PCB Tech - 5G communication challenges to PCB technology

5G communication is a huge and complex integrated technology. Its challenges to the PCB process mainly focus on: large size, high multilayer, high frequency, high speed and low loss, high density, rigid-flex combination, high and low frequency mixed pressure, etc. So many process technologies put forward new or higher requirements on PCB materials, design, processing, and quality control. PCB companies need to understand the changing needs and propose a full range of solutions.

Material requirements: A very clear direction for 5G PCB is high-frequency and high-speed materials and board manufacturing. In terms of high-frequency materials, it is obvious that leading material manufacturers in the traditional high-speed fields such as Lianmao, Shengyi, and Panasonic have begun to deploy high-frequency plates and introduced a series of new materials. This will break the current dominance of Rogers in the field of high-frequency panels. After healthy competition, the performance, convenience and availability of materials will be greatly enhanced. Therefore, the localization of high-frequency materials is an inevitable trend.

In terms of high-speed materials, 400G products need to use M7N, MW4000 equivalent grade materials. In the backplane design, M7N is already the lowest loss option. In the future, backplanes/optical modules with larger capacity will require lower loss materials. The combination of resin, copper foil, and glass cloth will achieve the best balance between electrical performance and cost. In addition, the number of high-levels and high density will also bring reliability challenges.

Requirements for PCB design: The selection of plates must meet the requirements of high frequency and high speed, impedance matching, stacking planning, wiring spacing/holes, etc. must meet the signal integrity requirements, specifically from loss, embedment, high-frequency phase /Amplitude, mixed pressure, heat dissipation, PIM these six aspects.

Requirements for process technology: The enhancement of 5G-related application product functions will increase the demand for high-density PCBs, and HDI will also become an important technical field. Multi-level HDI products and even products with any level of interconnection will become popular, and new technologies such as buried resistance and buried capacitance will also have more and more applications. PCB copper thickness uniformity, line width accuracy, interlayer alignment, interlayer dielectric thickness, control accuracy of back drilling depth, and plasma de-drilling ability are all worthy of in-depth study.

Requirements for equipment and instruments: High-precision equipment and pre-processing lines with less roughening of the copper surface are currently ideal processing equipment; and the testing equipment includes passive intermodulation tester, flying probe impedance tester, loss test equipment, etc. . Precise graphics transfer and vacuum etching equipment, detection equipment that can monitor and feedback data changes in line width and coupling spacing in real time; electroplating equipment with good uniformity, high-precision lamination equipment, etc. can also meet the production requirements of 5G PCB.

Requirements for quality monitoring: Due to the increase of 5G signal rate, the deviation of the board manufacturing has a greater impact on the signal performance, which requires stricter control of the manufacturing deviation of the board, and the existing mainstream board manufacturing process and equipment are not updated., Will become the bottleneck of future technological development. How to break the situation for PCB manufacturers is of vital importance. In terms of quality monitoring, the statistical process control of key product parameters should be strengthened, and data should be managed in a more real-time manner, so that the consistency of the product can be guaranteed to meet the performance requirements of the antenna in terms of phase, standing wave, and amplitude.