Printed Circuit Board FR4 Material

FR4 is a blend of fiberglass and epoxy resin, and manufacturers also call it a composite material. It resists flame and is highly used for PCBs as a substrate or base layer. FR4 circuit boards are now used instead of G10 boards due to their properties.

FR is also a great electrical insulator because it is completely water-resistant which means it does not absorb a little drop of water. Such qualities mechanically make it very strong and it maintains its qualities in all kinds of weather, including humid, hot, and dry weather.

Properties of FR4

FR4 is an inflammable material, and it is UL94V-0 compliant which means it does not spread fire, instead, it stops fire the moment the material starts burning. It has bromine that resists fire and does not absorb water as described above.
Moreover,the glass transition temperature is very high ranging from 115 to 2000 degrees Celsius, depending on the type of the resin and manufacturing method.Mostly such PCBs FR4 lies between the two layers of copper laminates.

Types of FR4 Material

FR4 material has different types, such as:
Standard FR4: Its heat resistance goes up to 140-a50 degrees Celsius.
High CTI FR4: The index of this type of FR4 goes beyond 600V.
High TG FR4: It has a high-glass transition value, such as 180 degrees Celsius.
FR4 without copper: This type of FR4 is suitable for insulating plates, and it can support the circuit board.

How To Choose The FR4 Thickness

FR4 thickness should be decided carefully as it contributes a lot to the applications of different PCBs. You should consider the following things in this case:

• Design and flexibility
• FR4 thickness should be compatible with components
• It should not take much space on a PCB
• Focus on the type of desired connections

Advantages of FR4

FR4 is cheaper than other substrates of circuit boards which makes it a standard material to develop small circuit boards. But, it is not good for high-frequency circuits or where the parts are suitable for flexible circuit boards.
FR4 is often suitable for RF applications with a frequency from 1GHz to 10 GHz. However, electric products having an FR4 have some disadvantages due to certain limitations.
FR4 material is one of the most popular choices for printed circuit boards because it offers a high degree of strength and rigidity. This means that your PCBoard will be less likely to warp or bend over time, which can lead to reliability issues. As already mentioned, FR4 material has excellent thermal stability, meaning it can withstand high temperatures without breaking down. This makes it ideal for use in harsh environments or in applications where heat dissipation is a concern.
As FR4 material is one of the most affordable materials on the market, which makes it is a great option for businesses on a budget. In addition to being cost-effective, FR4 material is also easy to work with, which can save time and money during the manufacturing process. It can be machined in a variety of ways, including deep draw and laser cutting, so customers are not limited in their design options
FR4 material is a great choice for PCBs because it offers good electromagnetic shielding. This means that it can help protect your circuit from outside interference. Additionally, FR4 is flame retardant, which makes it a safer option for use in electronic devices. It’s also strong and durable, so you can trust that your PCB will last for years to come.
It’s important to note that there are many different grades of FR4 material with different properties, so make sure you know what you need before ordering.

Some things worth considering when choosing an FR4 grade include: whether the PCB needs to support weight, how sensitive the device will be to temperature changes, how strong it needs to be, and how much flexibility is required.

Understanding PCB and Its Materials

Printed circuit boards manufacturers involve many steps, including design and finishing, leading to a huge production. Printed Circuit Board designers and engineers should consider the material in terms of its properties and applications. They should have it in Gerber files before sending the PCB design for manufacturing. In other words, PCB material determines the end product. Various PCB materials include the FR4, Teflon, PTFE, etc.
PCB substrates are made of phenolic and proxies, whereas PTFE is more costly than all others. Different PCB materials are available in the market, and you should choose them according to your needs.

Types of PCB Materials

Mostly PCB has four layers which are made one by laminating through a heating process. Each layer hasa specific PCB function and needs a specific material. PCB designersshould have full knowledge of materials in terms of their properties which should be suitable for specific applications.The end product with PCB is a specific device that needs a specific material, so it is a crucial factor.
PCB is composed of different materials from the base to the top, including copper, substrate or base layer, copper, solder mask, and silkscreen.
The subsequent layer of PCB is copper which is placed and bonded over a base material with heat and adhesive. The thickness of the copper layer is used according to the PCB and its application. Like, you can make it in one or two layers, depending on your needs. Mostly, cheap devices or gadgets have PCBs with a single layer of copper.
Like FR4, copper used in the circuit boards has different types in terms of resin, such as PF resin, epoxy resin, and polyester resin.
On the other hand, the silkscreen layer helps make marks or letters for programmers to read on a printed circuit board. The layer below a silkscreen is a solder mask and don’t forget to read our special post on solder masks.You can choose PCB materials by yourself or through an expert.

