Printed circuit boards are used in all electronics and devices that we use as a daily routine of our life. PCBs are made of single layer and or they can be of multilayer pool.
As a PCB designer, you must have a lot of queries about the different layers, how they are designed and the potential applications. We have created this in-depth guide on PCB layers so that you can find answers to all your questions on PCB and its layers.
In the next chapter, we will take a look at PCB layers.
1、What is PCB Layers
PCB or printed circuit boards are used in every electronic device that you see around yourself. You can have a single layer PCB or multilayer PCB which is made from multiple layers of conductive copper foils.
Several layers of double layer PCB are stacked together to form a single PCB. The different layers of the circuit board are known as PCB layers. The PCB layers are bonded together with heat-resistant insulation in between them. The outer layers are then sealed with a dielectric solder mask.
Image 1: PCB Layers
Now let’s find out what a layer stack-up is!
The arrangement of insulating layers and copper layers that create a PCB before the layout design is called stack-up. You can accommodate more circuitry on one board with a layer stack-up.
The stack-up allows you to minimize cross-talk, external noise, and radiation. You can get high signal integrity with a proper PCB stack-up, and it can also improve the electromagnetic compatibility of the device.
A stacked configuration of PCB always benefits multilevel printed circuit boards.
Layer stack-up refers to the arrangement of the PCB layers. The PCB layers are the conductive copper foil layers that make up a PCB.
Image 2: PCB Stack-up
Now it’s the turn to explore the different type of PCB layers.
3、PCB Layers Type
The application and purpose of a PCB determine the number of layers it should have. In this chapter, we will take a look at the most common types of PCB layers.
3.1 one Layer PCB
The single layer PCB or 1 layer PCB has been used since the 1950s. It is still widely used in simple home devices throughout the world. The one layer PCB is made up of one soldered and a laminated layer of conductive, dielectric material.
Being simple in design, the single layer PCBs can be produced in bulks as they are cheap to manufacture. There are fewer chances of any manufacturing issues as the design is uncomplicated. The manufacturers don’t have any problem in understanding the construction, and you can quickly order a large number of pieces.
One layer PCBs are found in many simple home and office devices such as basic calculators and alarm clocks found at the local store. You can also see them in kitchen appliances such as coffee makers. Sometimes they are also used in printers, LED lights and surveillance cameras.
The single layer PCB comes with one thermally conductive dielectric which is topped with a copper laminate and then finished with a solder mask. Generally, the PCBs are produced with copper laminate and have a thickness of one to 20 ounces.
One layer PCBs are meant to function between a temperature of 130 and 230 degrees C.
Image 3: One layer PCB
3.2 Two Layers PCB
Two Layers PCB or double layer PCB is the next technological step after the single layer PCB. It is the most common type of PCB used all over the world for its higher capacity. They are used in a wide range of electronic devices and are less complicated to produce compared to different multilayer PCBs available in the market.
There are many benefits of the double layer PCB. It has higher routing traces due to equal bottom and top sides. It is suited for a wide range of applications because of its flexibility. You can use it in modern appliances and devices as it has high density and low cost of manufacturing. You can find double layers PCBs in residential HVAC systems of different companies.
Two-layer PCBs are also used in amplifiers used in the music industry and a wide range of computer printers.
The double layer PCB resembles the one layer PCB but features an inverted, mirror representation at the bottom portion. The dielectric layer is also thicker in a double layer PCB and comes laminated with materials like copper on the bottom and top sides. Then solder mask is used to cover the copper on both sides.
3.3 Four Layers PCB
Four layers PCB has an elaborate design compared to single and double layered PCB. It comes with several rows of dielectric material while the single or double layered PCB has only one. The four layers PCB is equipped with multiple layers of copper and conductive material between the bottom and top solder masks just like any multilevel PCB.
The benefits of 4 layers PC include durability, and it is stronger than both single and double layered PCBs. It is also small in size and can be used in a vast range of electronic devices. The flexibility of the component makes it suitable for both simple and sophisticated devices.
It is also safe and prevents electromagnetic interference. You can also use it in sophisticated devices as it weighs less.
Four layers PCB are used in different handled devices such as tablets and smartphones. You can also find them in satellite systems that orbit planets. They are also used in space probe equipment used for in-depth space exploration.
The four layers PCB is made up of four layers of conductive copper and three inner dielectric layers consisting of one core and two prepreg. Finally, twin dielectric solder mask layers are applied to the bottom and top.
