Right until now, have you been searching for the buried secrets behind PCB etching? You are indeed in the right place; we would take you through the length and breadth of the etching.
As you might have known, the PCB etching revolves around the subtracting method used in the production of circuit boards.
In this guide, we will effectively take you through the pen, acid, kit, solution, process, machine, etc. involved in PCB etching. After you have successfully gone through this guide, wne would point you to the perfect place where you can get PCB materials. Now, let’s get down to the real deal.
1.1 What is PCB etching?
The PCB etching merely is defined as the selective removal of material from the surface of the Printed Circuit Board with the aid of the chemical action of an etching agent. Etching usually entails the removal of copper areas that are not needed on the completed Printed Circuit Board. The process of etching can be carried out by placing a cover that can shield the parts of the laminate and thereby excluding the copper layer. The PCB Etching is an easy and economical procedure that can be carried out at home or in the lab.
1.2 PCB etching Pen
The PCB Etching Pen is more like a water-proof pen enclosing permanent ink. The ink contained in the PBC etching pen has properties which can resist etching. The pen has a nylon tip that enables fast manufacturing of the printed circuit boards. An example is its use on Copper printed circuit board; Circuits can be drawn on plain copper laminate and then etched in Ferric Chloride or etchant solutions, this is allowed to dry for few minutes, then immerse the board in etching fluid until you confirm that the copper is dissolved. After the etching process, the ink can be evacuated with the aid of cleaning fluid or Printed Circuit Board Cleaner. After this processes have been successfully carried out, then the circuit board is ready to be drilled and assembled.
1.3 PCB etching acid
The PCB etching chemicals used industrially
Here in this section, wne would go through
1.4 Copper etching PCB
To get rid of undesired copper from copper clad substrates to form electronic circuits, two methods are discussed. They include;
Mechanical etching: in the mechanical etching, a special cutter and a machine tool are used to get rid of a narrow strip of copper from the boundary of each pad and trace. In doing this, the circuit elements are electrically separated from the rest of the foil.
Chemical etching: the chemical etching depends on the activities of a corrosive fluid to chemically disintegrate away undesired copper to clarify the desired circuit. In this process of chemical etching, etching is generally done by full immersion of the board in the chemical; an etching resist used to protect the desired copper from the etchant.
PCB Etching Kit
The PCB etching kit comprises of different tools (combining matching materials with chemicals) that can be utilized in fabricating the printed circuit board from the scratch to the completion. Now that you are familiar with the fundamental’s of PCB design, it is often difficult for starters to choose the suitable etching tools to fabricate their printed circuit board. The only difference that can be made with the tools is selecting the best out of various available ones in the market.
Although After merging the tools and chemicals, it might still not yield a perfect result, and this is because the chemicals might not be in a balanced ratio or the materials may not fit together perfectly. It is hard getting the small drill bits for making the PCB holes, and due to this reason, the PCB etching kit packages the required drill bits. Included in some starter’s PCB etching kit is a small dc driller motor that can be used in making the holes. The material’s quantity ratio must be carefully selected to avoid needless components. As time goes on, the skills to PCB fabrication can be perfected.
PCB Etching Solution
When we refer to the cheapest and readily available solution for PCB etching, then we are referring to ferric chloride. The ferric chloride is available in the form of a liquid, or in concentrated form, which must then be diluted. When this solution is used, immerse your PCB board into the liquid, wait for some little while and check to know how far it has gone.
Though heating the liquid can be of great help, it is not necessarily required. The ferric chloride is cheap, but it cannot be used over again, and also, it is not environmental friendly. Therefore after use, it is essential to dispose of it properly at a waste site.
Another solution is the Ammonium persulphate which is available for copper etching PBC, and it is often used in etching circuit boards. The Ammonium persulphate is a powdery substance that requires the addition of water to make it a solution. To ensure efficient etching of copper, the solution must be maintained in a hot state; ammonium persulphate decomposes on heating.
Due to this reason, it is mandatory to add a new solution everytime copper is to be etched and safe handling of the chemical should be observed. The hazardous effect of Ammonium persulphate is that it can cause skin irritation.
Materials required to etch with the ammonium persulphate successfully includes; Chemistry goggle, Gloves, Mask, Glass containers, Distilled water, Scale, Plastic spoon, Ammonium persulfate, Glass stirring rod.
