Blog  /  2 Layer PCB: What You Need to Know

2 Layer PCB: What You Need to Know

When it comes to PCBs, there are a few different types that you might encounter. One of the most common is the 2 layer PCB. This type of PCB has two layers of copper foil, which get separated by a dielectric material. In this blog post, we will discuss some of the key things you need to know about 2 layer PCBs!

What is 2 layer PCB/double-sided PCB?

 
Integrated Circuit Board of a Hard Disk

Integrated Circuit Board of a Hard Disk

2 Layer PCBs are the most common type of PCB. Plus, 2 layer PCBs are also known as double-sided PCBs because they have components on both sides of the board.

The 2-layer pcb fabrication is by bonding two layers of copper together with a dielectric material in between. And the dielectric material can be either an FR-42 or an FR-44.

Furthermore, the copper on each side can carry different electrical signals, which makes them ideal for applications where high speed and/or dense packaging is necessary. 2 Layer PCBs are also the most economical type of PCB to manufacture.

How does a double-layer PCB work?

 
pcb prototyping

pcb prototyping

A 2 layer PCB works by having electrical signals routed between the two layers of copper. Interestingly, these signals can be either digital or analog. Plus, the dielectric material in the middle of the board helps to keep these signals from interfering with each other.  

2 Layer PCB Thickness

 
Electronic printed circuit boards

Electronic printed circuit boards

So how thick is a 2 layer PCB?

A 2 layer PCB can be anywhere from 0.010” to 0.060” thick. In addition, the thickness of the board will depend on the dielectric material that you use and the size of the components mounted on the board. Also, the thicker the board, the better it is at reducing crosstalk between the signal traces.

2 layer board stack-up

2 layer stackup

2 layer PCB stack-up

It's clear that layer 1, or the top layer is a signal layer on the 2 layers PCB stack up. Both the top layer and the bottom layer are copper layers.

inner layer

 
Electronic printed circuit board bottom layer

Electronic printed circuit board bottom layer

The 2-layer pcb has an inner layer which is also a copper layer. And this is where most of the vias get located. Plus, vias are the tiny little holes that connect the top and bottom layers together. More importantly, they allow for electrical signals to flow from one layer to another.

ground plane

The solid ground plane is to help reduce noise in electrical signals. Therefore, we can also use it to provide a place for the electrical signals to return. Besides that, it also helps to distribute heat better, and you can use it as a power or ground layer.

signal layers

The signal layers are the layers that carry the electrical signals. The 2 layer PCB has two signal layers, one for the top and one for the bottom. Usually, the top layer that we use for the signals that need to be routed on the outside of the board. While the bottom layer, you can use for the signals that need to be routed on the inside of the board.

power layer

The power layer we use to distribute power to the different parts of the board. Also, you can use it as a return path for the ground signals.

prepreg layer

The prepreg layer is a thin layer of dielectric material. And it can provide insulation between the copper layer. Besides, it can also provide support for the copper layers. The dielectric constant of the prepreg layer is 2. 2, which is lower than the FR-408 dielectric constant.

solder mask layer

The solder mask layer is a thin layer of material that covers the exposed copper. In addition, it can protect the copper from oxidation and corrosion.

silkscreen layer

The silkscreen layer is a thin layer of material that is used to print the legends on the board. Also, you can use it to print the board's name and part numbers.  

How do You Make a 2-layer PCB /double-sided Circuit Board?

 
Vision measuring instrument inspecting PCB circuit board

Vision measuring instrument inspecting PCB circuit board

 

To make a 2 layer PCB, you need to start with a substrate. And the most common substrate is FR-4. Once you have your substrate, you need to add the copper in layers.

The first layer you added is the signal layer. This is where it will carry the electrical signals.

The second layer you added is the ground layer. And this is where the electrical signals will return to it. Once you have your two copper layers, you need to add the prepreg layer.

The prepreg layer is an insulating material. As a result, It provides insulation between the layers.

After the prepreg layer, you need to add the solder mask. The solder mask is a thin layer of green or black plastic that helps to protect the copper from short circuits and corrosion.

Finally, you need to add the silkscreen. The silkscreen is a white or yellow printing on the PCB that shows the name of the components and their values.  

2 Layer PCB Price

 
Digital circuit board with microchips

Digital circuit board with microchips

The price of a 2-layer PCB will vary depending on the size of the board,  the complexity of the design, and the quantity that you order. Plus, 2-layer PCBs are typically more expensive than single-sided board because they require more materials and labor to manufacture.

