High-Quality Layer Stack-up

Layer stackup is an essential part of PCB fabrication process.

So, before starting your next PCB fabrication project, read this guide.

It answers all questions you have about PCB layer stack up.

Keep reading to learn more.

What is a Layer Stackup?

PCB layer stack up photo courtesy

Layer stackup is an arrangement of insulating layers and copper layers that make up a printed circuit board.

You will use a PCB layer stackup in before you come up with the final printed circuit board design and layout.

Why Do You Need Layer Stackup?

As soon as you start making plans on the type of printed circuit board, you need to know the structure.

Part of the information you need to know about the structure is the size of the printed circuit board.

This involves knowing the number of layers that you will have on the printed circuit board.

The main reason behind knowing the layer stackup is to have a good plan on the type of PCB you need.

You will be in a better position of designing a proper substrate with minimal complications during the application stage.

Apart from that, you will have a better configuration as an important aspect on making the printed circuit board.

You will decide on whether you will use 4 layers or 6 layers and how the distribution of signals will occur.

Multilayer PCB

What are the Standard Dimensions of the Layer Stackup?

You can have the printed circuit board with number of layers ranging between 2 to 16 layers.

In the standard dimensions of manufacturing, you can choose from the number of layers that you need.

Apart from that, you should also look at the thickness of the board that you would like to make.

The thickness of the printed circuit board can range from between 0.4 mm to 3.0 mm.

On top of that, we also look at the thickness of the materials you will be using to manufacture layer stackups.

One of the most important considerations about the type of materials is the thickness of copper.

On that note, you should understand that the standard thickness dimensions range between 1 to 4 ounces.

The thickness of the inner layer of copper should range between 1 and 2 ounces.

In addition to that, you have to maintain the minimal spacing between the components at 4 mil.

In case you do not want a custom layer stackup, then, you can choose from the standard dimensions we produce.

Dimensions of 4 layer PCB

What are the Advantages of Using the Layer Stackup Design?

Having more than one layer on the printed circuit board will increase the ability of the board to increase energy flow.

Apart from that, the printed circuit board will prevent any form of cross-interference during the application stage.

In addition to that, you will have a printed circuit board that does not experience electromagnetic interferences.

With most of the interferences out of the way, you will have a printed circuit board that performs at high speeds.

This is because of the fact that you will have multiple electronic circuits on the PCB by increasing number of layers.

On top of the above benefits, here are other benefits that you will experience with the layer stackups.

Minimize Circuit Vulnerability

With the layer stackup, you will minimize circuit vulnerability to noise that comes from external sources.

Apart from that, it will minimize cases of radiation while decreasing crosstalk and impedance problems under high-speed applications.

Low-Cost Production

Having a good printed circuit board layer stackup will also help in eliminating the high cost of making PCBs.

It will place multiple circuits on one board thus streamlining production, reducing waste and the overall cost of production.

Improve Electromagnetic Compatibility

You will also be in a better position to operate machines that have great electromagnetic compatibility.

There will be very minimal interferences thus increasing the efficiency of operating the layer stack ups.

What are the Most Significant Factors to Consider When Dealing with Board Stackup?

You need to be very careful especially when you are making or dealing with the board stackup.

This is an important factor that should help in preventing mistakes that increase circuit noise and radiation.

To avoid making such mistakes, you have to consider particular factors when dealing with the stackup of the boards.

Here are the main factors to consider to avoid making mistakes on the printed circuit board layer stackups.

Number of Layers

Multi layer PCB

You have to know the number of layers that you will have on the printed circuit board depending on application specifications.

With this knowledge at hand, you will be in a better position to determine the final outcome of the entire process.

Types of Plans

You must also have knowledge about the types of plans that you will use on the power and ground plans.

Apart from that, you have to understand the right number of plans that you need for your PCB layer stack applications.

Sequence and Sorting of Levels

Here, you should know how much sorting and sequencing levels you will involve in the manufacturing of the layer stackups.

This is a very important aspect that will vary according to the number of layers and type of plans you have.

Spacing

You have to be very careful about the levels of spacing between the layers on the PCB layer stackup.

Of course, the level of spacing will also go hand in hand with the performance outcome you expect from the PCB.

Which Considerations Do You Look at When Deciding on Number of Layer?

There are very few considerations that people place on the other factors other than the number of layers.

When considering the number of layers on the PCB stackup there are different things you need to know.

