Which PCB Substrate is Best for Your Needs - 2021 Updated

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Wed, Apr 21, 2021

The PCB substrate, traces, and components make up a printed circuit board. The PCB substrate, also known as the base material or PCB core, is the material that supports the traces and parts and reinforces the performances of the circuitry.

There are many kinds of PCB substrates in the market. Different circuit boards have different functions so that they require different PCB substrates in their production. In this article, we will illustrate different kinds of PCB substrates in the market so that you can decide which substrate to make your PCBs.

Part 1. What Common PCB Substrates are There

PCB substrate

The most commonly used PCB substrate is  glass fiber. It is used to strengthen epoxy tar with a copper thwart bonding onto one or both sides.

Besides, there are glass-epoxy substrates, which are used for circuits that require strength, and insulation.

Paper phenolic is another kind of PCB substrate. Hardening paper base material with phenolic resin containing oil and fat makes this PCB substrate. If PCB manufacturers want to strengthen the PCB base, paper fortified phenolic tar is used with a fortified copper thwart.

Besides, there are composite substrates that mix paper and glass base materials, flexible substrates that can be bent using plastic films as base materials, and ceramic substrates, such as hybrid ICs and SAW filters are sometimes used.

For a quick look, here we list some common PCB substrate materials:

  • FR-4
  • FR-2
  • Aluminum
  • Flexible substrates like Pyralux or Kapton

Here are also some circuit board substrates that do not have as much utilization as the above.

  • FR-1
  • FR-3, FR-5, FR-6
  • G-10 and G-11
  • CEM-1 to CEM-5
  • PTFE
  • RF-35
  • Alumina
  • Polyamide

Here are some explanations for the above.

The FR4 substrate is woven fiberglass cloth with an epoxy resin binder.

FR1 and FR2 are both base materials made of cellulose paper impregnated with phenolic resin.

CEM-1 is a laminate based on a composition of cellulose paper and fiberglass with epoxy resin.

Part 2. Characteristics of Different PCB Substrates

How to choose circuit substrates for PCBs? We introduce different PCB substrates and list their characteristics below for you to decide which one is appropriate for your needs.

Paper Phenolic Substrate

This PCB substrate is made of paper impregnated with phenol resin.

It features high workability and low cost. It is mainly used for single-sided boards and is used in consumer electronic devices.

The range of materials for the production of microwave printed circuit boards is very wide: as a dielectric, both in pure form and in various combinations (to impart the necessary characteristics, for example, thermal stability), various polymers and ceramics are used.

Paper Epoxy Substrate

This is a PCB substrate made of paper impregnated with epoxy resin. 

It has superior heat resistance, hygroscopicity, insulation resistance, and high-frequency characteristics compared to paper phenol substrates.

However, these characteristics are inferior to those of glass/epoxy boards. In addition, they are positioned as intermediate characteristics between paper phenol boards and glass/epoxy boards.

It is mainly used for single-sided boards, and specific applications include consumer electronic devices.

Glass Composite Substrate

This is a PCB substrate made of a material in which epoxy resin is impregnated into a base material. It is a mixture of glass cloth and glass nonwoven fabric.

It has almost the same electrical characteristics as a glass/epoxy substrate. But it has poor mechanical strength and dimensional stability.

It is often used for double-sided boards.

Glass/Epoxy Substrate

This is a PCB substrate made of glass cloth impregnated with epoxy resin.

Although the dimensional change is small and the high-frequency characteristics and insulation resistance are high. Similarly, the cost is relatively high.

In addition to double-sided boards, it is also used in multiple types of PCB boards. It is used in personal computers, consumer electronic devices, and office automation equipment.

Teflon Substrate

This is a PCB substrate made of Teflon resin as an insulating material.

Due to its excellent high-frequency characteristics, it is used in electronic devices that handle signals of several hundred MHz to several tens of GHz.

Alumina Substrate

ceramic substrate PCB

Alumina substrate is also called the ceramic substrate. This is a PCB substrate that uses a green sheet that is made by mixing aluminum oxide and a binder and sintering it.

It is characterized by excellent high-frequency characteristics. The disadvantage is the high cost.

It is used in microwave equipment and wireless communication base stations.

LTCC Substrate

Low temperature co-fired ceramics (LTCC) is a PCB substrate used for multi-layer boards.

As aluminum oxide needs to be baked at a high temperature of 1500°C, it is not possible to perform simultaneous baking with a wiring pattern using low melting point copper. By adding glass-based materials to aluminum oxide, LTCC substrates can be fired at temperatures as low as 900°C.

This makes it possible to perform simultaneous firing with a wiring pattern of low melting point material such as copper or silver built-in.

It is used as a substrate for high-frequency modules and semiconductor packages.

TLCC substrate PCB

Part 3. Order PCBs Made of Appropriate PCB Substrates

Now you've understood most of the PCB substrates available in the market and their characteristics, and you should be able to decide the circuit board substrate most appropriate for meeting your demands. Then you should ask a reliable PCB to make your circuit boards. PCBONLINEis your trustworthy PCB manufacturer.

In the past 22 years, PCBONLINE has been specialized in advanced circuit board manufacturing, such as alumina PCB, high-frequency PCB, aluminum PCB, multilayer PCB, etc. And our order pooling technology allows us to accept orders of any PCB amount. We can deal with prototypes, large-scale manufacturing, small-batch production, and prototypes.

Our PCBs' high quality is guaranteed by good PCB materials and strict quality control. The below video shows how we fabricate PCBs.

Working with PCBONLINE, you can enjoy:

    • Circuit boards made of first-rate PCB substrates that are ready to use immediately
    • One-stop PCB manufacturing, the whole production is traceable
    • PCBs are ISO 9001, IPC-A-600, UL, and REACH certified
    • one-to-one engineering and customer support


In this article, we introduce what PCB substrates are there in the market, their characteristics, and common applications. If you still have concerns with PCB substrates or any technical questions about PCB, PCBONLINE offers free advice and tech support. You can contact us online or by email at info@pcbonline.com. Our experienced engineers are always there for you.