Lesson4. Electronic Production

by Jiyoung An

Electronics Production: PCB Fabrication Process

Preparing files for milling: Create Gerber Files from board and schematic
Everything that I did for this assignment was really new to me. I got to know about this software Eagle and provided with board and schematic files. I opened up the 'FabUSB' files and

Schematic file_looks like a a circuit pretty much.
Board file
then I also got two files called 'LPKF_2Layer.CAM' and 'LPKF.drl' from here(Fab Lab Aaachen). These are two setting files for the pcb mill provided by the Fab lab. With these files, next steps followed are described below.
  1. Open CamProcessor under 'File' menu.
  2. Open Cam files from 'Open' > 'Job'
  3. Select 'LPKF_2Layer.CAM' file.
  4. Change Device into 'GERBER_RS274X'
  5. In Drills to Excellon Tap, change Device into Excellon24 and Check whether the right .DRD file is included.
  6. Hit 'Process Job' button
  7. If you see '.TOP',',BOT','.DRD','.BOA' and several other files, you can consider that this step is successfully carried.

File > Open CamProcessor
File> Open > Jobs > select files for your milling machine('LPKF.cam' in my case)
Screen you can see
Check 'Excellon24' & load 'LPKF.drd' file

PCB milling machine.
We are using 'LPKF Protomat S62 PCB mill' in our lab. Here you can find detailed guideline for using machine. In milling station, you need to create .job files(called 'preprocessing', step5 in linked guideline) using 'CircuitCCAM' which will actually tell your 'BoardMaster' program and 'PCB mill' what to do.

  1. Create .job files from CircuitCAM program
    2. preProcessing step
  2. Set origin for cutting

    3. One tricky thing left is to set the position where to start cutting. We need to do it so as to mill the right parts from the metal sheet, as board is normally small, and we can mill several board with one large metal sheet which normally fits into the size of the machine. so setting zero point economically is somewhat important. After this step is done. there are just 3 buttons left until you get board ready to be soldered.

  3. Operate milling machine
      4. How milling machine is working (so it just needed 3 buttons from the 'BoardMaster' software)
    • Make drills
    • Draw circuit & Scrap other parts out
    • Cut the outline
    Job sent to BoardMaster
    machine is now Working
    after milling, you can send the other parts and circuit parts(?) to make the edge smoother and remove not-fully scraped area.
  4. separate you board from the plate, and trim the edge and circuit surface with sand paper.

Now we are ready to solder (or stuff)!

Collecting components for soldering
These is a list of components making FabISP.

  • Microcontroller Attiny 45
  • 2x3 Pinheader 2,54mm
  • 2 x Diode 3,3V SOD-123
  • 2 x 680 Ω Resistor
  • 1 x 1.8 kΩ Resistor
  • 1 x 100 nF capacitor 1206
I attached them using tape on the the paper for convenience, and noted some direction for Microcontroller and Diode.
Gathered components
  • Stuffing or soldering

    • Tips for easy soldering

    We actually tried making circuit by stuffing with silver paste at first. As pasting method of making a PCB didn't really work successfully, we later had to develop our skills on soldering, which I have feared of so long. And finally in a week of 13 thanks to 'Lukas' from our lab, who gave me Soldering101 Lesson, Milling and Soldering ent Easy! To share what I shared, here I wrote down tips. (can be redundant with Week13).

    • Heat the PCB and connecting parts first, before heating and trying to melt the Lead hastily. When PCB parts get heated enough, later melted lead will just surround the connecting parts.
    • You don't need to use lot of Lead, so maybe you can melt a little bit of lead first in your soldering iron, and try to connect PCB and chips.
    • Start with one part of SMD(small parts), it is hold well, then next step is way easy.
    • When soldering chip, you can also start with soldering one bottom leg and then the one up, across to it, to hold the rest of the parts.
    • When soldering Pinheader, you can attach it from bottom. Here you can heat to PCB and connecting parts first, and apply lead wire on the other side of the heat. Then you can get nice corn shape;)
    • Keep your soldering iron clean, otherwise it does not pass the heat properly.
    • In case of excessive drop felt into the connecting parts. Using small amount of gel, copper wire to soak the lead, syringe to pump(?) it up again might help.

    Testing
    After soldering, we programmed the board. To Program the board, we first set the Arduino as an AVR ISP(In-System Programmer). For this step, we followed the steps written here. And we also downloaded the software to program fabISP. We followed the way described in Anna Kaziunas Frances's tutorial till this point. When we were actually trying to program Attiny45 with the way it was written in her tutorial, it didn't work. And then We found 'Building the FabTinyISP' tutorial very helpful in programming Attiny45. Then we edited the code that Anna was provided and by changing the programmer, and added the USB variable to the make file. After this step, we connected the Arduino with FabISP and run the following commands:

    1. make
    2. make flash
    3. make fuses
    4. make rstdisbl
    make
    make flash
    make fuses
    make rstdisbl

    Below is result from the assignment.

    FabISP
    Here you can download file(s) that I created for this assignment:
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