What are the Internal Composition Layers of a PCB?

PCB Basics 
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Editorial Team - PCB Directory

Jan 6, 2023

PCB Layer

A printed circuit board is typically made of copper, a substrate, and resin. A standard PCB has sheet layers of copper laminated onto or between layers of conductive material. There are several different types of printed circuit boards (PCBs) based on the number of layers they have. Here are a few common types:

  1. Single-layer PCBs: These PCBs have only one layer of conductive material. Single-layer PCBs are the simplest and least expensive type of PCB, but they are also the most limited in terms of design complexity.
  2. Double-layer PCBs: These PCBs have two layers of conductive material, which are separated by a layer of insulation. Double-layer PCBs offer more design flexibility than single-layer PCBs, but they are still relatively simple and inexpensive.
  3. Multilayer PCBs: These PCBs have four or more layers of conductive material. Multilayer PCBs are more complex and expensive than single- and double-layer PCBs, but they offer the greatest design flexibility and allow for more components to be packed into a smaller space.

No matter which board you choose, it must have a fundamental foundation on which it is built, which is made of various materials that are laminated together.

Different types of Layers in a PCB

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 1.  Substrate Layer

The substrate layer of any PCB is typically made of fiberglass, which gives the board its rigidity. The majority of boards, except for flexible PCBs, which are constructed using flexible plastic, such as Kapton, typically have this substance as their substrate.

Other materials, such as epoxies, can be used to create substrate PCB layers, but they lack the durability that FR4 (found in fiberglass) offers for a high-quality board.

 2.  Copper Layer

The board is next laminated with a thin layer of copper foil using heat. When we talk about different layered PCBs, we're talking about how many copper layers are present in them. 

When making a single-sided PCB, the circuit board has one layer of conducting material on one side and is used for adding various electronic components on the other. Contrarily, with double-sided PCBs, the conductive copper and components can be mounted on both sides of the board instead of just one. Due to their ability to alternate between the top and bottom layers using vias, these double-sided boards enable closer routing traces. Because holes can be drilled into the board to connect the circuits on one side to those on the other.

A PCB's copper layer thickness depends on the amount of power it must withstand. The thickness of the copper layer increases if a PCB operates in high-power circuits.

 3.  Soldermask layer

The solder mask layer is placed on top of the copper layer after it has been applied. This gives the PCB its green color and serves as insulation for the copper layer, preventing it from coming into contact with any other metals or board components that might damage the copper traces. This layer aids the user in soldering in the proper locations, which is crucial for the manufacturing process where the components are attached to the board.

 4.  Silkscreen layer

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By adding letters, numbers, and symbols to the board, the silkscreen primarily serves to aid us, humans, in understanding the board and the operation of various pins or LEDs.

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