LTCC an Enabling Technology for RF-, Microwave, Bio- and Chemical Systems

摘要

Higher data rates, increased signal carrier frequencies and low cost demands put pressure on design and manufacturing of microwave modules. Among the material options to realize microwave modules or packages are organic laminates, thin film, thick film, High Temperature Cofired Ceramics (HTCC) and Low Temperature Cofired Ceramics (LTCC). Depending on the mission profile of the system (e.g. working temperature, power dissipation, hermeticity) the latitude of suitable materials is reduced. Since LTCC combines advantages of good microwave loss behavior (both dielectric and conductive), hermeticity, three-dimensional structuring (e.g. cavities), fair thermal conductivity and passive integration capability it offers excellent opportunities to manufacture microwave circuits using a System-in-Package approach. Miniaturization of LTCC by itself is not the major driving factor, reduced structure dimensions are demanded by smaller wavelengths and related parasitic effects. Line width, spacing and via diameter are often the limiting design features. By introducing 30μm lines and micro vias < 100μm it is possible to design lumped passives with a self resonance frequency above 10 GHz and line interconnects and transitions up to 60++ GHz. The ability to create real three-dimensional structures is not only a major advantage for microwave designs. The past years have shown a tremendous increase in interest for micro fluidic systems. These systems are used in biological and chemical applications. Biosensors for instance require channels to supply nutrients to keep the cells alive. First tests on LTCC materials have given an indication for biocompatibility. Long term studies started to verify the results. Resistance against many aggressive chemical substances and the possibility to integrate local heaters (e.g. buried resistors) and sensors within a hermetic package are good prerequisites for chemical micro systems. The presentation will give an overview about current research work with the focus of the applications mentioned and discusses material, design and technology requirements.