Fabrication and Analysis of High-Q Inductor on Anodized Aluminum for High Power Package

In this paper, we fabricated high-Q inductors on anodized aluminum substrate using low-k benzocyclobutene (BCB) as an interlayer and thick Cu plating process. The 2 nH inductors on 80 mum anodized aluminum have Q-factor as high as 30 at 2 GHz and self-resonant frequency as high as 11 GHz. Anodized aluminum substrate is useful and cost-effective for high power packaging because of high thermal conductivity. Image current arises on anodized aluminum substrate because aluminum as a conductor is closely located below spiral inductors on anodized aluminum (Al₂ O₃) layer. Inductances of spiral inductors were calculated considering image current through Grover´s method. Thus, the influence of image current on inductance confirmed through quantitative analysis