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8. Electronics Production

Group Assignment

  • characterize the design rules for your in-house PCB production process
  • submit a PCB design to a board house

1. PCB Design Rules

We went through the following PCB design process and learned how to use related tools step by step.

  • Design Tool: Fusion
  • CAM: mods CE
  • CNC Machine: Sainsmart Genmitsu Cubiko
  • GRBL controller: Candle

1-1.Design Tool: Fusion

In FabLab Kannai we use Genmitsu Cubiko CNC and V-bit 1/64 for traces and 0.7mm bit for interior which are commonly available in Japan.

To test what copper width and copper clearance are optimal, we used the below image already prepared.

line bit type image
Traces V-bit 1/64 traces
interior 0.7mm interior

1-2. CAM: mods CE

We opened mods CE CAM software on the web, and set parameters and obtained .nc file containing G-code instructions to the machine. First, we prepared the G-code for the traces.

  • Open mods CE and go to Programs > G-code > mill 2D PCB mill 2D PCB
  • Upload PNG file from read png menu upload png
  • Jump to on/off section and make it on so that we will be able to immediately download the file when the path is created on off
  • Go to V-bit calculator and set numbers as follows. We changed the units to metric mm here. Then click send calculate settings button. set_v-bit
  • Then goto mill raster 2D section, where the numbers are already input. Press calculate button and the software creates G-code paths and the .nc file is automatically downloaded to your PC. calculate

For the interior rectangle, the process was similar, but we used the default 0.79mm (1/32 inch) drill and adjusted it to 0.7mm in the mill raster 2D section. adjust 0.7mm

1-3. CNC Machine: Sainsmart Genmitsu Cubiko

We secured the raw PCB board on the MDF with sticky tape and also with the clamp attached to the machine Cubiko. And secured the bit to the collet of the machine.

1-4. GRBL Controller: Candle

Next, we connected Cubiko to our PC and opened the Candle software. Candle is a GRBL software officially recommended by Sainsmart and has a convenient height mapping feature which significantly improves the milling quality. The basic flow is as follows.

  • Make sure the machine and PC are connected
  • Set the raw PCB board with clamp
  • Connect the clip to the clamp
  • On Candle click Open and Upload the PCB file
  • Set the origin by jogging the spindle and ZeroXY
  • Zero-in the z height with Z-Probe
  • Find Heightmap menu and press Create
  • Press Auto, then Candle automatically set the height map area
  • Set probe grid to your preference
  • Click Probe to start creating heightmap, and when it’s done press OK
  • Save the heightmap file your preferred name from File menu.
  • Check Use Heightmap check box in the Heightmap menu
  • Before start milling, disconnect the clip from the clamp
  • Click Send button at the bottom so that the machine starts milling.
  • Once the milling is done, we poured some solvent to easily remove sticky tape. solvent

Note

Don’t manually probe z height, you can easily break the tip of the bit.

1-5. Result

Here is the result test PCB. The left one used the above V-bit calculator setting, and the right one used the default 1/64 flat option, and we like the left one which produced fine lines as thin as 0.006 mil. You can see that where the designed copper line is thinner than the bit tip size, there is no line milled. We decided to use the setting for our individual assignment.

result

2. Submit a PCB design to a board house

For this assignment, we used the board designed in the individual assignment and submitted it to JLCPCB.

  • On Fusion Electronics, Manufacturing > Export Gerber, NC Drill, Assembly and Drawing outputs > Save, then a zip file will be automatically created. export gerber file

  • Upload the zip file to JLCPCB. upload pcb file

It seems that’s it!　

Reference