Clock/Calendar Project: The PCB Fabrication

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Now that the designs were complete, it was time to fabricate it, starting with etching the PCB designs onto real copper-clad PCB boards.

As last time I used the PCB Fab in a Box toner transfer method.

The first step is to print the PCB designs using a laser printer onto special paper that has a water-soluble coating. Then use a laminator to fuse the exposed toner to the copper-clad board and dunk it into water to release the original paper, leaving just the toner image behind.

Here's a picture of the back of the clock PCB with the toner transferred:


Once that's done, the Fab in a Box kit has what they call Green TRF which is a green film on a thin plastic backer film that fuses to toner via the laminator and leaves a more impermeable surface before etching.
Here are a couple of pictures of the front of the clock PCB and the front of the clock face PCB with the toner and Green TRF adhered:



Then I used Ferric Chloride to etch away the exposed copper, leaving the desired traces behind:


And finally, the toner and Green TRF film are removed using acetone and the holes drilled. Here's a picture of the clock PCB front in the middle of that process:


So there you go! The only things left are pictures of the boards populated with the components and the working item in the fiberboard enclosure I made!

 

I used a standard solution of FeCl3 made for etching PCB boards, not an anhydrous powder or somesuch that needed dilution, so I'd have to look at the bottle to see if it describes the concentration.

How can you laminate what?

I'm not sure what you mean by minor track breaking. Do you mean in the transfer from the print to the PCB you get some gaps in the traces? I fixed those kinds of defects with a green Sharpie permanent marker. To reduce them depends on why you're getting gaps. If the toner is there in the printout in the same concentration but not adhering to the PCB, then you need to clean the PCB better. If the problem is that the toner is too light, you need to adjust your printer settings to increase the density. If the problem is that your printer is not very consistent in depositing toner onto the paper, there's not much you can do other than touch the defects up with a Sharpie.

I never had a problem with Sharpie permanent marker ink being removed by FeCl3; it took acetone to remove it just like the toner and Green TRF. But I also do not submerge the PCB in FeCl3; I use a sponge or cotton ball to wipe the board with FeCL3 until the unwanted copper is gone.