PCB Etching Process
The process of etching involves the careful transfer of the pattern to the metal with the aid of a material that can resist the dissolving action of an acid. Metals are protected in areas where this resist is applied and are etched in areas where they are not resulting in a raised pattern. In this article, a “press ‘n’ peel” paper (PNP paper) would be used to describe the etching process.
The PNP paper is a versatile resist and a type of blue acetate film. The paper has two sides, one side is shiny, and the other side is matte, the matte side is used to transfer patterns or images onto the metal. The pattern will transfer as a mirror image, so if the direction of the pattern is essential or includes lettering, it may be necessary to copy the pattern to clear acetate first and flip it so that it will be reversed on the PnP paper.
4.1 Materials used as the resist
Different materials can be used to resist, including:
A black permanent marker and Rubber stamps
Press-on letters and Lace stickers, etc.
Also, we have traditional types of resist, and they include:
The materials needed for PCB etching will be highlighted, and it is important to note that the availability of materials to work on can lead to a more yielding positive result. The materials include:
5.Laser printer or carbon-based toner photocopier
6.Brass, copper, or nickel for etching in 18, 20, or 22 gauge
11.Black permanent marker
16.Styrofoam, 1-in. thick
18.Glass dish or disposable plastic container, minimum 6 in. (15.2cm) square
19.Safety glasses and a Dust mask
4.2 Steps involved the PCB etching process
1: Transfer your design to the “press ‘n’ peel” paper
Here, the preferred design is transferred to the matte side of the PNP paper with the aid of a photocopier. The photocopier is adjusted in such a way that the darkest image is given without smudging clear areas. The design or image that has been photocopied will serve as a resist on the metal. The ideal heat required to transfer designs or images with the PNP paper is determined just below the temperature at which the backing film on the PNP paper starts to distort or collapse under pressure, and due to this, it is important to run a foretest of the iron to use since they vary in temperature. It is more advisable to use iron set one or two below maximum when transferring the pattern to the metal.
2: Snithe the metal
Often, a jeweler’s saw or metal shears are used to cut the metal to almost fit with the image or design. Make sure the metal is flat and clean its surface with a sandpaper or scouring pad. Rinse with water, dry, and wipe the surface of the metal with alcohol right before attaching the PNP paper, and ensure to hold the metal by its edges while performing this operation.
3: Apply the PNP
When you cut the metal, do not let it fit perfectly with the pattern but make sure to leave a metal border of about 6.5mm around the pattern. Cut out your pattern or image from the PNP paper and place the metal on a heat resistant surface. Position the PnP paper on the metal, with the matte side facing down and apply heat throughout the surface with an iron. During this process, the copper plate becomes very hot revealing the image through the paper’s film backing.
4: Separate the PnP paper from the metal
Wait for some time till the metal cools, separate the PnP paper from the metal and be observant enough to conclude that the pattern has correctly transferred and if otherwise, return the PnP paper to its position and apply heat again until you are satisfied with the result.
5: Get ready to etch
With the aid of a know more about the defects and probable solutions to PCB problems? contact paper, cover the back of the metal and coat the edges to prevent them from etching. Resist like nail polish, etc. can be used. Obtain a piece of expanded polystyrene foam, also known as styrofoam and join it to the back of the metal with double-sided tape. Ensure the area is well ventilated and you are on the apron, eye protection, and gloves throughout the process.
6: Etch the metal
Put a sufficient quantity of ferric chloride into a plastic container to aid floating of the metal, shake the plastic container gently, cover the container and leave the metal for some hours. A shallow etching can be achieved in minutes, usually 35-45.
7: Remove the PnP resist and clean the metal
Avoid removing the metal from the ferric chloride with your bare hands, but rather, wear nitrile gloves or plastic tongs in performing this process. To neutralize the ferric chloride, immerse the metal plate in a solution of 2 cups of water to a quatre cup of baking soda. Rinse in clean water and remove the tape. The PnP should be removed with a scouring pad and acetone and do the final touching with a brass brush and soapy water.
DIY PCB Etching
The benefit attached to PCB etching include longevity and relative ease of connection. During the etching process, copper is removed from sections of the board excluding areas where wired connections are present. The first step after obtaining your complete material is knowing how to go about designing your PCB. You can design your PCB using Eagle, do the necessary operations on your computer (remove the extra details from the board.
Select the layer option and un-check all the fields that are not required like the place, name, origin. Values. Now export the board file as an image. To do that open the board in eagle and then go to File>Export>Image. Select the monochrome option and save the image) and print the PCB using a laser printer. Other operations such as etching, drilling, and soldering follow, and then you test.
