The printed circuit board is one of the key concepts in electronics. Designers form them in such a way that they mechanically support and electrically connect electronic components using conductive pads, tracts, and other components notched from copper sheets laminated onto a non-conductive substrate. Printed circuit boards can be multi-layered, double-sided, or single-sided. Advanced PCBs may incorporate components like active devices, resistors, or capacitors, embedded in the substrate. All electronic products use PCBs, even the simplest ones. One of the interesting things to know about PCBs is that they are color-coded. From blue PCB to green PCB, red, purple, black, clear, and white, are some of the most common PCBs. Contrary to the circuit boards available in the market, blue PCB boards get people wondering what difference they make to the PCB board functionality.
While there is no visible difference between a blue PCB board and PCB boards of other colors, blue PCB electronics have become increasingly popular amongst engineers and electrical designers owing to their attractive color. But, is it just about the color?
This post discusses everything you need to know about blue PCB boards, from what is it to what are their features, and the significance of the color blue.
So, without further ado, let’s get started.
What do Blue Printed Circuit Boards Do?
Blue PCBs allow the assembly of data or electrical circuits into a functional piece of hardware. They offer necessary electrical connections and mechanical support via conductive pathways.
They are blue in color not because their paint, dye, or mark is blue but due to their resemblance to the solder mask. The blue color is exactly same the solder mask that protects the copper wires on the board. It bear a resemblance to the Arduino blue.
But they are not just known for their appearance. The contrast between plane traces and empty spaces is shallow. The magnification is considered essential in blue solder mask as it helps in detecting the manufacturing defects. This is why designers prefer blue circuit boards who are designing complex circuits and electronic systems, such as a gaming PC, RC robots, etc.
Because of their appealing nature, blue PCBs have multiple applications:
- Mobile devices
- Digital clock and signage
- Musical instruments, synthesizers, and amplifiers
- Televisions and stereos
- Computers and printers
- RC drones, robots, and other vehicles
They are extremely rare and not easy to source. This is why they are the most expensive of all the circuit boards available in the market.
A circuit board blue allows power and signals to route between physical devices. Designers use solder to make electrical connections between the electronic components and the surface of the blue PCB. Solder acts as a strong mechanical adhesive. And because it is metal, it can be easily seen on the blue surface. Soldering ensures that the components fit perfectly. In case of repairs, it allows designers to precisely remove any worn-out components from the blue substrate without damaging the others.
Composition of Blue PCB
Consider blue PCB like a layer of cake. It contains alternating layers of different materials. Designers use adhesive and heat to laminate the layers, resulting in a single object.
These layers are:
Let’s break down the blue printed circuit board and explain the functions of each layer.
#1 Substrate (FR4)
Let’s begin with the base part. The substrate or the base material is made using blue fiberglass. It is also referred to as FR4. The substrate is the core of a printed circuit board that gives the board its thickness and rigidity. Depending on the manufacturer, you will also find flexible blue PBCs. These are usually built on flexible high-temperature plastic. Based on the use case, you will find blue PCBs in different thicknesses. Nevertheless, two standard sizes include 1.6mm thickness and 0.8mm thickness. Manufacturers also make custom blue printed circuit boards as well. They are customizable for gaming PCs and RC devices.
There are some manufacturers who make blue PCBs with epoxy resin or phenolics. They are not as durable and functional as fiberglass PCBs. However, they are much less expensive. You can easily distinguish between a fiberglass PCB and an epoxy PCB. When you solder an epoxy blue PCB, it will produce a distinctive bad smell. They are typically found in low-grade consumer electronics.
It is vital that you check the material of the substrate before making a purchase. Low-end substrates can end up compromising your whole circuit system. Phenolics and epoxy have a low thermal decomposition temperature. This causes them to smoke, delaminate, and char when the soldering iron comes in contact with the board for too long.
The second most important component in blue PCB electronics is a thin copper foil. It is the second layer after the blue substrate. Adhesive and heat laminate these two layers. In double-sided blue PCBs, you will find the copper layer on both sides of the substrate. Low-end electronics usually have PCBs with copper on only one side. When we refer to 2-layer or double-sided blue boards, we are talking about the number of copper layers. This can be as few as one layer and as many as 16 layers. Depending on the usage and the manufacturer, the layers can be even more.
You can specify the copper thickness by weight (ounces per square foot) and it can vary. The vast number of blue PCBs have one ounce of copper per square foot. However, some customizable blue printed circuit boards can handle more power, hence may use 2-3 ounce copper.
#3 Solder Mask
The third layer in a printed circuit board is a solder mask layer. It appears on top of the copper foil. In traditional PCBs, the solder mask is responsible for giving them their color. However, because the substrate itself is blue in blue PCBs, the solder mask can be either transparent or blue in color. Its purpose is to insulate the copper layer from accidental contact with other metals, conductive bits, or solder. So, it is overlaid on top of the thin copper layer. It helps in soldering to the right places while preventing solder jumpers.
The silkscreen is the final layer in a blue PCB. It is overlaid on top of the solder mask layer. Its purpose is to add symbols, numbers, and letters to the blue PCB board. This allows for easier assembly as the symbols and numbers are etched in a human-readable format. These symbols act as indicators that help you better understand the circuit board. In some cases, board manufacturers also use silkscreen labels for indicating the functions of each LED or pin. A typical silkscreen is white. But in the case of blue PCB, designers prefer black and white inks. Nevertheless, it is uncommon to see multiple colors on a single PCB.
Different Types of Blue PCB Electronic Boards
Now that you understand the internals of a blue PCB, let’s discuss how many types of PCBs are available in the market, their characteristics, applications, and more.
- Single Layer Blue PCB: As per our discussion earlier, single layer PCBs feature a copper layer on the single side of the blue substrate. These boards are highly efficient in power supplies, printers, SSDs, radio and stereo equipment, cameras, and calculators.
- Double Layer Blue PCB: A double-layer printed circuit board features a copper layer on both sides of the blue substrate. Designers drill holes through the substrate to allow circuits to pass from one side to the other. Moreover, they make these boards for industrial controls, vending machines, amplifiers, auto dashboards, LED lighting, HVAC systems, instrumentation, and power supplies.
- Multi-Layer Blue PCB: Multi-layer PCBs use three or more double-layer blue PCBs. In these, the designer drills the holes in a way that allows circuits to pass through the board. Also, the largest multi-layer boards can have a maximum of 50 layers. These circuit boards are common in medical equipment, weather analysis machines, satellite systems, GPS technology, data storage devices, and file servers.
- Rigid: Rigid PCBs have a solid base material that keeps them from twisting. Designers make them sturdy to ensure they remain rigid throughout the lifespan of the electronic device. They can be multi, double, or single-layer in structure.
- Flexible: Flexible PCBs have the ability to twist and bend to meet the specific requirement of electronic equipment.
Blue Printed Circuit Boards vs. Conventional Printed Circuit Boards
As mentioned earlier, blue printed circuit boards are similar to that of conventional circuit boards. Nevertheless, blue boards are more appealing. They look futuristic as the designer etches the components to their surface. Compared to green and red circuit boards, the contract between traces, planes, and empty spaces is shallow in blue boards. Also, the blue solder mask requires inspection with magnification to determine manufacturing defects. Please note that the contrast between the silkscreen and solder mask is relatively high on blue boards.