The cost of a 2 layer PCB can range from $100 to $1000 per square foot. So, if you need a 2-layer PCB that is 2 feet by 2 feet, it would cost between $400 and $4000.

Double-sided PCB uses

  Electronic circuit board

Electronic circuit board

The most common use for 2 Layer PCBs is in electronic devices that require high-speed and/or dense packaging, such as:

-Computers

 
Using the computer

Using the computer

-Servers

-Cellular phones

A young adult using a smartphone

A young adult using a smartphone

-Tablets

Set of tablet computers

Set of tablet computers

-Medical devices

-Industrial control equipment  

2 layer pcb design Method

 

Electronic circuit

Electronic circuit

 

There are two main methods for manufacturing 2 Layer PCBs: through-hole and surface mount. In truth, through-hole 2 Layer PCBs use the method of drilling holes into the board and then soldering parts into those holes. However, surface mounts 2 Layer PCBs we make by soldering parts directly onto the surface of the board.

2 Layer PCB vs. 4 Layers Printed Circuit Board

 
Blue prototyping PCB in a hand

Blue prototyping PCB in a hand

Compared to 4-layer PCB, 2-layer pcb has some advantages and disadvantages. The 2-layer pcb is less expensive, but it does not offer as much flexibility in terms of design. In addition, 2-layer pcb is also easier to manufacture, which can be an advantage if time is of the essence.

Advantages:

- Firstly, it is less expensive

-Also, it's easier to manufacture

Disadvantages:

- Limited design flexibility

2 layer pcb is the most common type of PCB, and it is used in a wide variety of applications. If you are looking for a less expensive option, or if time is of the essence, 2-layer pcb may be the right choice for you. However, if you need more flexibility in terms of design, you may want to consider a different type of PCB, such as 4 layer PCB.

The Double-sided PCB Manufacturing Process

 
Electronic embedded system design process PCB layout routing ove

Electronic embedded system design process PCB layout routing ove

The 2 layer PCB manufacturing begins with the preparation of the copper clad.

The copper gets etched away to leave only the required traces and vias.

And this is usually done using a photo-plotter and dry film.

After the etching process, you should drill the board with small holes so that you can plate the vias and through holes with copper.

The next step is to apply a solder mask which will protect the exposed copper and prevent the solder from shorting between the traces.

The final step is to apply a silkscreen which will identify the different parts on the board.

With the 2 layer PCB manufacturing process, you can have your boards made quickly and easily. Also, you don't have to worry about soldering or drilling because it's all done for you. And all you need to do is choose the right 2-layer PCB for your project.

What is the difference between single and double-sided PCB?

  Assembling a circuit board

Assembling a circuit board

 

In this section, we will discuss single-sided vs double-sided pcb.

Firstly, single-sided PCBs have conductive traces on one side of the board only. While the other side is usually common for grounding purposes. This type of PCB is cheaper and easier to manufacture than double-sided PCBs. But it has limited space.

However, double-sided PCBs have conductive traces on both sides of the board. Therefore, this allows for more complex designs and higher component density. Besides, double-sided PCBs are more expensive and difficult to manufacture than single-sided PCBs.

So, which one should you choose? It depends on your application and budget. If you need a simple board with a few components, a single-sided PCB will suffice. If you need a more complex board with more parts, a double-sided PCB is the way to go.

Benefits of double layer pcb

Obviously, there are many pros to 2 layer PCBs. But the main benefits of 2 Layer PCBs over other types of PCBs are their high speed and dense packaging capabilities. 2 Layer PCBs also have a shorter manufacturing time and are more cost-effective than other types of PCBs.

In short, some of the advantages include:

-Firstly, it increases routing space on both the top and bottom layers.

-Secondly,  a 2 layer board provides for more design flexibility.

-Thirdly, 2-layer pcb can be made smaller in size as well as lighter in weight.

-Fourthly, they offer increased durability and reliability.

-In addition, 2-layer PCBs' signal integrity improves a lot.

-Finally, 2-layer pcb has a lower cost to manufacture than their multilayer counterparts.

Disadvantages of double-sided pcb

The main drawback of 2 Layer PCBs is that they are not as durable as other types of PCBs. In other words, 2 Layer PCBs are also more susceptible to crosstalk and noise than other types of PCBs.

And the disadvantages of double-sided boards are as follows:

-Firstly, they are more expensive to manufacture than single-sided boards.

-In addition, they require more solder mask layers and thus have a longer manufacturing production process.

