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Converting an Inkjet Printer to Print PCBs

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Step 12: Etching Revisited (October 24th edit)

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As many people in the comments have noted my boards had pinholes all over them and I was just as unsatisfied with that as anyone. As such I started to do some more research and try to find ways to correct this issue. Among the many suggestions I received I put two at the top of my list for researching. Firstly, I looked into a better etching setup as I've been considering this for some time and this seemed like the right project for the upgrade to a heated, aerated tanks. Secondly, a few people mentioned the ink I am using and that the proper setting temperature may be higher than I am actually achieving with my heat gun. Since those two things seemed easy enough to remedy I focused on them first to try and solve my pinhole problem.

To start I began looking at a few different etching tank designs and thinking about what I wanted out of my design. I came to the conclusion that I wanted something nice, but not overly expensive and building my own setup was the best option. As such I took a plastic cereal container that I found lying around the house and decided to use it as my tank base. This container is nice because it's large enough to fit bigger boards and has a snap on airtight lid, but not too large that it takes a whole gallon of etching solution to fill. From there I visited the local pet shop and purchased an air pump, some plastic tubing, a bubbling rock, and a small aquarium heater. With all the materials together I hot glued the bubbling rock into the bottom of the container and the plastic tubing up the wall of it. Finally I inserted the heater and was ready for the etching solution.

My second improvement was to heat the boards hotter and set the ink better in hopes it would adhere to the boards better. This was an easy fix as I found a coupon for a dual temperature heat gun at Harbor Freight Tools. This heat gun cost me $10 and has two settings of 570 degrees (F) and 1110 degrees (F) or so. This is more than enough heat as through some research I found the ideal heat for setting my ink is around 425 degrees (F). This is also great because at about 425 degrees (F) the copper clad board will start to turn a bit purple due to oxidation and the heat.

With my two problems solved I printed 2 new boards and tried out the new heat gun. This is where I must issue a warning. As much as you may think the higher 1110 degree (F) setting will heat your board faster and set the ink more easily do not try it. If you heat the board too fast it will warp. If you heat it too much, as I did with my first board, the adhesive holding the copper to the board will melt and the copper will bubble up. All that bubble took was a second on 1110 degrees (F) and the copper popped off.

My second board however I was patient with and used the 570 degree (F) setting and slowly heated the entire board until it started to turn purple. I tried to take an image of this for reference, but it's not visible on camera so you just have to keep your eye on your boards as you do this. Once the ink was set at this higher temperature I fill up my etching tank with some Ferric Chloride and let it heat up and bubble for a bit. When the solution was nice and warm I dipped my board into it and checked it every 30 to 40 seconds for progress. After about 3 minutes my board was done etching. (This type of tank and etching method is so much faster than rocking a container around by hand so I'd recommend the upgrade to everyone.)

After my board was complete I rinsed it off and took some pictures for this page. As you can see these two tweaks in my method produced results that are significantly better as this board has crisper traces and none of the pinholes that plagued the first few boards that I etched.
 
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