Tishitu explains Toner transfer Although I'd repeatedly read that glossy or photo paper was best to print the circuit for transfer onto the copper board, I didn't have any of these fancy papers on hand, and didn't want to make a trip to the store if I didn't have to. So I decided to try it with regular paper. but failed when scrub it out .. So it is better to with 150 GSM Photo paper I readied my otherwise unused clothes iron: Naturally I didn't turn it on until resting it on its back, and I wish more tutorials were explicit about whether or not you should have water in there or not. The answer is no. I cut my copper board to size and used a sponge to clean it with isopropyl alchohol (a 70% solution from the drug store). I grabbed a scrap piece of wood to do the ironing on: and it didn't work. After several attempts to iron the circuit pattern onto the pattern from regular paper, it just wouldn't stick. Whenever I'd move the iron around, the paper would slip and the result would be a smugged circuit pattern on the copper board. I really didn't want to make a run to the store for special paper, so I consulted Google instead. I found this great article explaining how you can use glossy magazine paper, the principle being that the laser toner dosen't stick very well to it, thus making it easy to transfer onto the copper — the same principle behind using special glossy or photo paper I'd previously read about. I set to work with the cheaper and more easily available magazine paper I already had around, trimming it to fit my printer before making a few prints of the circuit: Back to the ironing board: and it stuck! The paper stuck pretty much immediately after applying heat with the iron, and I was able to move the iron around and evenly heat the entire circuit. Soon I could see the traces through the paper: I let the board cool a bit, then put it in a sink of warm water. The magazine paper came off very easily, and the traces didn't budge or scratch away. I'd read that you need to let the paper soak for 5-10 minutes before it'll come off the board, but I found with the magazine paper it only needed to soak for 2 or 3. I'd also read that you need to press really hard while ironing, and iron for 5 or more minutes. I'm not sure so much force and time are required with the magazine paper technique, as I ended up with a few smudged traces: Specifically, there were a few pads that had shorted together on the transfer: Using an X-Acto knife, I was easily able to scrape spaces between the pads before etching. Etching Now the fun part: etching with chemicals! I decided to use ferric chloride since I didn't want to mix my own etchant with ammonium persulphate and water, or the like. I bought some handy etching trays with corner spouts at the local electronics store, and with some chemical resistant gloves, got set up in the utility sink: Rubber gloves on from this point: I filled one tray with water for rinsing, and I poured about a centimeter (0.4″) of etchant into the other one. I put the circuit board, traces up (more about this later), in the etchant, and let it soak for about 15 minutes. Not much seemed to be happening, so I decided to try the scrubbing technique It worked like a charm, the exposed copper started to come off the board, while the circuit traces held up well, even against fairly rigorous scrubbing. Caution needed to be taken at this step to avoid splashing etchant around, though! Here's the etched board with the toner still in tact. I think it looks silver/white from remaining fibres of the magazine paper: Next I used isopropyl alchohol or petrol and a sponge (seperate from the one I used to scrub with etchant) to clean off the toner. Some of the pads had smugged edges, faithful to the smudged transfer image, but the board had no short or open circuits: Drilling and assembly I trimmed to board to length, and drilled the holes. Since I already have a Dremel tool, I bought the Dremel drill press attachment and a package of small bits. I also bought the Dremel keyless chuck to accommodate the smaller bits. Despite not being carbide bits, as recommended by many tutorials for drilling PCBs, they worked fine, and didn't break or noticeably dull. Lastly, I populated and soldered the board: Not the most photogenic, but totally functional I wanted to tin the board, but the local shop where I got my supplies didn't have any tinning materials

• published: 28 Jan 2013
• views: 83188