What is the FR4 Trace?

FR4 thickness is often 1oz,2oz, or 3oz, and the copper layer can be populated according to the design. It is also tested against the UV rays before removing the chemical solution to have correct copper traces which connect different parts on the FR4 PCB.
FR4 PCB trace can have signal issuesdue to mismatcheddriver’s and receiver’s impedance. Such an incompatibility results in bumps on the layer that reflects signals at a receiver’s end, sending them back to the copper trace.
The signal reflection that occurs due to mismatched impedance can affect the signal integrity. So, as a thumb rule, you should be careful, especially if the edge rate is lower than 1/6 of the propagation gap or delay in the copper trace’s length.
In the case of copper trace, signals occur 1 inch in 6 ns. You must take care of measurements to manage the impedance, especially if the edge rate is 1ns, whereas the copper trace is larger than one inch.

How To Manage The FR4 Trace Impedance

• You can use resistive matching to make the driver and receiver’s impedance compatible. Such a technique involves a resistor having a value according to the source impedance. The resistive is set parallel with the receiver or in a series, depending on the requirements.
• Some other techniques also help in this case, minimizing the signal reflection. A long PCB trace causes high-signal reflection. So, you can also reduce the trace length in a circuit board to overcome the signal reflection.
• A signal’s return path is also important in this case because impedance can happen anywhere, including the signal trace or returning path.
• If PCB has high-frequency signals, you should route the traces on the plane of a returning path. But, don’t route signals on a split plane because it would result in a discontinued impedance.
• You must use advanced PCB design or analysis techniques to get precise results. The tools should possess advanced simulation.

Wrap Up

FR4 material is the standard fiberglass laminate that you’ll find in all PCBs (printed circuit boards). It has many uses, and each one will likely have its own set of requirements for using FR4 material. You’ll need to keep your specifications in mind when looking at FR4-based materials, but this will give you a good idea of what kind of FR4 laminates are available on the market today.
The FR4 board can be easily cut with a knife or saw and drilled through using a drill press or electric drill. You can even shape it using files or sandpaper if you need to, which makes it versatile as well as economical. So if you’re looking for high-quality circuitry in your next project, take a good look at what this particular type of PCB has to offer before making any decisions.
Would like to know more about the FR4 material or PC Board assembly? Email us at sales@pnconline.com

Written by Sam Sangani

Sam Sangani is the President & CEO of PNC Inc., a Nutley, NJ based Printed Circuit Board manufacturer. Sam graduated from L. D. Engineering College with a BS Degree in Mechanical Engineering. He also continued his education and graduated from Steven’s Institute of Technology where he acquired a Master’s degree in Computer Science.

After completion of his BS, Sam worked as a QC Manager, for Xerox, Romania and London. He was responsible for the Quality Control of Cable and Wire Harness imports from Romania. After completing his Master’s Degree, he worked as a Senior Programmer with IBM, Tucson, Arizona. Sam was responsible for leading the Mainframe System Programming Team.

In 1997, Sam acquired PNC INC., a Nutley, NJ based PC Board fabrication Shop. From 1997-2013, Sam has made tremendous improvements and changes within PNC INC., as he added many new Products and Technologies in PNC’s portfolio. With his proven track record and leadership, PNC has never had an unprofitable year and has continued its growth yearly since 1997.

His current responsibilities are Strategic Planning, Corporate Management, New Business Ventures, Sales & Marketing, Trade Shows, Professional Services and leading productive teams to achieve peak potential. He has also utilized Lean Management techniques which have built a foundation for PNC’s high-paced growth. Sam also enjoys real-estate investing, web design & SEO, trading stocks, options, futures and Forex markets.