Resistor Stability Research Articles

STUDI PROTEKSI DOUBLE BUSBAR AKIBAT PENAMBAHAN TRANSFORMATOR DI GARDU INDUK PEMECUTAN KELOD

Pemecutan Kelod Substation operated with four conductors, three transformers, one capacitor and one coupling with double busbar configuration, side by side with the Kapal and Pesanggaran substation to maintain electricity supply in Kuta, Legian, Seminyak, Denpasar City and surrounding areas. Due to increase in load in Denpasar area, PT PLN (Persero) Trans-JBJT added one transformer to improve the reliability of electricity in this substation, so Pemecutan Kelod substation operated with four transformers. To optimize the continuity of the power flow, it is necessary to analyse the relay settings on the busbar current and the appropriate protection settings as a protection system reference. In this study, the calculation of resistor stability (Rstab) of input current and output current after and before the addition of the transformer is carried out. The results of the calculation of resistor stability (Rstab) before the addition of the transformer is obtained with a total of 5.12 ?, the input current is 1030 A and the output current is 1010 A with losses of 1.9%. While the results of the calculation of resistor stability (Rstab) after the addition of the transformer is obtained with a total of 5.64 ?, the input current is 1070 A and the output current is 1060 A with losses of 0.9%. Those losses values complied with the SPLN No.1: 1987 standard for the 150 kV system.

Laser Trimming of CuAlMo Thin-Film Resistors: Effect of Laser Processing Parameters

This paper reports the effect of varying laser trimming process parameters on the electrical performance of a novel CuAlMo thin-film resistor material. The films were prepared on Al2O3 substrates by direct-current (DC) magnetron sputtering, before being laser trimmed to target resistance value. The effect of varying key laser parameters of power, Q-rate, and bite size on the resistor stability and tolerance accuracy were systematically investigated. By reducing laser power and bite size and balancing this with Q-rate setting, significant improvements in resistor stability and resistor tolerance accuracies of less than ±0.5% were achieved.

285°C Resistor Drift and Failure Analysis

In order to improve the reliability of down-hole electronics, Quartzdyne Electronics has invested millions of device test hours in life testing circuits in both powered and un-powered modes. In addition to time at temperature, these tests include thermal cycling and high impact drop testing. Resistors drift has become a significant wear-out mechanism in these tests. Prior testing has shown that resistor material, substrate material, resistance range and trim method each play a significant role in resistor stability at elevated temperatures. Some resistance ranges tested had no acceptable performers. The purpose of this study is to expand the range of values, materials and package sizes in hopes of identifying reliable resistors for high temperature applications. This study will focus on a broad range of NiCr-on-silicon resistors, including larger package sizes than were previously tested. Additionally, we will be testing several precision foil-type resistors. Resistors will be mounted in hermetic packages and aged at 285°C for 1000 hours. The packages will be removed from the oven periodically and the resistance of the devices will be measured at ambient temperature. This study is being done in cooperation with resistor vendors who have supplied some of the devices for this test.

Vapour Phase Curing of PTF Inks — A Commercial Reality?

The use of vapour phase heating as a rapid and uniform method of heat transfer is widely established in the electronics industry for reflow soldering of surface mounted devices. This technique has been extended to the curing of polymer thick film inks, an important and growing technology within the electronics industry. The availability of perfluoropolyether vapour phase fluids with boiling points from 130°C to 265°C now enables this technique to be used with a variety of different substrate materials, e.g., thermoplastic, paper phenolic and glass epoxy. This paper will examine the general benefits to be gained by curing PTF inks by vapour phase with respect to speed of cure, conductivity, resistor stability and solderability. It will discuss in detail a specific application for vapour phase curing using thermoplastic 3‐D printed circuit board where temperature of cure was of paramount importance. An outline of the production process will be given together with the results of a series of comprehensive electrical and long‐term life testing on the cured conductors and resistors. These will be compared with conventional methods of cure and the benefits of using vapour phase will be highlighted.

New U‐Cut Algorithmic Trimming for Lightning Protection

Large ohm film resistors that guard sensitive telecommunication devices against the hazards of lightning require a set of exacting characteristics for tolerance, endurance, and productivity. These characteristics largely depend on how the resistor is trimmed. Conventional laser trimming is unable to provide all the requirements for this important resistor application. A new technique developed by Teradyne Inc. called Algorithmic Trimming employs an algorithm and data base to calculate real‐time trim vectors that are used in a trimming hardware processor to overcome the drawbacks of conventional trimming. With this new technique 50‐ohm film resistors were trimmed to specification with 0·1% tolerance while attaining high resistor stability and a trim time of 300 milliseconds.

