Impedance Control for RF and Microwave PCB

Impedance control is most important to RF and Microwave PCB. Highfive Technology applications based approach provides innovative engineering and advanced process capabilities to pay attention to impedance control during all fabrication processes.

Impedance control
Impedance control

From defense/aerospace electronics, medical devices and imaging, or complex telecommunications equipment, Highfive team supports a wide range of frequency bands (L, S, C, X, Ku, K, Ka, V, W). We have extensive experience with a wide range of low loss laminates and a total of over 70 resin systems.

Our Field Applications Engineering team provides a long history of collaborative engineering support. Qualifications include MIL-PRF-31032, AS 9100, ITAR, IPC 6012 & IPC6018, NADCAP.

RF and Microwave substrate Material

Substrate material selection principle

RF and microwave band PCB board is not only the support of the circuit, but also the transmission medium of microwave electromagnetic field. Therefore, RF circuit PCB is best to choose high frequency and microwave plates.

4.1.2 RF circuit on PCB in addition to the general principle, considering the current size, must also consider the characteristic impedance of the printed line, strict impedance matching in PCB production line control considering impedance must be printed. The characteristic impedance of printed wiring is related to the material characteristics and physical parameters of the PCB, so the PCB designer must clearly understand the performance of the PCB sheet.
Generally speaking,

4.1.3 radio frequency board has high frequency and high performance, and usually chooses the substrate with high dielectric constant, high stability and low loss. In addition, the substrate must conform to the production process, such as high temperature reflow soldering. At present, our company commonly used RF substrate for FR4, TACONIC and ROGERS company’s series of sheet metal. See Appendix A. for details

4.1.4FR4 (flame retardant copper foil, epoxy glass cloth laminate), dielectric constant at 1GHz frequency is Er=4.3 + 0.2, glass temperature Tg=135 degrees centigrade. Ordinary sheet materials used in the following two kinds: ordinary sheet material, low cost, mature process; UV sheet material, commonly known as yellow board, with UV-BLOCKING blocking ultraviolet function, mainly used for the outer layer of PCB board. The performance is slightly better than that of ordinary sheet metal.

4.1.5TACONIC company brand is good, specifications complete, the price is higher than the FR4.

4.1.6ROGERS, the dielectric constant of the material with high precision, good temperature stability, low loss, commonly used in high power circuit, and PCB manufacturing, processing technology and FR4, the processing cost is low, but the adhesion of small copper foil.

4.1.7 common high frequency plate substrate and its performance as shown in table 1.

Impedance control

9.2.1 transmission line
In the design of characteristic impedance of circuits, microstrip structure is the most popular, so it has been widely promoted and applied. The microstrip line structure are the most commonly used 4 kinds: surface microstrip line (surface microstrip), embedded microstrip line (embedded microstrip), stripline (stripline), pairedstrip (dual stripline). Among them, the surface microstrip line model is the most widely used structure, and the impedance of the PCB signal line is related to the dielectric constant, PCB structure and linewidth of the plate. General radio frequency signal line as far as possible in the surface layer, in some cases can go inside, the most common is third strip line, impedance is 50. See Appendix D for details. Table 3 lists some typical PCB impedance (50) control parameters, and the newly designed PCB can be applied directly to these data.

Our Capabilities Include:

Tight Etch Tolerances on Critical RF Features

+/- .0005″ standard tolerance on etched features for unplated 0.5oz copper

Selective plated up layers allowing +/- .0005″ etch tolerances

Exact registration/laser direct imaging

Front to back registration of etched cores to +/-.001″

Mixed Dielectric constructions

Buried / Blind / Microvia

Ormet interconnects

Multilevel cavity constructions

Optical mill / drill

Laser routing

Sequential lamination

Formed PCB’S

Plated edges

Back Drill for Precision Stub Removal

Mechanical back-drilling (Minimal stub)

Laser drilling (No stub)

Laser modified controlled depth drill (Mechanical drill followed by laser cleanup, no stub)

Hole Fill

Conductive, non-conductive, and partial hole fill options

Thermal Solutions

Copper coins and slugs

Metal Core & Metal Back

Thermally conductive laminates

Heatsink assembly department to laminate heatsink or interface plates to the circuit boards

Embedded Capabilities

Planar Resistors

Ohmega and Ticer

Screened Ink Resistors


On board circuit

Embedded ferrites

Surface Finishes

ENIG – electroless nickel, soft immersion gold – standard solder assemblies

ENEPIG – electroless nickel, electroless palladium, immersion gold

Hard and soft wirebondable gold

Immersion silver

Assembly and Test

RF assembly of connector, surface mount component, drop-in cavity components, hand and automated solder assembly options

RF test center including 6 Network analyzers with combined frequency sweep coverage of 50MHz to 40GHz.

Custom anechoic boxes for antenna measurements

Switch matrix capability for multiple measurements between human interaction