Electronic – Home made PCB etching problem

pcbpcb-fabrication

I just tried to make my first PCB at home, but it did not work. I don't know what went wrong, so I'd appreciate some advice.

I was using the photoresist method, so I printed my circuit on a transparency using a laser printer and made this template:

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Next I exposed my presensitized PCB and developed it to get the following photoresist mask:

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The mask looks quite functional at this point. All traces are well defined.

Next, I submerged the PCB in Ferric Chloride to remove the unmasked copper. This is where things went wrong. The copper between the traces on the top side of the PCB just wouldn't come off. I ended up over-etching the board, as can be seen from the fact that the photoresist mask started to break down, yet the unmasked copper between the traces at the top still wouldn't come off! Here are the pictures:

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And after removing the photoresist mask:

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It seems that something was different with the top of the board, but what? Was it a defective board? Did I do something wrong? I'd really appreciate some advice before I try again.

Best Answer

I've had the same problem in the past, here's what I did to fix it:

  1. You have some fuzzy lines, probably because the mask isn't close the board in some places. Wedge your board and mask between two glass plates and clip them together with office clips.
  2. Your board looks a bit under exposed, in my case I had to double the exposure time.
  3. The longer the acid takes the more distortion your tracks incur. Try using the Hydrochloric & Peroxide mix. A 50/50 mix gave me an etching time of a minute.