Applications for millimeter-wave (mmWave) circuits are growing rapidly, from collision-avoidance radar systems in autonomous vehicles to high-data-rate fifth generation (g5G) new radio (NR) cellular wireless networks. Many such applications are driving higher frequencies, above 24GHz, where wavelengths are smaller and the smallest attention to circuit design and fabrication can make the biggest differences in electronic product performance. Understanding the differences between PCBs at mm Wave frequencies and lower frequencies can help avoid circuit manufacturing mishaps for many applications that are soon to require millions of double-sided and multilayer PCBs at those higher frequencies. Compared to lower frequency circuits, high-frequency RF/ microwave circuits are sensitive to circuit materials and fabrication processes. Whereas some electrical circuit functions such as power lines and digital control may be well-supported with low-cost FR-4 circuit materials, RF, microwave and mmWave circuits require much higher performance circuit materials to minimize signal losses and distortion. Many multilayer mixed-signal PCBs with many different electrical functions are a blend of different types of circuit substrate materials, with materials selected according to behavior best suited for the types of circuit functions fabricated on that layer.
展开▼
