Effects of varying laser trimming geometries on thin film resistors

Purpose - This paper studies the effects of varying laser trim patterns on several performance parameters of thin film resistors such as the temperature coefficient of resistance (TCR) and target resistance value. Design/methodology/approach - The benefits and limitations of basic trim patterns are taken into consideration and the plunge cut, double plunge cut and the curved L-cut were selected to be modelled and tested experimentally. A computer simulation of the laser trim patterns has been developed for the modelling process of the resistors. The influence of the trim length and resistor dimensions on the TCR performance and resistance value of the resistors is investigated. Findings - It is found that variation in trim length, within the range of 5 to 15 mm, can give significant increases in the TCR of the thin films. Thus, for the plunge TCR cut can reach up to 11.51 ppm/oC, for the double plunge cut up to 14.34 ppm/oC and for the curved L-cut up to 5.11 ppm/oC. Originality/value – Research on the effects of various laser trimming geometries on the TCR and target resistance accuracy is limited, especially for patterns such as the curved L-cut,which is investigated in this paper

Thick-Film and LTCC Passive Components for High-Temperature Electronics

At this very moment an increasing interest in the field of high-temperature electronics is observed. This is a result of development in the area of wide-band semiconductors’ engineering but this also generates needs for passives with appropriate characteristics. This paper presents fabrication as well as electrical and stability properties of passive components (resistors, capacitors, inductors) made in thick-film or Low-Temperature Co-fired Ceramics (LTCC) technologies fulfilling demands of high-temperature electronics. Passives with standard dimensions usually are prepared by screen-printing whereas combination of standard screen-printing with photolithography or laser shaping are recommenced for fabrication of micropassives. Attainment of proper characteristics versus temperature as well as satisfactory long-term high-temperature stability of micropassives is more difficult than for structures with typical dimensions for thick-film and LTCC technologies because of increase of interfacial processes’ importance. However it is shown that proper selection of thick-film inks together with proper deposition method permit to prepare thick-film micropassives (microresistors, air-cored microinductors and interdigital microcapacitors) suitable for the temperature range between 150°C and 400°C