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4 Layer PCB: What You Need to Know

If you’re looking for a more advanced PCB, you might want to consider 4 layer PCB. This type of PCB has four layers, which allows for more complex designs and a higher level of functionality.

In this blog post, we will discuss the basics of 4 layer PCBs and what you need to know before using them. We will also provide some tips on creating 4 layer PCBs that are both efficient and effective. 

Are you ready? Let’s learn.

What is a 4 layer PCB?

Electronic circuit board with electronic components

Electronic circuit board with electronic components

4 layer pcbs are printed circuit boards that have four conductive layers. These 4 layers are sandwiched between two insulating layers, the substrate. The 4 layers of PCBs are then laminated together to create a single board.

The 4 layers PCBs offer many advantages over the traditional two-layer PCB. For example, the additional layers allow for better signal integrity and improved thermal management. In addition, 4 layer PCBs are also much more versatile, allowing for a wide range of applications.

4 layer pcb stackup

4 layer boards stack up

4 layer boards stack up

For a standard 4-layer PCBs stack up, the stack is as follows, with GND and VCC switching depending on the layer with the most signals.

Outer layers:  These are the top and bottom layers.  They are for routing signals.

Inner layers:  These two inner layers are the two middle layers. They are to provide power and ground planes.

Then we will talk about each layer in detail.

Layer one:

It is the bottom layer and is typically made of copper. Besides, it serves as a foundation for the entire board and supports the other layers.

Layer two

This is the power plane. And it provides a clean and consistent power source for all components on the board. 

Layer three

It is the ground plane layers.  Also,  it provides a clean and consistent ground source for all components on the board.

Layer four

This is the top layer. And it is useful for routing signals and provides the connection points for components.

The function of the layers:

-signal layers

The signal layer is for the routing of signals. Plus,  it is the layer where most of the components we place. The inner signal layers are for routing of high-speed or differential signals.

-ground and power planes layers

The ground and power planes provide clean and consistent power and ground source for all components. Moreover, it helps to reduce noise on the board.

-solder mask layers

The solder mask is for protecting the copper traces from shorting and soldering. Besides, it provides a consistent and professional look to the board.

-wiring layers

The wiring layer is for connecting the different parts of the board. Plus, it provides structural support to the board.

-mechanical layer

The mechanical layer is for mounting the components to the board. Besides, It also provides support and stability to the board.

-ground-layer/gnd layer

The ground layer provides a common ground for all the components on the board. Plus, it helps to reduce noise on the board.

-reference layer

The reference layer provides a reference voltage for the components on the board. Plus, it helps to keep the components stable.

-two additional routing layers

There are additional routing layers on the 4-layer PCBs. These layers are useful for routing signals between the different parts of the board. Plus, they help to reduce crosstalk on the board.

Thus, 4-layer PCBs are very useful for a variety of applications.

-VCC layer

The VCC layer is for providing power to the components on the board. Plus, it helps to keep the components stable.

Four-layer pcb benefits

High-tech electronic PCB (Printed circuit board) with processor and microchips

High-tech electronic PCB (Printed circuit board) with processor and microchips

A 4 layer PCBs provides many benefits over a traditional two-layer board. For example, the extra layers allow for better control of signal integrity and timing. Moreover, they also provide increased routing options and improve thermal characteristics. Although 4 layer PCBs are more expensive than their two-layer counterparts, the benefits often outweigh the cost.

four layer pcb applications

Four layers PCBs are applicable in many areas, such as

  • Automotive

Such as engine control, body electronics,  and infotainment.

  • Telecommunications

This includes the base station equipment, routers, switches, etc.

  • -Consumer Electronics

Include  4K/HDR TVs, digital cameras and camcorders, Blu-ray players, etc

Such as  printers, scanners, and mice

  • Industrial Controls

This 4-layer pcb is used for programmable logic controllers (PLCs), lighting control, motor control, and security systems.

  • Medical

This 4-layer pcb applies to diagnostic equipment, hearing aids, and patient monitors.

  • And more!

If you are working on a project that requires high speed or precision, 4-layer PCBs may be the right choice for you.

2 layer vs. 4 layer pcb

During multiple layers,  four layers and two-layer pcb are the most common. When it comes to 4 layer pcb vs. two-layer PCBs, it’s important to know the difference to make the best decision for your project.  Here are some key points to consider:

– Cost 

When comes to the cost, a 4-layer PCBs is more expensive than a two-layer. The increase in layers means an increase in the overall price of the board.  This is because more material is necessary, and manufacturing is more complex.

– Designs

Four-layer pcb can be useful for more complex designs than two layers because you have more space to work with and can include more features.

Also, the pcb vias are more important in 4-layer pcbs. Also, they can be in use to connect different layers together and make the design more flexible.

-Functionality

Four-layer PCBs usually have more functionality than two-layer. This is because they can support more complex designs and include more features.  

One example of this is that 4-layer pcbs can support higher speed signals. As the extra layers can be applicable to route the signals faster.

4 layer circuit board can also support more power and ground planes because the extra layers can be useful to route the power and ground planes.

In addition, 4-layer PCBs can also support more trace widths and spaces. This is because the extra layers can be used to route the trace widths and spaces.

Besides that, 4-layer PCBs can also support more copper thicknesses. That is because the extra layers can be applicable to route the copper thicknesses.

-Comparing the Processes of Prototyping

Prototype printed circuit design

Prototype printed circuit design

As for prototypes, 4-layer PCBs are the best way to test your design before going into production. In truth, 4 layer PCBs can support more trace widths and spaces. This is because you can use the extra layers to route the trace widths and spaces.

Also, 4 layer PCBs can support more copper thicknesses. This is because the extra layers can be used to route the copper thicknesses.

