Tham khảo tài liệu 'three-dimensional integration and modeling part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 11 CHAPTER 3 Three-Dimensional Packaging in Multilayer Organic Substrates MULTILAYER LCP SUBSTRATES As the operating frequencies of radio frequency RF systems continue to rise system reliability becomes increasingly dependent on hermetic or near hermetic packaging materials. Higher frequencies lead to smaller circuits and low material expansion which is related to water absorption becomes more important for circuit reliability and for maintaining stable dielectric properties. Equally important is the ability to integrate these materials easily and inexpensively with different system components. The best packaging materials in terms of hermeticity are metals ceramics and glass. However these materials often give way to cheaper polymer packages such as injection-molded plastics or glob top epoxies when the cost is a driving factor. Plastic packages are suitable when cost and ease of fabrication are considered but they are not very good at keeping out water and water vapor. Ideally a hermetic polymer should have inexpensive material and fabrication cost and still function as a good microwave and millimeter-wave package. An organic material called liquid crystal polymer LCP nearly satisfies these criteria. The dielectric properties of LCP and the performance of various transmission lines on LCP substrates were recently characterized up to 110 GHz 53 through the use of ring and cavity resonators that derived the following characteristics er from to GHz and tan s up to 97 GHz. The low water absorption of LCP makes it stable across a wide range of environments by preventing changes in the relative dielectric constant er and loss tangent tan 1 D. C. Thompson M. M. Tentzeris and J. Papapolymerou Experimental Analysis of the Water Absorption Effects on RF mm-wave Active Passive Circuits Packaged in Multilayer Organic Substrates IEEE Transactions on Advanced Packaging Vol. 30 No. 3 557 August 2007 . The LCP material processing is still
