Laminates for mmWave PCBs: Different Solutions for All-RF Multilayer, Hybrid Multilayer, and Double-Sided PCBs

At high mmWave frequencies, all antenna features are smaller than ever before. This means that the RF base material for antenna printed circuit boards (PCBs) have to have tighter tolerances at the lowest loss. Different PCB solutions require different RF laminates: hybrid multilayers (RF laminate + FR4), all-RF multilayers, and double-sided PCBs. From electrical and mechanical reliability points of view, ceramic filled PTFE based materials provide a leading edge over thermoset resin system base materials. The high consistency of dielectric constant and loss factor of the thermoplastic material PTFE over the required operating temperature range at the resonance frequency of the antennas has been recognized by the RF and microwave industry for a long time. This technical presentation discusses the main reasons why such types of base materials are being used. All-RF multilayers are the main PCB type for phased array radar PCBs. There, the thin RF laminate must also show a very high dimensional stability in order to get combined with a suitable lowest loss prepreg, which is provided by an engineered selection of suitable glass fabrics. Hybrid multilayer PCBs are widely used for 77/79 GHz automotive radar PCBs. Tested electrical and reliability data confirm that very thin ceramic-filled non-reinforced PTFE laminates are most suitable in order to meet the requirements of next-generation ADAS sensors. Double-sided PCBs for mmWave systems usually consist of relatively thin (10 mil / 0.25 mm) thick laminates. There, the combination of PTFE resin, woven glass fabric, ceramic filler systems and ultra-low profile copper foil provides the lowest loss at the highest dimensional stability. The market introduction of an ultra-low profile ED copper foil provides an even improved insertion loss over rolled annealed copper foil, in addition to its lower cost. The higher the frequency, the better the value. Only PTFE laminates result in high enough copper peel strength even at repeated rework cycles. Almost all PCB manufacturers capable of making mmWave PCBs have processing experience of PTFE laminates; and several of these also use PTFE laminates together with the lowest loss RF prepregs. Speaker Manfred Huschka Dipl.-Ing. Manfred Huschka spent his entire professional career in the printed circuit board industry: After graduation, he was manufacturing printed circuit boards (Braun Ireland Ltd). Thereafter manufacturing FR4 base materials (AlliedSignal Laminate Systems), with his final position being Director Technology Europe. From mid-1997 until mid-2019 Manfred was with Taconic Advanced Dielectric Division. In those more than 20 years he was in charge of the Irish PTFE base material manufacturing plant for 10 years and was Vice President Global Sales for more than 10 years. Following the acquisition of Taconic ADD by AGC Manfred is now Vice President Global Marketing Coordination. Manfred is the author of several printed circuit board technology books including A comprehensive guide to the design and manufacture of printed board assemblies, Multilayer bonding guide, and Pocket dictionary PCB technology. He is also an author and presenter at many international conferences. Email: [email protected] Address: AGC Multi-Materials General Division, Ireland Registration https://events.vtools.ieee.org/m/278272  The Zoom link will be sent one day beforehand.   The event is co-organised by Australian IEEE AP-MTT Chapters.  For further details, please contact Fatemeh Babaeian ([email protected]).  

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