8. Electronic Production¶
This week, I explored electronic production by milling and soldering a PCB.
I am going to be producing the PCB which I designed in Week 6: Electronics Design.
Part 1: Understanding¶
What is a PCB?¶
A PCB is an electronic assembly that uses copper conductors to create electrical connections between components. Its structure includes conductive features like copper traces, pads, and planes, laminated between insulating materials. The board is plated, covered with a non-conductive solder mask, and often printed with a silkscreen legend for component identification.
PCB Structure
Types of PCBs¶
- Single-sided: Components mounted on one surface; the back is typically a full copper ground plane coated with solder mask.
- Double-sided: Components on both surfaces with traces carrying signals between them.
- Multi-layer: Multiple conductor layers, possibly including internal signal or plane layers; can be single or double-sided.
- Rigid: Fabricated on rigid materials like FR4-grade epoxy resin-impregnated fiberglass.
- Rigid-flex: Combines rigid sections connected by flexible polyimide ribbons, suitable for designs requiring movement.
- Flex: Entirely flexible, made of polyimide ribbons without rigid materials.
- Metal core: Features a metal core (usually aluminum) for increased rigidity and heat dissipation.
- Ceramic: Used in applications requiring high thermal conductivity to dissipate large amounts of heat.
Machine in our Fab Lab¶
Our fablab has two machines Roland SRM 20 and Protomat E44. Fo this week I used Roland SRM 20 for the production of my pcb. Link to know more about the machine
Roland SRM-20 is a compact, desktop CNC milling machine used for PCB fabrication, prototyping, and engraving. It’s designed for precision prototyping and PCB fabrication.
Understanding V-Panel¶
V-Panel is the software used to control the Roland SRM-20 milling machine. It helps move the machine, set the starting point (zero position), and start or stop the milling process.
Main Functions of V-Panel:
- Manual Control: Move the milling head along the X, Y, and Z axes to set the origin (zero position).
- Spindle & Speed Control: Adjust the spindle speed and feed rate for accurate milling.
- Depth & Tool Adjustments: Set the cutting depth and change tools as needed.
Strart your process by setting the origin of the tool bit.
Stick a double sided tape on your copper plate and Stick the plate on the pink surface that is the Machinable wax. Make sure that the copper plate is firmly stuck on the surface
Why machinable wax?
Machinable wax is used in PCB milling since wax is soft and easy to mill, it prevents damage to tools and helps avoid material waste.
Once this is done its time to insert the milling tool. With the help of Akhilesh sir I installed a 0.2 mm conical bit into the milling machine for engraving. We use allen keys to insert the bit and lock it.
Now with the help of the Vpanel software you need to set the origin. I set the XY origin first and then adjusted the Z- axis.
So there are two methods of setting the Z-axis. You can change the cursor step to 1 in V-Panel and lower the tool until it just touches the surface. But this method is risky because PCB milling bits are fragile and can break easily.
The second method is the one which I did. Instead of using V-Panel I manually Loosen the bit slightly using an Allen key hole it tightly and slowly moved it lower until it just touches the copper surface and then hit on set origin in the software.
Leraning: I forgot to set the Z-axis and started milling. I tool bit hovered above the copper. So i paused the machine and set the correct Z-origin, and restart the job.
Once the origin is set we hop on to Coppercam software.
Error encountered
I worked on my board outline because I initially exported it as an SVG file, but it needed to be in DXF format for proper processing in CopperCAM. Since CopperCAM does not recognize SVG files correctly for defining the milling contour, I had to re-export the outline in DXF format from my design software.
After fixing this, the software properly detected the board edges, and I was able to proceed with generating the toolpath for cutting the PCB outline.
Learning: CopperCAM does not support SVG for outlines, so always exporting the board design in DXF ensures proper recognition of the cutting path.
Understanding CopperCam¶
After setting the bit position in VPanel, you need to import Gerber files of the PCB design in the CopperCam software. CopperCam is used to set the cutting parameters. Once this is done a G-code is generated and sent to VPanel to start the milling process.
You start off by imported the top layer file (engraving) by clicking on the new project
We choose the top engraving layer first as, the process of engraving requires only a single but and in the drilling and milling (cutting the outer body) requires the flat end bit.
The bits we used:
- 0.2 mm conical for engraving
- 0.8 mm flat end mill for drilling and cutting out counters
You can set one pad as a reference and aligne the drill holes accordingly.
Once this is done you can trace the track contours and set the board outline as the card contour.
Learning: I added my logo in CopperCAM, but it was not engraved because it was not recognized as a milling path. I realized that CopperCAM does not automatically generate toolpaths for logos unless they are properly vectorized or defined as an engraving operation. Next time, I will convert the logo into a proper vector file.
Make sure to use the vacuum to remove the dust.
Once the engraving was done I changed the bit to 0.8 mm end mill for the drill file
Soldering & Final Adjustments¶
After milling the PCB, the next step is soldering the components onto the board.
Before starting, I cleaned the PCB with isopropyl alcohol to remove any dust or grease. This ensures that the solder sticks properly to the copper pads. I also gathered all the required components, a soldering iron, lead-free solder wire, and tweezers for handling small parts.
I started with the smallest components first, such as resistors to make soldering easier.Using tweezers, I carefully placed each component on the corresponding pads. The solder paste helps hold them in position. I used a hot air gun to melt the solder paste. I set the temperature and moved the gun in circular motions to heat the board evenly. As the paste melted, the solder flowed and secured the components in place.
Once all components were soldered, I checked the joints to ensure there were no cold joints (dull or cracked solder), solder bridges (unwanted connections between pads), or missing connections. I used a multimeter in continuity mode to check for proper connections.
Exercise files¶
Below are the files for: