PTFE Microstrip Microwave Circuit Board

ROGERS' RT/duroid high frequency circuit board material is a polytetrafluoroethylene (PTFE) sheet filled with ceramic or random glass fiber laminates with low dielectric loss, low water absorption, and dielectric constant that varies with frequency Stability and other advantages, can be widely used in high reliability, aerospace and defense applications. Recently, the company has added a new member RT/duroid 6002 microwave material to its RT/duroid laminate products. RT/duroid 6002 is a low dielectric constant laminate that meets the stringent requirements for mechanical reliability and electrical stability in the design of complex microwave structures.

Microstrip microwave circuit boards generally operate within a certain frequency range, and conductor and dielectric losses limit the performance of their designs. Conductor losses vary with frequency of operation, conductor width, thickness, surface roughness, and substrate height. Most designs so far are a compromise between high dielectric constant and low hygroscopicity. Materials with high dielectric constants allow the use of less space, but at the expense of higher moisture absorption. Among the RT/duroid series products, some are specially designed for high dielectric constant such as RT/duroid 6010, which has a dielectric constant as high as 10.2; RT/duroid 6035HTC is specially designed for high-power RF microwave applications. RT/duroid 6002 is a low dielectric constant laminate with a moisture absorption rate of only 0.02%, and its advantages lie in high mechanical reliability and electrical stability.

RT/duroid 6002 laminates fully meet filter, oscillator and delay line designers' needs for stable performance in their designs due to the strong temperature stability of their dielectric constant. The test results of the rate of change of dielectric constant with temperature from -55℃ to +150℃ show that the dielectric constant of this material has excellent resistance to temperature change. The typical value of the dielectric constant is 2.94, and the error is only ±0.04 . Extremely low losses ensure excellent performance at high frequencies, with a loss factor of only 0.0012 at 23°C and 10GHz.

Very low thermal expansion rate and high dimensional stability make RT/duroid? 6002 laminates have great advantages in reliability and dimensional stability. Its coefficient of thermal expansion (CTE) for X and Y axes is as low as 16ppm/°C, and its Z-axis CTE as low as 24ppm/°C ensures high reliability of plated through holes. The RT/duroid 6002 material has successfully undergone 5000 temperature cycling tests in the range of -55°C to 125°C with no problems with any of the tested materials. Excellent dimensional stability (0.2 to 0.5 mils/ft) is achieved by matching the X and Y coefficients of expansion of copper. This often eliminates double etching to achieve tight positional tolerances. The low tensile modulus in the X and Y directions greatly reduces the stress on the solder joints and allows the expansion of the laminate to be limited to a minimum metal with a low thermal expansion coefficient of 6 ppm/°C. This also increases the reliability of the surface mount.

RT/duroid 6002 laminates are also available with aluminum, brass or copper sheets and resistive foils. Electrodeposited copper at 0.5-2 ounces per square foot and 0.5-1 ounces of reverse treated deposited copper or 0.5-2 ounces per square foot copper rolls are clad at a specified dielectric thickness between 0.13 mm and 3.18 mm. Metal-clad laminates can be processed into various printed circuit boards.

RT/duroid 6002 is especially suitable for flat or curved applications such as antennas, complex multilayer circuits with interlayer connections, and microwave circuits for aerospace designs. Due to its low outgassing rate, RT/duroid 6002 is an ideal material for aerospace applications. The product has also passed the 0-94V flame retardant test of Underwriters Laboratories in the United States.

The field of radar systems is one of the main application fields of RT/duroid 6002. This type of laminate can be widely used in beamforming networks, phased array antennas, ground-based and airborne radar systems. In commercial environments, the use of RT/duroid 6002 laminates in applications such as GPS and commercial-grade aviation collision avoidance systems can bring high stability and reliability to the heel. In addition, this type of laminate can also be used in high-reliability complex multi-layer circuits.