Laser PCB Etching Process
You’ve only got little choice when you are making a custom-built circuit board; you can decide to solder things yourself with a perf board or take the time to settle for PCB. Wne would be discussing the use of a 40W laser to burn off paint, revealing copper which is now removed. In the first approach, the board is coated with distinct layers of black spray paint and enough time is permitted to allow it dry completely.
When the laser process is complete, ferric chloride is then used in etching it. The holes formed by the etching process in copper can now be cut out with the laser. This process is much faster when dealing with chemical etchant compared to the photoresist process.
PCB Etching Machine
A PCB laser etching machine can be used to remove any unneeded material on your PCB through the process of etching. You can do this by merely spraying out the sections to be removed and using your PCB etching machine to remove the unwanted sections.
7.1: PCB laser etching machine
Notice that most laser etcher utilize vector files to print. However, before you start printing, you need to come up with a correct schematic of your components and build traces. The PCB etching machine should then be used to cut out anything you think is not part of the trace. To help the laser cut away everything else other than the trace, it is recommended that we make the background black if your board is white. It would help if you then drew 1.5pt lines which are the smallest lines you can draw on a PCB board for etching purposes. In a case where you are making a double-sided board, ensure that everything is lined up and try to be efficient.
Using laser gives beautiful results, but you may not be ready to etch your board. Ensure that any paint residue left on copper is etched or it will block the solution from etching the board. To remove the paint, you may need to soak a q-tip in isopropyl or ethyl and spread it out to the exposed copper. It helps to polish the copper and prepares it for etching. You may use paint thinner or Xylene to remove any stubborn black paint on the board. It leaves you with a brilliant circuit that is ready to be etched.
Now PCBs have a wide range of application. Therefore, it requires that they are appropriately marked if you want them to remain efficient. Laser marking helps to make your work easier. It does not require the use of chemicals or inks and will allow you to mark your board and make etching easier sequentially.
7.2: Auto PCB Etching Machine
The PCB Etching machine was invented to help in the etching process by dissolving PCB most effectively and efficiently. With this machine, you no longer have to dissolve your PCB manually by moving the solvent vessel. Etching PCB manually required that you use HCL and water. The PCB should then be put on a tray or in a vessel for etching. Unfortunately, this process is slow and prone to accidents and spills. In some cases, the desired PCB may end up getting damaged
It is from this background that a PCB solvent that could help dissolve copper in PCB was invented. The PCB etching machine works by moving the prepared etchant solution through aeration to help accelerate etching of PCB. The machine works depending on your PCB size. The machine is capable of etching ten pieces of PCBs per hour. When compared to what can be accomplished which is 6 PCB per hour, we conclude that PEM is more efficient and increases PCB production. Also, the machine charges the etchant solution which is dangerous when inhaled.
7.3: Diy PCB Etching Machine
Constructing your etching machines helps you to save money and time. You can construct one by using a detergent container of length 25 cm, width 13 and height 6 cm. You will then need to use a knife to cut out an area where you will need to place your PCB. To get the best results, you may need to leave some space at the edge of your container. That is important because it prevents the etching solution from spilling out.
Using this method allows you to use the least amount of Ferric Chloride. For a PCB that measures 9cm x 7cm, you will need to use one teaspoonful of Ferric Chloride which should be diluted with 70 ml of water. It forms an etching solution that can be used to etch any PCB as long as it is entirely submerged.
Constructing the Motor Drive System
That is the most challenging part, but it is simple if you can follow the following tips.
First, all you need to do is to buy a wooden bar from the local hardware. Cut it to the required size and make a supporting beam. Secure your motor on the beam and the base. Cut another wooden bar 15 cm long and nail it on the side of the box. It secures the motor in place. The motor to be mounted should be a 12 Vdc with a moderate speed that can be controlled easily. You may need a car power window to help you drive the machine. Use screws to hold the car window power and the gears in place. The final product will look as below.
You may then add a timer control and a stopper switch which will allow you to control the PCB and help it stop at a predefined position. That allows you to leave the machine doing its work and will stop at the predetermined time.
PCB Etching Process Display
Like seriously! Etching can become frustrating if you don’t know your ways through it and with this guide, I believe you are already catching up on something. Many circuits can be etched at once; circuits can be very compact, identical etching leading to identical circuits, are some loaded benefits that etching a PCB has to offer. However, over-etching can occur as a result of imbalance of the ratio of copper etch that is required across the board, but this problem can be rectified by adding thieving to balance it out and decrease etch ant used.
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