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PCB substrate – the basic and beyond


What is PCB substrate?

PCB substrate is a thin, flexible and rigid material that is used to make circuit boards. It is also known as a printed circuit board (PCB), printed wiring board (PWB). It can be produced in many different shapes by printing different patterns on it. The most common types of PCBs are:


It is used in microelectronics and printed circuit board (PCB) is one of the most sensitive components in the board. It plays a key role in transferring the electric signals, heat dissipation and ensuring high reliability. It should be able to withstand high temperatures, high voltage and resists corrosion by airborne dust and water. The main reason why it is a critical component of PCBs is because its performance directly affects the quality of your entire circuit board or PCBA.

The substrate is the base material of a printed circuit board (PCB). It is also referred to as a deck. It is commonly made out of FR4, FR5 or BGA. These materials normally consist of a plastic such as polyamide, acrylonitrile butadiene styrene (ABS), epoxy or phenolic resin. Each of these materials has different properties and thus PCBs with different characteristics can be manufactured from them. 

The following article will give an overview about the types available in the market and for what purposes they are commonly used.

The PCB substrate has many different types and applications

The PCB substrate is the base of your PCB, and it includes many different types and applications. The main performance includes flexibility, heat resistance, hygroscopicity, adhesion and waterproofing.
It can be divided into two categories:

  ◆ Aluminum-based (Al) substrates (e.g., Al alloy)
  ◆ Copper-based (Cu) substrates

From the perspective of electrical performance, the common materials of PCB substrate include high-frequency material, epoxy high-frequency materials and thermosetting plastics. In addition to these three types of basic materials, there is also paper base copper-clad laminates. The production process is mainly divided into four steps:

  ◆Printing process (printing lines)
  ◆Coating process (coating with lacquer)
  ◆ Hot embossing process (embossing with hot air)
  ◆ Drying/curing

The common materials of PCB substrate

You will find that there are a few common PCB substrate materials, including:

  ★High-frequency material: This is usually epoxy or thermosetting plastic. It has excellent mechanical properties and high electrical conductivity. Its cost can be relatively low, but it doesn’t have many other advantages over other types of substrates.

  ★Paper base copper-clad laminates: These are cheaper than high-frequency boards because they’re made from recycled paper and don’t need as much expensive raw material to make them. They also work well in temperature ranges below -40 degrees Fahrenheit (-40 C), which makes them good for areas that require minimal heating or cooling during operation—such as industrial machines used outdoors in cold weather conditions.

The main performance of PCB substrate

  • Flexibility: the flexibility of the substrate is important because it allows the implementation of new designs and the realization of complex shapes.
  • Heat resistance: the heat resistance of a material depends on its ability to withstand high temperatures, which may be caused by friction against other materials or during soldering, etc., without deformation or softening.
  • Hygroscopicity: hygroscopic substances absorb moisture from the atmosphere through their surfaces; therefore they tend to swell when exposed to humidity. This property can be used in many applications where there is a need for water-proofing construction materials such as wood panels and concrete walls (or any other surface).

The flexibility is related to the dielectric constant and loss tangent of a polymer material. The higher its dielectric constant value is, the harder it will be for the material to flow while still maintaining its shape during processing steps such as curing or printing.

On the other hand, reducing this parameter will ensure that you get a more flexible product with better mechanical properties such as bending strength or tensile strength at breakage points where cracks may occur due to strain relief requirements in some applications (e.g., high-speed trains).

Why the PCB substrate so important?

The PCB substrate is the base material of a printed circuit board that provides electrical insulation, mechanical support and mechanical strength. It has many different types and applications. From the perspective of electrical performance, the common materials include high-frequency material, epoxy high-frequency materials, thermosetting plastic and paper base copper clad laminates.

The PCB substrate is the foundation of the PCB board. It determines the performance of your product, including its electrical performance and mechanical reliability.The most important thing is that it can affect your products’ overall lifetime-to-failure (LTF). A high LTF means you have more years of use left in your electronics products before they fail.

How to produce PCB substrate?

The sub-layer of the PCB substrate is made of copper foil, a dielectric layer and copper cladding. The copper foil is the main material. A dielectric layer is used to protect your board from electrical charges and dust.

The next step is the soldering process where you will apply solder on all sides of each component with some flux to help wick away unwanted gases during the heating process (soldering). It is a very important material in the electronic industry. It is used to make the circuit board, which is an important part of the electronic product. It consists of materials such as epoxy resin, glass fibre, paper and copper foil.
The process of making PCB substrate includes:

1)Cleaning up the surface before processing it into a finished product;

2) Setting up drying ovens for different stages of processing; 

3) Applying primer coat evenly on all surfaces; 

4) Applying two layers of protective coating (one layer for top & bottom layers); 

5) Drying out after applying a protective coating

How to choose proper PCB substrate?

When you choose a PCB substrate, you should consider the following factors:

  • The material of the board and its quality. Some materials can be damaged easily and will not work well for some applications. Therefore, it is necessary for customers who use these boards to check the compatibility of materials before purchasing them.
  • The main performance: Can it withstand heat or humidity? Does it have enough space between signals? Are there any defects in its design that could affect performance? If so, these defects must be corrected before starting production; otherwise, they may cause problems later on such as poor performance under extreme conditions or even damage caused by water polishing processes during assembly operations with circuit boards made from other materials (such as plastic).


PCB substrate is the base of PCB, and it has many different types. From the perspective of electrical performance, the common materials include high-frequency material, epoxy high-frequency materials, thermosetting plastic and paper base copper clad laminates.

In addition to their excellent mechanical properties (hardness and flexibility), these materials also have good dielectric properties (dielectric constant) when they are used as substrates for printed circuits or laminated boards.

It has many applications, including the production of printed circuit boards and general wiring. In addition to electrical performance, it also has strong mechanical properties, corrosion resistance and adhesion. It mainly includes flexibility, heat resistance, hygroscopicity and adhesion.



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