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mistermikev

Etching a preamp pcb for fun and

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Recently did an etch of some pcbs for a few things I'm going to build... figured it might be nice to take pics along the way and make a short tutorial.  Not groundbreaking, there are other tutorials, but this one is how I do it.

 

I like to do several boards at once... because it's better to spread the work/cleanup over several boards.  I usually do a little layout in photoshop with a gray area showing me the size of my actual copper clad board.  This way I can rotate and move them to get a decent compact layout and maximize my copper board.

I print it out on some plain paper...

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then I take masking tape and tape press n peal blue to the paper, and run it thru my laser printer.

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next I cut close to the edge - usually leaving about an 1/8"... and I leave little tabs at the edges to make it easier to handle w/o touching the printed area.

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I then take my copper board and wet sand it from 800- 1500.  then wash it off with whater, then hit it with 2ooo grit dry, then whipe it down with acetone.  at this point... it's important to NOT touch the copper side as the oils in your hand will actually prevent the etch in the areas you touch (you'll see some of that later!).

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then to the iron... early on I struggled a LOT to get a good transfer.  I've used everything from magazine paper to the leftover sheets from sticky postage labels... to anything in between.  pnp blue works consistently best for me.  I set my iron to a low temp (between 3 and 4 on my iron).  initially I use a blank piece of paper between the iron and the pnpblue just until the transfer paper gets hot enough to stick to the copper.  then I go direct on the pnp blue with the iron and I watch the dark in pattern emerge...

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(did you see my toe?)  anywho, once you get a nice clear pattern on the whole sheet yer done:

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I let it cool for about an hour and gently peal it back...

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usually there are some spots where I either got it too hot and got 'crackle' or otherwise lifted some ink when I removed the transfer... so I go back and edit my board with a etch pen:

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put it in a nice thick ziplock bag, then inside two grocerty store bags... then in a plastic tray.  Really don't want the etchant getting on anything else.  There are different etchants you can use... but I like ferric chloride.  I keep some baking soda handy so that once the etch is complete I can neutralize the acid with backing soda. 

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pour in the etchant... I check back about 1x an hour to move it around to ensure the whole board gets etched.  about 3hrs total to etch with the stuff I use.  and voilla... all the hard work is done!  Now I just have to drill holes, use thinner to clean off the ink, sand it up to a nice shine, and wire it up.  You can see a few spots where it didn't get etched - drats (bottom right)!  So I just take an exacto and cut a channel into the fiberglass. 

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hope someone finds this useful... and hey - you did get to see a few shots of my big toe so... totally worth it.

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Takes me back to the bad old days of doing my own PCBs. I could never get 100% perfect results with Press 'n Peel Blue. I usually ended up going over the transferred design with a Dalo pen before etching due to some part of the transfer not taking properly. Ammonium Persulphate crystals dissolved in warm water was what I used to use, gently rocking the tank as it went. Agitating the solution massively sped up etching time.

With my designs gradually becoming more complex and the price of one-off prototype PCBs from China falling so much I eventually abandoned home etching altogether. Have you tried sending your PCB designs off to some of the fab houses yourself?

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4 hours ago, curtisa said:

Takes me back to the bad old days of doing my own PCBs. I could never get 100% perfect results with Press 'n Peel Blue. I usually ended up going over the transferred design with a Dalo pen before etching due to some part of the transfer not taking properly. Ammonium Persulphate crystals dissolved in warm water was what I used to use, gently rocking the tank as it went. Agitating the solution massively sped up etching time.

With my designs gradually becoming more complex and the price of one-off prototype PCBs from China falling so much I eventually abandoned home etching altogether. Have you tried sending your PCB designs off to some of the fab houses yourself?

right on.  I've used ammonium persulphate b4... had a few issues with it... A) you have to get yer mixture right B ) seemed to create more waste in the sense that I generally had more liquid to dispose of at the end of everything... but admittedly I only used it a few times. 

afa pnp blu - yeah, at best i get the boards 90% perfect.

afa chinese pcb - certainly makes for nice stuff.  the 'old school' way of doing it is for me a better option.  I don't have to wait, and since almost everything I do is a one off... hard to justify the work for pro pcb mfg.  also, I freq etch pedal enclosures and other things... so it's a valuable skill to hone.  I plan to etch some pickup covers at some point.  also, this etchant works great for relic'ing parts.  win win all around for me. 

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