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What Is Fiberglass PCB and Why Fiberglass Used in PCB Manufacturing ?

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What Is Fiberglass PCB and Why Fiberglass Used in PCB Manufacturing ?

In the production of printed circuit boards, the utilization of various materials is necessary, and fiberglass is a ubiquitous material used in the manufacturing of PCB laminates. The incorporation of fiberglass in PCBs has significantly contributed to the enhancement of its quality and performance. Laminate composites that are reinforced with fiberglass offer ample advantages when applied in varied contexts, resulting in improved and innovative PCB designs.

The development of technology has led to a surge in the use of fiberglass in PCBs. Newer fiberglass materials have been introduced, which come equipped with superior characteristics and resin formulations, matching the electronic industry’s cost and performance requirements. With the availability of these advanced materials, PCB design engineers can now create PCBs that perform optimally while complying with the industry’s demands, leading to improved overall electronic systems.

What Is Fiberglass of PCB Circuit Boards ?

● In the realm of PCBs, fiberglass is a widely used material that is essential for creating the core and prepreg components of the Printed Circuit Board Copper Clad Laminate (PCB CCL and PP). The fiberglass material is made by interlacing fibers of glass yarn, which resemble a fabric-like sheet, and then impregnating them with an epoxy resin.

● To achieve optimal PCB performance, it is essential to choose the right fiberglass density and thickness because the dielectric constant of the PCB laminate is affected by the weave type. Loosely woven fiberglass can cause impedance fluctuations, signal propagation skew and consequently, inconsistent dielectric constants in the PCB laminate. When a trace is routed directly across a fiber weave of a sparse weave glass style, one leg of a differential pair may be adversely impacted compared to the other leg that is routed between the weaves, resulting in different electrical constants of the differential channel.

● To eliminate waveform distortion, traces are typically routed at an angle relative to the fiberglass strands in a zigzag pattern to balance the on-weave and off-weave traces’ number. However, this routing technique requires more space on the circuit board, causing feasibility issues for PCB designs with limited capacity. Therefore, selecting a fiberglass material with tighter weaving, such as glass style 2116 for the high-speed trace layers, is an excellent alternative to address the impedance issue.

● Considering that higher-quality, tightly woven glass styles can increase the PCB cost, selecting a medium-weaved glass style, such as glass style 2116 for high-speed signal layers, and a less expensive 106 or 1080 glass type for lower-speed signal layers, could be a cost-effective compromise. Finally, spread glass materials are recommended for ultra-high-speed transceiver signal board designs to avoid any inconsistencies in dielectric constants.

Fiberglass: Types And Forms

In the production of Printed Circuit Boards, fiberglass is an essential material used to manufacture the core and prepreg components of PCB Copper Clad Laminate. It’s worth noting that multiple varieties of fiberglass exist, and their types depend on the ratio of raw materials used during their production process.

Fiberglass Boards Raw Materials

Types of Fiberglass

 A Glass:As a PCB manufacturer, we know that This particular fiberglass consists of 72% silica and 25% alkali. Glass, being see-through, is typically used for window glass. This glass, on the other hand, is not very resistant to heat.

 C Glass: This type of fiberglass consists of boron oxide and sodium borosilicate as its main components. Its outstanding durability and corrosion resistance make it a highly desirable material in applications that mandate these properties.

● D Glass: The borosilicate-based fiberglass boasts of a low density and an impressive dielectric strength, which enhance its electrical performance significantly. This type of fiberglass has undergone critical improvements to its electrical properties, making it an excellent choice for use in PCB manufacturing.

● E Glass: E Glass is a type of fiberglass that features high electrical current resistance. It consists of alumina-calcium borosilicate, which makes it a glass-reinforced plastic (GRP) that’s capable of performing various tasks. Due to its high resistance to electrical current, E Glass is an excellent material of choice in applications requiring high electrical resistance.

● ECR Glass: In PCB manufacturing, ECR fiberglass is a type of fiberglass that comprises calcium alumino silicate as its primary component. What makes ECR fiberglass advantageous is its excellent corrosion resistance, which prevents corrosion from breaching the material’s defenses.

Forms of Fiberglass

 Fiberglass Tape: It bears mentioning that this product is comprised of glass fiber strands that deliver superior thermal insulation when compared to other products available on the market.

 Fiberglass Rope: This specific product is a braided yarn composed of glass fibers which make it ideally suited for use in packing applications.

● Fiberglass Cloth: This particular item is available in multiple iterations, including glass fiber yarns, and has a diverse range of uses as a heat shield, making it suited for a variety of applications.

