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.
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 -RF Microwave Impedance
Substrate material selection principle
1. 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.
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.
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. FR4 (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.
5. TACONIC company brand is good, specifications complete, the price is higher than the FR4.
6. ROGERS, 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.
7. Common high frequency plate substrate and its performance
How to do RF Microwave Impedance Control
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:
A. Surface microstrip line .
B. Embedded microstrip line.
D. Pairedstrip (dual stripline).
Among them, the surface microstrip line model is the most widely used structure for our PCB design, and the impedance of the PCB signal line is related to the dielectric constant, PCB structure and linewidth of the plate.
Radio frequency signal line as far as possible can be placed on the surface layer, in some cases, you can place it inside of PCB design, the most common is third strip line, impedance is 50. Please contact us for much more details.
Our Capabilities Items for RF Microwave Impedance
1. Tight Etch Tolerances on Critical RF Features.
2. +/- .0005″ standard tolerance on etched features for unplated 0.5oz copper.
3. Selective plated up layers allowing +/- .0005″ etch tolerances.
4. Exact registration/laser direct imaging.
5. Front to back registration of etched cores to +/-.001″.
6. Mixed Dielectric constructions.
7. Buried / Blind / Microvia.
8. Ormet interconnects.
9. Multilevel cavity constructions.
10. Optical mill / drill.
11. Laser routing.
12. Sequential lamination.
13. Formed PCB’S.
14. Plated edges.
Back Drill for Precision Stub Removal RF Microwave Impedance
1. Mechanical back-drilling (Minimal stub).
2. Laser drilling (No stub).
3. Laser modified controlled depth drill (Mechanical drill followed by laser cleanup, no stub).
4. Hole Fill.
5. Conductive, non-conductive, and partial hole fill options.
6. Thermal Solutions.
7. Copper coins and slugs.
8. Metal Core & Metal Back.
9. Thermally conductive laminates.
10. Heatsink assembly department to laminate heatsink or interface plates to the circuit boards.
Embedded Capabilities for RF Microwave Impedance
1. Planar Resistors.
2. Ohmega and Ticer.
3. Screened Ink Resistors.
5. On board circuit.
6. Embedded ferrites.
7. Surface Finishes.
8. ENIG – electroless nickel, soft immersion gold – standard solder assemblies.
9. ENEPIG – electroless nickel, electroless palladium, immersion gold.
10. Hard and soft wirebondable gold.
11. Immersion silver.
12. Assembly and Test.
13. RF assembly of connector, surface mount component, drop-in cavity components, hand and automated solder assembly options.
14. RF test center including 5 Network analyzers with combined frequency sweep coverage of 50MHz to 40 GHz.
15. Custom anechoic boxes for antenna measurements.
16. Switch matrix capability for multiple measurements between human interaction.