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I was working on making my own PCB but faced a problem during etching. I used an iron to transfer the circuit to the copper board, some of the sketch wasn't fine so I used a permanent marker to make it clear. After putting in the ferric chloride and copper removed I found that the copper was perfectly removed and the traces were fine. But as I used a thinner to remove the black markings, even though they were covered, many traces had holes and gaps. This was unexpected as the markings after removal from the ferric chloride solution were fine but after using a thinner, the copper inside was missing. I dont know where is the problem. Is there any problem with the use of permanent marker or with thinner??? Kindly help me as this is the third time I am facing these results. The image is shown below: enter image description here

I am using solder now to fill the gaps.

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  • \$\begingroup\$ Can you post a picture of your mask? If you have large areas of copper that need to be removed then you have to keep the board in the solution longer which can lead to tracks being worn away. Leave as much copper on the board as possible using ground plains. \$\endgroup\$
    – scotty3785
    Jul 11, 2023 at 8:12
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    \$\begingroup\$ Also you need to give the copper a very good clean before etching. Use an abrasive "scotchbrite" pad to remove any oxidation and then a solvent like isopropyl alcohol to remove any oils/dirt. \$\endgroup\$
    – scotty3785
    Jul 11, 2023 at 8:13
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    \$\begingroup\$ @scotty3785 Ive added the image of the PCB. \$\endgroup\$
    – kam1212
    Jul 11, 2023 at 8:17
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    \$\begingroup\$ Decent sized ground plain and not much excess copper removed. I'd try again but be extra careful to have a very clean board. Also if you are using a laser printer to print your mask that you iron on, then increase the "darkness" setting on the printer to put more toner on the transfer. \$\endgroup\$
    – scotty3785
    Jul 11, 2023 at 8:51
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    \$\begingroup\$ Looks to me as though you need more toner from the printer. You may need to find if it has an "extra dark" or similar setting. Are you printing onto normal paper and then ironing off that onto the PCB, or are you using a high-temperature transfer film instead of paper? \$\endgroup\$
    – brhans
    Jul 11, 2023 at 12:20

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To improve toner adhesion, set the printer to the slowest feed speed possible. That's usually done by telling the printer that there's heavy glossy paper loaded - even if that's not what you're printing on. You also need a genuine cartridge for good results. Remanufactured ones are usually just a bit worse than brand new ones. If you have remanufactured cartridge, use it for everyday printing. Replace it with a genuine cartridge that you keep only for PCB work.

That slight difference can be all the difference between a usable result and a board that looks like a sieve.

Is there any problem with the use of permanent marker or with thinner???

Not at all. You've done that right although normally the marker is unnecesary.

For ultimate results you may want to use a color laser printer, and ensure that the printing is done using all toners (C, M, Y and K) for extra heavy coverage. I'm not sure how other people do that, but I usually print from KiCad to PDF, convert that to Postscript (PS), then edit the Postscript file so that all of the toners are used. The recently-passed Don Lancaster's Guru Lair site has a lot of Postscript know-how if you'd want to learn that :)

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The problem with a marker pen is that the coating of ink is very thin, if you use something thicker (paint, nail varnish) you may get better results.

Even is there is some porosity in the copper, tinning the tracks may give good results.

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