Like many VHS members I’ve gotten PCBs manufactured at Seeed Studio, AllPCB, DirtyPCBs, JLCPCB, and the like. The quality has always been excellent and the main differentiator is shipping options, ease of ordering, customer service, advanced features, etc. Last year I used Seeed Studio Fusion PCBA (Printed Circuit Board Assembly). This is a service where they solder all the components onto the board for you.
Here are some notes about my experience. Disclosure: Seeed has offered me a coupon for my next order if I make a post. In any case, I’ll try to be honest here…
Ordering
Ordering PCBA is a bit more complicated, because you have to supply a BOM (Bill of Materials) so that the manufacturer knows what to put on the board. If you’re used to getting bare PCBs and soldering them yourself at VHS, this presents a number of challenges…
- You need to only use parts they can procure (more on this below)
- You need to be careful with component designators on your board design to make it easy for them to know where each part goes
- If you choose the wrong footprint, the manufacturer isn’t going to bodge them on for you — you’ll just be out of luck
Selecting components
Seeed Studio publishes a list of parts that they keep on hand called the OPL. If you can use these parts exclusively, then ordering is much easier. If you need them to source other components, it will take longer because a human will have to get back to you with a quote.
You may expect that the OPL is mostly passives and other basic components, but it includes plenty of microcontrollers (including the ESP8266) and sensors and stuff. Where I’ve found it lacking is connectors, as it doesn’t have a given connector in all pin counts.
In my case, I made a risky move and completely redesigned my board so that I could use 100% OPL components. I decided this one-time risk would be worth it in order to make re-ordering easy. It turned out fine in my case.
Speed
Seeed seems to run a lot of promotions. I first used PCBA when they had a very good deal, and that probably contributed to very high demand for the service. It took 3-4 weeks before my finished devices shipped, which was fine for me. My second order was a bit faster.
Price
If you’re expecting the insane cheap prices of PCBs, you’ll have sticker shock with PCBA. Getting 10 copies of even a fairly simple board is going to cost a couple hundred bucks. That’s still great value, but it doesn’t make sense if you just need a single board for a hobby project. The key is to design a board that will be useful for a bunch of different projects.
Update: For the project pictured below, the price was about $200 USD for 10 units. I did two batches a few months apart, for 20 units total. This included the PCBs, parts, assembly, and shipping.
Quality
The quality has been excellent. Much better than I can do with solder paste and the VHS toaster oven. The solder joints look professional and the boards are nice and clean. Out of 20 units, I did have one that required a tiny bit of rework. For me that’s acceptable.
Photos
For this project, I buy enclosures from Digikey. The boards click in perfectly with no fasteners.
Next project
I’m gearing up to do a much larger board with Seeed PCBA, using an ESP32 and some other components that are not on the OPL. That’s why I need my coupon. 
