Solder Mask material is a fine layer of polymer. In terms of application, engineers will often use this material for copper traces in a circuit board, PCB. It is an essential material in circuit building projects, protecting the PCB from oxidization. This is, however, not the only use case and benefit of solder masks when it comes to the construction of circuit boards.
PREVENTS THE BRIDGES FROM DEVELOPING
Printed Circuit Boards or PCB usually has components of copper placed extremely close to each other. The solder masking helps an engineer avoid solder bridges from manifesting due to the pads spaced closely.
Solder bridge refers to an electrical connection between two copper components on a PCB board. Therefore, the correct application of a Solder Mask can be instrumental in avoiding this issue. Their use case for PCBs is increasingly widespread and fine-tuned into the mass production of circuit boards.
Hence, you will not only find the solder mask material as a hand assembly use case but also integral to the mass production companies of PCB. Companies involved in mass production often use wave or reflow techniques to solder their circuits.
The application process of solder involves firstly, applying the solder material on the board, and then following it up with making openings into the material for the copper components. Engineers that craft circuit boards will make these openings, often by using photolithography techniques.
Traditionally, solder mask material has a green physical appearance, but you can find it in many other colors as well. You can also use solder-masking techniques to construct your very own solder mask at home.
Hence, the quantity, quality, or type of the solder mask material ultimately depends on the particular PCB. Every PCB is different, not only in terms of size but also in terms of applications. PCBs for certain electronic instruments may have more components than some others.
Therefore, the physical dimensions of a particular PCB, the number of openings, and the volume and sizes of components are considerations that factor in before every soldering process.
Typically, you can find four types of solder mask materials, each having its unique physical properties and distinct applications.
TOP-BOTTOM SIDE MASKS
The use of this type of solder mask is common amongst electronic engineers. They use this type of solder to recognize the openings in the solder layer. The layering of this solder mask often follows a film or an epoxy technique.
EPOXY LIQUID SOLDER MASKS
This is one of the cheaper solder masking options since it is a polymer that you can easily silkscreen on the PCB. Silk-screening refers to a printing method in which you have to apply woven mesh to hold the ink patterns.
LIQUID SOLDER MASK/PHOTO IMAGEABLE SOLDER MASK
This solder material is often the more superior out of the four. In terms of property, it is a mixture of two different liquid components. For this reason, it has a much higher shelf life than other solder mask liquids. Furthermore, it is also versatile in its application, meaning, that you can use multiple techniques to apply this solder mask material type.
DRY FILM PHOTO IMAGEABLE SOLDER MATERIAL
This type of solder mask material is excellent for high-density wiring boards. Since the film is dry, it is less likely to escape through the holes. Moreover, when using dry film, you should use the vacuum lamination application technique.
Solder mask materials are emphatic for the PCB industry. Without their application, all circuit boards are vulnerable to damages due to short circuits. Moreover, they also have an essential role in the functionality of the particular circuit board, and they allow aspiring circuit board creators to practice their PCB crafting skills.