Here are the main factors to consider when looking at the number of layers on the layer stack up.

 Number of layers in PCB

Number of Signals

You should look at the number of signals that you will have on the entire printed circuit board.

In addition to the number, you must also be considerate of the cost of signals to route on the PCB.

Frequency of Operation

You must also know the frequency at which your PCB will operate in relation to the number of layers.

This factor will not only have an impact on the number of layers but also on the number of signals.

Emission Requirements

You should also determine the impact that the PCB will have on the environment in terms of emissions.

In this case, you need to classify the emissions under Class A emissions or under Class B emissions.

Position of the PCB

Here, you will look at the location of the PCB and determine whether it will be in a shield container or not.

You will have more freedom to have more layers on the PCB in case you position it within a shield container.

EMC Regulations

You must also know if the design team handling the PCB have the right knowledge on EMC rules and regulations.

It is very important to work with a team of designers who understand the basics of EMC regulations and rules.

You should note that all the above factors are important when considering the number of layers stackups.

As a rule, the higher the number of layers stackup, the lower the noise that you are likely to experience.

Are There Rules and Criteria for Management of Good PCB Layer Stackup?

Absolutely, we have rules and regulations that govern the management of the printed circuit board stackups.

You have to follow these rules and regulations for proper management, maintenance, and performance of the PCB layer stack up.

There are numerous rules that you ought to follow for the good management of the PCB layer stackup.

Here are the main ones that will apply in most of the applications.

• You should consider using the ground plane boards because they give way to signal routing in strapline or microstrip configuration.

It will also help in reducing ground impedance as well as the ground noise on a fairly significant level.

• You should route high speed signals on intermediate layers that you will find between various intermediate levels.

This will enable the ground planes to act as shields and block the radiation that comes from tracks at very high speeds.

• You must also place the signal layers at points where they are very close to one another.

There are, however, no exceptions to this rule as it includes adjacent planes as well.

• In addition to that, you must always place the signal layer at an adjacent point to the planes.
• You should consider using multiple ground planes due to the numerous advantages that come with it.

It will help in lowering the ground impedance and reducing radiation in the most significant manner.

• You must also consider rigorous coupling together of mass and power planes.

The best mode that you can employ to achieve the above strategies is by using more than 8-layer stackups.

If NOT, you will have to modify or bend the rules to fit your application requirements.

Here are some of the alternative rules you can follow.

• You can implement a cross-section which will prevent different forms of deformation on the layer stackup.
• You should also have a symmetric configuration such as having a plane layer on level 2 and 7 on 8-layer stackups.
• You can improve EMI and noise performance by making the insulation between signal layers and adjacent planes thinner.
• You must also consider the electrical, thermal, chemical and mechanical properties when selecting the right materials.
• In addition to that, you should also choose a very good software to help you with the designing process.

What is the Significance of Careful PCB Layer Stackup Design?

You have to be extra careful during the designing process of the PCB layer stackups.

Designing the PCB layer stackup is an art that will give you the best blueprint for your printed circuit board.

A good design will increase electrical performance, power delivery, signal transmission, as well as long term PCB reliability and performance.

You will also be in a better position to plan and budget the cost of manufacturing the PCB layer stackup.

It will also have an impact on the price as well as delivery time as soon as the manufacturer receives the final design.

How Many Layers Should You Have on the PCB Layer Stackup?

Well, a PCB layer stackup simply means having more than one layer that make up the printed circuit boards.

Implying that, you can have numerous layer stackups that make up the printed circuit board according to application specifications.

In other words, it is a multilayer printed circuit board that can have 2, 4, 6, 8, 10-, 12-, 14- or 16-layer stackups.

Multilayer PCB

You should also note that every layer on the stackup represents a series of wire connections.

The more wire connections you want on your PCB, the higher the number of layers you ought to have.

It will provide you with a series of conductor patterns which must be an even number including two outer layers.

Due to lamination, you might go through a hard time trying to determine the number of layers on a particular stackup.

Which Technologies Do You Use for Component Packing on the PCB Layer Stackup?

Among the most important factors to consider on the PCB layer stackup is the component packing.

Component packing is the process by which you will place components on the different layer stackups.

There are two main technologies that you can follow to help in component packing of PCB layer stackup.

Here are the two main technologies that you have to look at.

Through Hole Technology

This technology involves having components on one side of the PCB while the legs appear on the other side.