-Also, the through-hole vias can be difficult to solder.

-Besides, the manufacturing of double-sided PCB is more difficult than that of single-sided PCB.

-Last but not least, the yield rate of double-sided PCB is lower than that of single-sided PCB.

In short, the disadvantages of double-sided PCB include higher price, longer manufacture process, more difficulty to solder, and lower yield rate.

Multilayer PCB

 
Multiplied printed boards PCB

Multiplied printed boards PCB

 

Multilayer PCBs are made up of multiple layers of circuit boards stacked on top of each other. Also, they are the most complex type of PCB and are applicable in high-end electronic devices.

Advantages of multilayer PCB:

-Firstly, they have a higher density of components and traces than single or double-sided PCBs.

-Plus, they can have very thin layers, which helps to reduce the overall size of the PCB.

-Also, they can have very thin and precise traces, which helps to reduce electromagnetic interference (EMI).

Disadvantages of multilayer PCB:

-Firstly, they are more expensive to manufacture than single or double-sided PCBs.

-In addition, they are more difficult to repair if they get damaged.

single-sided pcb applications

single layer PCBs are only one layer, common in many applications,  including:

-Automotive

-Avionics

-Consumer electronics

-Industrial controls

-Instrumentation

-Medical devices

-Telecommunications

-Test and measurement equipment

How to choose 2 layers PCB or four layers PCB?

 
Soldering iron tips of automated manufacturing soldering and assembly pcb board

Soldering iron tips of automated manufacturing soldering and assembly pcb board

The decision of how many layers to use in a PCB is typically based on the following factors:

-Cost

Your budget is important when deciding how many layers to use in your PCB. Plus, 2-layer pcb are less expensive than four-layer PCBs.

-Size

The size of your PCB will also affect how many layers you need. However, larger boards typically require more circuit layers to minimize the risk of signal crosstalk and other issues.

-Complexity

If your PCB is complex, you may need to use more pcb layers to accommodate all the components and traces.   Blue circuit. layout of tracks

Blue circuit. layout of tracks

 

-Thermal considerations

In some cases, thermal considerations may dictate how many layers you use in your PCB.  For example, if you need to dissipate heat quickly, you may need to use a four-layer PCB.

-The density of the component placement

If you have a lot of components on your PCB, you may need to use more pcb layers to accommodate them all.

-Signal integrity

If you are working with high-speed signals, you may need to use more layers to minimize the risk of signal integrity issues.

-Performance

The performance requirements of your PCB will also play a role in how many layers you use. For example, if you need high-speed signaling, you may need to use a four-layer PCB.

-The environment in which the PCB will operate

The environment in which your PCB will operate can also play a role in how many layers you use. For example, if your PCB will be exposed to high temperatures, you may need to use more layers to prevent the board from warping.

In general, two-layer PCBs are the most common type of PCB. They are typically applicable for low-speed applications and are less expensive to manufacture than four-layer PCBs.

If you're not sure how many layers you need, it's best to consult with a PCB manufacturer or design engineer. They will be able to help you determine the best type of PCB for your application.   Chip on Board

Chip on Board

 

-The expected lifetime of the product

The product's expected lifetime will also help determine the number of layers. If you are designing a product that will have a long lifespan, it is important to use materials that will not degrade over time.

This is especially important for products that will be exposed to the elements, such as outdoor products or medical devices.

If you are unsure about the expected lifetime of your product, it is best to consult with a PCB manufacturer or design engineer. They will be able to help you select the best materials and designs for your application.

Size and weight

As the number of layers in a PCB increases, so does the thickness of the finished product. This is due to the need for additional insulation and routing layers between the signal layers. Also, the increased thickness can be a problem when designing products that are size- or weight-sensitive, such as portable electronics.

-Manufacturability

The number of layers in a PCB also affects the manufacturability of the finished product. Generally, the more layers in a PCB, the more difficult and expensive it is to manufacture. This is due to the need for additional processing steps, such as drilling and plating, and the increased complexity of the overall design. Besides, 2-layer PCBs are the most common type of PCB and are therefore the most cost-effective to manufacture.  

Summary

 

The circuit board and schematic

The circuit board and schematic

 

In conclusion, PCBs are an important part of electronic devices and circuits. They provide a platform for components to connect and communicate with each other. While there are many different types of PCBs, the two-layer variety is the most common. This style has been used in countless devices over the years and is still popular today. If you’re looking for a quality PCB that will meet your needs, contact us today. We can help you create a custom board that fits your specific requirements.