Understanding PCB Insulation Materials: Types, Functions, and Applications

A printed circuit board consists of an insulated substrate, the board itself, and printed wires or copper traces, which provide the medium for electricity to travel through the circuits. The materials of the substrate also serve as PCB insulation materials that provide electrical insulation between the conductive parts. Multilayer boards will have more than one substrate separating the various layers. What are typical PCB substrates made of?

PCB Substrate Materials

PCB substrate materials must be made of substances that do not conduct electric currents, as this will interfere with the path of electricity as it travels through the printed wires. In fact, the substrate materials are PCB insulation that functions as a laminated electrical insulator for the circuitry of the board. Each layer of circuitry connects through holes that are plated through the board when connecting traces on opposite layers.

Materials that serve as effective substrates include fiberglass, Teflon, ceramics and certain polymers. The most popular substrate today is probably FR-4. FR-4 is a fiberglass-epoxy laminate that is affordable, a good electrical insulator and is more flame-resistant than fiberglass-only boards.

PCB Substrate Types

There are five main PCB substrate types you will find in your printed circuit boards. Which substrate types you will use for your specific printed circuit boards will depend on your PCB manufacturer and the nature of your specific applications. The PCB substrate types are as follows:

• FR-2: FR-2 is probably the lowest grade of substrate you would use, although it is flame-resistant, as indicated by the FR designation. It is made of a material called Phenolic, a type of impregnated paper that goes over fiberglass. Cheaper consumer electronics tend to make use of printed circuit boards with FR-2 substrates.
• FR-4: One of the most common PCB substrates, this is a woven fiberglass substrate containing a flame-resistant material. However, it is stronger than FR-2 and is less likely to crack or break, which is why it is used in higher-end products. To drill holes in or machine fiberglass, PCB manufacturers use tungsten carbide tools due to the nature of the material.
• RF: RF, or radio-frequency substrates, are for printed circuit boards that you are going to use for applications with high-power radio frequencies. This substrate material consists of low dielectric plastics. This material gives you very strong electronic performance properties but very weak mechanical properties, so it is important to tailor RF boards to the right type of application.
• FLEX: While FR boards and other substrate types tend to be very rigid, some applications may require the use of flexible circuit boards. These flex circuits use thin, flexible plastics or films as substrates. While the manufacturing of flex boards is more complicated, these boards have special benefits. For example, you can bend a flex board to fit in a space where a normal board would not fit.
• METAL: When your application involves power electronics, good thermal conductivity is a requirement. This means a low-thermal resistivity substrate like ceramic, or a metal that can handle the high electrical currents you get with power electronic printed circuit boards.

Millennium Circuits Ltd. for All Your Printed Circuit Board Needs

Millennium Circuits Ltd., an established leader for printed circuit boards and related PCB products in Pennsylvania, can meet all your printed circuit board needs at the volume you require. We offer traditional printed circuit boards as well as flex circuits, rigid-flex boards, heavy copper boards, RF and microwave boards, aluminum-printed circuit boards and more. If there’s a type of printed circuit board or a related product you need, get in touch with MCL, and there’s a very good chance we can accommodate you.

You’ll want to order your printed circuit boards from MCL due to our commitment to customer service and quality assurance. We offer friendly, professional service with in-house support and quick turnaround on your order. We happily take both small- and high-volume PCB orders, and are ready at a moment’s notice to fill your requirements. Our quality control program makes sure our boards adhere to the most stringent standards, with rigorous testing procedures and highly trained personnel making sure your boards are of the highest quality. We even offer a free file check to make sure your design is error-free.

Contact MCL for Any and All Printed Circuit Board Needs Now

To find out more about how MCL can serve all your PCB application needs, or for a free quote on your first order, contact MCL today.