What Is a Fiberglass PCB ?

As a PCB design engineer, it is noteworthy that Fiberglass is a commonly used material in the construction of Rigid circuit boards. It constitutes both the composite and fiberglass components of the PCB, displaying outstanding dielectric and mechanical characteristics while being highly resistant to moisture and heat. Furthermore, Fiberglass is renowned for its robust insulating properties.

Fiberglass serves as a prevalent substrate for PCB production, effectively strengthening the polymer matrix to form a composite. Essentially, glass fiber, a type of reinforced plastic, and Fiberglass, a plastic material reinforced with fiber, are one and the same, interchangeably known as glass reinforced plastic or plastic reinforced with glass fiber.

Moreover, Fiberglass is lightweight, less brittle, and well-suited for molding into intricate shapes. As a result, it has gained popularity in the manufacturing of PCBs. Fiberglass PCBs exhibit exceptional anti-corrosive properties and do not conduct electricity, serving as an insulator and preventing galvanic corrosion in the process.

Comparison With Other PCB Materials (e.g. FR-4)

FR-4 is another popular material used for manufacturing PCBs, and it has some similarities and differences from fiberglass PCBs. Here is a comparison between the two materials:

 Composition: Both materials are made from fiberglass fabric and a resin binder. However, FR-4 uses a woven glass fabric, while fiberglass PCBs use a non-woven fiberglass fabric.

 Electrical properties: Both materials provide good electrical insulation properties. However, fiberglass PCBs have a lower dielectric constant, making them more suitable for high-frequency applications.

 Thermal properties: Both materials have good thermal stability and can withstand a range of temperatures. However, fiberglass PCBs have a slightly higher thermal expansion coefficient, making them more prone to warping.

 Cost: Fiberglass PCBs are generally cheaper than FR-4, as they use less expensive materials and have a simpler manufacturing process.

 Availability: FR-4 is more widely used in the electronic industry and is readily available from most PCB manufacturers. Fiberglass PCBs are less common and may require more specialized manufacturing.

In a word, both materials have their advantages and disadvantages, and the choice between them depends on the specific requirements of the application.

Fiberglass Circuit Boards Thickness

Manufacturing of Fiberglass PCBs

The manufacturing process for fiberglass PCBs typically involves the following steps:

Design: The circuit design is created using computer-aided design (CAD) software and converted into a physical layout for the PCB.

 Substrate Preparation: A fiberglass substrate is prepared by cutting and drilling the panel to the desired shape and size.

 Layering: A layer of copper is then added to the top and bottom of the substrate using a process called lamination. The copper is etched away in areas where the circuit is not required, leaving the desired circuit pattern on the board.

● Drilling: The PCB is then drilled to create holes for components and connections between layers.

 Plating: The holes are plated with copper to make electrical connections between the layers and to create the through-holes for components.

● Solder mask: A layer of solder mask is applied to protect the copper traces, and openings are made for component placement.

● Silk-screening: A white silk-screened layer is printed on the PCB with a legend to indicate the locations of components, testing points, and other critical information.

 Testing: The finished PCB is tested to ensure that it meets the required specifications and standards.

The manufacturing process for a fiberglass PCB can vary depending on the manufacturer and the specific requirements of the design, but the above steps are generally followed.

Fiberglass PCB from JarnisTech: Growing Your Business

As a PCB manufacturer, JarnisTech places tremendous importance on the satisfaction of its clients. As a result, we offer the highest quality of service feasible for purchasing Fiberglass PCBs. Our capabilities extend to handling various PCB designs, from basic to complex.

We take pride in our comprehensive range of PCB boards that provide essential support to a diverse range of digital gadgets and systems. PCBs can be found in numerous applications, encompassing commercial, military, and communications industries.

JarnisTech has earned the trust of clients globally, reflecting our commitment to delivering reliable solutions. Our Fiberglass PCBs are designed to facilitate the realization of your objectives. Thus, we invite you to contact JarnisTech and leverage our expertise. The opportunities to advance are available now.

What Are the Advantages of Making PCBs with Fiberglass ?

 High Strength: Fiberglass PCB boards exhibit an impressive strength-to-weight ratio, which makes them an outstanding option for applications that demand high levels of strength.

● Thermal Conductivity: Fiberglass boards are the preferred material in high-power applications due to their low coefficient of thermal expansion and excellent thermal conductivity. Furthermore, their low thermal conductivity enables efficient heat dissipation.

