Hello everyone out there in the world of home brewed PCB making.
My name is Mario Hanczarek and during my years of existence on this planet I messed up with PCB making as a professional and a hobbyist.
But enough about me--lets go to what is a common point to all of us: PCB’s.
During my years of experience I start making PCB’s by hand and made progress along with new technology. One thing that I’ve learned is that accuracy and price are the main focuses for production, both for industrial purposes and amateur purposes alike. Availability of prime materials and the process used for transferring the artwork influence these two factors.
Since I reached my low point in life I kept my high enthusiasm for my hobby, but I lost the capability to make the PCB’s by hand due to weakening eyesight and lost patience. With that, I started searching online for a more efficient way to continue my work. I came up with a “new” way to make them by compiling some of the techniques from different sources on the web and adding some of my ideas and improvements.
In my view this is as cheap as it gets and you have a device that can be used with any materials posted on other web sites. The cost is about $20.00 for all the parts involved in the construction of this device, the transfer material is extra but I still think it is a better price than other material offered by Digi-Key and similar.
Overall the secret of a good result is based more on the technique and less on the prime material used for transfer. A good heat transfer method, a good flat surface on PCB clad (that is a challenge), will give you your expected results. Later you will see in this article some idea of how to compensate for PCB imperfection.
The basic method I adopted is by using old heat transfer process, some new material for artwork support, and some additional reliability techniques and home made utensils.
- Heat transfer material (I will provide a new material details information later in the article) or you can use one that is friendlier to you. I chose the one mentioned above because is cheaper, at least for me. I might have some extra if you are interested.
- Aluminum plates, two ½” 11”x 8” (or any size you wish, or fit your needs) this one will cover most needs. I want to stress that with this method you can make a much bigger PCB since the plates allow you to apply even pressure all over the surface and aluminum will also distribute the heat evenly over a bigger surface.
- One cheap thermometer up to 400 –450 degree F ($1.50 was what I paid)
- Two ¼” bolts with wing nuts strong enough to keep the plates in place. They’re $2.00 at the hardware store (you can use four). You could also use clamps (more expensive), placed on the sides of the plates, any other device will be fine to use as long as is convenient and efficient for you.
- A source of heat that will deliver enough to make the plates reach 275-300 degrees F in about 10-15 minutes. Can be electrical or you can use your gas stove for that purpose. You might try to put it in the oven and set the temperature to 300 degree on the dial with the stove timer set for 15 minutes and you have an automated control On-Off device.
- For electrical heater users: one temperature controlled circuit activating a relay connected in series with the Heating device for auto disconnect of the heat source at 300 degree, and you can come up with this one, I’m sure of that.
- One important thing I almost forgot about it, laser printer or copier for getting the artwork on transfer material.
- Additional material that you can use is touchup pen, Film Green TRF for masking from Digi-Key, one piece of hard rubber heat resistant mat of about ¼” to ½” 11” x 8” or based on your size plates (I will explain later what to do with it).
This is the list of materials choices, and now let’s go make them!
First, as I said before I found a new material that works much better or at least the same as all other ones used on the web articles but it comes cheaper than these.
That is K&E (Keuffel & Esser Co.) 58-1360 Dulseal matte surface transparent overlay.
The material is a Film on paper support that is used for art transfer in various environments.
If you are familiar with Dry Transfer technique from Letraset, (see home page) you will understand on how this film works.
As a variation of my technique you might explore Letraset web site, they make sheets by order for all kinds of designs.
Compared with Letraset this film is an industrial size blank roll of Letraset like material, 20 yds. X 12 in. with the same functions as Letraset, with glue on the backside and non-stick paper support. The transfer characteristics amazed me, high temperature tolerance without deformation, very good transfer rate even on dirty copper, as you will see on some pictures. No need to soak in water or any other solution or liquid, it separates by design after the heating process. I recommend that you don’t use the original backing paper because it’s not heat resistant and is making a mess on your aluminum plates.
This is the way I use it:
- First I map the PCB design on a plain sheet of paper using a laser printer
- Second I cut a piece of the transfer film about 1/4” over the PCB edge for safety.
- Third I remove the film from the original support paper and place it over the preliminary art design alignment printout, remember it is sticky on the backside after the support paper removal.