Implying that, you will mount the component on one side and then solder the legs on the other side of the PCB.

You will have to drill one hole in the layer stackup for every leg of the component this taking up space.

Apart from that, you will also have fairly large connection points thus making them stronger.

It is the best mechanical mounting technology that supersedes the surface mount technology of components.

In other words, it has the best connectors that will help withstand the mechanical stresses on the PCB.

 Through hole vs surface mount

Surface Mounted Technology

Here, you will mount the legs of the components on the conductor patterns without drilling through holes.

You will have the components on the upper side including the solder legs thus making them easy to lodge.

Implying that, you do not have to drill holes in the layer stack up but just connect them to the surface.

It does not have the same resistance to mechanical stresses as you would experience on the through-hole technology.

In addition to that, the surface-mounted components that you will have are smaller in size than through-hole components.

You will, therefore, have a denser PCB when using surface mount technology than when you are using through-hole technology.

On top of that, surface mount technology also makes the cheapest layer stackups in comparison to through hole technology.

SMD vs THT

What is the Designing Process of the PCB Layer Stackup?

Designing the layer stackup is the first process that you will perform after formulating the idea in mind.

Here, you will be actualizing the idea in your mind on designing software to ensure that it can actually work.

It is the reason why you can make custom layer stackups without going through stressful losses.

Here is a step-by-step process that you can follow when designing the layer stackups.

Step One: System Specification

You will begin with the formulation of the system specification of the layer stack up you would like to have.

Here, you will specify specific functions such as size, cost limits, as well as operating conditions among others.

You can begin the process by drawing a system block diagram detailing the major functions of the system.

You will also specify the relationship that exists between the different systems on the PCB layer stack up.

After that, you will partition the whole system into the number and types of PCBs you need.

As soon as you complete that, you need to determine the technology you will use and the size of the layer stackup.

Finally, you will come up with a schematic that will detail all the requirements of the PCB layer stackups.

The best way of doing this is using computer-aided designs (CAD) among other software in the designing process.

On top of the schematic, you have t simulate the design thus ensuring that the layer stackup will work well.

Step Two: Component Placement

As soon as you complete the first plan, you will proceed with the second plan which involves placing components.

You will place the components on the layer stackup depending on the type of connection you need.

Remember to place them in positions that will enable simple and easy connections of the routing wires.

You should test whether the wire connections will form a bus that works even during high-speed operations.

In other words, you will perform proper scheduling and referencing of the layer components on layer stackups.

Step Three: Routing

This is the point where you will bring the plan into a reality through computer-assisted designs (CAD).

Here, there are sets of rules that specify the minimum and maximum dimensions on the layer stackups.

These rules will also determine the mechanical, electrical, chemical, and thermal properties of the layer stackups.

You will follow the rules in terms of the speed of the circuit and the power of signals running through the layer stackups.

Apart from that, these rules will ensure that you design a layer stackup that is of very high quality.

Step Four: Testing the Layer Stackup

As soon as every detail is in place, you will have to confirm that the design will actually work.

In this case, you will test the layer stackup accordingly just to ensure that it will work.

If the design passes the function test, you will go ahead and make or create the manufacturing files.

You will produce them in a format which the manufacturer can understand easily.

The most important one is the Gerber file which has most of the details for designing the layer stackup.

What is the Significance of Addressing the Electromagnetic Compatibility Issues?

You have to look at the electromagnetic compatibility during the designing process of the layer stackup.

It is important to consider electromagnetic compatibility (EMC) to reduce electromagnetic energy radiation.

If you do not take that in consideration, you may cause interference that is undesirable to the nearby electronics.

Electromagnetic compatibility is an important aspect that has limits on the following aspects:

• Electromagnetic Interference (EMI)
• Electromagnetic Fields (EMF)
• Radio Frequency Interference (RFI)

With this in place, you will set standards for proper operation of the numerous electronic devices with layer stackups.

It also affects the devices that are closer to the PCB layer stackup thus interfering with the performance.

You have to keep the electromagnetic compatibility in check so as to limit conductive and radiative emission from the devices.

Apart from that, it will also reduce the susceptibility of the design to external sources of electromagnetic interference.

In addition to that, it will reduce susceptibility of electromagnetic field and radio frequency interference.

You can deal with electromagnetic interference by using ground and power planes that shield emission inside metal boxes.

