Since I was about 15 I begun to build my small soldering / electronics station in my room; which I mostly used to disassemble old electronics & reapair the broken electronics (such as phones) of friends and family.
However I had never soldered "surface mount" components but only "through holes" which is much simpler. I had also never used the milling machine
I was sick for this lecture, so I had re-watch it at home.
During this lecture Neil went through the procosses of making PCBs (both industrial and through the use of a milling machine), the components we are going to use and how that applies to this weeks assignment.
The assignments for the first week were:
I. Make an in-circuit programmer
Highlighted necessary tools:
>> Small milling machine
Preparing The Copper plate:
Note: For the process to go well the copper plate must be completely flat, otherwise it will not cut out the copper properly.
The copper plate is mounted on an acrylic bylayer which is made to fit on the Roland Modela and to be fixed with two screws. Between the first layer of acrylic and the copper plate we want to cut out there is another copper plate which we call "Sacrficial layer", which is needed to prevent damages to the acrylic, and is changed roughly bi-annualy. The copper plate is fixed onto the sacrificial layer with the use of double-sided tape.
The Process of Using The Small Milling Machine (Hardware):
I. Turn on the machine by pressing the on button
II. Set the machine in "View mode" by pressing the view button.
III. Replace the mill-bit with the one you will use for your PCB (1/64 to make traces; 1/32 to cut out). This must be done carefully: the small hexagon-socket screw, at the base of the rotary axis of the milling machine (only on one side), will loosen the mill-bit which you must hold at all times to avoid it from falling and thus getting damaged. The reverse process is done to insert the new, desired, bit. (Make sure that the bit is inserted deep within the rotarty axis at first, to make sure it does not crash against the copper plate once it is taken out of view mode)
IV. Insuring that the mill-bit is well fixed to the rotary axis, the machie is taken out of view mode, then by pressing the up or down button we adjust the height of the z-axis to roughly what we need.
V. We un-screw the mill-bit once again to adjust the height to exactly what we need, remember to accompany the bit until it touches the copper plate (do not let gravity do the work, this will damage the bit)
The Process of Using The Small Milling Machine (Software):
I. Turn on ubuntu computer
II. Open Terminal; type and enter "fab". This will start the fab module application.
III. Selec image file format, for us .png, and machine model, for us Roland Modela => Select "make_png_rml", this will open up a new window
III. Load the png file from the FabAcadmey folder; our choice was between Andy & Zaerc models (I chose the latter, preferring to have the LEDs)
IV. Select "make path" and adjust the different paramenters to fit your preference, then once again "make path" to apply the changed parameters.
V. Then you must select a xmin and ymin value as the starting point for the mill-bit on the copper plate as preferred by the user.
VI. Finally you can select "make .rml", this will show you the estimated amount of time need, as welll as an option "Send it!" which once pressed will send the file to the machine which will start cutting out your desired design.
1# Its a good idea to press view a few moments later you sent your rml, to check out how the cut/trace is going
2# After you are finished cutting out the PCB, prey it up with a spatuala to remove it from the rest of the plate
3# Remove the double sided tape from your PCB cut-out
4# Close the wooden enclosure of the Roland Modela to decrese the sound produced
5# In the 10ish minutes it takes to trace out the circuit, go hunting for components! Its a good use of the time.
How It Went For Me:
Well, I failed on mutiple occasions. It took me five tries to make a proper ISP. (All documented in the google document)
On my first try the tracing went great but for the cutting out I didn't screw the 1/32 mill-bit tight enough, this made it go loose during the cutting obliterating the bit and cutting into my ISP (this was quite scary). ( I always kept the offest at -1 to make sure all the copper is removed and the error at 1.0)
On my second try, after getting a new 1/32 mill-bit, I managed to cut out the ISP and the traces seemed beautifully shiny. I discovered this was not such a good thing, it meant the copper had not been cut out properly.
On my third try I started again to trace, but the traces were again not deep enough, so I attempted to quit the job... This failed since I didn't know the proper procedure. Cicillia came to my rescue and thought me how to quit a job:
>> Pressing up and down at the same time on the Modela
>> Opening the terminal on the computer
>> Pressing "control-c"
>> pressing up and down at the same time once again). I gave up for the day and went home with a few "not finished ISPs" to practice my soldering.
On my fourth try on the next day I removed the copper plate and placed new double sided tape on the sacrificial layer to make sure it was perfectly flat, I also increased the depth from the standard -1.0 to -1.5. I started the job and once again the traces were not deep enough right from the start, so I quit the job and increased the trace depth from -1.5 to -2.0 and I traced over the existing traces, this worked out great and I managed to make my first perfect ISP PCB.
Sadly while I was stuffing it I created a short which I could not find and so I had to make my fifth attempt, which worked out from start two finish without any hick-ups (Offset =-1 error =1.0 depth =2.0), and would later become my final ISP.
Stuffing & Programming:
I followed closely the instructions from Zaerc, this made it quite simple. At first I took a few unfinished ISPs from previous years, desoldered the components and put the back, I did this at home. I also unsoldered some other components from old electronics and tried soldering them on, just for practice, since I never had practices with surface mounted components.
With my first ISP, I followed what Zaerc did to the letter, however I created a short and was unable to find it, and I knew it would have taken me longer to find it then to make a new one, so I did.
The components had to be fished from a huge arrey of small shelfs, which was rather challenging at times.
On my second go, I placed the solder on the "cardinal pads" first, then placed all the components, then put the solder on the other ends. This was a mistake, I did this in attempt to use less solder, thus decreasing the chances of creating bridges, however I discovered there is such a thing as undersoldering, and while I had no bridges (since I checked constantly with a multimeter) some components were not even connected to the copper plate... Finding all the missing connections took a while.
(I also switched the green LED with a blue one, which makes no difference but looks better in my opinion. I then switched the location of red and blue LED, this was a mistake, but since the red one is on most of the time, this was a productive mistake; I also got the orientation of the LED wrong, on my defense the blue LED had a counterintuative label).
Emma aided Marije and I in the programming of the ISP, she sent us an additional tutorial and download page which helped us set up our macs for flashing the ISP. We used Emma's ISP to flash our ISP, by connecting them through the 6 pin-connector. Following Zaercs tutorial everything went pretty smooth. (Mac usesrs also need to install XCode).
=>Place an eye-lens on the front of the camera of your phone to get great pictures of small components.
=> Cover backside of ISP with cardboard to make it stable within the USB port.