Advanced electrical and stability characterization of untrimmed and variously trimmed thick-film and LTCC resistors (original) (raw)
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Trimming and stability of thick-film resistors with reduced dimensions
2001
The increase of packaging density in electronic modules demands miniaturisation of passive components. This is related also to thick-film resistors, which are non-equilibrium heterogeneous systems. The as-fired resistors have the resistance tolerance within 20% range. Therefore they have to be trimmed in majority of thick-film hybrid circuits. The most appropriate trimming method is looked for thick-film microresistors at this very moment. This paper presents long-term stability of laser or high-voltage pulse trimmed cermet thick-film microresistors made on alumina substrate using 100 /sq. or 10 k /sq. inks from Du Pont or Institute of Electronic Materials Technology, Warsaw. The as-fired and laser (increase of resistance by about 30-40%) or pulse voltage trimmed (resistance increase by about 10%) resistors were thermally aged for 500 h at 180 o C or 100 h at 300 o C. There are no significant differences in long-term stability between as-fired, laser trimmed and high voltage pulsed components. The level of fractional resistance changes is dependent mainly on kind of resistive inks. In general Du Pont resistors prevail IEMT ones. Resistors aged at 180 o C exhibit slight resistance increase versus ageing time whereas the resistance of those aged at 300 o C is decreased.
Stability of miniaturized non-trimmed thick- and thin-film resistors
Microelectronics Reliability, 2018
This paper is focused on reliability tests of non-trimmed miniaturized thin-film and thick-film resistors. Thickfilm resistors are screen printed by polymer paste on LTCC (Low Temperature Co-fired Ceramic) substrate by two different approaches. Nonstandard precise screen printing process provide tolerance of resistivity less than 5% and thus further trimming is not necessary. OhmegaPly material with Nickel Phosphorous (NiP) metal alloy is used for thin-film resistors fabricated by subtractive process. Miniaturized resistors have dimensions 0.5 × 0.5 mm, and thus 1 square, with thickness 1 μm for thin-film and 20 μm for thick-film resistors. Stability of miniaturized resistors were tested by humidity test, thermal shocks, long-term thermal ageing, direct current stress, current pulses and simulation of soldering process using VPS (Vapour Phase Soldering). Resistivity of resistors is measured by four wire method before and after each set of test and relative change of resistivity is plotted in graphs. Influence of every test on each type of resistor is analysed.
Thermal effects in embedded thin- and thick-film resistors in comparison to chip resistors
Circuit World, 2014
In this work environmental behavior of resistors embedded into Printed Circuit Boards (PCBs) and discrete chip resistors assembled to standard PCBs are co mpared. The investigations were based on the thin-film resistors made of NiP alloy, thick-film resistors made of carbon or carbon-silver inks as well as chip resistors in 0402 and 0603 packages. Thin-and thickfilm resistors were made in the bar form. In addition, poly mer thick-film resistive films were screen-printed on the several types finishing materials of contact terminations such as copper, silver, and gold. To determine the sensitivity of embedded resistors versus s tandard assembled chip resistors on environmental exposure the climatic chamber was used. The measurements of resistance were carried out periodically during the tests, and after the exposure cycles.
Thermal effects on the electrical degradation of thin film resistors
1999
Recently we introduced a biased percolation model to study the electrical failure of thin-ÿlm resistors. Here we extend this model by allowing thermal interactions among ÿrst neighbour elemental resistances and accounting for the dependence of each elemental resistance on the local temperature. Monte Carlo simulations are performed to investigate the main properties of the ÿlm degradation such as: damage pattern, ÿlm lifetime, evolution of the resistance and of the 1=f resistance-noise spectrum.
This paper presents the correlation between processing conditions and microstructural, electrical and long-term stability properties of surface or buried LTCC resistors. The microstructure development (investigated by X-ray powder diffraction, scanning electron microscopy and energy dispersive X-ray analyses) is analysed for components made of three various resistive pastes with 10 kohm/sq. nominal sheet resistance (CF 041, DP 2041, ESL 3414B) prepared in/on DP 951 ceramic tape. The resistors were fired at standard (850 o C/15 min, 875 o C/15 min) or nonstandard (950 o C/15 min or 950 o C/180 min) temperature profile. Sheet resistance, hot and cold temperature coefficients of resistance, dependence of resistance in a wide temperature range, current noise index and their dependencies on resistor's aspect ratio and processing conditions have been measured as basic electrical properties. Moreover all processing variants of resistors were subjected to the step-increased long-term thermal aging at five different temperatures -162, 207, 253, 300 and 350 o C (the samples were kept at every temperature for 200 hours). Both the relative resistance changes and the changes of hot temperature coefficient of resistance versus the storage time and the temperature have been measured and analyzed.
