The Properties and Applications of Fiberglass PCB

The manufacturing of a printed circuit board involves the use of several materials. Fiberglass is commonly used in the production of PCB laminates. This material has had positive impacts on modern PCBs. Laminate composites reinforced with fiberglass offer great benefits to most applications.

As technology advances, the use of fiberglass in PCBs has increased. There are new fiberglass with better properties and best resin systems. This material has been able to meet the cost and performance demands of the electronic industry.

What is a Fiberglass PCB?

A fiberglass is a material commonly used for rigid circuit boards. The fiberglass PCB comprises fiberglass material and composite material. Furthermore, this PCB features exceptional dielectric and mechanical properties. Also, it features moisture resistance and heat resistance. Furthermore, fiberglass is a good insulator.

It is a common substrate in PCB manufacturing. Also, fiberglass reinforces the polymer matrix to create a composite. Fiberglass is a plastic reinforced with fiber in which the glass fiber is a reinforced plastic. Therefore, it is also glass fiber reinforced plastic or glass reinforced plastic.

Furthermore, fiberglass as a material is less brittle and lightweight. However, this material is moldable into different complex shapes. This is one of the reasons it is widely used in PCB fabrication. Fiberglass PCBs offer great features that make it corrosion-resistant. Also, this board is electrically non-conductive. Therefore, it serves as an insulator and gets rid of the chances of galvanic corrosion.

Fiberglass PCB Construction

The fabrication of fiberglass PCBs start with placing fiberglass fabric on a warp beam. This beam features individual strands of rolled yarn over a master beam. These yarns constitute the warp direction. After that the manufacturer runs the warp yarns through some lubricants. Therefore, this helps to prevent any damage during weaving.

Also, the weaving process starts by placing the warp beam on a loom’s back. At the same time, the manufacturer inserts the fill yarns as the yarns go from the loom’s back to its front. Initially, the Draper looms were available. Here, a wooden shuttle would go back and forth from a side of the loom to another side. Also, this will help to insert the fill yarns.

The newer looms function on water or air jet. Here, the jet moves the fill yarns across the loom. In addition, a warp beam can comprise thousand meters of warp yarns in the modern looms. After weaving, the manufacturer scours the electrical grade glasses with a water rinse. Also, this helps to eliminate excess sizing from the yarns.

After that, the manufacturer heats the warp yarns in an oven for a long period. The fabric is then treated with finishing agents. Also, after weaving the fiberglass, the manufacturer adds several resins to strengthen the board.

Properties of Fiberglass PCB

Fiberglass PCBs have unique properties that make them widely used in some applications.

Moisture resistance

Naturally, fiberglass has the ability to withstand moisture. Furthermore, fiberglass PCB doesn’t absorb moisture. Therefore, it is ideal for use in applications exposed to moisture. This PCB can survive in any given circumstances.

Dimensional stability

Fiberglass PCBs don’t change in size in response to a given temperature. The dimensional stability of this PCB is very high. Therefore, it is suitable in high power applications. Also, this board has a low coefficient of linear expansion. Therefore, it isn’t sensitive to changes in hygrometry and temperature.

Chemical resistance

This is another great property of fiberglass boards. Most chemicals don’t have any effect on fiberglass boards. However, strong alkaline substances can affect fiberglass.

Fire resistance

Fiberglass doesn’t burn or support combustion. Also, this inorganic material is naturally incombustible. Therefore it doesn’t produce smoke when exposed to heat. Also, fiberglass retains about 25% of its strength at 540 degree Celsius.

Electrical properties

Fiberglass boards are great in electrical insulation application. Also, these boards feature low dielectric constant and high strength. Therefore, this makes them ideal for high end applications.

Thermal conductivity

With its low CTE and thermal conductivity, fiberglass boards are ideal in high power applications. Also, its low thermal conductivity enables it to rapidly dissipate heat.

High strength

Fiberglass boards have a high-strength-to-weight ratio. Therefore, they are a great option in applications demanding high strength.

Applications of Fiberglass PCBs

PCBs featuring high-temperature insulation offer thermal barriers. Fiberglass is naturally safe and durable. Therefore, it is a common material for PCB fabrication. Furthermore, fiberglass boards are commonly used in the applications below:

Aerospace and defense

Fiberglass boards are commonly used in aerospace and defense applications. Also, these boards help in manufacturing parts of aerospace devices. Furthermore, GRP is extensively used in aerospace. Examples of GRP applications are instrument enclosures and storage bins.

Consumer electronics

Consumer electronics like computers, radios, and cellphones feature fiberglass PCBs. Also, these boards offer great electrical and mechanical properties.


Due to its low thermal conductivity and dimensional stability, fiberglass PCB is commonly used in medical devices. Also, some medical devices like X-ray machines feature this type of PCB.


The automotive industry relies on fiberglass boards. These boards are extensively used in the automotive industry. They are widely used to produce the parts of vehicles.

Types and Forms of Fiberglass

Fiberglass is in different types. This depends on the raw material and their proportions.

A glass

This fiberglass features 25% of alkali and 72% silica. A Glass is transparent and ideal for window glass. However, this glass has poor heat resistance.

C Glass

This fiberglass comprises boron oxide and sodium borosilicate. This fiberglass is durable and it is a great choice for applications demanding corrosion resistance.

D Glass

This is a borosilicate fiberglass featuring low density and great dielectric strength. This fiberglass features improved electrical performance

E Glass

This fiberglass is electrically resistant. E Glass comprises alumina-calcium borosilicate. Therefore it is a glass reinforces plastic that serves great purpose. It is ideal for applications that require high electrical resistivity.

ECR Glass

This is a fiberglass that consists of calcium alumino silicate. ECR fiberglass is resistant to corrosion.

Forms of Fiberglass

Fiberglass cloth: This is available in different variants like glass fiber yarns. It is widely useful as heat shields.

Fiberglass rope: This is a braided glass fiber yarns. It is ideal for packing purposes.

Fiberglass tape: This comprises glass fiber yarns. These yarns have exceptional thermal insulation properties.


Fiberglass PCBs play a crucial role in the production of electronic devices. Also, these boards are very versatile. Hence, they are suitable for use in a wide range of applications.

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