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PCB-Etched Photo

April 7, 2011

Using the Etching technique, described in my previous post, it is possible to print photos on copper (see the image below)… to be more precise, on a PCB. This nice effect will be achieved by using toner transfer; this technique is the same used by many amateur to build custom circuit boards, but we will use it with some more “artistic” intent.

PCB-etched photo

While this process can be done on any copper surface, the best effect is obtained when the copper layer is very thin and, by etching it, we can completely remove it and unveil the surface below, obtaining a two-color image. PCB copper-plated boards come in a variety of different sizes  (remember that you will need a container large enough to submerge it completely in the etching bath) and are quite cheap (a couple euros for the one i used). I buyed both the PCBs and Etching liquid online on an electronic supply website. Most electronic supply shops have this kind of things available.

The photo should have a good contrast (you can increase it in any image manipulation tool) and, since the result will be monochromatic, starting from a black&white photo will help. I started from two hig-contrast black&white photos of two friends of mine.

The first step is to prepare the photo: it is not possible to etch a grey-scaleimage, but we need to obtain an image composed only by element either black or white. In Photoshop and other image-editing tools, there is a filter called halftoning. Halftoning is the name of an old technique used by illustrators to overcome the limitation of old-times ink printing (where, like in this case, it was possible only to have two colors: ink or paper). The principle is using a pattern made by pure black small elements on a pure white background. The size and density of the elements change according to the luminance of the corresponding part of the original image. If the pattern is small enough, at a distance the    There are different kind of halftoning: dots (often used in old newspapers), lines, and even filters which let you use custom shapes as the basic pattern elements. I chose to use continuous diagonal lines, which gives the photo an antique, woodprint-style, look.

Halftoning filters are almost automatic, a few paprameters (size and density of pattern elements, detail level…) have to be specified, and it is a matter of trial and error to find the perfect settings, taking in account the carachteristics of the source image and the size of the PCB board. You may want to keep the pattern visible, to add some personality to the image. This process works better on a high resolution images so, before starting, crank up the resolution (in my case, i used started froma 2Mpixel image and upscaled to 15Mpixel; yes, it gets blurry, but it will be sharp in the final halftone pattern).

The next step is printing the image using a laser printer, but using a glossy paper for inkjet printers; this is important, since we need the toner used in the laser printers, but we do not want it to penetrate inside the paper, hence, we use glossy inkjet paper. Since this will be a mask (black will mask out the etching), invert the image before printing. The printed image should then be transfered on the PCB, this is done using a cloth iron. Place the printed image face down on the PCB (copper side) and, when the iron is hot, apply it to the image. This process will heat the toner and make it stick to the copper on the PCB: 2-3 minutes will be enough. Let the PCB cool down then, with water, soak the paper and slowly peel away the paper. If everything went ok, you will see the toner on the copper surface.

The etching process is quite simple… put the PCB in a bath of etching liquid (face up) and slowly move the container to help the process. After few minutes (5 to 10, depending on the liquid temperature and liquid concentration, read the instruction on the etching agent box) the etching will be over and the PCB will have the image impressed. If done correctly, the result will be a very sharp detail in the pattern and the image perfectly visible from distance.

The result can be framed / displayed as it is or used as a screen in front of a lamp, to exploit the semi-transparency of the PCB. In this second case, do not invert the image before printing, as the etched part will be brighter than the copper.

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One Comment
  1. lillaccia permalink

    mmmm I think I know the subject of the first images…. great job though, and not only this… all of your creation are amazing!

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