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  • Flexible PCB, Rigid flex PCB, Polyimde rigid PCB
  • Pyralux Series, Felios series, VT-901/VT-90H, SH260
  • Arlon 33N, 35N, 37N, 38N, 47N, 49N, 51N, 84N, 85N, 86HP
  • Impedance Control, Back drill, Backplane, IC Substrate
  • A Brief Introduction to Polyimide PCB
  • Blind & Buried Vias, Micro Vias, HDI
  • VIPPO, Conductive & Non-Conductive via plugging
  • A Brief Introduction to Polyimide PCB

A Brief Introduction to Polyimide PCB

As the name implies, Polyimide PCB is a circuit board made of Polyimide material. Polyimide PCB have superior performance characteristics, for example, high-temperature resistance over 400°C, long term use temperature range is -200~300°C, some materials do not have an apparent melting point, high insulation, the Dielectric constant ( Dk ) is 4.0 under 103 Hz, Dielectric loss is very to 0.004~0.007 etc. Therefore, it belongs to F to H grade insulation material.

Polyimide is a highly temperature-resistant material with high dielectric strength and excellent chemical resistance. It is also an ideal choice for applications that require very thin boards, as it can be manufactured in thicknesses as low as 0.1 mm or less. Polyimide has been used in the aerospace industry for many years due to its reliability, durability and performance under extreme conditions.

Due to its superior characteristics in thermal resistance and high flexibility. Polyimide PCB is always used in high-temperature end-use electronics, and electronics products need to bend or move.
In recent years, Polyimide flexible PCBs have become increasingly popular in consumer electronics due to their ability to withstand higher temperatures than conventional FR4 boards while still providing maximum flexibility and performance at a fraction of the cost.

Polyimide PCBs provide reliable operation even in demanding environments such as automotive, medical device and industrial applications where high-power components need exceptionally reliable connections without any risk of failure or damage from heat or vibration.

Because of the outstanding features of Polyimide in the performance and synthesis aspect, whether used as a structural or functional material, its huge application prospect can’t be ignored. It has also been called a problem solver in the material industry. It also believes that “without Polyimide, there would be no microelectronic technology today.”

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    Why Choose Viasion for Your Polyimide PCB

    Are you looking for a PCB manufacturer to help bring your product ideas to life? Look no further! Viasion is an expert at building high-quality polyimide PCBs that meet your needs.

     
    • Viasion pays great attention to the quality of products. With excellent equipment, scientific management, reasonable technology and a perfect quality assurance system, we provide customers with high-level technology and high-quality products and services.
    • Viasion aims to meet the needs of customers. While providing high-quality products, we attach great importance to the after-sales service of our products and obtain feedback from customers promptly.
    • Our team (including sales staff, engineers and technicians) has extensive experience in PCB manufacturing and assembly, ensuring that the goal of high-quality production is achieved.

    What Kind of PCB Need to Choose Polyimide Material?

    After the simple introduction of Polyimide material, you probably know something about Polyimide material. Still, not much, so when your PCB board need any characteristic as below, you may choose Polyimide material for your flex PCB or other circuit boards need high reliabliity and long usage life. Viasion is one of the most trusted polyimide PCB manufacturers with more then 16 years of experience. Please contact our sales team freely to quote your polyimide PCB price.

    Most types of Polyimide material ( not including the low fluidity Polyimide ) have outstanding flexibility; they can be bent and moved more in the product. As with any other material, this material also has limitations, but the exceptional flexibility is beneficial for absorbing shock. In addition, if the products are badly hit, it can help them last longer. So polyimide material is usually used in flexible PCBs and rigid-flex PCBs.

    Like their outstanding flexibility, Polyimide materials also have excellent tensile strength, which means Polyimide materials are tough and warp resistant. So when you make products that need physical durability, it will help a lot, including most of the handheld electronic equipment. Those products will move around and collide frequently.
    Polyimide material will not change temperature fast, so materials are rarely damaged when the temperature changes. The exact strength depends on the polyimide material, but the current selection allows them to function in the temperature range of – 200 to 300 degrees Celsius. Compared with many other materials, Polyimide material working temperature range are much bigger, which makes Polyimide material become the best choice when working in a severe temperature range.
    In addition to heat resistance, polyimide materials are also chemically stable (chemically resistant). As a result, even these materials exposed to hazardous chemicals are virtually immune to corrosion or contamination with dangerous chemicals. Therefore, it will be beneficial if you need to operate machines that are exposed to these chemicals.
    Most Polyimide materials handle physical stress, which means Polyimide materials can keep their shape even in physical stress conditions or severe thermal conditions. That makes the PCB made of Polyimide material highly durable.
    Polyimide materials have excellent space radiation resistance, can use in space, and will not be affected by space radiation to produce any physical and chemical changes. That can make sure the stability of the electrical performance of the material.

