PCB Fabrication

Our first lesson in electronics’ production was about PCB fabrication. This lesson’s assignment was to fabricate a PCB of an already made design. The design is for a simple micro controlled board using Atmel ATtiny45 chip and it was made by the great Daniele Ingrassia .

We will be using three software programs for the electronics' assignments

Eagle PCB design software we use Express version which is a free version with some restrictions but it will be sufficient for the assignments.

GIMP Photo Editor Software it is an open source.

Fab Modules To control the CNC machine it is also open source.

Making the PCB

As we already have everything required to start making the PCB I could have started to mill the board using the CNC machine. But for the sake of knowledge I tried to export the design myself.

First step is either to open the schematic file or the board file it is fine both ways as long as you have them both in the same folder. I started by opening the schematic.

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To go to the board click on switch to board button.

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This is how it looks.

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You can see that the default for eagle is to view some layers of the board. To make the PCB we just need the tracks and the pads to do this click on layers icon.

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Now click on None then Top, Pads and then apply.

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Now the design is ready to be exported. Click on File, Export and choose Image.

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Name the file as you wish, choose its destination and increase resolution to 1500 to have a higher quality image.

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Time to edit the image to get the final one for the CNC machine.

Open GIMP click on File and choose Open. Choose the image exported by eagle and press Ok.

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Use the rectangular select tool (rectangle icon on Toolbox) to select the area of the tracks leaving couple of millimeters between tracks and selection then click on Edit and choose Copy.

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To paste the selected area go to File and choose Create from clipboard.

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Now we have the tracks image ready for the CNC.

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Save the image as it is (.png format).

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The last step now is to cut the board after milling the tracks. Make a new selection, Go to Select and Choose rounded rectangle.

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Choose the raduis for the fillets of the rectangle (I chose 10) and Press Ok.

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Click on Edit, Choose Fill with BG color and save the image.

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Milling the PCB

For this assignment I used Roland mdx 40 CNC machine and Fab Modules To control it.

Connect your computer to the network of the CNC machine in my case it was FabLab's network connection called FabLab.

You need to open the Fab Modules wesite using IP Address and Port number. In my case it was 192.168.102.134:12345 This is how it looks like.

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Click on Input formats and Choose image(.png) Select your tracks image and press Ok.

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This is how it should look like.

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Time to set the settings:

Machine: MDX-40

Speed: 4

Send Command: mod_lp.py/dev/usb/lp0

Server: 192.168.102.134:12345

Cut depth: 0

Tool diameter: 0.2mm

Number of offsets: 8

Offsets Overlap: 55

Press calculate.

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Last thing to set is the zero position of the head of the machine by default the zero of the software is bottom left corner. Choose the value for X, Y and Z wisely and use small steps to avoid crashing the tool to the material. Sometimes the zjog changes when entries of coordinates make sure always to bring it to zero. As a precaution keep your hand on the emergency stop button when you get closer to the material. Because the tool is of very small diameter 0.2mm it not very easy to detect if the tool is touching the material or not a very good way is to use the buzzer of a multimeter.
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After milling of the tracks it is time to cut the board. Upload the cut image, change the tool and keep the X Y of the zero position as they are just adjust the Z for the new tool and start the cutting job.

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Components

1uF Capacitor

100nF Capacitor

10nF Capacitor

Pin headers

10K Resistor

LED

499 Resistor

Soldering

I used a fine soldering iron tip along with soldering wire of diameter less than 1 mm at a temperature of 335°C .

It is hardly recommended to spend time in placing, soldering the components and checking their soldering using the buzzer of the multimeter rather than spending much time and effort later on to try to troubleshoot a problem.

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Final product

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Testing

I will be using an Arduino board and of course Arduino IDE as a programmer for my board and I will be trying to run very simple Blink code.

Setting Arduino IDE

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Installing ATtiny support in Arduino 1.6.13, you can install the ATtiny support using the built-in boards manager.

Go to File, Open the preferences dialog in the Arduino software and find the “Additional Boards Manager URLs” field near the bottom of the dialog.

Paste the following URL into the field (use a comma to separate it from any URLs you’ve already added): https://raw.githubusercontent.com/damellis/attiny/ide-1.6.x-boards-manager/package_damellis_attiny_index.json Click the OK button to save your updated preferences

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Go to Tools, select Board and then Boards manager.

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Scroll to the bottom of the list; you should see an entry for “ATtiny”.

Click install. The word “installed” should now appear next to the title of the ATtiny entry.

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Now you should be able to see the ATtiny 45 board. Select the Arduino Uno first and choose the port it is connected to.

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Go to File, Examples, Arduino ISP and choose ArduinoISP. Click upload to upload your code to be able to use the arduino board as a serial programmer.

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After the code is uploaded Go back to boards select ATtiny25/45/85, change the Processor to ATtiny45, the internal clock to 8MHz and Programmer to ArduinoISP.

Finally press Burn bootloader.

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Uploading the Blink code

Go to File, Examples, 01.Basics and choose Blink. Keep all the Settings as they were .

Now Cross Your Fingers and Click Upload and Hope It Works !! :D

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Result

YAAAAAY !! My Board works .

Downloads

Hello Board schematic
Hello Board
Tracks image
Cut image

Electronics Design

Next week's assignment.

License

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