Circuit World, 2014
This work presents the results of the thermal analysis of cermet resistors made on alu mina or LTCC substrate and polymer thick-film resistors embedded in FR-4 substrate. The research was carried out with an addit ional consideration of such factors as sheet resistance (which depended on the type of resistive paste), the size and topology of element and the kind of contact material (Cu, Ag or Ni/Au). A few key points on the element were specified fo r wh ich a mo re thorough analysis were carried out. The results were approximated by physically acceptable function which allowed to determine the influence of different mechanis ms of heat transfer, and determine their t ime and thermal constants .
Electrical properties of thin-film resistors in a wide temperature range
Circuit World, 2015
Purpose -The purpose of this paper is to characterise electrical properties of Ni-P thin-film resistors made on FR-4 laminate in a wide range of temperature (fro m -180 to 20ºC). Design/methodolog y/approach -The study was performed using resistors made of nickel-phosphorus (Ni-P) foil with two different thicknesses (0.1 μm or 0.05 μm) and the same different sheet resistances (100 oh m/sq or 250 ohm/sq). The resistance rectangular resistors had length and width fro m the range between 0.59 and 5.91 mm. The resistance vs temperature characteristics and their distribution as well as resistors durability to low-temperature thermal shocks were investigated.
Effects of high voltage pulse trimming on structural properties of thick-film resistors
Science of Sintering, 2017
Nowadays, compact and reliable electronic devices including up-to-date ceramic micro-electro-mechanical systems require thick-film resistors with significantly reduced dimensions and stable and precise resistance values. For that reason, instead of standard laser trimming method, high voltage pulse trimming of thick-film resistors is being introduced. This method allows controlled and reliable resistance adjustment regardless of resistor position or dimensions and without the presence of cuts. However, it causes irreversible structural changes in the pseudorandom network formed during sintering causing the changes in conducting mechanisms. In this paper results of the experimental investigation of high voltage pulse trimming of thick-film resistors are presented. Obtained results are analyzed and correlations between resistance and low-frequency noise changes and changes in conducting mechanisms in resistors due to high voltage pulse trimming are observed. Sources of measured fluctu...
Stability of thin-film resistors embedded in printed circuit boards
2011 International Students and Young Scientists Workshop "Photonics and Microsystems", 2011
Long-term stability of embedded passives is very important issue. To determine this matter an aging process can be used, where test samples are exposed to environmental conditions. Objecti ve of this research was analyzing reliability of thin-fil m resistors based on Ohmega-Ply® technol ogy. Resistive material was a nickelphosphorus (Ni-P) alloy (wi th sheet resistance 25 Ω/sq or 100 Ω/sq) on FR-4 substrate. A number of vari ables were considered in this study (sheet resistance, geometry of resistor, type of cl adding, l aser trimming, pulse stress and environmental conditi ons). Two di fferent accelerated ageing processes-Ex-Situ (samples exposed to elevated temperature and/or rel ati ve humi di ty but resistance measurements made at room temperature) and In-Situ (resistance of test samples performed directly at the ageing condi tions) were carried out to perform long-term behavior analysis. The results revealed a significant influence of thickness of resistor, type of cladding and temperature on stability of investigated structures. Signification of other factors was negligible.
Characterization, evaluation, and comparison of laser-trimmed film resistors
IEEE Journal of Solid-State Circuits, 1987
Methodsfor predictingthe performanceof laser-trimmed film resistors taking into account the properties of the heat-affected zone (HAZ) are discussed. A figure of merit based npon a sensitivity fnnction called HAZ sensitivity, SHA z , is introduced which is useful for determining aging and temperature effects of an arbitrary film-resistor geometry with an arbitrary trim strategy.~H4 z is also shown to be useful in predicting performance of ratio-matched resistor structures. The proposed technique is incorporated in FIRE, a Fortran programfor analyzing arbitrary film structures with a given trim path. Examples using popular resistor geometries and trimming atgoritfnns illustrating the use of the suggested figure of merit are presented. The performances of these structures are compared quantitatively.