How to build "do it yourself" printed circuit board (DIY PCB) by using thermal transfer method

This article is intended to explain how to build a double sided printed circuit board (PCB) prototypes with one side copper PCB, by using the thermal transfer method. This article covers all steps excluding PCB design and PCB printing from CadSoft EAGLE.

PCB design printing 

Before we start with thermal transfer, the PCB must be printed with the laser printer and the glossy photo paper. Without glossy photo paper the thermal transfer will lose in quality, but feel free to try with different types of printing papers. How to print PCB to the paper over the CadSoft EAGLE is not covered by this tutorial. Anyway, printing could be done in many different ways. For example, zilsel-invent print PCB design to the PDF file format, because it is easier to find a printing service in case if you don’t have glossy photo paper and/or printer device at home. In that case, you can send your pdf files with PCB design to the printing service and they will print PCB on glossy paper for you. Also, there is a possibility to print PCB design to glossy photo paper directly from CadSoft EAGLE by choosing printing device from combo box labeled as “Printer”. As you can see, print to pdf file option is also available throughout the combo box. This is really your choice, but pay attention about which PCB side should be mirrored before it is printed (as you can see there is a mirror option under Print dialog), figure #1.

Figure #1: Glossy photo paper (left). Eagle CAD printing options (right).
PCB copper cleanup

When printing is completed the next step is thermal transfer. Before we start with thermal transfer, it is necessary to clean PCB with some detergent, because copper oxidized when it is in contact with air. It is important for copper side to be clean as much as it is possible in order to achieve a certain level of quality. Without clean PCB (copper side) you will lose quality, so clean your PCB before you start with thermal transfer. 

Thermal transfer

To start with a PCB thermal transfer we do need: PCB with clean copper, printed PCB design on glossy photo paper, iron device and stopwatch device, figure #2. Thermal transfer starts after the printed PCB design is placed to the copper side of the PCB, be aware that paper is aligned correctly with PCB borders. After that, place iron device on the paper and do slow motions for about 15 minutes or more (depends on the size of the PCB design). The more time you spend by doing slow motions over the glossy photo paper, the better results could be achieved.

Figure #2: Printed PCB design, PCB, stopwatch and iron device.

When thermal transfer is completed do not touch PCB with your naked fingers, wait for some time before you do that, because copper as well as PCB is very hot, figure #3. Do not forget that copper has excellent thermal transfer characteristics and that is the reason why it is widely used as passive cooling systems (heat-sink).

Figure #3: Hot copper, do not touch with naked fingers!

Remove glossy photo paper

Now, place PCBs into the water in order to remove glossy paper from the PCB board. Depending on the paper quality, this step could take some time and it is important to be patient at this stage. If you try to remove glossy paper quickly, there is a possibility to remove laser toner from the copper side of the PCB as well, at the same time, all your work was for nothing. That also means that you will have to start your “do it yourself PCB” project all over again, from scratch. So, be aware that paper must be removed slowly, in order to preserve laser toner on the copper side of the PCB board.

As it is presented in figure #4, if the paper is removed correctly, it will look just like it is presented. The laser toner is transferred to the copper side of the PCB completely, and that is a good job. So stay patient, nothing else. All other parts should be removed in the same way from the PCB. This stage in some cases can take for a couple of hours, but at the end, you will be more than satisfied with your work. When glossy paper is completely removed (figure #5-right), the PCB is ready for copper etching.

Figure #4: Remove glossy paper from the copper side of the PCB.
Figure #5: Glossy photo paper removed from the PCB.
Copper etching

In order to remove unnecessary copper from the PCB it is necessary to complete copper etching stage successfully. For this stage it is necessary to make etching acid consisted of: muriatic acid and hydrogen peroxide or feel free to use ferric chloride, your choice, figure #6. The ratio between muriatic acid and hydrogen peroxide is not so important to start with copper etching. What do you need to know is that the laser toner does not react on the muriatic acid + hydrogen peroxide mixture. Which means that copper under laser toner will not be etched with the acid mixture during the copper etching process. The ratio between muriatic acid and hydrogen peroxide can be changed during the etching process. You will see for sure, is it necessary to add more muriatic acid or to add more hydrogen peroxide, or both. Figure #7 presents a copper etching process. Figure #8 presents completed PCBs, both sides: top and bottom, after the etching process has been completed. The next step is drilling the PCB holes, but before that, clean/wash the PCB with detergent in order to remove laser toner (figure #8.) from the printed copper wires. As a result, the PCB color should look like it is presented on figure #9 (left) - reddish brown color.

