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Multilayer PCB and its advantages

In this post today, I’ll walk you through Multilayer PCB in detail.

Printed Circuit Boards (PCBs) are the basic building blocks of most electronic units today, offering a simple and reliable solution to join different electrical components together. The PCB provides mechanical support where all electrical components are connected through conductive signal traces made up of copper. PCBs manufactured in the past were simple single-layer designs – imagine the PCB designs in old TV sets, however, with the recent advent of modern technology and to offer better functionality in less space, PCB designs have evolved. Now you can find Flexible PCBs to acquire certain shapes and the ones installed in supercomputers and motherboards for high speed and greater efficiency.

Different types of PCBs are available including single layer, double layer, multiple layer, rigid, rigid-flex, flexible, and aluminium PCB. In this post, however, we’ll only cover multilayer PCBs and their advantages over other PCBs.

Let’s jump right in.

What is Multilayer PCB?

A multilayer PCB is the type of circuit board that contains three or more layers of conductive copper material.

In double layer PCB, the circuit board contains two conductive layers on the bottom and top of the PCB substrate. A multilayer circuit board has a design similar to a double-sided board but comes with stacked conductive layers on both sides of the board. The layers can be 4, 6, 8… based on the application.

The demand for simple, small-sized, high speed, and densely populated electronic circuit boards has made multiple-layer PCBs popular. The single-layer circuit boards are used in simple electronics that require limited functionalities, however, where the demand of the board goes complex, multilayer circuit boards are used like in computer motherboard.

The minimum number of conductive layers that are laminated and glued together is three, however, based on requirement you can add as many layers as possible stacked on both sides of the board. Know that the maximum number of layers that designers could include to make a multilayer design is 129.

Image of a Multilayer PCB

The commonly used multiple layer PCBs in electronics come with 4 to 8 layers and about 90% of these boards are rigid multilayer boards as the manufacturing of flexible multilayer PCBs is complex, costly, and time-consuming.

The electronic components can be placed on both the top and bottom layers of the board. And the inner stacked layers are used for routing. Both through-hole and surface mount technology (SMT) can be used to solder the electronic components on the board.

Designers prefer laminating an even number of layers together over an odd number since handling the odd number of layers is too complex and can lead to many issues.

Manufacturing of Multilayer PCBs

The multilayer PCB manufacturing process starts with designing the layout of the PCB with the help of PCB designing tools like DesignSpark PCB, Eagle, Proteus, OrCAD.

After creating the PCB layout, you need to create vias.

Construction of a Multilayer PCB

Creating normal vias while manufacturing the multilayer board would cover more space; the reason blind or buried vias are preferred.

The different layers on the multilayer circuit boards are named as different planes such as power plane, ground plane, signal plane, etc.

The multilayer circuit boards are made by combining the number of layers at high pressure and temperature, offering a compact structure by removing any trapped air between the layers.

Adhesive material and resin are used to glue different layers together. Several materials can be used to build multilayer PCBs such as epoxy glass, ceramic, and Teflon.

The lamination process is carried out at high pressure and temperature that combines the prepreg and core layers. After the lamination process, give some time to the melted layers to cool down which adds strength and hardness to the circuit board.

While making a multilayer PCB, when current passes through conductive layers, it can create a magnetic field which may affect the overall performance of the board. To combat this situation, the ground plane is used as a solution that acts as a shield and helps to offer a return path for the unnecessary signals. You need to avoid 90-degree traces to make sure there is no EMI (electromagnetic induction) issue.

Advantages of Multilayer PCBs Over Other Circuit Boards

Some important factors make the usage of multilayer PCBs a common practice in modern electronic units.

  • Multilayer PCBs are preferred over other conventional boards due to their small size. Consider the boards used in smartphones and LCDs; they all use multilayer boards. Earlier 4 to 8 layer multilayer boards were used in mobile phones, the recent smartphone technology uses circuit boards that contain up to 12 layers.

Example of a multilayer PCB design

  • The multilayer circuit boards are highly durable and cost-effective compared to the manufacturing of flexible PCBs.
  • Though the multilayer designs support both through-hole and SMT (surface mount technology), the latter is preferred since it covers less space, making the overall combination of the board and components lightweight. The reason multilayer boards are an ideal pick for small medical devices like heartbeat monitors, blood pressure monitors, and pacemakers.
  • These boards support high component density which means you can place several electrical components in a small space.
  • Multilayer circuit boards high speed and high capacity in a single compact package which makes these boards a right fit for complex electronic design circuits.

Applications of Multilayer PCBs

The applications of multilayer PCBs include:

  • Cell phone transmission and GPS technology
  • Industrial controls and Nuclear detection systems
  • Satellite systems and Central fire alarm systems
  • X-ray equipment and Test equipment
  • Fibre Optic Receptors and Handheld devices
  • Computers and Signal transmission equipment
  • Space probe equipment Cell phone repeaters
  • Heart monitors and pacemakers
  • Data storage and Cat scan technology
  • Weather analysis and Atomic accelerators and Fiber optic receptors

That was all about multilayer PCB. If you have any questions, you can pop your comment in the section below. I’d love to help you the best way I can. Thank you for reading this article.

HI, I am a student of Electrical Engineering. I am currently working for an electronic store. I work at the electrical components there. I am learning many useful practical concepts there. On the other hand, I give online tuitions to some students of high school I love electrical and electronics devices and have a plan to have a Master's Degree in Electronics.
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