Image 4: Multilayer Pool
3.4 Six Layers PCB
Six layers PCB falls within the advanced level of multilayer PCBs and powers a wide range of electronic devices, industrial applications and technology devices.
Six layers PCBs are thicker and stronger than double or 4 layer PCBs. It is also compact and comes with higher technological capabilities. Coming in 6 layers, they are highly capable and cut back the chances of electromagnetic interference and cross-talk.
Six layers PCB is used in advanced computing applications, and you can find them in personal computers and laptops. You can even see them being used in data storage devices like hard disks. The PCBs also find application in fire alarm systems which make them more efficient.
Additionally, you can even see six layers of PCBs in fiber optic receivers, mobile phone transmission, GPS devices, industrial controlling devices and health equipment such as heart monitors.
The six layers PCB construction is similar to the four layers PCB, but it is equipped with two extra rows of dielectric material two layers of copper. In the setup, the second and fourth rows of dielectric material are the cores. Out of the six conductive copper rows, the second and fifth are labeled plane while the others are signal.
3.5 Eight Layers PCB
Eight layers PCB are excellent resources which harness computing power and efficiency in electronic devices. The eight layers of PCB is much like the six layers PCB though it comes with four copper signal layers and four plane layers.
Many computer systems and high technological devices use the eight layers of PCB. Their introduction has enabled us to move from kHz computer frequencies to GHz high-speed devices of the modern time.
You can find the use of 8 layers PCB in various industries such as healthcare, aerospace, governmental systems, and many commercial applications.
In total, you can find eight layers in this PCB which is held together by seven rows of inner dielectric material. Dielectric solder mask is used to seal the eight layers PCB on the top and bottom part. You can find many similarities between the six layers PCB and eight layers PCB, but the latter is equipped with extra pairs of prepreg and copper columns.
3.6 Multilayer PCB
Multilayer PCB s can go up to some layers such as 10 or 12 or even beyond that. The stack-up uses additional layers of dielectric material and conductive copper, and the number goes up as you keep on increasing the layers.
For example, the ten layers of PCB comes with a total of 4 copper plane layers and six signal layers. Nine layers of the dielectric material bond the copper in the ten layers PCB out of which 4 are core and 5 are prepregs. Dielectric solder mask is used to seal the stack-up on both ends.
You can also find twelve layers of PCB in the market which has higher capabilities than the ten layers PCB. It comes with eight conductive signal layers and four plane layers. They are bonded together by five columns of core dielectric material and six signal materials. Both the ends of the 12 layers PCB are sealed off using a dielectric solder mask.
The multilayer PCBs are used in advanced computing, medical equipment, and other high-tech applications. The PCBs are high in capacity and compact in size. They have higher ease of use and can be utilized in high capacity computers and aerospace devices. Many industrial types of equipment also use the multilayer PCBs.
Image 5: Multilayer PCB
3.7 32 Layers PCB
32 layers PCB is one of the most advanced multilevel PCB that you can find. In this PCB, 32 layers are bonded together to provide the functionality of a single PCB. Manufacturing 32 layers PCBs require high precision and use of advanced manufacturing methods. You cannot manufacture 32 layers PCB using standard PCB etching methods.
32 layers PCB is required to embed all necessary system electronics in a compact PCB. The layers in between the stack-up can also be made to accommodate components assembly though it is limited to top and bottom layers generally.
You can find the use of 32 layers PCB in industries such as aerospace. Such applications need a lower level of electromagnetic emissions which can be achieved during manufacturing the PCB. Each layer can be dedicated to a specific function, and it doesn’t create any conflicts with the other layers.
Double layer PCBs have used building blocks of any multilayer PCB. Here 32 double layers are sandwiched together with an insulating material such as fiber epoxy called the prepreg. You will also need advanced machines to handle the intricate design of the 32 layers PCB.
Multi-layer PCBs are used in a wide range of professional and commercial electronic devices such as computers and military devices. The PCBs offer high capacity, high speed and high functionality coming in a compact size. Devices are becoming smaller by the day, and single and double layer PCBs are not adequate to match the high-density requirements.
You have to use advanced equipment to manufacture multi-layer PCBs as the design is complicated and you need high precision. The cost of production is also higher for the same reasons.
Now that you have the idea about the most common forms of PCB layers, next let us move on to multilayer pool.
The designing of a PCB starts with software. You can use tools and multilayer pool provided by Eagle software for an efficient and error-free process. Let’s go through the stages briefly.
4.1 Create a Schematic
Please look to start with a schematic which will act as the foundation of your PCB design. Access the file menu and provide a name for the project and launch the schematic editor window.
