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Since its inception in 1985, Optiprint has specialized in fabricating PCB products for radio frequency (RF) and microwave (MW) applications. In recent years, there has been commercial exploitation of so-called millimeter-wave (mmW) frequencies. Generally speaking, this commenced with automotive radar; however, increasingly the telecommunications sector is offering radio products operating in V-band (57–66 GHz) and E-band (71–76 GHz and 81–86 GHz) portion of the radio spectrum. The attraction is the comparatively high volume of data that can be transmitted wirelessly to cope with a demand for bandwidth, driven by growth in mobile data traffic for portable devices and machine-to-machine communications. The expectation is that mmW radio architectures will be deployed in future “5th generation” cellular mobile” (5G) networks and to ease “spectrum congestion” in current 4G and earlier configurations.
In 2013, Optiprint joined a European collaborative project called “MiWaveS”, a three-year project to develop key technologies for mmW wireless access and backhaul in future 5G heterogeneous cellular mobile networks. Optiprint’s role in MiWaveS was to support the collaborative partners in the design and manufacture of PCBs for local access and backhaul radio transceivers and antennas. This article describes the PCB technology requirements of fabricating PCB articles designed for the distribution and propagation of mmW signals with emphasis on the work done to support MiWaveS project.
The PCB, often referred to as an organic substrate, represents an economically attractive and mature technology for mmW hardware interconnect and antenna given the ubiquity of PCB and PCB assembly manufacturing capability. Interestingly, the MiWaveS project also involved LTCC ceramic substrate technology; however, a review of that is outside the scope of this article. From a PCB manufacturing perspective, the needs for distributing and propagating signals in millimeter wavelengths have a direct influence on the choice and thickness of substrate, PCB feature (and feature-to-feature) positional accuracy and feature dimensional accuracy. The requirements for matching manufacturing and metrology capacities are discussed in this article.
To read the full version of this article which appeared in the April 2017 issue of The PCB Magazine, click here.