    Polyimide resin material has high TG, providing excellent PTH and solder pad reliability. Its thermal decomposition temperature reaches above 360 ℃. High thermal decomposition temperature can make the material withstand high-temperature soldering ( like lead-free soldering etc. ). The higher the TG value, the smaller the expansion of the Z-axis when PCB is heated ( no matter the process of technology or the actual application ). It can reduce the stress of PTH and then reduce the hidden PTH defects so that it will have higher PCB reliability.

    And the higher the TG value, the lower possibility for the pad and circuit to drop off from the PCB surface when in PCB repair. That’s why almost all the military PCB use Polyimide material for production because reliability in the military field is paramount.
    And the higher the TG value, the lower possibility of the resin drop-off because of the difference between resin and glass thermal expansion coefficient.

    Polyimide resin has high TD, making it used in high-temperature environments.
    Polyimide resin materials have stable dielectric constant, which is very suitable for impedance control applications.

    If we keep increasing the temperature of FR-4 material from 23℃ to 150℃ as a cycle, after 1000 cycles, the PCB will lose efficacy. But Polyimide material can stand 5000 cycles before PCB lose efficacy. It’s five times more than FR-4 material. If under extremely high-temperature conditions ( Above 220 ℃ under harsh environments or operational conditions ), FR-4 fabric may lose efficacy in about ten cycles, but Polyimide material can stand for about 100 cycles.

    Because the higher layers, especially those involved to blind/buried via design, maybe use multiple sequential laminations, the material needs considerable high-temperature resistance. In addition, it needs to ensure PTH’s reliability, so choose Polyimide resin material is a perfect choice.

    Notes of Polyimide PCB Production

    Polyimide material is not very difficult to produce, but we still need to pay attention to some notes below during Polyimide PCBs production:

     
    • The solidification temperature of Polyimide material is higher than FR-4 material, around 200℃. So when we choose the inner layer oxidation treatment, we need to select those oxidation systems with high-temperature resistance, such as browning oxidation etc.
    • The solidification of Polyimide material will last longer than FR-4.
    • Polyimide materials are easy to absorb moisture, so we must pay attention to the storage conditions for PP and have to vacuum packing to storage. Even the transient process from low to room temperature also needs to ensure they are vacuum packing. Then, after the inner layer oxidation process, before the lamination process, we need to oven-dry them.
    • The resin system of Polyimide material is a little different than FR-4, so we need to improve parameters in the drilling process and avoid broken drill pins.

    Some Polyimide Material Introduction

    Polyimide materials are mainly used in two kinds of electronics: high-temperature end-use electronics and electronics with flexible and rigid-flexible PCBs.
    For the Polyimide material used in polyimide flex PCBs, we also call it Kapton PCB. The most famous type is Pyralux series from DuPont company and Felios series from Panasonic company.
    The other one is pure Polyimide resin which is also called PTFE material, like 85N, . Although it does not contain flame retardant materials and has the highest high-temperature resistance, the shortcoming is that it cannot meet the UL flame retardant requirements, and the lamination cycle is a little long.
    And the early Polyimide material also has the problem of brittleness, which makes the drilling very difficult. Arlon company is based on years of research and development experience in Polyimide materials, resin filling modification, and adding flame retardant. That improves the drilling problem, makes drilling easy, and shortens lamination time. According to the difference in flame retardant, there are 33N(UL-VO), 35N(UL-V1), two kinds of material, and 35N has better machinability.  If you use Polyimide material for filling blind and buried vias, you can choose powdery 84N material. On the other hand, if you use Polyimide material for rigid-flexible PCB, you can use low-mobility 38N PP. Some material information is below:
    DuPont company produce the most advanced polyimide material for polyimide flex PCBs, which are normally used in multilayer rigid-flex PCBs. There are many types of materials such as Pyralux® APR, Pyralux® AC, Pyralux® AG, Pyralux® AP, Pyralux® HT, Pyralux® TA/TAS, TAH/TAHS.
    Felios series have two types: R-F775 for double-side and R-F770 for single side PCBs. They are widely accepted by customers worldwide.

