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Comparing Polyamide and Polyimide: What’s the Difference for PCB?

There are some excellent chemical substances that have an amazing ability to resist temperature. These typical substances are polyamides and polyimides. These are basically thermoplastic elastomers that are crucial for some technical domains.

 One main difference between these two comes in their chemical properties. Their structures are not similar. The chemical groups of these two polymers are different, which sets them apart from each other.

 There are some common properties of these two substances, including electrical attributes, physical characteristics, and impressive thermal stability. 

What is Polyamide?

Polyamides are common elastomers. They have a special chemical group called the amide group in their chemical structure. One fine example of polyamides is Nylon. It is an ancient polymer that has crucial applications in different domains.

 There are some excellent properties of these substances that come in handy for major uses. These are:

  • Higher temperature control
  • Heat aging ability
  • Solvent resistance
  • Good modulus/impact abilities
  • Less coefficient of friction
  • Higher resistance to abrasion

What is Polyimide?

Polyimide Stencils

Polyimides are another type of polymers. They are different from Polyamides due to their chemical group. The chemical group for Polyimides is the imide group. There are two further categories of Polyimides.

 These can have open chains and closed chains. You cannot expose them to hot temperatures for a long period of time. 

 There are some salient chemical properties of polyimides that you should know. These include:

  • Good thermal stabilization
  • Electrical conductance
  • Resistance to abrasion and solvents

Due to the aforementioned properties, polyimides have important applications in different which are:

PCB Material of Polyamide and Polyimide

Polyimides are chemical derivatives of imide monomers. Polyimides can be artificial or natural. It mainly depends on the type of product you want to use polyimides for. Some simple examples of polyamides are silk and wool. 

However, when it comes to producing PCBs, artificial polyamides are efficient on all counts. You can develop artificial polyamides by combining imide chemical structures. Keep in mind that bis maleimides and maleic anhydride are important for making artificial polyamides. 

The additives you will use in this process determine the type of polyamide as the final product. 

Here you will find some good examples of artificial polyamides:

·        Pure Polyimides: Pure Polyimides are basically 2nd generation polyimides. You don’t have to brominate these, unlike other polymers. It is much more time-saving to produce second-generation polyimides. Due to this, these are important for thermal stabilization and temperature control. 

·        3rd Generation Polyimides: These polyimides are all those substances that can prevent flammability. It is important for some electronics as they can catch fire due to electrical glitches and short circuits. However, these are not much impressed with thermal stabilization. You can rely on them for fast production because of their low temperature. 

·        Filled Polyimides: Filled polyimides come with a filler. They are excellent for resisting thermal resistance and have more flexibility. The purpose of a filler is to keep the resin damage as minimum as possible. It prevents cracks when it comes to drilling, which can lead to further problems if not handled in time. 

·        Low-Flow Polyimides: These polyimides include different types of resins that are important for opposing flexibility when needed. 

When Should Polyamide And Polyimide Be Used?


Polyimides have increased the market demand over the years. The products, including polyimides, are useful for their durability and flexible nature. However, there are more factors that make polyimides favorable for many PCB producers around the globe.

You must determine the characteristics of your PCBs when selecting a particular polyimide so that you will be able to save time, money, and energy due to this.

Below are some factors that will help you in this regard:

·        Excellent Flexibility: Polyimides have no parallel when it comes to increasing the flexibility of rigid and flexible PCBs. As polyimides already have excellent flexibility, they never fail you in this pursuit. 

·        Excellent Tensile Strength: These polymers can impressively oppose warping. When your devices need a higher degree of durability, use polyimides to ensure their robustness and strength on all counts. 

·        Very Thermally Stable: Polyimides show excellent stabilization when exposed to hot temperatures. Besides, they are good in thermal conductivity, which helps in alleviating damage during PCB production

·        Resistant to Chemicals: Polyimides are stable chemical polymers. It means that you can combine them with corrosive and unstable substances without any fear. 

·        Highly Durable: Not only Polyimides can handle hot temperatures and unstable chemicals. These never fail to perform naturally under stress. No matter the external environment, their shapes never undergo drastic changes. Due to this, these are important for devices that perform extreme functions in different domains. 

Applications Of Polyamide Material

All types of polyimides have important use cases in different industries. You can find polyimides in vehicles, clothes, and consumer electronics. However, one major application of these remarkable polymers is in PCBs. The polyimides pass on great properties to the rigid and flexible PCBs. 

Below are some significant applications of polyimides that you must know:

·        Computer Electronics: Computing devices like PCs and desktops need to be flexible and robust to perform different tasks. Such properties help these devices to deliver quality performance under stressful conditions. However, sometimes these devices can become overheated. In this case, polyimide PCBs help in cooling down these devices. These are important to save them from possible damage due to heat. 

·        Automotive ElectronicsModern automotive electronics always rely on durable and heavy-duty electronic parts. These components include polyimide PCBs that absorb vibrations to a large extent. Not only this, these are important for cooling down these parts from the heat generated by a device.  

