Well, I am finally getting the hang of PCB isolation routing. My first early success makes me very happy indeed.
It’s taken lots of effort and learning, but I can finally claim success in PCB isolation routing. You may recall that this is a technique to isolate copper traces on printed circuit boards. If you look at the picture above, you will see that all the traces and pads in the circuit are isolated from the rest of the copper plane.
You use a CNC machine create a gap in the copper surface to isolate your circuit connections. The trace is around 0.8 mm wide, and the circular pads around 2 mm in diameter. The isolation gap that you carve is about 0.25 mm wide. It’s amazing that these cheap CNC machines like my Genmitsu 3018 can be so accurate.
And, of course, if you change the cutting bit for a drill bit, your CNC can drill all of your holes in the pads perfectly. (Drilling holes manually has always been a tedious and error prone process for me, one that I am glad to avoid.)
After milling the board, all you have to do is insert your through-hole components from the other side, and solder the leads to the pads. I will finish that up and show you the completed high pass filter board next week.
It’s very easy to check your work for isolation and continuity. Just use a simple ohm meter to make some tests. You need to find continuity along each trace, as well as isolation between traces and the broad copper ground plane.
PCB Isolation Routing – Plastic Mounting Jigs
You may have noticed in the picture that I have 3D printed some plastic mounting jigs or brackets. These plastic parts hold the printed circuit boards firmly about 20 mm above the CNC metal bed. Each is connected with a 4 mm machine screw which attaches to a T-nut inside the aluminum extrusion.
I am hoping to avoid gluing the PCB onto waste board, and then clamping the board to the work surface. As long as the PCB are small, there should only be a minor sag across the board. I am using 70 by 100 mm stock. Typically, I am holding these boards in place with six jigs.