-Stack ups Compared

green embedded microcircuits

green embedded microcircuits

Compared to the 2 layers circuit board,  4 layer pcbs offer many benefits that can’t be provided by the former. In addition, 4 layer pcbs allow for smaller trace widths and spaces. And it also supports a wider range of copper thicknesses, more silkscreen colors. 4 layer pcbs also have better mechanical strength. 

4 layer pcb price

Macro Close-up Shot of Circuit Board with Computer Motherboard Components

Macro Close-up Shot of Circuit Board with Computer Motherboard Components

4 layer PCBs price depends on many factors, and the following are:

-Board size

Firstly, you should consider the board size. As 4 layer pcbs size varies, the larger 4 layer pcbs will cost more.

– Layer count

Then, the four-layer board needs more materials. As a result, it will cost more than the double-sided boards.

– Material used

Thirdly, 4-layer PCBs use multiple materials, and the cost of each material is different. Therefore, 4 layer pcb price varies from $38 to $100.

– 4 layer pcb complexity

Moreover, 4 layer PCBs are more complex than double-sided boards, so it will take more time to design and manufacture 4-layer pcb. Thus, 4 layer pcbs price is also higher than the double-sided board.

– Copper thickness

Also, you should note that 4-layer pcbs generally have thicker copper than the double-sided board, which also contributes to the higher 4-layer pcbs price.

– Surface finish

In addition, 4-layer pcb generally has a better surface finish than the double-sided board. And this is because 4-layer pcb can have more layers of copper, which can provide better support for the surface finish.

4 layer flex PCB

LED flexible printed circuit board strip for various lighting applications

LED flexible printed circuit board strip for various lighting applications

4 layer flex pcb is a kind of 4 layer pcb made of flexible material. However, a 4-layer flexible pcb is more expensive than a four-layer board, but it has many advantages.

Pros of the four-layer printed circuit board

connector and reflection on a black background.” class=”wp-image-66388″/>

Orange flex circuit board with white connector and reflection on a black background.

  • Firstly, 4-layer flex pcb is more flexible, and you can bend or fold, which is very convenient for various applications.
  • Besides, 4-layer flex pcb is also more resistant to vibration and shock, making it ideal for use in harsh environments.
  • In addition, 4-layer flex pcb is more resistant to heat and can withstand higher temperatures than 2-layer pcb.

Although 4-layer flex pcb is the best choice for many applications, it is more expensive than 2-layer pcb.

4 layer PCB Thickness

Computer board with visual effects in a futuristic style

Computer board with visual effects in a futuristic style

How thick is a 4 layer PCB? You may wonder about this.

The thickness of 4 layer pcb is generally 0.13-0.15mm, but the thicker 4 layer pcb is also available with the thickness of 0.20-0.25mm. What’s more, 4-layer flex pcb can be made even thinner with a minimum thickness of 0.05mm.

4 layer PCB Manufacturing Process

Assembling a circuit board

Assembling a circuit board

The 4 layer pcb manufacturing process is as follows:

– The first step is to create the inner layers.

This involves laminating the inner layer stackup, drilling, and milling vias. And then adding any plated features such as pads.

– The second step is to create the outer layers.

This involves laminating the outer layer stackup together and drilling and milling vias.

– The third step is to assemble the 4 layers.

This involves bonding the inner layers to the outer layers using a special adhesive.

4 Layer PCB:Close-up view of man looking at circuit board through a magnifying glass

Close-up view of man looking at circuit board through a magnifying glass

– The fourth and final step is to finish the 4 layer pcb.

This involves adding any final plated features such as solder masks or silkscreens. Once the 4-layer PCB is complete, it is ready for use in your electronic device.

As you can see, 4-layer PCBs are a bit more complex than your typical two-layer pcbs. But with the help of a professional 4 layer PCBs manufacturer, you can get the 4 layer PCBs you need for your next project.

4 layer pcb manufacturers

4 Layer PCB: Fantasy digital room with electronic components in the interior

Fantasy digital room with electronic components in the interior

There are many 4-layer PCBs manufacturers to choose from. But how do you know which one is right for your project?

Here are a few things to consider when choosing a 4 layer PCBs manufacturer:

– Price:   You want to find a 4-layer PCBs manufacturer that offers a competitive price. So be sure to get quotes from several manufacturers before making your final decision.

– Quality: Quality is important when it comes to 4-layer PCBs manufacturing. Therefore, finding a 4 layer PCBs manufacturer that has a good reputation for manufacturing high-quality PCBs.

– Delivery:   When it comes to 4-layer PCBs manufacturing, you’ll want to find a pcb manufacturer that can deliver your PCBs on time.  So be sure to ask about lead times when getting quotes from 4-layer board manufacturers.

– Minimum order quantity:   Many 4-layer circuit manufacturers have an MOQ, so be sure to find out what the MOQ is for the 4-layer pcb manufacturer.

– Service:  Last, you’ll want to find a 4-layer PCBs manufacturer that provides good customer service. 

With these things in mind, you should be able to find a 4 layer PCBs manufacturer that is right for your project.

Summary

4 Layer PCB: Circuit boards populated with some components

Circuit boards populated with some components

PCB fabrication is a complex process that can be difficult to understand. We’ve walked you through the basics of each layer and what happens during the fabrication process. Now that you have a basic understanding, it should be easier to communicate with your fabricator about your project. If you still have questions or need help getting started, our team is here to assist you. We look forward to working with you on your next PCB project!

Hommer Zhao
Hi, I am Hommer, the founder of WellPCB. So far, we have more than 4,000 customers worldwide. If you have any questions, you can feel free to contact me. I really appreciate any help you can provide.

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