    33N, 35N material and PP： High Tg value ( Tg > 250℃ ), low coefficient of expansion; Very suitable for lead-free technology and the application of high-temperature environment.
    37N, 38N Non/low flow PP： These two PP can use for Heat-Sink production.
    84N PP： It is a hole-filling PP.
    85N material and PP： These materials are the basic Polyimide materials. The TG value > 250℃, Td > 400℃, T300 > 60 minutes. Usually used in long-term high-temperature environments, like products: Aircraft engine instrumentation, Downhole drilling, Automobile engine, and Industrial high-temperature sensor.
    45NK material： The Dk = 3.9, TG value 170℃, used in no pin ceramic chip carrier that coefficient of thermal expansion lower than 6ppm/ ℃ and other low expansion chip designs.
    45N material： The Tg value is 170℃, used in high layers of multi-layer PCB and backboard.
    35NQ material： The Tg value ≥ 250℃, low dielectric constant and low loss ( DK = 3.5, Df = 0.009 ). Suitable for RF/microwave frequency applications.

    ceramic-loaded polyimide material for high temperatures and high reliability in electronics.
    Used for products that need ultra-high thermal performance, such as Burn-in Board, Aircraft and Aerospace, these products need to work under high temperatures for a long time.

    The Disadvantages of Polyimide PCB

    • Polyimide material PCB costs more than FR-4 material PCB.
    • Polyimide material may be harmful to health
    • after decomposition.
    • Polyimide materials are alkali intolerant.
    • The elongation of Polyimide material is slight.
    • Solidification temperatures are too high, high requirements for synthesis process.

    Polyimide Material PCB VS FR-4 Material PCB

    As we said above, the cost of Polyimide material is higher than FR-4 material, but why choose Polyimide material but not FR-4 material for your PCB? The main reason is flexibility. So if you need a flex PCB, you usually will use Polyimide material for the production. On the other hand, FR-4 material presses the copper layer to the glass epoxy plate, then becomes a durable and very rigid material, so if your need to install your PCB into a product that is not easy to receive components, and you don’t need the PCB are rigid, then you can choose Polyimide material PCB. But the disadvantage of polyimide flex PCB is less dimensional stability and different thermal properties.

    Although polyimide circuit board is more expensive than FR-4 PCB, Polyimide PCB can solve many PCB integration problems, so many companies think it is worth it. Polyimide PCB material has lightweight, has good flexibility, good heat resistance and good chemical resistance advantages. So this material is used in various electronic products, not just PCB, but also cable and insulating film. It also can be used as an adhesive to resist high temperature and mechanical stress. Viasion is polyimide PCB supplier with rich production experience. Please contact us any time for a free polyimide flexible PCB quote.

    Applications of Polyimide PCB

    Polyimide PCB can use in a lot of different industries. Below is some industry that uses polyimide circuit board: 

    Many companies use Polyimide PCB material for their Computer Electronics equipment. People will pick them up, put them down, move them, and usually hit their electronic devices, so durability and resistance to temperature changes will be essential for most modern electronic equipment. Polyimide printed circuit boards is beneficial for that equipment.

    Automotive Electronics products usually face more harsh environments than other types of computers and systems. Between the heat of summer, the cold of winter and the collision and impact of various forces, automotive electronics products will need higher durability than ever before. Especially with the increasing popularity of electronics and smart cars, polyimide circuit board may be the only practical option.
    Consumer Electronics products are different from Computer Electronics products. It is a more widely category, including many commodities that need consumers’ attention. Those products need PCB, so many of those products will be required to use the Polyimide PCB performance.
    Medical industry electronics have special requirements not found in most other industries, making Polyimide PCB laminate technology beneficial. Besides entering the harsh environment, many medical industry electronics equipment need to keep portability and minimize signal interference, so any polyimide circuit board has a significant advantage.

    Military and Avionics electronics equipment can see the worst environment in the global, including deadly explosions. Polyimide PCB is not invincible, but its durability can keep them functioning even in harsh environments until they are completely overwhelmed. It may be the difference between soldiers’ life and death or critical flight or mission success.

    Also, the reliability requirements of Military and Avionics electronics are very high, and light control products cannot tolerate any application with PCB failure risk, so much use Polyimide as its PCB base material. Because this kind of application can’t appear any problems, it directly involves pilots’ lives under extreme conditions. So polyimide printed circuit boards are always the best choice.

    For the control system of space satellite rockets, because of the work conditions of PCB in space, there is a lot of space radiation, so to ensure the stability of electrical characteristics and very high-reliability requirements for PCB, must use Polyimide as its PCB base material.

    Also, the reliability requirements of Military and Avionics electronics are very high, and light control products cannot tolerate any application with PCB failure risk, so much use Polyimide as its PCB base material. Because this kind of application can’t appear any problems, it directly involves pilots’ lives under extreme conditions. So polyimide printed circuit boards are always the best choice.