It will help in shielding emission and creating signals layers as the metal boxes shield the components.

What is the Manufacturing Process of PCB Layer Stackup?

With the design in place, you can now proceed with the manufacturing process of the PCB layer stackup.

As soon you receive the design in your hands, you will begin with the testing process.

You must test the functionality of the layer stackup in terms of the application requirements.

If any of the factors are missing from the system, you will have to make the relevant corrections on the system.

In case everything checks out, you will proceed with the manufacturing process.

Here is a step-by-step process that you can follow during the manufacturing process of the layer stackup.

Step One: Preparation Stage

First, you will begin the manufacturing process by preparing every detail that you need for the manufacturing process.

This includes having the right machine for manufacturing the layer stackup and the right materials as well.

The main materials that you will use in this case are glass epoxy substrates and conductive materials such as copper.

You can make the work of preparing all the materials easier by referring to the bill of materials.

Having the bill of materials at hand will detail all the materials, machines, and even processes of manufacturing layer stackups.

As soon as every detail is in place according to the plan, you will proceed to the next manufacturing step.

Step Two: Preparation of Base Materials

This is the step where you will create the main foundation of the layer stackup.

Here, you will begin with the process of making the base materials for manufacturing the layer stackup.

With the materials at hand, you can make the layer stackup using glass epoxy materials.

It is the best type of material for the substrate because of the mon-conductive or insulation nature of the materials.

In addition to that, it has great glass transition temperature which allows it perform well even under high temperatures.

In reference to the manufacturing details, you will proceed with the process by cutting the substrate into the right size.

You should also remember that the thickness of the substrate also matters and you have to take care of it.

Step Three: Imaging

You will proceed to imaging which involves the formation of the conductor patterns.

The conductor patterns will provide the connection between all the components on the layer stackup.

In other words, you will have to establish the electrical connection between every aspect of the layer stackup.

You can employ the subtractive transfer technique of the pattern or artwork into the metal conductors.

Here, you will cover the entire base substrate with thin copper films before removing the superfluous copper.

You can also employ the additive pattern transfer technique in this process even though it is not as common.

The main process of imaging begins with cleaning the surface of the substrate and then applying a photoresist film.

After that, you will place a mask or the photo plot of artwork over the photoresist film before exposing the photoresist film.

As soon as you expose the photoresist film, you will proceed with the development of the photoresist image.

As soon as that is complete, you will transfer the pattern to the copper film and perform etching.

To complete it, you will strip off the photoresist thus leaving the pattern that you so desire.

In this case, you will add copper on selective areas such as the parts where the connective or conductive wires should form.

In case you are making layer stackups with double sides, you will have to cover the base substrate on every side.

You will still use copper as the main base material for covering the base on both sides of the substrate.

Since we are making a layer stackup, it simply means that we will have multiple layers of the substrate.

Here, you will make numerous copies of the same depending on the number of layers you want on the layer stackup.

You will make them and restrain from piling them together until a later stage when every detail is in place.

Step Four: Drilling Holes and Planting Components

Since we are making a multilayer printed circuit board layer stackup, with blind or burred vias, you will isolate the layers.

In other words, you will ensure that you complete the drilling process.

Planting of holes and plating on every layer.

You can also opt to laminate the layers together first before you begin the drilling and plating process of the holes.

There are special machines that you will use in the drilling process of the holes on every layer of the PCB.

You should also choose the right drill files which will help you with the right drilling size on the drill holes.

After drilling, you must plate the inside of the holes according to the plated through hole technology.

Plating of the holes will create an electrical connection through the entire layer and also through the conducting materials.

You must also remove any drill smear within the holes of the layer stackups before plating can start.

It is important to remove the drill smear because it usually covers the conductors within the inner layers.

The process of removing the drill smear and plating of the layers are chemical processes.

Step Five: Lamination Process

This is the point where you will place every layer of the PCB on top of another to form the layer stackup.

Here, you will use an insulating film in between every layer to glue them together thus making multilayer stackups.

In case you have holes that go through every layer, you will have to repeat the whole drilling and plating process.

As soon as you complete the lamination process, you will proceed with placing the conductor patterns on the surface layers.

You will do this by emulating the imaging process which places the conductor patterns on the two outer layers.

Step Six: Solder Mask Application

At this point, you will proceed with the application of the solder mask over the wires on the outer part.

