8. Electronics Production¶
Group assignment:¶
- Characterize the design rules for your in-house PCB production process: document feeds, speeds, plunge rate, depth of cut (traces and outline) and tooling.
- Document the workflow for sending a PCB to a boardhouse
- Document your work to the group work page and reflect on your individual page what you learned
Individual assignment:¶
- Make and test a microcontroller development board that you designed
Useful links¶
Students Who Helped Me¶
KiCad¶
The first step of Kicad was to downloade it. The downloading steps are in week 6. After downloading it I could began making the schematic.
Making Schematic¶
The first step of the schematic process was to make a new project. To do this, in the upper left hand corner I went to file then to new project. This then takes you to a place to name the project and to choose the folder that you would like to have the schematic in.
After making the new project, the next step was to got to the schematic. The following button take you there.
When you open that up, it takes you to a blank page looking like this.
The next step is to add the symobols to make the PCB. To add the symbols, first you you go to the symbol library browser. It is the highlighted symbol.
Once you are in the symbol library browswer, it looks like this screen. We used the fab library that was given to us by our teachers.
Once you have selected the symbol you would like to use, you click the following button to add it to the schematic.
This is the what my finished schematic looks likes. When making schematics its important to make sure the positive and negative are all correct because if they aren’t then it will be harder for later. Schematics provide a clear, easy to read overview of a system’s components and their connections, and are then used to inform the creation of layout drawings.
Once the schematic is done being made, before you can move on to the PCB editor, it is important to make sure you items have footprints. Footprints are what tell the PCB editor what type of symbol it is, which them tells the machine what to mill out and what not to mill out.
To get to the footprints, first you go to properties. You can eater click on the symbol then click the letter “E” on your keyboard. Or another way is to right click on the symbol once you select it and it brings up the following drop down. Then go down to “Properties”.
Once you are in properties, it should look like the following image.
Once you are in there look for the following section labeled “Footprint”. It may have something already in that section, byt that does not mean a footprint is selected. if you don’t do anything to it, it will not show up later. So add a footprint even if you think its already there. Once you find the footprint section, click on the middle box under “Value”. It will look like the image below once you do. Then click on the thing that looks like books.
Once you click on the books, it should look like this. This is inside the foorprints called the “Footprint Chooser”. It is important to find the exact symbol that you are using in the footprint chooser.
As you can see, I used the Seeed Xiao Esp32C3 in my example. And when I found it under our fab folder, and clicked on it, this is what it looked like. On the side is a preview of what it will look like. Once you are satisfied, click “OK”.
After you have done one, then you need todo it for the rest of the symbols. The more times you do it, the easier it gets. After the footprints are all finished and selected, then the next step it the PBC editor.
Setting Up PCB Editor¶
Switching to the Mode¶
The first step to editing in the PCB editor is to switching to that mode. If you click the following button, then it will automatically switch and set it up.
Once you have entered the PCB Editor, it will look like this.
Adding the Footprints¶
To get the footpints you chose into the editor, click the following button.
It will then look like tis once you do. As you can see, I have zero errors and zero warrnings. If you have these, I highly recommend fguring out what they are and fixing it. If you don’t, most lickly the board will not work. Once you have fixed them all, they I clicked “Update PCB.” Once that is clicked then the object shoule be in one blob. Then you need to spread then out but still keep them close.
Tracks¶
The next step is to add the tracks and connect the pieces together. To do this, make sure you are on the F_Cu on the side. Then you click the following button.
Then, click on the plate of one of the symbols and it should show you where it needs to go. Follow that and it makes it very easy. Make sure that no line is crossing over eachother. If they are then that isn’t going to work. If you are using a Esp 32 C3 like me, it can go under that, but no other peices.
Edge Cuts¶
NEED PICS
3D View¶
Once you are finished connecting the plates together, then you will want to check what it will look like in a 3D view. To do this click the following button.
The following image is what the 3D view will look like. This is mine.
Changing Width of Tracks¶
Before I milled my board, I noticed that I would need a very small bit for them. Therefore, I needed to change the widtch of my tracks. The tracks are automatically set at .25 mm in width. I decided to change then to .5mm. Later I realized they still needed to be bigger and I changed them later after my first test.
To change the tracks, make sure you are on the F_Cu again. Then you want to make sure in the bottom right corner, all of but tracks are deselected. It should look like this.
Then using the select tool, which looks like this:
Draw a select box around the whole thing. If only the tracks are selected on the side, the the select tool should only select the tracks. Then either click “E” on the keyboard or right click and go down to properties. Once in properties, it should look like this:
Under the “Track Width”, type in the number in mm that you want and then click “OK” and it will change the width.
This is what my final PCB looks like
Getting the Files¶
Before getting the files, make sure that you save you file just in case. THen in the top bar, go to this sybmol and click on it.
Once you are in here, it should look like this.
In here, the only two things that need to be selected it F.Cu and Edge.Cuts. Everything else can be deselected. Then at the top is where the files will be plottng to. If you don’t like that location, it is important to change it and it is important to know where they are going.
Once you are satisfied with everything, then you can just click the follow button and you are ready to mill.
Milling¶
Wen milling, the fisrt step is to up load in your file. Once you have downloaded the file onto the computer then you go to open file.
Once you are in there, select your files. You only need to do the FCu.gbr and the Edge_Cuts.gbr files. Once you add then, click clear on all of the options that is gives you.
After adding your files in, then it’s important to double check the material sizes. This is important because if you have a big job then, you don’t want the bit to go off the side. This is also important when you reuse material and you need to put your board not in the bottom left corner. Below are the measurements of the material that I used.
The next imprtant step is to select your bit. If the bit you are using is already in the machine then you dont need to go through the process of adding one, but if it’s not then you do. For the edge cuts, I chose a 1/32” Flat End Mill. Then, I had only outline on. This is important do the mill knows that the cut is only for cutting the board out. The Trace Depth and the Trace Clearance are the default settings. I decided not to change those. Then the next thing that needs to be pressed is the plot drill bit so then it send to the machine. Once you do that you will see what the edge cuts will look like on the display.
The next part is doing the same steps but for the F_Cu.gbr file. The only difference for this one is that I needed a smaller bit for. This means that I needed to change the bit mid drilling. Then the other difference is that you only meed the traces and the holes on because otherwise it wouldn’t mill right if you had all of then on. Other than those two things, they are the same set up.
The last step is to set up the off set. This means that rather milling directly from the orgin, It will mill slightly off of it depending on what settings you chose todo. My edge cuts were perfectly allined, but the F_Cu cuts needed to be moved over. Therefore, I changed the off set to the following.
Once all the settings are added in, I added the matiral into the machine. Todo this the first step is to add double layed tape to the bottom os the PCB.
THen after the tape, I pressed the board down ad hard as i could in to the bed. You want to do this because you don’t want the material flying off. IF this happens it could ruin the machine or bit. Once that was done it looked like the following image.
How to Change the Tool Bit¶
Homing¶
Milling Second Board¶
This week our school had spring break. I traveled on a plane and decided to take my fab work with me. While on the plane, the PIR sensor ripped the tracks therefore I needed to mill a new board. The steps stayed the same but the difference this time was the position.
This time I was using a scrap peice meaning I needed to change the offset. Here is what it was and a good example of how todo that. BAove is the edge cuts and below are the F.Cu cuts.
This is the second board ready to mill again and as u can see, this is where the offset has placed the board.
Adding Board¶
Dopler Sensor¶
