Laser trimming is the most effective and popular trimming method of thick-film and LTCC resistors at present. It is also still a subject of continuing theoretical and experimental analysis and optimization. Very recently a new approach to this process was suggested. It consists in replacing two-contact bar resistors by three-contact distributed structures trimmed by narrow cuts just around additional contact of different shape [1,2]. This paper presents experimental verification of such an approach. The relative trim characteristic and sensitivity are analyzed as a function of additional contact shape and cut length. Next long-term stability, pulse durability and low frequency noise are compared for two- and three-contact resistors versus trim pathway length. These investigations are completed by simulation of electrical potential distribution in two- and three-contact resistors with various length of trimming kerf.

No abstract

No abstract

RF packaging is one of the most challenging topics in LTCC technology. Today LTCC is particularly capable for advanced packages and systems-in-package because of its electrical, functional, thermomechanical properties as well as its excellent long-term stability and reliability. LTCC combines the potential for miniaturization, low loss handling of high frequencies up to 110 GHz and offers the opportunity to integrate additional features. Therefore it has to go through various manufacturing steps and several refirings without any performance degradation or loss of dimensional accuracy. This paper discusses the impact of thermal post processing on RF characteristics and geometrical properties of LTCC. Ceramic substrates with radar front ends, calibration structures and other test vehicles made of Du Pont Green Tape® 943 and 9k7 were cofired following the recommended conditions and refired several times in order to investigate and compare the influence of the postfiring. The flatness, dimensions and RF performance of the ceramics up to 110 GHz were evaluated and compared.

AbstractÀRF packaging is one of the most challenging but also the fastest growing topic in low temperature cofired ceramic (LTCC) technology. Today LTCC is particularly useful for advanced packages and systems-in-package because of its electrical, functional, and thermomechanical properties as well as its excellent long-term stability and reliability. LTCC combines the potential for miniaturization and low loss handling of high frequencies up to 110 GHz and it also offers the opportunity to integrate additional features. Therefore it has to go through various manufacturing steps and several refirings without any performance degradation or loss of dimensional accuracy.This article discusses the impact of thermal postprocessing on RF characteristics and geometric properties of LTCC. Ceramic substrates with radar front ends, calibration structures, and other test vehicles made of DuPont Green Tape W 943 and 9K7 were cofired following the recommended conditions and refired several times in order to investigate and compare the influence of the postfiring. The flatness, dimensions, and RF performance of the ceramics up to 110 GHz were evaluated and compared.