- Place the paper with the film attached to it in your printer again and print the art work again, as a suggestion you can do it more than once, make sure that you have a reference point for alignment so the printout will not shift.
- With the artwork printed, place the film with the paper on your PCB blank board. Make sure that you clean up the side that is supposed to be processed
- What I did is I placed the copper clad with the artwork between two aluminum plates described above, and applied pressure with the help of the two bolts I also mentioned above. (I will detail the plates and bolts later). I also used a rubber mat placed between the aluminum plates over the artwork film.
- Apply heat up to 300 degrees F for about 10-15 minutes then let it cool down. Remove the film, which will most likely come off by itself. You can also try with higher temperature.
- From here just check the artwork integrity and make any corrections if necessary, you can apply the TRF Green Film if you wish.
- Etch and use it as planned.
Now the detail on the aluminum plates:
I bought them on eBay for$ 9.95 plus shipping, make sure they have a very flat surface. I placed two holes to fit 1/4” bolt with a wing nut on the 8” side at about ½” from the edge. Apply enough pressure using the wing nuts so the copper clad will not move between plates and the plates will not slide around.
Also make sure that you tighten the wing nuts evenly so no side will apply more pressure that the other, apply parallel pressure. For that reason I would use a four-bolt device: it is much easier to apply parallel pressure. Depending on your thermometer should place the probe or whatever means of temperature-reading your device has in the middle of the Bottom plate, the one that is in direct contact with the copper clad. For that you can drill a hole on the side of the aluminum plate and insert the probe permanently, or you can “fit” the probe in the hole for easy insertion and removal. Make sure you have a good heat transfer, as recommended try heat transfer grease used on semiconductor assembly.
Just to remind you on how to achieve this:
- At first turn the wing nuts until they touch the surface of the top plate, then pursue with short turns from each bolt opposite from the start one, you can select your start bolt, or you can number them on the upper plate and start from there (for example you will start with 1 then go to 3 after that go to 2 and finish with 4) and so on.
- Again, very short turns, you do not need to tight the wing nuts so that plates will bent, just hand tight.
About the rubber mat:
- The reason for using this rubber mat is that the copper on the blank PCB is not perfectly flat, or evenly laid on the fiber support. If you look more carefully you will see that the surface has dips between the fiber laces. That is one reason people fail at successfully transferring the artwork to the copper. Another reason for using rubber mat is that it will decrease to some extent the effect of unevenly applied pressure by the wing nuts.
- To make a successful transfer I found out that placing this rubber mat between the two aluminum plates and over the film artwork only. Rubber being a relatively flexible material will make the film to mold better in the shape of the copper clad and fills in the dips on the copper. I’m not talking about deep scratches or imperfections on the PCB surface, I’m talking about any quality PCB: this is a manufacturing process result that can’t be avoided. When you lace fiber and apply pressure to make it stick together, the space between the fibers will create dips on the overall surface. This dips as well as the toner on the transfer material are micron size layers and any imperfection on one of them will affect the results, so by taking this measures we minimize the risk of failed transfer and waste of transfer material, which is quite expensive. As an alternative you can try with some other materials, like using a few more sheets of paper, kind of fluffy paper, like news paper or any other paper that is not fine and hard pressed. You get the idea.
Here are some pictures with the finesse of the edge of the artwork and the result of applying the artwork on an untreated copper surface.
This will give you the idea of how it will work if you clean up the surface.
You might ask why I don’t have some pictures with some recent production, I don’t have a camera, and these are preliminary tests while trying to develop the technique with my friend’s camera.
Anyway you can see by judging the zoom ratio what capability this film and technique has. The size of the board is 4” x 3.5”
This is the original Printout of the PCB before the transfer; the faded spot is from the flashlight
Updates to this text will be added as they become available.
Since this process involves extreme heat with possibility of severe burns, electrical circuits with possible exposure to electric shock, and mechanical tasks with the possibility of getting hurt, I decline any responsibility for your use of all or any of the materials, instructions and techniques in this article. You are advised that you are solely responsible for everything you pursue based on this article and recommendations, and you are assuming all of the risks involved in this process. Your involvement should be based on your own level of ability and skill to perform and follow any or all of the tasks described in this article.
The publishing party is also released of any responsibility of possible mishaps and risks involved by posting this article.
For additional information, explanations, and advice email me at: firstname.lastname@example.org