this is because the solder resist has a very large clearance around exposed pads. The directions that any pads appear misshapen when you look at the photos, either in length or shape is where the trace connects into the pad. Many of the boards I've had made in the past through more expensive board houses typically have had a far tighter clearance between exposed copper and the resist leading to a more uniform look. This is probably the biggest compromise that you need to make when using this service.

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tl;dr version, silkscreen is good, but the alignment is slightly off, lead-free HASL finish is close to perfect, etching has no issues, but the solder resist has large clearances especially where traces meet exposed copper as can be seen with the blue light through the board around the LDO's pads. I have no comment on the drill hits as they all appear to be central to their pad, but I also used large pads in case of mishits.

Finished Result

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Something I feel is often missed in reviews is the post-assembly end result. The PCB also has to be able to withstand assembly and some PCBs don't withstand the heat very well. The board was assembled with solder paste and hot air. I did not order a stensil so it was mostly done by feel for how much paste to add, most components went down fine, a few had too much solder which I then had to clean up, but the board in most parts handled being heated and soldered fine. There were a few spots on the first board which I assembled where the vias solder resist peeled back from when a small ball of the excess paste found the hole, but I mostly solved that problem by reducing the amount of flux I used. The bond between the solder paste, HASL finish and components all finished nice and strong, no delamination occurred under the hot air gun on any of the boards and the heat spread fairly evenly through the board leading to reasonably nice bond between components.

Conclusion

If you are looking for a cheap board and don't need tight clearances on the solder resist finish PCBWay will do the job. The board I got made was built to 6mil/6mil traces and 0.30mm, they do include options for far smaller but I can't comment on the capability as I have not used it. Everything from a PCB perspective works as expected and there are no critical issues. All up the board cost $17 for 10.