LTCC and Thick-Film Microresistors * Andrzej Dziedzic 1) , Edward Mis 1) , Lars Rebenklau 2) , Klaus-Jurgen Wolter 2) 1) Faculty of Microsystem Electronics and Photonics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland e-mail: adziedzic@pwr.wroc.pl , phone: +48 – 71 – 355 48 22, fax: +48 – 71 – 328 35 04 2) Electronics Technology Laboratory, Dresden University of Technology, D-01062 Dresden, Germany * An earlier version of this paper was presented during 54 th Electronic Components and Technology Conference and was published in Proc. 54 th Electronic Components and Technology Conference, Las Vegas, June 2004, p.1885- 1890 Abstract The dimensions of discrete passives, passive integrated components (arrays, networks) and embedded integral ones should be significantly reduced in the nearest future. Therefore the relations between minimal geometrical dimensions, technological accuracy and limitations and electrical properties become more and more important. This paper presents systematic studies of a wide spectrum of geometrical and electrical properties of thick-film and LTCC microresistors (with designed dimensions down to 50×50 μm 2 ). The geometrical parameters (average length, width and thickness, relations between designed and real dimensions, distribution of planar dimensions) are correlated with basic electrical properties of resistors (sheet resistance, hot temperature coefficient of resistance, their distribution) as well as durability of microresistors to short electrical pulses. 1. Introduction The dimensions of passives, passive integrated components (arrays, networks) or embedded integral passive structures should be reduced significantly during nearest years. For example, passive components with 01005 package size will be commercially available before 2010. Therefore the relations between minimal geometrical dimensions, technological accuracy and limitations, and electrical properties become more and more important. Previously the size reduction of LTCC and/or thick- film circuits was connected mainly with miniaturisation of line/space width of conductive or dielectric layers. But during recent two years a possible significant reduction of such resistors was reported [1-4]. In the case of miniaturization the relations between real and designed dimensions and the relative (or absolute) tolerance of geometrical parameters are very important for electrical properties of microresistors (some of such parameters depend on dimensions directly or in indirect manner). Therefore this paper presents systematic studies of a wide spectrum of geometrical and electrical properties of thick-film and LTCC microresistors. The geometrical parameters (average length, width and thickness, relation between designed and real dimensions, distribution of planar dimensions) are correlated with sheet resistance and its distribution, hot temperature coefficient of resistance (HTCR) and its distribution as well as durability of microcomponents to various short electrical pulses. But both geometrical and electrical properties were related also to the technological parameters connected with microresis-tors’ manufacturing. 2. Fabrication of Microresistors Conventional screen printing permits to fabricate in volume production only 100 μm conductive lines and spaces. This is why photoimageable thick film technology is used in applications requiring high packaging density. Various photosensitive thick-film conductor and dielectric inks are commercially available. But such resistive compositions are only at the research and development stage. The 1 kohm/sq. experimental RuO 2 -based Fodel resistive ink from Du Pont and Ag-based DP 6453 Fodel conductor were used for microresistors` fabrication on alumina as well as onto LTCC substrate (in this case both postfired and cofired resistors were made). The conductors were made in full Fodel process whereas the resistors were screen-printed or made in Fodel process. Two basic test structures (A and B) were designed. Structure A consists of 5 identical 50× 50, 100× 100 or 200× 200 μm 2 microresistors. Structure B also consists of five microresistors with constant width (50, 100 or 200 μm) but various resistor length (50, 100, 200, 400 or 800 μm) [1,4]. The microresistors on alumina were made using two various fabrication procedures. In variant I conductor tracks were made at the beginning based of Fodel process and next resistive layer were conventionally screen-printed through 325 mesh stainless screen. In variant II resistive film was CARTS Europe 2004: 18 th Annual Passive Components Conference, October 18-21, 2004 135