 Electrical Properties: Fiberglass PCB boards are a highly desirable option for use in applications that require electrical insulation. They possess a low dielectric constant while exhibiting exceptional strength, making them ideal for use in high-end applications.

 Fire Resistance: It is worth noting that Fiberglass does not burn or propagate fires. Moreover, as an inorganic material, it does not have the capacity to spontaneously ignite, which results in the absence of smoke production when subjected to heat. Additionally, Fiberglass exhibits a high degree of strength retention, retaining roughly 25% of its strength even at temperatures as high as 540 degrees Celsius.

 Chemical Resistance:Fiberglass PCB boards possess an outstanding quality, namely, resistance to most chemicals without any adverse effects. However, it is important to note that powerful alkaline compounds have the potential to cause damage to fiberglass PCB boards.

 Dimensional Stability: Fiberglass PCBs exhibit excellent dimensional stability, meaning they do not expand or contract in response to temperature changes. This property makes them highly suitable for use in applications that demand high power. Additionally, their low coefficient of linear expansion provides immunity to the impacts of temperature and humidity changes.

● Moisture Resistance: As design engineers, we understand that Fiberglass exhibits exceptional moisture-resistance properties. Furthermore, Fiberglass PCBs do not absorb moisture like some other materials, making them well-suited for use in applications that may be exposed to damp environments. This PCB is designed to withstand diverse conditions, exhibiting remarkable versatility in terms of its ability to perform under various circumstances.

Disadvantages of Fiberglass PCBs

While fiberglass PCBs have many advantages, they also have some disadvantages. Here are a few of them:

 Limited flexibility: Fiberglass PCBs are relatively inflexible compared to other types of PCBs, which can make them difficult to use in certain applications that require more flexibility.

 Limited Durability: While fiberglass PCBs are durable enough for many applications, they are not as strong as some other materials such as ceramic, making them susceptible to cracking or breaking under high-stress conditions.

 Higher Thermal Conductivity: Fiberglass PCBs have a higher thermal expansion coefficient compared to some other materials, which can cause mechanical stresses and potentially lead to warping or cracking under certain thermal cycling conditions.

 Environmental Impact: Fiberglass PCBs contain materials that can be harmful to the environment if not properly recycled, such as the resin binder and copper cladding.

● Limited Availability: Compared to FR-4 or other materials commonly used in PCB manufacturing, fiberglass PCBs may be less readily available from some manufacturers due to lower demand and more specialized manufacturing processes.

These disadvantages do not necessarily make fiberglass PCBs unsuitable for all applications, but manufacturers and designers need to consider them when selecting the appropriate materials for a specific application.

Which Fiberglass PCB is Used in Electronics Application ?

Fiberglass printed circuit boards (PCBs) come in various types, depending on the specific application, along with stacking and other design considerations. They serve as an outstanding choice for enhancing the performance of electronic applications. Fiberglass circuit boards, in general, can effectively meet all the necessary requirements in this regard.

The most notable types include:

High Frequency Fiberglass PCB

● High-Frequency Fiberglass PCB: With the frequency range of modern electronic devices spanning from 500 MHz to 2 GHz, it is crucial to maintain the currency of one’s electronic equipment. A high-frequency fiberglass printed circuit board offers an optimal solution to this issue, allowing for swift signal transmission and unwavering performance. Consequently, the demand for such circuit boards is on the rise.

● Rigid Fiberglass PCB: Rigid PCBs have gained a reputation for their robustness in harsh environments and long-term serviceability. Among these rigid PCBs, fiberglass-based boards stand out for their extended lifetimes and optimal performance even under intense thermal stress.

● HDI Fiberglass PCB: HDI (High-Density Interconnect) technology paves the way for circuit boards that are compatible with modern-day technologies. In the domain of fiberglass PCBs, HDI facilitates 5G applications and provides support for RF, RFID, RFLink, and other pertinent technologies. Additionally, this PCB features a high wiring density, rendering it an exemplary choice for high-density PCB applications.

● Multilayer Fiberglass PCB: A multi-layer fiberglass circuit board is a proven method that has withstood the test of time. Its construction involves numerous layers that interconnect seamlessly, while impressive features such as impedance control and heat management further enhance its performance. Moreover, its cost-effectiveness is remarkable and satisfies the demands of modern electronic equipment. Because of these benefits, customers prefer multilayer PCBs over their single-layer or double-layer counterparts.

