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- November 29, 2022
- PCB knowledge
- (0)
- 06 mins
Green PCB – a detailed review of what it is
You must have already noticed that most PCBs are green in color. Have you ever asked why they possess this color? Is there a significance behind it? In this piece, we’re going to look at the reasons for a green PCB and more. In fact PCBs don’t usually have to be green. There are several other colors that can be used in PCBs including blue, red, white, and even black.
What is green PCB?
So, what really is a green PCB? PCBs have a PCB solder mask that has a main role of safeguarding the copper circuits on the fibre glass core. This helps to cut down on any possible errors in the soldering and short circuits.
The color used on the PCB gives it its appearance. But does it do anything else apart from just the aesthetics?
During the manufacturing process, a green PCB doesn’t take that color. What you see as green is just but the outer layer that’s typically known as the solder mask. This color is printed on the boards afterwards.
The purpose of the solder mask is to ward off any form of contamination and moisture that could affect the circuitry. In the middle of the circuitry, the color is yellow. However, the solder mask can have different colors, green included.
But if so, then why do PCB manufacturers mainly just use green?
Why are printed circuit boards usually green?
Typically, you will always find a green PCB. And you might wonder if there’s a reason for this occurrence. There are a number of explanations and theories that try to explain the reason behind a green PCB and not any other color often.
For instance, some people argue that since the army had a pivotal role in the emergence of PCBs in the 1950s, then the color had to match their own, which was green.
On the flip side, other people argue that it has been the industry’s tradition or norm to use the green color on PCBs, hence the reason why it is still in use to date.
The truth is that nobody has a definite answer, as there are several other colors that a PCB can be in. Nonetheless, the following are some of the more established guesses or reasons for a green PCB:
1.Exposure – darker colors need more exposure rate. For instance, black would be the highest in exposure rate requirement. Green has just the right exposure rate for PCB manufacturers.
2.Contrast – the contrast of the color green with the routing and text on the PCB is another reason for its preference for manufacturers. Most PCB makers rely on human inspection till date for a higher quality assurance rating. Therefore, green helps to reduce the strain on human eyes for extended periods of time. Also, because of the contrast it has, it becomes easier to monitor all of the parts of the board. Lastly, workers are more used to a green PCB than any other colors. It would become harder to check several PCBs in other colors than checking those in green.
3.Military – the required standard for circuit boards used by the military, such as the USA military, has been green. So, many manufacturers who supplied PCBs to the military used the green color. But note that these same manufacturers also had civilian customers. And it was easier to supply PCBs to them in green color too, than create them in other colors. In addition, they usually had a surplus that was intended for the military, which civilians got at a bargain. This influenced the use of a green PCB.
4.Materials – this is a significant reason for a green PCB. Glass epoxy has always been green in color. And it is the material used in the construction of a soldering mask. This made green the typical color to use within the industry.
What the green part of a circuit board is?
The green part you see on a PCB is the solder mask. It is normally made of resin (hardened) with pigments of colors. This part is quite essential to the functioning of the circuit, as it helps to prevent dust and moisture.
How to make PCBs green?
In order to make a green PCB, a liquid photo ink is necessary. The process takes place inside a darkroom. Thereafter, the board dries in front of a fan or cooling system. Sunlight exposure for about 10 minutes can also help in the drying process. After removing the layout, washing with high pressure water follows.
Are PCBs available in other colors?
Yes, you can get PCBs in other colors other than green. Different colors can work just as well as green, or even better. Some of the alternatives include the following:
- Blue – high contrast and works best with high labelling requirements.
- Red – for a fresh and unique appearance with comparable contrast levels.
- Black – good for easy monitoring of large components and to see labels. Downside is low heat dissipation.
- White – appropriate for show models.
Difference between green PCB and blue PCB
The main difference between a green PCB and a blue one is that the contrast that lies between empty planes and spaces is rather shallow. Therefore, because of the high contrast of a blue PCB, the use of a magnifying lens is necessary when trying to observe defects on the board.
This is unlike a green PCB, which makes it easier for line workers to check the board carefully as they notice any abnormalities.
How to choose PCB color?
Choosing a color for your printed circuit board is all about how you’re going to use it. But also note that the color determines how efficient the circuit will be and a save on cost too.
Different colors can cut down on errors that occur in a mixed assembly. Here are a few more reasons why color selection is important for your PCB:
- For clarity purposes.
- Different colors either make things smaller or brighter.
- Consider the light reflectance when choosing the color.
- Absorbance and heat dissipation should also be considered closely.
- Transmission and flow of current matters too.
How to select the right PCB manufacturer for green PCB?
For your green PCB needs, here are some of the factors to consider when choosing a manufacturer:
- Lead time and delivery.
- Scalability when you have huge orders.
- Ensure that the manufacturing and shipping locations fit your needs.
- Check for relevant certifications.
- Responsiveness and flexibility.
- Expertise and experience.
- Capabilities and capacity.
- Quality control.
- Review of the layout.
Green PCBs have a solder mask that has a main role of safeguarding the copper circuits on the fibre glass core. This helps to cut down on any possible errors in the soldering and short circuits.
The green part you see on a PCB is the solder mask. It is normally made of resin (hardened) with pigments of colors.
- Blue
- Red
- Black
- White
Final thoughts
We have now come to the end of this guide on green PCB. The need to choose a suitable color for PCBs is very important as noted above. But still, green stands out as the most preferred option. We have shared the reasons why in this guide.
Have in mind that at IBE, we’re always ready to answer all the questions you may have surrounding printed circuit boards. We’re also ready to offer solutions to your PCB needs. Check out our website for more information or request a quote. We meet every customer’s PCB assembly needs because of our in-depth experience. Welcome to collaborate with a company that puts user needs first.