    High-temperature applications include probe control systems for oil drilling, semiconductor performance testing at high temperatures (often referred to as ageing testing), and high-power power supply modules. The high-temperature resistance of Polyimide material is the main reason it has become the first choice for this kind of application. For example, the Schulmberger oil drilling control and INTEL chip ageing test adopt 85N material.

    Some Outstanding Properties of Polyimide Material

    1
    High-temperature resistance
    Polyimide materials are known for their excellent high-temperature resistance, capable of withstanding temperatures up to 500°C. In addition, this kind of polyimide has a low thermal expansion coefficient, meaning it can maintain its shape and physical properties even when exposed to extreme temperatures.
    2
    Excellent mechanical properties
    Polyimide materials have excellent mechanical properties, making them popular for various engineering applications. The polyimide material has high tensile strength and toughness, displaying superior resistance to impact and wear. Additionally, polyimide has a high flexural modulus, which can be bent or stretched multiple times without permanently deforming.
    3
    Chemical and solvent stability
    Polyimide materials exhibit excellent chemical and solvent stability, making them an ideal choice for use in environments where they may be exposed to harsh chemicals or solvents. In addition, the polyimide material is resistant to most common acids, alkalis, alcohols, and solvents, including gasoline, oils and lubricants.
    4
    Low flammability
    Polyimide materials have very low flammability, due to their extraordinary heat resistance. This material also has a high ignition point, meaning it won't start burning until exposed to temperatures above 500°C. Additionally, polyimide materials are self-extinguishing and will not support combustion in the event of an open flame or spark. These features make polyimide materials ideal for various engineering applications, such as electrical insulation systems and aerospace components.
    5
    Abrasion resistance
    Polyimide materials can withstand high abrasion levels, making them an excellent choice for applications where wear and tear are ordinary. This polyimide material is resistant to scratching and scuffing, as well as other forms of mechanical wear. In addition, polyimide material has superior creep resistance, meaning it can maintain its original shape and form even when exposed to high-pressure levels.
    6
    Good dielectric properties
    Polyimide materials have excellent dielectric properties and are often used to manufacture electrical insulation systems. This polyimide material has a high dielectric strength, effectively insulating against the electric current while dissipating heat. In addition, polyimide materials have a low dielectric constant, allowing them to be used in high-frequency applications.
    7
    Electrical insulation

    Polyimide materials are often used in manufacturing electrical insulation systems due to their excellent dielectric properties. This polyimide material has a high dielectric strength, effectively insulating against the electric current while dissipating heat.

     
    8
    Low water absorption
    Polyimide materials also boast low water absorption rates. Therefore, it is beneficial for electrical insulation systems, as polyimide insulation is resistant to humidity-induced degradation and decomposition.
    9
    Flame retardancy

    Polyimide materials have superior flame-retardant properties. That is because polyimide polymers and films have a low flammability rating, making them difficult to ignite and burn at slow rates when exposed to extreme temperatures. In addition, polyimides boast an oxygen index of over 25%, making them one of the most flame-retardant polymers on the market.

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    Frequently Asked Questions

    Polyimide PCB, also known as polyimide printed circuit board, is a circuit board made from polyimide film. Polyimide is an advanced polymer containing imide groups. Polyimide material provides superior thermal stability, excellent chemical and mechanical stability, and high-temperature insulation.

    Polyimide PCB material is an advanced polymer and a class of high-performance plastics, and this kind of material offers high-temperature resistance, excellent dimensional stability and dielectric properties.

    From the perspective of a PCB manufacturer, we think there are two types:
    Rigid polyimide PCB: it is commonly used in microwave and RF circuit boards. This kind of base includes such as Arlon 33N, 35N, 84N, 85N, AGC RF-30A,  RF-35TC, etc;
    Flexible polyimide PCB: it is usually used in applications that need to be bent. This kind of base includes Dupont Pyralux series, AP series, Panasonic Felios series, etc. 

    In general, the basic process of polyimide PCB design is as follows: pre-preparation → PCB diagram design → PCB layout → trace routing → routing optimization and silkscreen → network and DRC check and structure check → PCB production.

    Let’s look at some of the benefits of using a polyimide PCB.
    1) High-temperature resistance
    2) Low dielectric constant
    3) Low moisture absorption
    4) Superior electrical insulation properties
    5) Excellent thermal stability
    6) Excellent chemical resistance

    Board cutting → Drilling → Dry film and exposure → Copper etching → Solder mask printing → Components marks printing → Surface treatment → outline profiling → testing → Quality checking → Packaging & shipping

    Polyimide PCBs are the circuits produced by polyimide materials. Generally speaking, there are two kinds of polyimide PCB boards: polyimide flex PCB and polyimide rigid PCBs. Kapton PCB is a circuit boards produced by Kapton which ithe polyimide material produced by Dupont company. So Kapton PCB is just a kind of polyimide PCBs.