● Double Layer Fiberglass PCB: Compared to a single-layer fiberglass circuit board, this printed circuit board (PCB) is relatively pricey. However, its utilization can significantly enhance the functionality of medium-level electronic equipment. Crucial applications for this board include heating, ventilation, and air conditioning (HVAC), in addition to medical and power devices, among others.

 Single Layer Fiberglass PCB: The most significant characteristic of a single-layer fiberglass circuit board is its cost-effectiveness, making it a standout option. It is a suitable choice for basic electronic appliances, such as dishwashers, home appliances, and similar devices, with most of its applications found in the residential sector.

Fiberglass Circuit Board Applications

In the realm of electronic devices, high-temperature insulation PCBs play a vital role in thermal management. With its innate dependability and safety, fiberglass constitutes a widely adopted material in the PCB manufacturing process. Additionally, fiberglass boards are commonly utilized in a diverse range of applications, including:

● AutomotiveFiberglass PCB boards represent a crucial component in the automotive industry, catering to a wide range of manufacturing needs in this sector. These boards are extensively leveraged in the production of varied automobile components, thereby contributing significantly to the automotive industry.

● Medical: Fiberglass PCBs are characterized by low heat conductivity and impressive dimensional stability, making them an ideal candidate for medical equipment. The utilization of this type of circuit board is frequent in various medical devices such as X-ray machines.

● Defense and AerospaceFiberglass PCBs have found widespread adoption in both military and aerospace applications, where they are actively employed in the fabrication of critical device components. In addition, Glass Reinforced Plastic (GRP) is commonly embraced by the aircraft sector for crafting various items such as storage bins and instrument boxes.

● Consumer Electronics: The deployment of fiberglass PCBs is commonplace in consumer electronics ranging from computers and telephones to radios. These circuit boards exhibit outstanding mechanical and electrical properties, making them a preferred choice in the industry.

Importance of Using Fiberglass PCBs in Electronic Devices

The importance of using fiberglass PCBs in electronic devices lies in its ability to support complex circuit designs and high-frequency signals. Fiberglass PCBs are widely used in various electronic devices due to their superior thermal performance, low moisture absorption, and high chemical resistance.

Additionally, they have a long operational life and exceptional durability, which make them ideal for use in harsh environments, such as in automotive and aerospace applications. Fiberglass PCBs also offer cost-effective benefits as they can be manufactured using standard processes and materials, making them an economical choice for electronic manufacturers.

What Kind of Tests Are Conducted on Fiberglass PCB ?

Prior to putting fiberglass PCBs into application, manufacturers subject them to an extensive battery of manual and automated tests to quickly evaluate their performance. These tests serve as useful benchmarks to assess the circuit board’s functionality. Some of the examples of such tests may include:

● Automated Optical lnspection: A well-constructed AOI machine captures 2D and 3D images of PCBs from multiple angles, which are subsequently compared to the ideal PCB images using an algorithm. This testing approach facilitates dimensional defect detection, functional deficiency analysis, and identification of missing components in a rapid and efficient manner.

Despite its advantages, this testing method incurs high costs due to the sophisticated technology required for the AOI machine.

Fiberglass PCB Flying Probe Test

● Flying Probe Test: The inspection process for fiberglass printed circuit boards involves the use of electrical probes to establish contact with specific locations on the circuit board. During the test, the inspector sends a signal and simultaneously evaluates various electrical parameters, such as power, current, voltage, etc.

One of the chief benefits of this testing approach is that it doesn’t require any additional functions, making it highly cost-effective compared to other testing methods. However, due to its detailed nature, the testing procedure is time-intensive and requires comprehensive examination of the entire circuit board for accurate results.


Fiberglass PCBs are printed circuit boards made from a composite material consisting of a woven fiberglass fabric and a resin binder. They offer excellent electrical insulation properties, high mechanical strength, and thermal stability, making them an essential material for electronic devices that require durability and longevity.

Some of their advantages include cost-effectiveness, resistance to harsh environments, and support for complex designs and high-frequency signals. However, fiberglass PCBs also have some disadvantages, such as limited flexibility, limited durability, and possibly negative environmental impacts.

Despite these limitations, fiberglass PCBs remain an essential material for electronic manufacturers and are commonly used in various applications, such as automotive and aerospace sectors. Overall, their importance in the electronics industry stems from their ability to support complex circuits and withstand a range of harsh conditions, making them an ideal material for many modern electronic devices.

JarnisTech has garnered extensive acclaim for its dependable PCB assembly and manufacturing services over the past two decades. We are committed to delivering quality products that align with your specific requirements. Please feel free to reach out to us without hesitation for professional services tailored to your next PCB project.