Week 04: Electronics Production¶
The Week 4 Group Assignment is to characterize the design rules for the in-house PCB production process and also to send a PCB out to a board house.
PCB Milling¶
Roland Modela MDX20¶
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Roland Modela MDX20 is a desktop CNC 3-axis milling machine used primarily for rapid prototyping, small-scale fabrication, engraving, and similar precision work with various materials like plastics, light metals, and wood. This machine can be used to mill and cut PCBs.
- Power Button: To switch the machine on and off.
- View Button: To start the process of sending files. It also acts as a pause button.
- Up and Down Button: To move the bit in vertical axis. By pressing both the button together, it deletes all the files in the queue.
Mill Bits¶
In our lab we mainly have 3 size mill bits: 1/100”, 1/64”and 1/32”. In this 1/64” bit is commonly used for milling and 1/32” bit is used for cutting.
Safety Measures¶
- Handle the bits with care.
- Clean the bed after every use.
- Close the cover while the machine is working or use safety goggles to protect yourself.
- Make sure to remove the sticky residue after each use or else there is a chance of irregular height.
- Wash your hands after using the machine.
Steps to follow:¶
The Roland Modela MDX20 comes with a dedicated software. But here in our lab we use MODS-Project. MODS Project or Fab Modules is an open source software that can be used to run any fab lab machines. It provided a set of software tools for designing 2D and 3D objects, functions to generate 2D and 3D toolpaths and GUI workflow from design files to machine commands. It is a much better alternative than installing and using different softwares for different machines.
Once MODs is opened right click to Programs < Open Programs< Roland MXD PCB
The line test PCB design was provided by Fab Foundation. So, we imported the .png file to MODs starting of with the trace file.
Now, switch ton the machine and the system will move to its home position. For our group assignment, we tried all three bits to trace.
To place and change the bits in the machine we use an allen key on the collet chuck.
For the PCB board we used FR-1. It is a flat, hard and non-conductive PCB material and is made up of a thin layer of copper that covers the paper laminates.
We use a double-sided sticky tape to place the PCB board on the bed. Always ensure that the sticky residue from previous work has been removed from the bed before next.
Once it is placed, now we have to set the origin. That has to be done through MODs. Enter the corresponding values in the box provided and click on move to origin and the module will move to the position.
After positioning, use the allen key to loosen the bit and move it downwards to gently touch the PCB board and secure the position again.
Click on calculate to set all the values and then click on view to see the path that will be traced by the bit. Once done, click on send file to transfer the file to the machine and machine will start milling.
For cutting we use 0.8mm bit. Once, milling is over, just follow the same steps with replacing the bit in machine and changing the selected bit on MODs. We imported the file below for the outer and selected 0.8mm bit.
Results from Milling¶
0.4mm Bit Milling¶
Result:¶
Observation:¶
- The diameter of the bit is less than 16 mills as the bit was not able to cut through the material below that.
- All the trace lines were clear and precise.
0.8mm Bit Milling¶
Result:¶
Observation:¶
- The diameter of the bit is less than 20 mills therefore no cuts were done on the material and even the numbers on the board were not clear.
- All the trace lines were clear.
Note: We changed the diameter of the 0.8mm bit to that of 0.4mm so that the machine will identify it as milling operation.
0.25mm Bit Milling¶
Result:¶
Observation:¶
- The tool broke in between the process.
- Causes of breakage can be due to high speed or the positioning of the tool.
PCB Laser Engraving¶
Our Super fablab is equipped with a versatile laser engraving machine that can handle both fiber and CO2 wavelengths, making it powerful enough to directly etch metal surfaces. This opens up exciting possibilities like engraving PCBs for precise copper removal.
We are already familiar with Trotec Speedy 400 flexx in Week 3 Assignment.
We milled a small piece of FR1 plate for engraving.
For laser engraving, we imported the PNG file. The design was opened in Inkscape, and we extracted the trace using Trace Bitmap option.
We placed the Copper clad PCB in the corner of the Laser Engraver’s bed.
After placing the copper clad, we opened the Trotec software in the PC. These are the parameters we used for engraving
We have provided 8 passes for the engraving and the results was cool.
Observation:¶
The line test results shows how much we can engrave using the Laser. From the result, it’s possible to achieve 1 mill traces and space between in traces with laser engraving process. But the 1 mill trace came off the board. From my observation it’s better to keep 5 or 6 mill while design for PCB laser engraving process.
For the quality inspection, I placed it under the vision 3D microscope in our Super Fablab.
Sending PCB Design to Board House¶
The second part of this week’s group assignment was to send a design to a Board House. There are many PCB Manufacturing Industries, of them the most famous one is JLCPCB , which is a chinese company and it has been the first preference of Super Fablab Kochi over the years. But this time, we thought of ordering from an Indian company, Lion Circuits. So, we availed the service of LionCircuits to place an order of Quentorres Version 1 board.
We opened the site and registered. We created a new project.
Here, we need to upload the gerber file. So, we took the files available in Quentorres Fabcloud and zipped the files for Version 1. Once uploaded, we were able to view the board.
We applied for 10 boards.
Then we provided the billing address and other required details and the order was placed.
We expect to receive the order by March 1st week.