Figure #6: Muriatic acid (left) and hydrogen peroxide (right).

Figure #7: PCB copper etching process.
Laser toner does not react on muriatic acid + hydrogen peroxide mixture.

Figure #8: PCB - both sides, after completed etching process. Laser toner still exists on the PCB (black lines/wires).


Video clip: PCB prototype Adjustable Variable Frequency Driver. The copper etching process, in this clip you can see how copper is etched with acid mixture (muriatic acid and hydrogen peroxide). Careful during copper etching stage, since you are working with acid. NOTE: Wash your hands and face after copper etching.

PCB Drilling

At this stage, feel free to drill PCB holes as you wish. The only thing you should think about is the PCB hole diameters and drill diameters. Drill diameter should fit hole diameter, that is the only rule. Figure #9 presents drilled holes for one side of the PCB. When both sides are drilled, connect both PCB sides with superglue (and that is enough). By doing so, your double side PCB is ready for electro-mechanical components assembling.

Figure #9: Drilled PCB, Laser toner is washed from the PCB, reddish-brown color (left). PCB ready for assembling (right)
The thermal transfer method is commonly used by zilsel-invent for the PCB prototyping as a cheap technique with very good quality (in some cases extra quality). DC motor controller/driver with code-name: SERPENT I (Figure #10) is developed with thermal transfer technique, including SERPENT II DC motor/Stepper motor controller/driver (Figure #11) with code-name: Pit VIPER Rattle. Professional PCB manufacturing is done in cooperation with third party manufacturing services specialized for the PCB production (by using Gerber and Excellon files generated by CAM processor throughout the CadSoft EAGLE software) and electro-mechanical component assembling.

Figure #10: H-Bridge DC motor controller/driver, code-name: SERPENT I

Figure #11: DC motor/Stepper motor controller/driver, code-name: SERPENT II - Pit VIPER Rattle. Bottom side (left), Top side(right).

Related videos:
PCB prototype Adjustable Variable Frequency Driver. Remove photo paper from the copper side of the PCB... Part #1
PCB prototype Adjustable Variable Frequency Driver. Removing photo paper from the copper side of the PCB... Part #2
PCB prototype Adjustable Variable Frequency Driver. Removing photo paper from the copper side of the PCB... Part #3
PCB prototype Adjustable Variable Frequency Driver. Removing photo paper from the copper side of the PCB... Part #4
PCB prototype Adjustable Variable Frequency Driver. Copper etching stage... Part #1
PCB prototype Adjustable Variable Frequency Driver. Copper etching stage... Part #2
PCB prototype Adjustable Variable Frequency Driver. PCB Drilling stage... Part #1
PCB prototype Adjustable Variable Frequency Driver. PCB Drilling stage... Part #2
PCB prototype Adjustable Variable Frequency Driver. PCB Drilling stage... Part #3  

zilsel-invent assumes no responsibility or liability for any errors or inaccuracies that may appear in the present document.
Specification and information contained in the present schematics are subject to change at any time without notice.

Comments

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    ReplyDelete
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    1. @PCBWay (http://www.pcbway.com/xx) Thank you for comment. If you have more information just send to us over the blog page. Thanks! Best Regards.

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  2. Also , we provide other cheap and high quality pcbs for your designing and researching .

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  3. Nice post. I like it, i know that heat transfer printing method is one of the simplest method among amateur process. This method is commonly used by electronic enthusiasts. It takes advantage of the anti-corrosion characteristics from the laser printer toner.

    ReplyDelete
    Replies
    1. First of all, thank you for the comment! Yes, heat transfer printing method is easy and cheap technology to build PCB prototypes with very good quality. This technology is commonly used by Zilsel-Invent in order to build PCB prototypes before manufacturing process by third party PCB services.

      Delete
  4. Printed Circuit Board assembling is new for me which information I got from here, thanks for sharing. prototype pcb assembly

    ReplyDelete
    Replies
    1. Thank you for the comment stephen! Best Regards!

      Delete

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