PEI The replacement of PEEK, the upstart in the dielectric field

What is PEI?

Polyetherimide, referred to as PEI, the English name is Polyetherimide, and its appearance is amber. It is an amorphous thermoplastic special engineering plastic that introduces flexible ether bonds (-R-O-R-) into rigid Polyimide long-chain molecules.

PEI structure

As a thermoplastic polyimide, PEI can significantly improve the poor thermoplasticity and difficulty of processing of polyimide by introducing ether bonds (-R-O-R-) into the main chain of the polymer while retaining the imide ring structure. question

Features of PEI

Advantage:

High tensile strength, the strength is above 110MPa;

High bending strength, the strength is above 150MPa;

Excellent thermal mechanical bearing capacity, thermal deformation temperature is greater than or equal to 200 ° C;

Good creep resistance and fatigue resistance;

Excellent flame retardant properties, low smoke combustion;

Has excellent dielectric and insulating properties;

Excellent dimensional stability, low thermal expansion coefficient;

High heat resistance, can be used for a long time at 170°C;

Can pass through microwaves.

Shortcoming:

Contains BPA (bisphenol A), restricting its application in infant-related products;

notch shock sensitive;

Alkali resistance is average, especially under heating conditions

Application of PEI

PEI has good high temperature resistance and dimensional stability, as well as chemical resistance, flame retardancy, electrical properties, high strength, high rigidity, etc., and its superior thermal stability can be used to make high temperature and heat resistant devices; using its good Mechanical properties Adding glass fiber, carbon fiber or other fillers can achieve the purpose of reinforcement and modification; these characteristics also make PEI widely used in high temperature resistant terminals, IC bases, lighting equipment, FPCB (flexible circuit boards), liquid delivery equipment, aircraft interiors Parts, medical equipment and household appliances and other fields.

Electronic and electrical industry

In the electrical and electronic industry, PEI with excellent mechanical properties can be used to manufacture many parts, such as connectors that require high dimensional stability, small relay casings, circuit boards, etc.

PEI can also be used to manufacture high-precision fiber optic components, such as fiber optic connectors. Using PEI instead of metal to manufacture optical fiber components can not only maintain the optimal structure of parts, maintain more accurate dimensions, simplify the assembly process, but also reduce manufacturing and assembly costs. In addition, PEI is often used as some parts such as switches and bases, and is used in the instrument industry.

Automobile machinery field

It can be used in mechanical high-temperature friction parts, such as bearings, heat exchangers, carburetor covers, etc.

Aerospace field

It can be used to manufacture some internal parts of aircraft, such as rocket fuze caps, aircraft lighting equipment, etc.

Medical field

Used as handles for medical surgical instruments, trays, clamps, prosthetics, medical light reflectors, and dental appliances, and in medical equipment such as ventilators, anesthesia machines, sterilization trays, surgical guides, pipettes, and laboratories Animal cages, etc.

Household appliances

Can be used as a tray for product packaging and microwave ovens.

PEI is widely used

It is worth mentioning that PEI is considered to be a very promising polymer dielectric material for energy storage due to its good thermal and mechanical properties as well as low dielectric loss and excellent energy storage performance. In addition to dielectric energy storage, PEI's excellent dimensional stability, electroplatability and wave transparency make it another huge application scenario in 5G communication.

Optical Communication

PEI materials dominate the field of optical communications and are widely used in optical fiber connectors and optical components of optical transceiver modules.

PEI material has very good infrared penetration, and the transmittance in the 850-1550nm optical communication frequency band is more than 88%. Its high refractive index can remain constant with changes in temperature and humidity, and can withstand up to 2000 hours. Double 85 (85°C/85% humidity) harsh test; second, it has excellent long-term dimensional stability, which can provide reliable optical connection for signal transmission; third, it has high strength and high modulus, and can replace metal to make optical fibers Connectors, adapters and other structural components; Fourth, it has the characteristics of high dimensional stability and high strength, as well as very good weather resistance, which can be applied in the field of waterproof connectors for optical fiber splitting boxes or base stations, and can meet the waterproof requirements of IP67, and Significantly improve the long-term airtightness and reliability of the product.

RF connector

RF connector insulator
RF connector insulators require materials to provide good dielectric properties, low and stable dielectric loss, good mechanical properties, excellent dimensional stability for easy assembly, and reliable mass production performance. PEI materials are excellent in all aspects above It can meet the application requirements and has become the first choice of insulator material for RF connectors

Filter

As an amorphous material with a high glass transition temperature, PEI material has a linear thermal expansion coefficient similar to that of aluminum alloy, excellent heat resistance and dimensional stability, long-term reliability, low and stable dielectric loss, electroplating, and It has good metal adhesion and other characteristics, and shows incomparable advantages in cavity filter applications that other plastic materials cannot match. In addition, the 5G base station antenna cavity filter unit made of PEI material can achieve a weight reduction effect of up to 30%; and it can be mass-produced through injection molding processing, maintaining dimensional accuracy between batches and reducing production costs.

With the development of 5G technology, the size of products is reduced, and the requirements for precision and mechanical properties are stricter, and the application advantages of PEI are becoming more and more significant.

Phase shifter

In base station antennas, PEI is also widely used in phase shifters. Whether it is the dielectric sheet of the dielectric phase shifter or the PCB bracket in the ring phase shifter, it benefits from the good size and stability of the PEI material in a wide temperature range. Stability of dielectric properties, low dielectric loss, high mechanical strength and excellent resilience. With the gradual commercialization of 5G base stations and the pursuit of further reducing energy consumption and cost, traditional dielectric phase shifters or ring phase shifters will have the opportunity to replace chip phase shifters and be widely used in 5G massive MIMO antennas.

PEEK Appearance

The scientific name of PEEK is Polyetheretherketone. It is a high polymer composed of repeating units containing one ketone bond and two ether bonds in the main chain structure. It is a special polymer material. The appearance of PEEK is beige, with good processability, sliding and wear resistance, good creep resistance, very good chemical resistance, good resistance to hydrolysis and superheated steam, and high temperature radiation resistance. In addition, its thermal High deformation temperature, good intrinsic flame retardancy.

PEEK was first used in the field of aerospace to replace aluminum, titanium and other metal materials to make aircraft internal and external parts. Due to the excellent comprehensive performance of PEEK, it can replace traditional materials such as metals and ceramics in many special fields. Its high temperature resistance, self-lubrication, wear resistance and anti-fatigue properties make it one of the most popular high-performance engineering plastics today.

As a thermoplastic polymer material, the characteristics of PEI are similar to those of PEEK, and it can even be said to be the replacement of PEEK. Let's take a look at the differences between the two.

Compared with PEEK, the comprehensive performance of PEI is also more eye-catching, and its biggest advantage lies in the cost. This is also the main reason why some aircraft design materials choose PEI composite materials. The comprehensive cost of its parts is higher than that of metal, thermosetting composite material and PEEK composite are low.

It should be noted that although PEI is cost-effective, its temperature resistance is not too high. In chlorinated solvents, stress cracking is prone to occur, and the resistance to organic solvents is not as good as that of the semi-crystalline polymer PEEK. In terms of processing, even though PEI has the processability of traditional thermoplastic engineering plastics, it requires a higher melting temperature.