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I'm trying out making PCBs for the first and I'm using the UV photo resist method. It seems to me I have the exposure and developing working very well but I'm having some issues with etching. I'm using standard ferric chloride for now.

Here is my developed board, it was exposed for 2 minutes (Ignore the spelling mistake!) Developed PCB

Then this is the result of the board that was taken out as soon as the last bit of copper was etched away.

After etching the PCB

So as you can see traces on the right have dissapeared and others have thinned a lot compared to the width of the tracks after developing.

I've been doing the etching outside in a little plastic container and takes around 8 minutes. I have not heated the etchant.

Does anyone have any thoughts on what is going wrong?

Thanks

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    \$\begingroup\$ take a look here: electronics.stackexchange.com/a/85637/11861 it is over etched because of a misbalance of amount of copper etch required across the board. Add thieving to balance it out and decrease etchant use. \$\endgroup\$ – placeholder Oct 26 '13 at 21:00
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    \$\begingroup\$ Thanks for that link! Good read. However, I've seen hundreds of diy PCBs all over the internet that don't have copper planes in the ampty spaces or thieving. Also the board I did is really small. I find it hard to believe that this small amount of empty space is enough to cause over etching?...as I said because of what I've seen others manage to achieve. \$\endgroup\$ – binarysmacker Oct 26 '13 at 21:09
  • \$\begingroup\$ Are you using presensitized boards? \$\endgroup\$ – Ignacio Vazquez-Abrams Oct 27 '13 at 11:50
  • \$\begingroup\$ Yep, otherwise I wouldn't even get the design on the board after developing?! \$\endgroup\$ – binarysmacker Oct 27 '13 at 12:37
  • \$\begingroup\$ I personally think the board was left too much in the ferric chloride. If you didn't, you should increaese the traces width. The minimum traces width I use is 1mm for 2,54mm distance between the pins. \$\endgroup\$ – machineaddict Apr 19 '15 at 12:00
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I my experience the etching is not the critical step. It looks like you have problems with light exposure of your traces. In my setup I addressed this problems by using two masks one above the other to make sure they are impermeable to light.

An other possible error cause is the developer. Make sure the powder is evenly distributed before putting in the exposed boards. But as I just mentioned - with a good contrast in exposure this is not very critical.

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