This will help in preventing the solder from attaching on the outer part of the solder pads.

After that you will print the silk screen for labeling purposes and then plate the edges with gold for high quality connection.

You will complete the whole process by testing the layer stackups to ensure that they are working perfectly.

Which Factors Should You Consider to Reduce Manufacturing Cost of PCB Layer Stackup?

PCB layer stack up

Another important aspect of using the printed circuit board layer stackup is the cost of manufacturing.

You will have to consider every aspect of cost and how much money you can save on the PCB layer stackup.

You have to consider quite a number of factors to ensure that you make the cost of PCB layer stackups low.

Here are some of the factors to consider in order to reduce the cost of manufacturing PCB layer stackups.

Dimensions of the PCB Layer Stackup

You should consider looking at the PCB layer stackup size as one of the most significant factors affecting the cost.

Of course, the bigger the size of the layer stackup, the higher the amount of money that you will pay for it.

The number of layers on the PCB layer stackup also plays a very significant role in the cost.

Mode of Production

It is also very important to choose the right mode or technique of manufacturing the PCB layer stackups.

For instance, using through hole technology will cost you more than using surface mount technology.

In this case, you will also have to look at the quality as through hole technology creates mechanically stronger components.

Number of Vias

Generally, an increase in the number of vias on the printed circuit board layer stackups generates more costs.

You will also pay a lot more for the buried vias in comparison to the vias that go through all the holes.

Testing Process

There are numerous tests that you should also have a look at especially when testing the layer stackups.

You will understand that different testing techniques such as flying probe testing technique will cost you a lot more than others.

In a nut shell, you will have to budget for the production of the layer stackups before you proceed with the manufacturing process.

How Do You Select the Right Materials for PCB Layer Stackup?

You will use different materials in the manufacturing process of the PCB layer stackups.

The choice of materials that you will use will depend on the application specifications.

Implying that, you will have to use materials with the properties you desire of the final application.

Here, you will look at the physical properties, chemical properties, thermal properties, and the electrical properties.

What is the Significance of Material Loss Considerations?

In addition to that, you will also consider the loss properties of the materials.

It is important to address the material loss considerations in order to prevent malfunctions on the final application.

Apart from that, you have to look at material loss considerations to improve the efficiency of operating the PCB.

You can mitigate the losses that you might experience with the materials, by looking at specific factors.

Some of the factors that you will have to look at during the materials selection process are:

• Relative Dielectric Constant
• Loss Tangent
• Composition of Fiberglass Weave
• Skin Effect

Looking at such factors, you will note that they have significant impact on the properties of the materials.

It will affect the electrical properties thus important for consideration during the designing process

What is the Consideration of Glass Transition Temperature on PCB Layer Stackup?

You should also look at the thermal properties of the materials that you choose for the PCB layer stackup.

Among the most important thermal properties that you will look at are the glass transition temperature.

Glass transition temperature (Tg) is an important consideration because it rates the maximum operating temperature.

TG PCB

It will inform you of the best temperature range of operating the PCB layer stackup without causing damages.

In other words, it is the maximum temperature where the glass epoxy materials will change from hard to soft.

Usually, beyond this temperature, you will experience a soft rubber-like feeling on the layer stackup.

It is also a very important aspect that will inform you of the temperature limits during the manufacturing process.

What are Signal Layers on the PCB Layer Stackup?

In case you are working on high-density layer stack-ups, you must have numerous signal layers for full breakout.

It is a matter of doing the right calculations and getting the right number of signal layers you need.

As soon as you have the right number of signal layers for your layer stackup, you must arrange them properly.

You must also have a plane layer to provide proper current return path and maintain impedance control.

Depending on the stripline or microstrip topology, you will choose from the numerous signal layers available.

What is the Plan for the High-Speed Signal Layers for PCB Layer Stackup?

Well, it is very important to have a plan that will guide you through the implementation of particular factors.

A good plan will enable you achieve the right goals thus the importance of planning for high-speed signal layers.

In case of limited transceiver channels, you can assign few signal layers for all the channel routes.

This will help you minimize the stubs on the through vias as well as eliminating the additional cost of back drilling.

On the other hand, in case you need high channel counts, you will have to increase on the number of layers.

Increasing the number of layers will help you come up with a significant mode of accommodating the signal layers.

In such a case, you must include back drilling and blind vias to help in the mounting process and signal accommodation.

