Group Assignment: Characterize the design rules for your PCB production process

For group assignment we had to charcterize the design rules like what minimum distance in-between traces can be detected by PCB milling machine or what effect does the width of trace posses. Below is attached the board we made as a group assignment. We found it in fab academy weekly notes.



Next we needed to generate machine readable files that will be in .rml format. To do so we first need to go to fab modules Now click on input format and select .png > another window will pop up and will ask you to select a png file to be converted > click-on/open that file > select .rml as output format > now click on process and select milling bit either 1/64 or 1/32 for traces and cutting respectively. Select your machine and write dpi for your image (Note the dimensions) Note: First print traces and then cut the file. Once you have set-up everything click on calculate to get rml file and then save it to your local directory.

Now repeat all above steps but this time for the outline. Note: This time in processes we will select 1/32 bit because this will cut the frame out.

By now hopefully you have your rml files ready. So lets move to machine and learn operating it. Note: Before operating machine we need to paste FR-4/copper board in machine on which we will mill our boards. Now open the software to operte your machine, that in my case is Roland SRM20 shown below. Next caliberte your co-ordinates and define your (x-y-z) origions by clicking left/right/up/down keys shown below. You can increase or decrease your bit movement resolution by selecting cursor step as x1, x10, x100, or continue.. Also integrate the bit of 1/64 to your machine first for traces.

Next click on cut > delete previous files by clicking delete all> open/import your .rml file and select output. Remember: Always while milling board first we print traces and then cut the board.

That is it your machine has started assigned work.

Th: Generally in PCB's trace is the conduction path for current. What PCB milling machine does is that it cuts on copper surface in a way that we get very neat and clean conduction paths. Trace in milling is like engraving in laser cutter hence we dont cut parts apart rather we cut them half way to write text, images etc on wood and various other relavant materials. Below we can see the final PC board. We made a mistake while generating rml files and that is why our board is not printed as per its design dimensions. Error: We mistakenly changed dpi for rml files from 5000 to 2000 and that disturbed our files dimension and it had to - obviously. 2000 dpi is the resolution for files we design ourself in PCB designing softwares. Hence we had to generate rml files again and repeat all above steps, but this time with default dpi ratio of given image and we printed it perfectly. Below you can see both of the boards. The smaller board is the actual board we were supposed to print ultimately.

Individual Assignment: Make an in-system programmer(ISP)/Programer/Burner by milling the PCB, and then program it

For individual assignment i initially made atinny45 but that didn't worked out well so i had to move to atinny44.
Below attached is my failed attempt to make atinny45. Below we can see atinny45 traces and outline image i used to generate rml files.



Here i generated rml files using above image by going to fab modules as we learned above. Once the rml files were ready i then went to machine (SRM20) to mill my board as discussed earlier in group assignment. I used above shown atinny45 ISP images and gnerated below shown board.

Once the board was ready i had to solder it, hence below you see the soldered board. You can learn soldering by following these instruction and precaution.

Failing to program atinny45, i went on to make atinny44 and it worked for me. First i took above files from weekly notes and generated rml files for them by going to fabmodules.org and following steps we learned earlier. Below we can see the rml files i generated. After that it was about milling and for that i repeated all of the steps we learned in group assignment. Hence below we can see the new atinny44 board.

Next step was to solder it.. to do so let's first figure out what componets we need?

As we now have components so let's for below shoen board..

Below we have our board ready.

Now we need to program it.. Programming it with windows was very complex and diffuclt so i chose to program it in linux/ubantu. Below you can see how i programmed it. Just follow the link and you will be able to program your ISP on your own.

If you are done with programming then congratulations! Your ISP/programmer is ready.

Now just remove these jumpers (zero ohm resistors) so that it can be used to program other programmers.

Click here to get design files.. Mill/Program atinny board and enjoy!



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