Which of the various Solder Mask Colors available on the market. what should I choose? Do these Solder Mask Colors have any special meanings or symbols in the industry? Will the color of the solder mask and screen printing have an effect on the PCB‘s functionality? What is causing the solder resist on my electronic PCB board to fall off? Today, the editor will summarize to explain the mysteries of solder mask .

What is a PCB Solder Mask?

The solder mask layer is a solid-colored protective film . formed on the PCB by the welding resist after high-temperature baking . To protect non-solder parts from solder. we usually distribute it on printed PCB boards where no soldering is required. It is the permanent protective film to scratched. During component soldering, the deposition or diffusion of solder on the non-solder area . also serves the purpose of preventing a short circuit between wires. The solder mask also has anti-moisture, anti-chemical, heat resistance, insulation. and a lovely appearance.

What Exactly is Solder Mask Ink?

To protect the circuit pattern, solder resist is an insulating ink that applied to the surface of PCB. When mounted components on the board. one of the primary functions of solder resist is to prevent solder from adhering to undesirable areas. various types of solder resist ink .and also have various Solder Mask Colors.

UV Curing and Thermal Curing

Thermal and UV solder masks are made by combining welding resist and a strengthening agent. With a specific amount of toner, according to the needs of the customer. However, the PCB produced by this ink has oil leakage and jump printing issues, and the appearance is poor.

Soldermask Ink LPI

Most factories are using liquid photo-imaging solder resist ink with better results. Tamura DsR2, TaiyoPSR, Cotes XV, Toyo K, Gin Hwa DSR, and Lea Ronal. Danachm, and other company products, two-component, these models have all been UL certified. Green is the most common color, but yellow, black, white, and other colors are also used. Asian products are generally shiny, whereas European and American products are predominantly matte.

What are the Different Colors of Solder Mask Available?

GREEN

Because it makes everything visible. green is the most commonly used PCB soldermask color. The white text on green soldermask has a high contrast. and the finish is not too bright to reflect too much light, reducing glare. Because it does not interfere with display wiring. green is the most commonly used solder color.

WHITE

White soldermask applications are becoming more common. because they enhance the appearance of PCBs in a clean environment. However, because the white solder resist layer hides traces. pcba placement processing can be difficult. In this case, checking the wiring is nearly impossible. especially if you are in a room with only direct overhead lighting.

BLACK

When compared to white soldermask, black soldermask causes slightly less visibility issues. It is frequently used in high-end and large-scale assemblies. The disadvantage is that the light may catch the component and cast small shadows. making it difficult to see traces. Because of the increased heat, which can discolor the silkscreen and make the board more difficult to clean. the black PCB soldermask option is also generally not recommended.

RED

It’s a very nice board, just like white. Because they provide good visibility and contrast for flat surfaces, traces. and even your blank space, red boards are becoming a popular choice. Although it is not as contrasty as a green board. it will give the PCB a new look when compared to the stale industry standard. The screen printing stands out against the red.

BLUE

Blue soldermask used for heavily labeled boards. because it contrasts sharply with the screen print. The trace becomes more difficult to see without proper lighting and magnification. so this is the balance of this blue option. Blue is commonly chosen due to its appearance. It’s not as striking as white or black, but it does provide a striking aesthetic option. that hints at complexity and craftsmanship, especially when mounted on an LCD.

YELLOW

Many new colors are being introduced, but they can be difficult to work with. Although yellow is a pleasant color, it contrasts poorly with screen printing and traces. making it difficult to use in any practical application. Various colors will balance various needs, such as cleanliness, visibility, and style.

How Do You Choose the Right Solder Mask Color?

The three colors of green, black, and white each have their own set of applications. Other colors, such as red, yellow, and blue, have no specific application reasons . and chosen for personal aesthetic reasons. Some companies may use different colors to differentiate between product grades. such as green low-end, red mid-end, blue high-end, and so on.

Some businesses define the blue board as the board during the trial development period. We set the means of different color PCBA, and the color itself serves no purpose. Other than green, we use the majority of the colors on the PCB of finished product transactions. The appearance of the circuit board. such as the motherboard and graphics card. without a casing will be more appealing and will attract buyers.

Because the customer cannot see the PCB inside the shell. he or she cannot determine whether the color is acceptable. So, whether for practicality or cost considerations, go with the most traditional green. Using the same 10cm2 FR-4 PCB as an example, Matte black PCB is 34 $ more expensive than green solder mask PCB. Light green, sun green, dark green or matt green. red, blue, white, black, yellow. and other standard solder mask colors are currently available on the market.

Does the Solder Mask Color Effect its Functionality?

The color of the solder mask has no effect on PCB performance. It has no meaning in and of itself, and if you have a purpose, you give it. It may have a minor impact on the exposure process of the electric PCB board. but it will have an impact on overall quality, which we can almost ignore.

If no special requirements exist, we recommended to use a green solder mask, at the very least to save money. If you care about the appearance of the PCB or want to sell branded semi-finished products. go with the color you prefer. Remember to choose the solder mask ink brand before going into production. do an excellent processing pre-treatment, and debug and control the solder resist. Get rid of solder resist and screen printing issues.

Why does Apple use black Solder?

What is the distinction between a green and a blue mask?

Not only is the iPhone’s black electric circuit board black. but so are the core circuit boards of many high-end brands. Under normal circumstances, the supplier does not recommend the use of black solder mask oil . because it causes the entire board to be black, making it difficult to see the circuit. the appearance inspection of the board factory, and the later product debugging and maintenance to have a large impact. so the cost of black ink will be slightly higher than other noise.

However, because of this, black ink is frequently used to represent high-end PCB boards. a confident display of its products, and the protection of its technology. This color ues more frequently on computer motherboards, graphics cards, and development boards. It has a thick and soothing feel in the hand.

For example, used it on the motherboard in the beginning, while other brands are still green. Because the black appearance is not natural to check. after-sales repair will be difficult and expensive, necessitating high PCB quality. The ASUS motherboard uses black to demonstrate its excellent quality . and dependable after-sales service. as well as to enhance the brand’s Product image.

Now that more and more brand manufacturers are aware of the issue. they will propose relevant requirements for the PCB solder mask color of some products.

Why does the PCB Solder Mask a fall off?

The solder resist can fall off for a variety of reasons. including improper storage, but the majority of them caused by process factors. From the standpoint of the process, divide it roughly into the following situations:

The proportion of solder resist is unreasonable before curing. or the quality of the solder resist is inadequate, resulting in poor adhesion.

The pretreatment before curing is missing. resulting in excessive impurities on the board’s surface. There are bubbles and contaminants between the solder mask and the board surface. after curing and the stroke layout.

The ink thickness is too thin, making it easy to scratch and fall off. Mask for soldering Inadequate curing time results in incomplete adhesion.

How to Fix the Solder Mask Peeling Problem？

• Change to the proper ink.
• Add a solder resist pre-treatment process and improve the pre-treatment process.
• Increase the amount of exhaust air by using the proper temperature and time.
• Change the dosage or add other additives.

There are 27 conventional solder mask and screen printing problems and solutions. I have put them together and put them in the form of the link below. If you need it, you can click to download it.

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