What are the Main Components of the PCB Layer Stackup?

During the designing process of a PCB layer stackup, you have to include every possible aspect or component.

With the help of a good design software, you are in a better position to create and implement all the components.

Here are the main components that you must have on the printed circuit board layer stackup.

· Top Layer

This is the upper most part of the printed circuit board layer stackup where you will mount the main components.

It will also have the solder mask, surface finish, and also the main components of the PCB layer stackup.

Prepreg

After the top layer, you will have the prepreg which is a non-conductive material that forms part of the substrate.

It has great thermal properties such as glass transition temperature as well as proper insulation to prevent leakage.

Ground Plane

This is the flat or nearly horizontal flat surface that conducts electricity and signals thus acting as part of the antennae.

It will also help in reflection of signals and radio waves that may interfere with the normal operations of the PCB.

Core

This is the glass like rigid surface at the center of the layer that provides the main foundation for the layer stackup.

Usually, it is at the center of the layer with non-conductive properties and is covered with conductive materials such as copper.

Inner Layers

This is the inner part of the layer stack up which has more or less similar components as the upper layer.

You can have numerous inner layers with the prepreg, conductive materials, and the core depending on the application.

Power Plane

You can also refer to this as the main conductive materials on the printed circuit board layer stackup.

It is a copper material that will supply or conduct electric current through the layer stackup thus enabling communication.

Bottom Layer

Just like the upper surface of the PCB layer stackup, we also have the bottom layer of the PCB layer stackup.

It also has a few components with proper lamination and conductive materials that enable efficient function ability.

Which Methods Do You Employ to Adjust Copper Thickness of PCB Layer Stackup?

Definitely, you will need a PCB maker to help you in the manufacturing process of the PCB layer stackups.

It is a machine that will also help in adjusting the normal sizes of the layer stackup materials.

You will use the PCB maker to adjust copper thickness using two different methods.

Here are the two main methods of adjusting the thickness of copper according to the application specifications.

Interlayer Offset Technique

Here, you will not use the choked flow pad but instead use the resin recession groove in designing the board side.

For proper positioning, you will employ rivet plus hot melting which will help solve the problem of stackup offset.

Stackup Misalign Technique

Here, you will add silicon pads and epoxy plates to balance the pressure during the process of board arrangement.

This will help in the elimination of stackup measles and control the uniformity of the thickness on the layer stackup.

Why Should You Determine Sets of Signal Layers that Need Adjacent Ground Reference Layers?

It is very important to determine sets off signal layers that need adjacent ground reference layers.

Here are the reasons why you should determine the sets of signal layers that need adjacent ground reference layers.

Controlling Impedance

You should determine sets of signal layers in such a situation to help in controlling of impedance on the layer stackup.

Here, you will place the signal traces and ground planes near one another to define the impedance of different traces.

Planning Return Paths

It will also help in planning of the right return paths for signals in high frequency or high-speed systems.

You will be in a better position to experience small loop inductance for all the traces on your board and prevent crosstalk.

Suppressing Electromagnetic Inductance (EMI)

You will also help in the suppression of electromagnetic inductance (EMI) radiated from external and internal sources.

You will achieve this through placement of ground planes near the most sensitive signals on the layer stackup.

Assists in Isolation

In case you are using mixed signal boards, you will have to isolate the digital signals from the analog signals.

You will place them in different positions and the isolate them with ground planes thus suppressing digital signal noise.

How Does Power Integrity and PCB Layer Stackup Design Relate?

In case you want to reduce voltage ripple and jitter, it is important to have a ground plane close to power planes.

This will help in solving the problem of impedance on the PCB layer stackup this increasing power integrity.

What are Some of the PCB Layer Stackup in the Market?

Well, there are numerous types of multiple layer or PCB layer stackups.

You will differentiate every aspect of the layer stackups by looking at the number of layers.

Here are the main types of layer stackups that you can choose from.

• 4 Layer Stackup
• 6 Layer Stackup
• 8 Layer Stackup
• 10 Layer Stackup
• 12 Layer Stackup
• 14 Layer Stackup
• 16 Layer Stackup

In addition to that, you can have custom layer stackups that can go to as much as 100 layers.

What are the Significant Features for PCB Layer Stackup Design Tools?

During the designing process, there are quite a number of tools that will help you align the components better.

It will help you come up with the best PCB layer stackup and prevent any damages along the way.