·        Consumer Electronics: Consumer electronics like smart devices include rigid and flexible PCBs because of their excellent properties. These PCBs are important for consumer electronics to save them from undergoing possible damage due to stress. 

·        Medical Industry Electronics: Almost all types of electronics need to be flexible to enhance their longevity. It comes in handy for prosthetics, imaging technology, and implants in different fields. 

·        Military and Aerospace Electronics: Aerospace and military devices all rely on polyimide PCBs as well. It is because such PCBs are not only durable but serve with precision in the long run. A perfect option to choose for stressful fields like military and aerospace when it comes to protecting integral gear. 

What Is Fr4 PCB Material?

FR4 is a typical substrate used for specific printed circuit boards. However, it is only a grade of suitable material used in developing PCBs. If a PCB is FR4, it means it is flame resistant. Now this material is important for developing fiberglass

It is important for melting the glass and making long strands of it made of fiber yarn. You need to enhance the adhesion of individual fiber yarns, and for this, you need to cover them with a suitable resin. 

After this, it is important to laminate the board with a piece of copper foil before starting the PCB production. 

The properties of different types of FR4 substrates are different. Due to this reason, these properties give rise to different FR4 substrate types. These are:

·        Standard: Standard FR4 helps in making a special fiberglass that contains more bromine than others. It assists this fiberglass in opposing electrical flames and sustains the material’s quality. 

·        High Glass Transition: The temperature at which fiberglass loses stability is high glass transition temperature. Normally the FR4 PCBs are low in transition temperature. However, the PCBs with higher glass transition are excellent in stability. It eventually leads to boosting thermal resistance as well. 

·        Halogen-Free: Halogen-Free FR4 PCBs do not contain bromine which can cause life-threatening problems. No doubt that bromine is good at resisting electrical flames. However, halogen-free PCBs are important for those devices that include human workers or users and ensure their protection. 

When Should FR4 PCB Material Be Used?

Isola FR406N PCB

FR4 has vast applications throughout different domains. It does not mean that you can use FR4 for all types of applications and devices. There are some factors to consider when you want to use an appropriate FR4 for different devices.

Following is the list of those factors that will help you make a suitable decision:

·        Strength-To-Weight Ratio: Those devices that are heavy-duty need FR4 PCBs because of their excellent strength-to-weight ratio. It is because FR4 has many integrated components that contribute to boosting its strength. 

·        Versatility: You can use FR4 for different natures of PCBs. These can be with one side or two sides and might contain more than one layer. 

·        Chemically Resistant: FR4 offers great resistance to corrosive and noncorrosive chemicals. It is also beneficial to use when to want zero absorption of water. 

·        Dimensional Stability: FR4 PCBs have no parallel for their dimensional stability. They can sustain their shape under the worst stressful conditions.

·        Great Electrical Insulator: Now, this substrate is also good with electrical insulation. It is important since different applications need this degree of insulation that only FR4 offers. 

 Applications Of Fr4

The properties of FR4 make it important for various technical use cases. Below are some complex applications of FR4 in different industries. 

·        DC Board Applications: No DC device can work without FR4. It is because of accessibility and affordability. 

·        Low-Frequency Applications: FR4 PCBs come in handy for devices that work on low frequencies. It is because FR4 is affordable and performs much better than other substrates available. 

·        Digital Applications: FR4 is useful in digital devices as well. These devices include consumer electronics and other digital displays. However, using FR4 for high-frequency devices is not recommendable at all. 

Why Choose Polyamide And Polyimide Over Fr4?

Many manufacturers rely on FR4 PCBs instead of polyimide boards. It is because FR4 has much bigger advantages than polyimide boards. These are cost-efficient and accessible as well. However, it is better to compare these two materials to get an idea about their weak points clearly.

The following are the properties of polyimide that make it useful for different applications:

·        Flexibility: Polyimide PCBs are much more flexible than FR4 ones. Due to this reason, these are beneficial for those devices that need a higher degree of flexibility for their functioning. 

·        Good Heat Resistance: FR4 PCBs are not a good option to consider when your device is working under extremely hot temperatures. It is because FR4 PCBs are heat resistant. They never allow more heat to dissipate. Instead, use a polyimide PCB to save your system from heat damage.

·        Resistant to Chemicals: Polyamides are more reliable than FR4 in terms of chemical resistance, especially in the domains like aerospace and defense, where technical gear involves fuels and hydrocarbons. Polyimides are useful as they oppose reacting with chemicals and prevent possible abrasion. 

·        Durable: FR4 is too rigid to work efficiently with sensitive devices that you cannot expose to high vibrations and hot temperatures. In this case, polyimide PCBs will provide impressive durability and robustness to your devices. 

· Solves Integration Problems: Polyimides PCBs give enough to each component to fit in them properly. FR4 boards are not recommendable in this aspect since they oppose the post-integration of components if needed. 

Polyimide PCBS are not affordable, but they offer more benefits than FR4 substrate. In this post, you have learned about both types of PCBs through a detailed comparison. Always make sure that the type of PCB you are relying on fits well with your needs to avoid future complications. 




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