What is the 8 Layers of PCB Board?

The 8 Layers of Pcb Board Is?

PCB stands for printed circuit board and it is commonly used in dozens of electric and electronic appliances. Though the whole thing might look small, there is quite a bit of technology and workmanship involved in it. There are many layers that make up any standard PCB. In this article we will look at the various layers. If you ask anyone who knows about printed circuit boards they will talk about 8 layers PCB board. Hence it would be interesting to know more about it from a common man’s perspective.

It is complicated and tough

We need to understand that the more we add layers to something, the more complex it becomes. A simple analogy perhaps can explain it better. Those who take on multiple players in a chess match, have to keep a tab of multiple boards at one go. This is quite complex and this is what happens when we keep adding layers to a PCB Board. There is quite a bit of memorization required but it is not as complicated as 3D chess playing or other such things. Having said this, there will have to be 8 layers of PCB stacking up. This has to be done very carefully and the balancing of designs around EMI is a tricky thing. There are also other elements that have to be taken care of and these include power plans, digital signals, frequency and also analog signals. It calls for the right experience and expertise and we will be sharing a few more interesting facts about it over the next few lines.

Why the need for 8 layers PCB stackup?

Whenever we look at a typical PCB design, it is common to see double layer or single layer PCB being used. It has been found that a double layer PCB is good enough to handle requirements of most projects. If you ask experts they would suggest that it makes much better sense to keep the overall PCB design simple and easy to design. This helps in more ways than one. It brings down the risk of various unnecessary problems. However there could be some situations where there could be a need for multilayer PCB design. This is where 8 layers PCB board requirements become necessary and unavoidable.

When we talk about a multilayer PCB we refer to a PCB that comes with a minimum of three or more conductive layers. These layers are usually sandwiched between the insulative core and the prepregs as far as PCB stackup is concerned. Prepregs are raw materials that are insulated where the core layer has layers of copper attached to it. This helps to improve space on the outer layers and leave space for components to be fixed. It also helps in better heat management and the power plane distribution strength also would increase.

Let us now have a closer look at the 8 different layers as far as any PCB Board is concerned.

• Top layer;
• Ground Plan;
• Prepreg;
• Inner Layer 1;
• Core;
• Prepreg;
• Power plane;
• Core2;

Apart from the above, the signal layers should also be separated so that it brings down EMI susceptibility and also reduces emission.

While the above are common in most PCB, the designers will also take into account the preprags and the various core materials. These are used for the purpose of constructing the multilayer PCB. It also is needed for the 8 layer stackup that we are talking about.

A look at some useful techniques for 8 layers PCB board

It would be wrong to assume that having an 8 layers stack up would be able to solve all the EMI woes. You need to fall back to some best practices so that you are able to get the best out of the multilayer stackup. Here is a brief look at the techniques.

• Re-routing of direction

8 layer PCB consists of important signal players and there are six of them. There is a need to reduce cross talks and this must be done with the help of adjacent layers and it would be better to route them perpendicularly. It would also be advisable to route the various signal layers over subsequent layers even if they are separated by ground planes or power planes.

• Importance of return path

There also is the need to understand the importance of return path especially when it comes to high speed signals. It does not matter even if the signals are located on the inner layers. You must, however, ensure that the signal has a very short return path. It should not also lead to interference when it comes to other components.

• The ground plane

Ask any expert about PCB circuits, they will talk about rule of the thumb. It is all about not having a split ground plane. This is because it may lead to impedance discontinuity. Further, you also must make sure that the various components of the outer layer do not have excess impedance. This happens when they get connected through vias that are attached to the inner ground planes.

• Blind vias

The speed of the routing can also be further increased by going in for blind vias or buried vias as they are referred to. However, there is a need to have the same checked with the manufacturer. The same should be within its capability and should be able to produce the same vias in the PCB.

The importance of having the right tool

The task of designing the right 8-layer PC will become simpler and easier if you have the right software tools. It would be ideal to go in for the right CAD PCB Designer. This will give you better control as far as the layer stackup is concerned. You also should invest in the right DRC tools that will make it easy for efficient production processing and also as far as easy documentation are concerned. Special attention should be paid to simulation tools and other such important things.

The final word

The whole process of putting up eight layers of PCB Board is not easy and it takes quite a bit of understanding of the subject matter. There are many slips that could occur between the lip and the cup and these should always be factored. It would be better to take professional help who will be able to a much better job of it, taking the various things into perspective.

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