Here are the main tools that you must have on your designing software.

Layer Stackup Generators

You should have the layer stackup generators in place to help in generating the number of layers that you need.

It will use the values that you enter into the software to help in proper generation of the layer stackups.

Alongside the number of layers, you have the freedom to enter the type of materials, dimensions, as well as characteristics.

Impedance Calculators

Your layer stackup design tool must also have impedance calculators that will help in calculating the right size for impedance control.

Using the results from the layer stackup generators, the impedance calculators will provide the right specifications.

In other words, you will have the right knowledge on how to control impedance from the size of layer stackups.

Circuit Analyzers

You will use the circuit analyzers to provide quite a number of factors on the layer stack up such as:

i. Crosstalk

ii. Signal Integrity

iii. Power distribution

iv. Return Path Integrity

v. Main Design Performance Metrics

It will also make it easier for you to know whether you need additional layers on the layer stackups.

Which Tips Should You Follow When Coming Up with Layer Stackup Designs?

Designing the PCB layer stacks may not be as easy as you think it would be.

Well, despite the difficulty, there are particular tips that you will follow to help in the designing process.

In addition to the design software, here are the tips that you can follow to help in the designing process.

Determine Right Number of Layers

First, you must determine the number of layers that you will want to have on your layer stack up.

Here, you will look at various aspects such as low speed and high-speed signals, ground or power planes.

You must, however, be very careful and prevent any form of signal mix in the inner layers of the layer stackup.

Determine the Layer Arrangement

In this case, you need to determine how you will arrange the layers on the layer stackup.

Here are the rules that you will follow when arranging the layers on the layer stackup.

i. Make sure that you have the minimum thickness microstrips and route them with high-speed signals

ii. You should place the signal layers next to the interlayers of power to enable tight coupling.

iii. You should also make sure that the ground and power planes have minimal spacing in between.

iv. It is important to keep all the signal layers away from each other and not close together.

v. You should also make sure that the stackup is symmetric from the top to the bottom

Determine Types of Materials for Layer Stackup

Here, you will have to determine the signal that you want of every layer by looking at the type of materials.

It is also very important to consider the thickness of the materials you are using on the layer stackup.

Determine the Right Vias and Routes

 Types of vias

You should also determine and rout the traces as well as the vias on the printed circuit board layer stackup.

Here, you will determine particular factors such as:

i. Weight of Conductive materials such as weight of copper

ii. Position of the vias

iii. Type of vias

Which Quality Specifications Govern Manufacturing of PCB Layer Stackup?

One of the other significant factors that you have to pay close attention to is the quality of layer stackups.

This is, however, quite simple to consider especially due to the fact that there are international quality specifications.

Here are the main quality specifications that you ought to pay very close attention to.

• ANSI/ AHRI Quality Certifications
• CE Quality Certifications
• RoHS Quality Certifications
• International Standards Organization (ISO) Quality Certifications
• UL Quality Certifications

What are the Main Applications of the PCB Layer Stackup?

You will use the PCB layer stackups to perform or manufacture a printed circuit board.

With the printed circuit board, you can manufacture different machines for different industries.

Here are some of the industries where the layer stackups come in handy.

• Medical Industry
• Automotive Industry
• Aviation Industry
• Manufacturing and Processing Industry
• Electronics Industry

What are the Main Specifications of Selecting the PCB Layer Stackup?

You have to be very specific on the type of PCB layer stackup that you want to have.

The best mode for selecting the best PCB layer stackup is by looking at the specifications.

Here are the specifications that you will look at in order to get the best PCB layer stackup.

Board Thickness Tolerance

You have to have specific dimensions on board thickness tolerance according to the type of stackup you need.

The board thickness tolerance can range from less than 1 mm to more than 1.6 mm depending on your needs.

Minimum Board Thickness

You will also look at the minimum board thickness when selecting the PCB layer stackup.

Here, the minimum board thickness will vary depending on the number of layers you have on the board.

Type of Materials

You must also specify the type of materials that you will use in the manufacturing process of the layer stackups.

In this case, you will look at specific features of the materials such as:

i. Board materials which can be TG-170

ii. Loss Tangent @ 1 MHz which ranges between 0.016 and 0.020

iii. Loss Tangent @ 1 GHz ranging between 0.012 and 0.014

iv. Permittivity of Dielectric Constant @ 1MHz ranging between 4.3 to 4.5

v. Permittivity of Dielectric Constant @ 1GHz ranging between 3.8 to 4.0

vi. Lead Free Assembly

Solder Mask Material Specification

In this case, you will look at three most important factors which determine the solder mask materials specifics.