    Although most polyimide PCBs are flexible, there are also rigid polyimide PCBs which are produced by rigid polyimide PCB material, and they are usually used in microwave and RF PCBs. Such as Alron 85N, 33N, AGC RF-35TC, Rogers RO3003, RT/duroid 5880, etc. 

    Yes. Although most of polyimide printed circuit boards are flexible. But there are also rigid polyimide PCBs. For example, Arlon 33N, Arlon 35N, Arlon 84N, Arlon85N, Arlon HF-50high, Nelco N7000-2, Ventec VT-901, etc., these materials always have extremely high Tg 250℃, suitable for high reliable and long service life electroncis such as burn-in Boards, backplanes, electronics used aerospace, military, avionics, space industry.

    PI PCB is short for polyimide PCB but usually only means flexible polyimide PCBs. So when we say “PCB PI”, it means the polyimide material used in flexible circuit boards. For rigid polyimide PCBs, we also call them PTFE PCBs or Teflon PCBs.


    When designing polyimide PCBs, specific considerations must be taken into account.
    For example, polyimide has a much higher thermal coefficient of expansion than other PCB materials, which can affect the overall size and shape of the board.
    Additionally, polyimide has a much lower dielectric constant than other PCB materials, making it essential to consider how this will impact signal speed and integrity.
    Thirdly, due to the unique parameters of this particular kind of plastic material, there are a lot of challenges in PCB manufacturing processes, such as lamination, drilling, copper plating and outline profiling. So a very experienced engineering and production team is needed. 

    Polyimide material is a special kind of plastic which is very difficult to degenerate. Proper manufacturing and disposal practices should be employed to reduce environmental risks associated with polyimide PCBs to minimize hazardous material release into the environment.
    Furthermore, any polyimide waste should be recycled or disposed of under applicable laws and regulations.

    Polyimide PCBs must be stored in a temperature, humidity-controlled and dust-free environment to prevent damage caused by contaminants, moisture and temperature changes. The shelf life of polyimide is usually 3-6 months. Special equipment, techniques and supportive tools will be needed in production. 

    The most standard finishing options for polyimide PCBs are as follows.
    1) electroless nickel immersion gold (ENIG)
    2) organic solderability preservatives（OSP)
    3) electroless silver
    4) tin plating
    5) hot air solder leveling (HASL)

    We can take a look at the following techniques for soldering polyimide PCBs.
    1. Use lead-free solder paste with polyimide-compatible flux.
    2. A supportive tool may be needed in SMT assembly since polyimide PCB is more flexible.
    3. Try to keep soldering time to a minimum.
    4. Reduce overheat by using techniques such as preheating or cooling stages.

    The testing methods performed on polyimide PCBs are as follows.
    1) Electrical Test for Open and Short Circuit
    2) Automated Optical Inspection
    3) Flying Probe Testing and Fixture Testing for Open/Short
    4) In-circuit Testing
    5) Functional Testing
    6) TDR Impedance test
    7) Hi Potential Testing (Hi Pot PCB Testing).
    8) Any other tests customers required
    9) Tape Test (adhesion test)
    10) Peel Test (conductor peel strength)

    Polyimide PCB material has two main properties.
    1. Excellent thermal stability.
    2. High TG, polyimide PCB material always has very high TG, typically >= 250℃.
    3. High mechanical stability.
    4. Robust and can be used in harsh environments.
    5. Some polyimide PCBs are flexible.

    Polyimide materials are widely used in printed circuit board production. The following are their main advantages:
    1. Very low issipation factor, so it is widely used in microwave and RF circuit boards.
    2. Very reliable and can used in very tough environments such as high humidity and extremely low and high temperature. So they are used in the aerospace, military, space, and avionics industries.
    3. It is flexible. So, most of the flexible PCBs are produced by polyimide materials.

    They are totally two different kinds of PCB materials. Their main differences are:
    1. Usage is different. Polyimide PCBs are always used in flex circuit boards, microwave and RF applications, and highly reliable and long-life electronics. However, FR4 materials are always used in standard rigid circuit boards.
    2. Prices are different. Polyimide PCBs are much more expensive than standard FR4 circuit boards. So, polyimide PCB designers should understand this.
    3. Production processes and techniques are different. Due to the unique characteristics of polyimide material, special processes and techniques are needed in the drilling, lamination, plating and board-cutting processes in PCB production.