Circuit boards are green due to their protective solder mask, which enhances contrast for easier inspections. This particular green also became a standard thanks to U.S. military influence, making it the go-to choice for quality and visibility.
Also known as printed circuit boards (PCBs), these boards are an important part of modern electronics and are often designed to stay green for performance. These green-colored boards are essential in your devices, from smartphones to computers and everything in between. OurPCB is a professional PCB manufacturer, and we want to dive into the interesting mystery of why are circuit boards usually green. In this article, we're going to go into the reasons behind your green circuit board.
Contents
Key Takeaways
- Green solder masks on circuit boards improve visual inspection and contrast.
- Military standards popularized the use of green for these boards.
- The green color helps in the photolithography process during fabrication.
- Circuit boards can be manufactured in various colors, but green remains the industry standard.
- Choosing alternative colors might impact cost and manufacturing processes.
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Why are PCBs Green?
The green color of printed circuit boards is not just an aesthetic choice but serves a few practical purposes in the manufacturing and inspection processes, too. We’ve summarized the main reasons for printed circuit boards’ green color below.
| Description | |
|---|---|
| Materials Used |
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| Military Influence |
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| Contrast & Visibility |
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Materials Used
The traditionally green PCB color mainly comes from the solder mask, a protective layer applied to the PCB during fabrication. This solder mask is usually made from an epoxy resin called liquid photo-imageable (LPI) solder mask. The green pigment in the solder mask oil is added to the resin before it's applied to the board.
The green solder mask has multiple helpful uses. It protects the copper circuits from oxidation, prevents solder bridges from forming between closely spaced solder pads, and provides insulation. The fact that these boards are green also means it gives you fantastic contrast against the copper traces and other components on the board.
Most PCBs are made using FR-4, a composite material consisting of woven fiberglass cloth and a particularly useful flame-resistant epoxy resin binder. The green LPI solder mask is applied on top of this FR-4 substrate, covering the circuit board underneath. So, when it comes to your printed circuit board, green is typically the color seen quite often due to the materials used.
Military Standards
The popularity of green PCBs can be linked back to military standards set by the United States military. In the early days of PCB manufacturing, the U.S. military was a huge consumer of electronic components. They standardized the use of green solder masks for circuit boards supplied to them.
As manufacturers that supplied circuit boards to the military took on this standard, it became widespread in the industry. The green color became so common that it was often called “military green”. Over time, it just became a standard that printed circuit boards were green, and this military standard influenced the entire electronics industry. Green PCBs became the norm, even for non-military applications.
Contrast and Exposure
PCBs are also green because of contrast and exposure. The green color of PCBs plays an important role in the manufacturing process, especially during the photolithography stage of PCB fabrication. The solder mask is a liquid when it’s applied, but it’s then exposed (or “heated”) to UV light through a photomask, which hardens the treated areas. The green part of a circuit board in the solder mask is sensitive to green-light, which is used in this process.
Green is commonly used for PCBs because it offers excellent contrast for visual inspection. The human eye is particularly sensitive to green-light, making it easier to detect defects or issues on the PCB. This explains why green remains a popular choice for PCB coloring.
This high contrast between the green solder mask and other components like copper traces, silkscreen, and the fiberglass board underneath improves the quality control process, both for manual and automated inspections. The green part you see makes it simpler for you to inspect the board, it's as simple as that!
Do PCBs Have to Be Green?
Many people believe that the green on PC boards is naturally green, but this is not the case! While green was chosen as a great screen mesh for circuit boards for a variety of reasons, it's not a requirement. PCB manufacturers can produce boards in different colors such as blue, red, black, white, and even yellow. These alternative colors are available for standard production, or manufacturers can produce custom colors or corporate branding on request.
However, it's important to note that choosing a non-green color for your PCB might have some complications. Different pigments can affect the solder mask's properties, potentially affecting its conductive performance in protecting the circuit, especially when using a new solder mask oil. The solder resist property may also be impacted and may have trouble resisting heat during soldering.
On top of that, some colors might not provide the same level of contrast as green, which could make inspecting and observing the boards more difficult. You might also end up paying a premium for non-green PCBs, as they could require special handling or extra steps in the manufacturing process. Actually, green is just the best choice all around, so it's best to keep it traditional!
OurPCB: Experienced PCB Manufacturers
OurPCB is an experienced PCB manufacturer that understands the nuances of circuit board production, from traditional green boards to custom-colored PCBs. With a deep knowledge of materials, processes, and industry standards, OurPCB can guide you through the PCB design and manufacturing process.
Whether you need standard green PCBs or are considering alternative colors for your project, OurPCB's team can jump in to help. We can answer your questions, give you insights into the pros and cons of different PCB colors, and ensure that your circuit boards meet the highest quality standards. Reach out to our expert team today and see the results for yourself.
FAQs on Why are Circuit Boards Green?
Does the color of a circuit board matter?
No, the color of a circuit board does not necessarily matter. The color of a circuit board mainly affects aesthetics and branding rather than functionality. However, it can also change heat dissipation slightly, as darker colors absorb more heat.
What does the color of a circuit board mean?
Different colors can indicate specific manufacturing processes or materials used in the board. Green is the most common color, usually due to the use of a green solder mask for visibility and contrast.
What color shouldn't PCBs be?
While there are no strict rules, bright colors like neon pink or yellow may not be the best idea for professional or industrial applications. These colors can detract from the board’s readability and could indicate non-standard manufacturing.
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