The PCB Etching Process

Home » Candor Blog » The PCB Etching Process

Jul 6, 2022|Product Innovations and Design, Technological Advancements and Materials

Most people don’t know the complicated process of making their everyday electronics. Everything from the designing process to the shipping of their products can seem daunting, but it no longer has to be.

At the centerpiece of most electronics lies the PCB, a printed circuit board, which supports and connects the electronic components of your device to ensure the technology works. With the following knowledge of the PCB etching process, you will know how a PCB became etched.

What Is Etching?

Etching is the central step in creating a PCB, which involves removing material from its surface. There are three alternative processes for etching PCB, including chemical etching, laser etching, and plasma etching. Each of these processes provides different methods for the PCB etching process, all with pros and cons.

Check out each of these methods below for a more in-depth look into what they offer.

Etching Processes for PCB Manufacturing

So, what are the steps in PCB etching? The circuit board etching process involves the removal of the substrate material through liquid chemicals, laser, or plasma before fabrication. After removing the copper and displaying the circuit patterns, the tin plating will become stripped.

During PCB manufacturing, the application of tin plating ensured that the circuitry was protected, making removing copper much easier to be cleaned. The following shows how each method goes about this process.

Chemical Etching

Chemical etching is one of the three alternative methods to etching PCB that will be discussed here. After being developed during the Renaissance, this method has proved helpful in the PCB etching process.

This method consists of placing metals through chemical baths to get the preferred shape for the metal. The corrosive chemical then causes a reaction that dissolves the solid material.

Laser Etching

Next up is the laser etching method, which has fewer steps and is less expensive than other etching methods. For this method, a computer controls the laser to ensure precise trace lines, resulting in the best quality PCBs available. In addition to eliminating copper traces, inks, acids, and toxic chemicals, this laser carves designs quite smoothly.

Plasma Etching

The last method is the plasma etching process, which reduces liquid waste by using chemically active radicals. In this method, the plasma of a gas mixture will cleanly structure the material for the intended outcome. Plasma etching is known to be a dry process that improves the efficiency of the PCB etching process.

PCB Etching Processes To Fabricate the Board

The beginning steps of making a PCB are designing and creating a substrate that holds the components, then printing the inner layers. After this process is complete, the photoresist will need to be hardened by placing the laminate under ultraviolet lights. This step etches better than ammonia based etching and protects the circuitry. The excess photoresist then becomes washed away to show the bare copper.

The unprotected copper will be removed, leaving the inner layers with only their copper circuitry. Repeat this step for every inner layer until it is time to laminate and press the layers. Clamp the layers together to begin laminating the inner layers. Apply a prepreg (epoxy resin) to the basin, then place a layer of substrate on top of the prepreg.

Cover both the top and bottom of the board with a thin layer of copper foil to ensure the board is ready for the laminating press to apply heat and pressure to the layers. Once done, a drill controlled by a computer will drill holes in the board to show the inner layers.

The next step is plating, which consists of fusing layers that will be cleaned with chemicals and leaked into the holes. Apply a layer of photoresist to the outer layer and plate with copper.

Tin is applied, as well, to prevent the copper from being etched off. Next is etching PCB, which establishes the PCBs connection and removes unwanted copper again. The rest of the board surface no longer has any hardened photoresist, and the unprotected copper foil will become etched away with just the tin-protected copper circuitry.

The board is now ready for final processing once the tin is removed. This concludes the fabrication process.

Now onto the PCB assembly process.

PCB Assembly

The PCB assembly process is the final step of this operation. Fabrication itself entails many steps to construct each board according to its specifications. So, even though the raw circuit board may be complete now, there are just a few more things to do. Now that all the panels are clean, it is time for the solder mask to be applied. This is how the green color you typically see becomes applied.

Silkscreening, which is the next step, is how information is imprinted onto the PCB and is then finally coated for a clean surface finish. All that is left is to send the PCB to a technician to put it through trials. This ensures it is ready for component assembly and to verify that there are no electrical shorts.

The trace widths and spacings also need to be within their requirements. Contract manufacturers are aware of these requirements and will select the most suitable fabrication partner for the task at hand.

Conclusion

Clearly, the PCB etching process involves a lot to provide the electronics you hold so dear. This process demands designing, creating a substrate, printing layers, removing copper, drilling, plating, and much more. And you can’t forget the etching process, which makes all of this possible.

Now you know all there is to know about the long PCB etching process and how theperfect etching is achieved. You also know how there are multiple ways to complete the etching process, such as with chemical etching, plasma etching, or laser etching. Either way, you can rest assured your electronics will function properly.