White Solder Mask - NextPCB

Definition of White Solder Mask

White solder mask is a type of material that is used in printed circuit board (PCB) fabrication. Adding a polymer layer to PCB surfaces shields copper traces and pads from oxidation, moisture, and other environmental factors. The purpose of the solder mask is to prevent solder from sticking to areas where it is not intended to be, ensuring that electrical connections are made only where they are supposed to be.

White solder mask is so named because of its color, which is typically a bright white or cream color. This color is chosen because it provides high contrast against the green or blue solder mask commonly used in PCB manufacturing, making it easier for technicians to inspect the board for defects.

In this article,

• Definition of White Solder Mask
• Importance of White Solder Mask
• Advantages and Disadvantages of Using White Solder Mask
• Operation of Applying
• Equipment used in applying White Solder Mask

Importance of White Solder Mask

• Protection: The primary purpose is to protect the copper traces and pads on a PCB. 
• Insulation: Provides insulation between the copper traces and pads. This prevents short circuits and other electrical issues when the traces come into contact.
• Identification: The white color of the solder mask is a useful feature for identifying different components and traces on the PCB. 
• Aesthetics: This can also improve the aesthetics of a PCB. It provides a clean, uniform appearance that is pleasing to the eye.

Advantages and Disadvantages of Using White Solder Mask

Advantages:

• High Opacity: The primary advantage of using a white solder mask is its high opacity, which ensures that the underlying copper traces and other components are not visible. 
• High Contrast: Provides high contrast between the copper traces and the solder mask, making it easy to identify any defects or issues during inspection. This is particularly important during the assembly process, where any defects can significantly impact the PCB's functionality.
• Improved Aesthetics: It gives the PCB a clean and professional appearance, which is essential for products that are sold to consumers. It also allows for custom branding and labeling, which can be an essential factor for product differentiation and branding.
• Improved Solderability: White solder mask has excellent solderability, which means that the solder can easily bond to the copper traces, improving the overall functionality and reliability of the PCB.

Disadvantages:

• Cost: White solder masks are generally more expensive than other solder masks, which can increase the overall cost of PCB fabrication.
• Limited Availability: It is not as widely available as other types of solder masks. This can limit the options for PCB manufacturers and designers.
• Potential for Yellowing: White solder mask has a higher potential for yellowing over time, which can impact the overall appearance and functionality of the PCB.
• Reduced Adhesion: White solder mask has lower adhesion than other types of solder masks, which can impact the PCB's mechanical and chemical stability.

Operation of Applying

Step 1: Cleaning the PCB

The first step in the process of applying a white solder mask is to clean the PCB. Typically, people clean by using a solvent such as isopropyl alcohol that quickly evaporates and leaves no residue.

Step 2: Applying

After cleaning the PCB, you can apply the white solder mask.

Typically, one applies the mask by screen-printing it onto the board through a stencil. To accomplish this, one places the stencil over the board and uses a squeegee to apply the mask. We then use a heat source such as an oven or a UV lamp to dry the mask.

Step 3: Curing the Solder Mask

After the mask has been applied and dried, it needs to be cured. We do this to ensure that the mask fully cures and does not crack or peel over time. The curing process requires heating the mask for a set time, based on the mask type and temperature.

Step 4: Removing the Stencil

Once the mask has been cured, the stencil is removed from the board. The user peels the stencil away from the board, leaving the white solder mask in place. Then, the inspector examines the board for any defects or imperfections in the mask and corrects them using touch-up methods if needed.

Equipment Used in Applying White Solder Mask

Screen Printing Machine

The screen printing machine is used to apply the white solder mask to the PCB. The machine utilizes the stencil to apply the mask, which then dries and cures, creating a protective layer on the board.

UV Lamp

The lamp emits UV light, which causes the mask to harden and become more durable. PCB manufacturers can use UV lamps to apply white solder masks and other types of coatings, which showcases their versatility in the manufacturing process.

Oven

We use the oven to cure it, after applying and drying it. The oven exposes the mask to heat for a specific amount of time, depending on the type of mask and the curing temperature. This ensures the mask undergoes full curing and will not crack or peel over time.

Conclusion

In conclusion, NextPCB offers high-quality services that are cost-effective, making it an ideal choice for businesses of all sizes.

Additionally, our cutting-edge technology and state-of-the-art manufacturing processes guarantee precision and efficiency in every production run. Furthermore, our skilled and experienced team of engineers and technicians ensure that every detail is accounted for, from design to delivery. Consequently, our customers receive excellent quality PCBs that meet or exceed industry standards, all at a cost-effective price point. In conclusion, trust NextPCB for all your needs and experience top-notch service and quality every time.