Millimeter Thick Magnetic Print Circuit Boards with a High Relative Permeability of 50~150 and Related Devices

The attainment of elevated magnetic permeability within printed circuit boards (PCBs) has constituted a primary objective for numerous electrical engineers, as the magnetic PCBs lead to much more compact and power-efficient antennas, inductors, transformers, and other electronic components. These advancements can potentially revolutionize electronic devices by providing unprecedented benefits in terms of size, weight, and power consumption (SW&P). Conventional PCBs are non-magnetic with a typical dielectric constant ranging from 2 to 13. Magnetic PCBs with a relative permeability of 6 have been recently commercialized through the integration of magnetic powders into polymer matrices. Despite these notable strides, various challenges persist, including large loss tangents, particularly at frequencies exceeding 400-500 MHz, cost-intensive manufacturing processes, constrained size and weight parameters, and intricate production procedures. In this work, an innovative approach employing spin spray deposition is proposed for depositing thick ferrite films onto FR4 PCBs forming mm-thick ferrite/PCB laminates with high magnetic permeabilities. This technique produces substantial improvements, yielding large-size magnetic PCB panels with an enhanced and tunable relative permeability of >100 and relative permittivity of 4.5. These new ferrite/PCB laminates exhibit cost-effectiveness, scalability, tunable permeability and permittivity, and better performance metrics. Notably, these laminates have the potential to bolster antenna gain and bandwidth by 5-10 dB, while simultaneously optimizing the operational efficacy of power inductors at 400 MHz frequencies. Meanwhile, the utilization of low-temperature spin spray ferrite further enhances the overall effectiveness and practicality of these magnetic PCBs.