Black Printed Circuit Board: The Complete Guide
Manufacturers often produce Printed Circuit Boards (PCBs) of different colors, even if it makes their components more costly. It helps to distinguish PCBs by purpose, which is beneficial for mistakes prevention and quality assurance compliance overall.
Not many people actually know what’s the meaning for black PCB color, how to fabricate a black PCB, and its pros and cons. It results in misunderstandings between specialists of different companies and even industries.
You will learn from this post more about black PCBs specifically and how the coloring of PCBs is helpful overall.
What is a Black Printed Circuit Board?
For starters, PCB is a piece of electronics – a laminated structure comprising conductive and insulating layers needed to provide electronic connection.
As evident from its name, black PCBs are ones that are black-colored. It is achieved due to the use of a black solder mask in the production process, instead of green, red, blue, or any other.
In its turn, a solder mask is simply one protective lacquer-like polymer layer applied to a PCB. It helps electronics to resist oxidation and reduces the risk of solder bridges (unintended electrical connection). As a bonus, the different solder masks may enhance PCBs with features that you will discover in the below text.
Types of PCB Colors
When it comes to solder mask colors and, respectively, colors of PCBs, there are many of them:
- Green. It is the basic color for PCBs, appreciated by most experts for ensuring the visibility of all the traces, planes, and spaces. Green offers good contrast with the white legend of a PCB. It is typically available in glossy and matte types.
- Blue. Solder masks of this color are widespread in the fabrication of Arduino PCBs. The purpose is basically the same – to ensure good contrast between the mask and elements on it. It is important for optical testing of the quality of PCBs. It is also considered a more aesthetic color than green.
- Black. Such a solder mask offers even greater contrast with the white legend than blue and green do. But it compromises the visibility of black elements such as traces. The kicker is that black absorbs light, improving the visibility of its elements even more. Glossy and matte black are both common.
- Red. It is another professional-looking color that contrasts with traces and empty spaces.
- White. Such a solder mask is never used to highlight the legend of the PCB (white-colored typically). But in contrast to the black, it makes additional elements, especially dark-colored ones, more visible.
- Yellow. This one offers the contrast to traces of a PCB. But the visibility of the white legend is typically rather moderate.
- Purple. It is known as an expensive solder mask color. It shares pros and cons with the red color. It is rarely used and suits mostly aesthetic purposes.
This is the complete list at the moment. But, there are good chances that more colors will be available in the future.
Is a Black PCB Board more High-end?
The simple answer is – No, they aren’t. You see, all the specified above colors have one clear main purpose – facilitating the quality testing by ensuring greater visibility with certain parts of PCBs. And the secondary purpose – enhances the aesthetics of electronics overall. It does not have anything in common with the superior performance of PCBs themselves.
To prove this claim, we gathered for you several misconceptions about black PCBs and refuted them:
- Black PCBs lower the rejection rate. Well, in the case of DIY fabrication of black PCBs, the rejection rate would likely be even higher. But reliable PCB manufacturers have X-ray automatic defects detection equipment. It means that they are capable of detecting a bad quality PCB regardless of its color.
- Black PCBs have high heat dissipation. They naturally do but to a minor extent. If a manufacturer needs higher heat dissipation, it typically chooses ceramic material to make its PCBs from.
- Black PCBs enhance the brand image. Sometimes, the use of a particular color decision impacts the way a brand is perceived overall (same as with a logo). But it neither affects performance nor is a distinct feature of black.
Therefore, black is just an aesthetic color compared to others. It offers high contrast with white. It has some functional properties that make performing quality testing on black-colored PCBs easier. But it is not even close to the same as a high-end product.
Black PCBs Materials
In essence, the very materials that ensure this color of PCBs are the solder mask itself and the black ink. These are described below. All other materials any PCB is made of are not listed not to degrade your attention to the text.
- Solder mask. Most affordable masks are made of composite resin (epoxy liquid) that is melted and mixed with an inc. Then it is homogenized and is ready to be screen printed onto a PCB’s surface.
- Black ink. In its turn, the dye is the combination of solvents, pigments, dyes, resins, lubricants, stabilizers, surfactants, and other components. The basis (solvent) for more inks is oil, water, or petroleum. For solder masks, only synthetic black inks are used, as natural ones are not that heat resistant.
Benefits of Using Black PCBs
Despite the above claim that black PCBs do not perform better than PCBs of any other color, there are some strengths that are attributed specifically to this color:
- Anti-plagiarism. Yes, You are not mistaken. As stated earlier, black traces are nearly invisible on black-colored PCBs. While it is not a huge problem for manufacturers themselves, it protects companies from small-sized competitors that try to DIY fabricated PCBs. Luckily, black components are not that easy to counter-pirate.
- Enhanced appearance. Some of you may argue against this point. But, black is a highly aesthetic color. It is also closely associated with luxury. That’s why black PCBs suit many designs and are appreciated by marketers.
- It matches most front panels. It is vital to say that many PCBs are visible on the front panel of many products, complementing the previous point. Considering that electronic products’ cases are traditionally fabricated in black or white colors, black PCBs just help to complete the design.
- It suits users’ preferences. It is known that the top three PCBs’ colors are green, black, and blue. It is a great reason to manufacture such components just to ensure they are sold well.
- High light adsorption. This feature that no other color offers is to minimize light reflections. It additionally enhances the visibility of contrast elements of PCBs.
Depending on whether a glossy or matte solder mask was chosen, the extent to which these strengths may be expressed may slightly fluctuate.
Limitations of Black PCBs
Black PCBs also have natural weaknesses that you should consider while choosing to manufacture such components.
- Low surface resolution. It is good that black PсавCBs’ designs are hard to copy, but this feature may be a situational weakness. In case of insufficient light, it is nearly impossible to distinguish the tracks on the component’s surface. That is why a visual inspection (which may be obligatory as per Quality Assurance policy) is complicated.a
- Stains and scratches. Once you scratch a PCB, such a defect will be clearly visible forever, especially on matte black surfaces. So if you fabricate black PCBs, make sure they are transported safely to a retail supplier.
- Black inks are toxic. Well, it is not like other dyes are completely safe. But, because of the components that comprise black ink, such as petroleum, it is considered more hazardous than other colors. So you should thoroughly plan ways of black solder mask and black PCBs disposal.
Summary
Now, you may consider yourself an expert in PCBs’ solder masks’ color types. Black PCBs are not high-end compared to other PCBs, but they definitely offer a high level of aesthetics, protections from counter-pirates, and superior contrast with white. Additionally, such PCBs’ traces are better visible under light.
Generally, you may be advised to choose color based on the convenience of visual inspection and the electronic goods’ designs.
As the professional supplier for PCB manufacturing, PadPCB offer rangle of color for options. Feel free to contact us if you have any concerns.
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