Here are the three main determinants of solder mask specifications.

i. Type of solder mask which can be a 2-component liquid photo imagable solder mask

ii. Initial insulation resistance at 2.8 x 10¹³Ω and conditioned resistance at 2.5 x 10¹²Ω.

Do You Have Custom PCB Layer Stackup?

Yes, we have custom PCB layer stackup that we manufacture according to your specifications.

You have the opportunity of coming up with unique designs of the layer stackups.

In this case, you will have to determine the right number of layers that you want on the PCB.

Apart from that, you will determine the dimensions in terms of size and thickness.

In addition to that, you will dictate the components that we will place on the custom PCB layer stackup.

What Does Splitting Interconnect Blind Vias Into Stackup Vias Involve?

You may think that the manufacturing process of the PCB layer stackup is harder than it actually is.

To make work easier, the best solution to this problem is to split interconnect blind vias into stackup vias.

For instance, you may have a challenge when it comes to placing vias on a 4-layer stackup.

This happens, especially when you want to have vias on layers 1 – 2, 1 – 3, 4-3, and 4 – 2.

As much as it may seem different, the reality behind it spells no difference in the process.

In that line, the best solution is to split the vias and then stack them to interconnect blind vias into stackup.

In this case, you will split the 1 to 3 drill and begin with the 1 and 2 then proceed to the 2 and 3.

In case of the 4 to 2 drill, you will split it into 4 and 3, and then 3 and 2.

After that you will proceed with the stacking process in a particular order beginning with the 1-2 over 2-3.

On the other hand, you will begin with the 4 – 3 and then proceed to the 3-2 drill.

Which Options Do You Have for Filling Vias on the Layer Stackups?

There are quite a number of options that you can use to fill vias on the layer stackups.

You will begin with filling the vias on the inner layers allowing the laser to reflect from the smooth surface.

In case you fail to do so, you will have dimples on the via hole location thus leading to voids on the final stackup.

You can, therefore, proceed with the filling process using one of the following methods.

• Filling with Resin
• Non-Conductive Via Fill (NCVF)
• Copper Fill

In most applications, you will have the copper fill as the most common type of filling vias on layer stackups.

This is because coper is the best thermal conductor despite the fact that it will cost you more.

In terms of cost, you should consider resin fill which acts as the most economical mode of filling.

What is Multiple Lamination Cycle for Layer Stackups?

 PCB lamination

Lamination is the process of pressing multiple PCB layers together with plating on the outside.

In this case, you will have to add more lamination cycles when splitting interconnect vias into stacked vias.

You will, however, pay more for the multiple lamination cycles because it increases the manufacturing processes.

Multiple lamination is the best process that you can use in the lamination process of multiple layer stackups.

Do You Perform Back Drilling on the Layer Stackups?

Yes, we do perform back drilling on the layer stackups.

This is the process we use to drill all the layers on the layer stackup in a straight-line using control depth drilling.

In this drilling process, you will drill all the layers from one side to the other and sever all the unnecessary connections.

For instance, in case you are drilling a 6-layer stackup, you will begin with drilling straight from layer 1 to 4.

After that, you will back drill by flipping the back side and then drill from layer 6-3, 6 -4 and 6-5.

This drilling process will help in serving all the connections that are not wanted.

It is also the best form of drilling that you can perform on control depth drilling without spending too much.

It is, however, the most economical method to use when the printed circuit boards do not have tight pitch BGAs.

What are the Most Common Drill Sizes on the Layer Stackups?

Well, there are numerous drill sizes that you can have on the layer stackup depending on application specifications.

In case you are drilling microvias, you have to make sure that the size of the drill is greater than dielectric thickness.

You can opt to have the thickness of the dielectric at 1 mil lesser than that of the microvias.

Aspect ratio of the layer stackup will determine the mechanical drill size.

In this case, you will look at the ratio of drill size to the ratio of board thickness.

Here is a table with details on the mechanical drill sizes that you can opt for.

At Venture Electronics, we will help you choose a perfect PCB layer stack up, depending on your unique requirements and specifications.

So, if you have any question or inquiry about PCB layer stack up, contact Venture Electronics team now.