Printed Circuit Boards (PCBs) are specially designed using different electrical components. Each part is essential to the device’s functionality. They all play a vital role in ensuring the machine runs smoothly. So, which are these components that make up a black PCB board? They are;
Types of PCB boards
There are different types of black PCB boards available in the market. They are;
- Single-Sided PCBs
- Double-Sided PCBs
- Multilayer PCBs
- Rigid PCBs
- Flex PCBs
- Rigid-Flex PCBs
Why do Black PCB manufacturers use different colors?
PCB manufacturers have been using the green solder mask for so as the industrial standard color. However, the color of solder masks has changed significantly, and today, there are various colors for solder masks available. In the past few years, assemblers have driven the growth and use of colors in PCBs other than green.
Some of the main reasons for using different colors when making PCBs are;
- To please the end-users by offering a visual indicator of revision changes.
- The properties of light absorbance, reflectance, and transmission have an impact when assembling PCBs. The need for a color other than green can be generated by applications when intending to produce the anticipated contrast or brightness.
- Alternative colors have a massive influence on recognizing lead-free assemblies.
The color of the solder mask does not affect the PCB’s performance. Red and blue solder masks match the PCB green mask ink in resolution. Transparent colors have greater resolutions than green, while black and yellow colors have less resolution.
Types of PCB solder mask colors
Solder masks play an important role when it comes to improving the aesthetics of PCBs. Some of the color options solder masks are available includes the following:
It is the most common solder mask color open for inspection. Due to its immense popularity, most people misunderstand that not all PCBs are green in color. The green color gives transparency to the PCB, as it produces a bright contrast with a white-colored text, thus improving readability. Also, a green finish helps to minimize glare as it reflects less light. Therefore, green is an essential selection for PCBs that demand thorough scrutiny. Its color code is #008C4A.
White PCB solder masks are gaining vast popularity as they appear clean in different environs. Even though white is sometimes referred to as bright show models, it is not ideal because of its affinity to hide traces. While working with a single overhead light, it is hard to inspect a white PCB board. Its color code is #ECECDF.
Yellow solder masks are catching a lot of attention globally. Like other new colors, yellow can easily help achieve different necessities, like style, visibility, and cleanliness. Although yellow is also an amusing color, it possesses a major hitch. Using a yellow PCB for several standard applications is hard as the color contrasts with silkscreens and traces. Its color code is #F6A624.
A blue solder mask is a perfect fit for heavy tag boards, as it offers a marked contrast with silkscreens. Although a blue circuit board is not as outstanding as black, green, or white, it is still ideal as it provides an excellent aesthetic choice. A blue PCB is perfect for mounting on an LCD. This is because it does not produce bright contextual colors and sharp contrasting edges. Its color code is #4990E2.
Most PCB manufacturers are slowly adopting red solder masks because of the specific benefits they offer. A red PCB board gives excellent visibility while at the same time well-defining contrasts for planes, traces, and empty spaces. A red background gives PCB silkscreen colors a sharp look. Its color code is #D0011B.
Black solder masks are becoming more popular the same way as white solder masks. Black PCB give less contrast, and they allow easy tagging when dealing with large components. Nevertheless, its major shortcoming is that it produces a small shadow when some of its components catch the light, making tracing more difficult. Black solder masks are unsuitable in applications that involve high heating since they can tarnish the silkscreen. Also, black PCB has a small conductivity as they feature a blend of carbon and cobalt. Its color code is #000000.
Why the green color is primarily used in PCBs
The color is green always comes to mind whenever a circuit board is mentioned. So, for which reasons have green been the most preferred color over the years?
Green minimizes visual fatigue
Most PCB manufacturers go for a dull shade of green as it isn’t as bright as red or pink. The color works well and for long on the board compared to more brilliant colors.
Another critical factor is contrast levels. Green gives visible differences in the PCB’s empty spaces, planes, and traces. Thus, making it easy to identify and sort a problem when doing repairs and inspections.
Facilitate mass production
Since the green color has existed for a long time, PCB manufacturers have considered it the universal color code. This makes its production resources easily accessible and widely available in large volumes to PCB manufactures. The green PCB color RGB facilitates mass production as it is the color most people use.
When mass production is high, the accessibility also becomes more, thus considerably reducing the prices. Green is dominantly the standard color on most PCBs due to its affordable cost. Also, extra payments are needed when customizing the colors of a solder mask.
How to select the right PCB colors
When selecting the suitable PCB ink for your board, how should you choose the final color? Why green?
PCB product considerations
While working on your solder mask, one of the natural colors that stands out is green. Usually, green has a 0.1 mm thickness layer; hence it is the thinnest of all coats. Also, green has been improved to work well with most PCB components and make repairs and assembling easier.
Glossy and nonglossy surfaces considerations
The designer is entirely entitled to either go for a nonglossy or glossy finish when assembling a PCB. Both work impeccably well, with the nonglossy finish a darker feel and a porous-like finish, while the glossy surface is more reflective and seems to have a hard shell-like finish.
Green is always top on the list when picking out the color of a PCB. Of all colors, green is the most reasonably priced and extensively accessible in vast quantities.
Process of applying solder mask colors on PCBs
Step 1: Cleaning the board
Before applying resin to the board, cleaning and removing rust is essential to avoid functionality issues. Oxidization is also removed during the cleaning process.
Step 2: Applying resin
After cleaning the board, place it on a transparent blank film and use a syringe or plunger to apply resin onto it.
Step 3: Resin spreading
Cut a small transparent film and place it over the resin positioned on the board. This enables the resin to spread evenly all over the board without leaving any spots.
Step 4: Resin squeegeeing
Dispense the resin on the hard-to-reach parts, most specifically on the edges, using a squeegee. It is essential to apply resin without putting on too much force, or else you get bad spots on the board that can broadly impact the circuit board’s functionality.
Step 5: Solder mask placing
After spreading over the resin, now mount the film of the solder mask all over the board. Then align the film properly.
Step 6: Exposing ultra-violet to the resin
Expose UV light to the resin using a UV flashlight that shields the entire board. Focus the UV flashlight on the PCB for around 10 minutes, and make sure you maintain a distance of about 2 to 3 inches.
Step 7: Film peeling
Lastly, peel off the film gently.