Now browse the toolbar and use the necessary tools to replicate your handmade schematic. You can add components to the working area and create your design. The components can be moved or rotated to make a comprehensible schematic drawing.
After you have finished your schematic, check to ensure everything is accurate.
4.2 PCB Layout
You have to next work with the PCB layout, and you can take help of two different ways.
You can start by drawing the specifications of the PCB and arranging the board by placing via and components to it can be only done when you have decided on the shape of the board, the number of layers and positions of the components.
You can select appropriate grids to design and work on specific layers with a range of routing options. You can also choose and deselect layers using the layer setting button.
You can also use the multilayer pool option which automatically creates the PCB design. You can then evaluate the components, layers, specifications, and texts to make sure they are correct. Finally, you can use the design rule check function to get the final layout of your PCB.
Now comes the turn to check out the multilayer PCB and know a little bit about the applications.
Image 6: Multilayer Pool
By now you have gained a definite idea about multilayer PCBs. Multilayer PCBs generally are made of the even number of layers of double layered PCBs.
The layers are stacked one upon another to form a PCB with high strength and compactness of size. There are three or more conductive layers, two of them featuring on the top and bottom part.
One or more layers are stacked with the insulation board and provide high functionality and flexibility. Multilayer PCBs are used in several applications which require high computing and used in industrial equipment. You can also find them in military devices and space probe equipment.
Multilayer PCBs are high precision materials which require a high cost of production.
Now let us see how we can create a DIY multilayer PCB design.
Image 7: Multilayer Pool
6、DIY Multi-Layer PCB
Now we will take a look at how you can design your PCB. We are going to use CAD and also give you some helpful designing tips.
6.1 Adjust Library for Multi-Layer PCB Designs
You will need to configure your CAD library to make multilayer designs.
6.2 Negative plane layers
You may use negative image plane layers to create ground planes and power on your PCB layout. You may need to allow clearances for some tools which are found in footprint shapes and pads for holes drilled in negative plane layers. Ensure that your negative plane layers have proper clearances for using footprint and pad shapes.
6.3 Inner signal layer pad shapes
Your pads on inner and outer layers may differ. For example, pin one pads come in square shapes for easy recognizing while they come in round shapes in hidden layers. It would help if you set up your library to get different pad shapes.
6.4 Drawing pieces
If you are using your assembly drawings from layout tools to create the design, then you have to modify them for multilayer designs.
6.5 Fabrication Shop Requirements
You should check with your fabrication shop if they can handle the complexity and precision of your multilayer PCB design. Otherwise, you may not get the desired results.
6.6 Design Tips
Take help of these multilayer design tips to create a perfect design:
♦Route one signal layer vertically and the other horizontally if you are using adjacent signal layers on the second and third layer.
♦For greater signal integrity and even distribution of ground and power, use ground and power plane layers.
♦You can reduce the pad sizes for more routing channels if your fabrication shop allows it.
Image 8: PCB Design
It doesn’t matter why you are looking for a multilayer PCB pool; you are sure you would need the right one for you. Now, there are a few things for you to consider – whether it be the design or the radiation levels. Choosing the right one will ensure that you can have a PCB pool that will last years. While the initial set up can be tricky, ensuring that you follow the basics and our guide is sure going to make things easy for you.
Multilayer PCBs are used widely for industrial, residential and commercial applications. Get in touch with us to create your custom multilayer PCBs following strict specifications. We deliver high-quality precision PCBs with as many layers as you need for your application.
A microprocessor conventionally is a single chip which has many electrical connections on its pins. It can be used to select an “address” in the main memory and another set of pins to read. Write the data stored at that location. In most cases, the CPU and memory share signaling characteristics and operate in synchrony.
The bus connecting the CPU and memory is one of the defining characteristics of the system and often referred to only as the system bus. It is possible to allow peripherals to communicate with memory in the same fashion, attaching adaptors in the form of expansion cards directly to the system bus. It is commonly accomplished through some standardized electrical connector, several of these forming the expansion bus or local bus.
However, as the performance differences between the CPU and peripherals varies widely. Some solution is generally needed to ensure that peripherals do not slow overall system performance, direct memory access. Most modern systems combine both solutions, where appropriate. As the number of potential peripherals grew, using an expansion card for every peripheral became increasingly untenable.
It has led to the introduction of bus systems explicitly designed to support multiple peripherals. However, these high-performance systems are generally too expensive to implement in low-end devices, like a mouse. It has led to the parallel development of some low-performance bus systems for these solutions. The most common example being the standardized Universal Serial Bus (USB).