It might surprise you to know that it is both possible and affordable to create custom PC Boards in small quantities for use on your layout. I first did that five years ago when I created the first boards I call duinoNodes. Back then I used a Shenzhen, China company PCBWay to fabricate the boards.
I have done several small prototyping projects with PCBWay since that first one. Obviously, I’m happy with their work because I chose them to be my manufacturing partner for my Lew’s Duino Gear commercial project coming online this Spring.
What Exactly is a PC Board?
As ubiquitous as they are, some may not know what a PC Board is: the initials PC mean “Printed Circuit.” A PC board is an electronic circuit embedded on a substrate, such as fiberglass or some other material.
In a traditional PC board, a layer of copper is laminated to both sides of a fiberglass substrate. The circuit is created by etching the copper to remove portions, creating a network of wires called “traces.” The original process used photo lithography to “print” the circuit design on the board. Today, computer programs guide the etching, drilling and routing and other processes involved in fabricating a PCB.
The circuit design includes places to mount components: copper plated holes for “through hole” components, and copper pads for surface mount components. Adding components to a PCB can be done by hand or automation. Automated assembly prefers surface mount (SMD) parts. It is possible to hand apply even the smallest SMD parts, but through-hole parts are easiest to work with by hand and usually the best choice for hobby projects.
My Current Project
I just received delivery of a batch of boards from PCBWay for the Lew’s Duino Gear line. These are partially assembled boards; they have all components mounted except the terminal blocks. To complete assembly we add the terminal blocks (which are through-hole parts) and then package the unit.
I’ve become a connoisseur of PC Board quality. Having bought a lot of Arduino compatible accessory boards, I can attest that the quality of PCB fabrication is all over the map. Today I can readily tell the difference between the good and the poor.
Attention to detail is the best way to judge workmanship: the accuracy and finish of cut surfaces, the finish of exposed copper, and the quality, evenness and accuracy of the solder mask.
The quality of the details I can see gives me confidence that the workmanship of the parts I can’t see is equally good. That’s why I use and recommend PCBWay.
Creating a Board for Your Layout
Lets say you have designed and hand built on a breadboard or prototyping board a circuit that does something useful on your layout, and you can use more than one or two of them. Does it make sense to have PCBs made?
It can, especially if the circuit is complex and difficult to replicate by hand. PCBWay specializes in quick turnaround, small batch PCB fabrication. You want 5, 10 or 20 boards? How does $5 per board, delivered, for a 100mm x 50mm basic, 2 layer board sound? Want them in a week? They can do that.
Its affordable, but not for the faint of heart. Preparing a design for manufacture takes effort and, if you are a newbie, an investment of time in learning the tools.
To create a board, you have to use a specialize CAD program for creating PCBs. Fritzing, an open source project, is great for beginners with relatively uncomplicated designs. One of the unusual things about Fritzing is the “breadboard” sheet, that helps you breadboard a schematic you’ve created. Fritzing carries you through the entire process of creating a PCB: schematic design, breadboarding, and final board design. If you’ve never created a PCB before, fritzing is a great place to start.
For me, the big issue is the parts library. You need CAD models and data for every part in order to correctly layout a PCB. Fritzing’s libraries are thin and dependent on user contributions. You can create your own parts from the info in parts data sheets, but that takes a lot of time and effort.
For that, and other reasons, serious PCB design calls for a more advanced CAD program, such as Eagle from Autodesk. Eagle is not an easy program to master, but the reward is extensive, manufacturer supported parts libraries and tools for analyzing and validating your designs. Once you’ve used a high level tool like Eagle, its hard to go back to anything less capable.
The Design Process
The process of working with software to design a PCB is too big a subject for a single blog post, and the details vary depending on which CAD program you use. But in general, there are 3 major steps:
- Create a Schematic. Using your chosen software, select the “schematic” side of the software and “draw” a schematic of your circuit. You add parts from the software’s library, then “draw” the connections, or wires, using the software’s drawing tools.
- Layout the Board. Next, you switch to the “board” side of the software. Here you will initially find all the parts from the schematic connected by “air wires.” — symbolic connections that you turn into real wires on the board. Like schematics, its a process of “drawing” with the software tools.
- Create Gerber Files for Fabrication. Whatever you use to design your PCB, in order to manufacture your design you will need to produce Gerber files. Gerber files are the standard for describing the layout of a PCB for fabrication. Your PCB design program should package the Gerber files in a single Zip file for uploading.
Working with PCBWay
Now that you’ve done the hard part, designing a PCB, the rest is easy.
Go to the PCBWay home page, input the dimensions of your board and the quantity you want on the “Instant Quote” form at the top of the page. Click “Quote Now” to be taken to the online quote form.
The form has a lot of options; follow help links for anything you don’t understand. The initial defaults in the form are generally fine, but a couple merit special attention:
- Surface Finish: This refers to the finish applied to exposed copper (most copper is covered by the solder mask). This finish is important in that it protects the copper from corrosion and affects soldering/resoldering of parts. The least expensive finishes — HASL and HASL Lead Free — cover the copper surface with solder. Its fine for most purposes, but resoldering parts is difficult and tends to cause deterioration of the contacts. Immersion Gold, required for automated assembly, provides a durable and highly solderable protective finish. For prototyping, where changes in parts and resoldering is likely, Immersion Gold is worth the small extra cost.
- Finished Copper: This refers to the thickness of the copper layers, expressed in ounces of copper per square foot of board. Copper thickness affects current handling capacity of a board. Thicker copper also improves resolderability of the board. For low current applications, 1 oz is fine. For higher current applications, such as passing track power through a board, 2 oz will be the better choice.
Once you’ve set your options, click calculate, and if you are satisfied with everything, place the order.
At this point you will need to upload your Gerber files. Then you need to wait for PCBWay to review your files and approve them for ordering which typically takes an hour. Now you can pay for your order and start the manufacturing process.
That’s it. On small orders, the boards are usually in my hands within a week to 10 days. Projects like this one that include automated assembly take longer because it takes time to acquire the parts. Still, I received these boards less than 30 days after ordering which is excellent turnaround.