Thin Film Technology for Prototypes and Small Scale Production—Equipment Needed, Experimental Results, Applications

This paper gives a popular introduction to thin film and some reasons for using this technology. The miniaturisation techniques at Brel & Kjaer are described and the background for the work with thin film techniques is given. The company's method of realising thin film circuits is described by going through the resistor materials, resistor design and photolithography and etching steps. The kind of equipment needed and what B & K use to make prototypes and small scale production are shown. TCR‐values and the resistor stability after 10,000 hours at different environmental exposures are given. Examples of applications with single layer and double layer structures are shown. A thick film circuit is transformed to thin film, and the size reduction can be seen. Finally, for this circuit, the cost calculations are stated for both versions.

Au/Ti resistors used for Nb/Pb-alloy Josephson junctions. I. Electrical stability

Bilayered Au/Ti films are very attractive for use as resistor materials of experimental Nb/Pb-alloy Josephson junction devices. In order to predict the electrical stability of the Au/Ti resistors during storage at room temperature, changes in microstructure and electrical resistivity of Ti and Au/Ti films during isothermal annealing at temperatures ranging from 298–473 K were studied using transmission electron microscopy, x-ray diffraction, and electrical measurements. Growth of Ti grains during annealing was observed in these films. The activation energy for the grain growth was determined to be 1.51 eV. Decreases in the sheet resistance measured at 4.2 K were observed at the early stages of isothermal annealing. By analyzing the annealing temperature dependence of rates of resistance changes, the activation energy of 1.49 eV was obtained. This energy value is very close to that obtained for the grain growth and, therefore, one of the main causes in the resistance decrease is believed to be due to the growth of Ti grains. Based on the present results, a model to predict the electrical resistance change for the Au/Ti films during storage at room temperature was established. The model predicted that change in the resistance can be significantly reduced by preannealing the resistors at an elevated temperature. The prediction was supported by the experiment and an excellent quantitative agreement between measured resistance values and those predicted by the model was obtained. Based on this model, the change was predicted to be −1.5% after about 3 years at room temperature, if the resistors were preannealed at 353 K for 10 h. This resistor stability is satisfactory for designing logic and memory circuits of Josephson devices, and it can be increased simply by preannealing for longer times at 353 K.

TCR Control of Ni/Cr Resistors

A detailed study was made to identify the important deposition parameters and to determine how they interact to affect the TCR and sheet resistance of Ni/Cr films deposited on alumina. Wire-fed flash evaporation is described as a simple method for the control of composition, deposition rate, and thickness. The Ni/Cr ratio, substrate temperature, amount of Au in the Ni/Cr, and the film thickness have major effects on TCR. Deposition rate and pressure and the effect of a Ni barrier layer between the Ni/Cr and the Au conductor were also investigated. The use of a Ni barrier layer degrades the resistor stability somewhat. Approximately 50 percent Cr is necessary to get the TCR on alumina below about +100 ppm/°C, but variation from 50 to 70 percent has little further effect, while Au in the Ni/Cr depresses the TCR, and can make it negative. Reduced substrate temperature during film condensation and increased film thickness also reduce TCR. Sheet resistance is affected by thickness, Au content, and substrate temperature. A particular value for each of the above parameters was found that when used together produced 'zero' TCR and 180 \Omega/square sheet resistance.

Reducing Post-Trim Drift of Thin-Film Resistors by Optimizing YAG Laser Output Characteristics

A study to determine the effects of laser parameters on tantalum nitride resistor stability is presented. A model Of the laser heat affected zone is proposed which relates laser pulse width, power, wavelength, repetition rate, and waist size parameters to energy delivered to remaining resistor material. Samples of qualified tantalum nitride resistors are trimmed with a range of laser parameters, and the results are compared with the model. The excellent agreement between the model and experiment allows these results to be used for process control and throughput versus tolerance calculations.

Resistor stability and power dissipation : William E. Counts. Solid St. Technol. p. 59 (October 1977)

Resistor stability and power dissipation : William E. Counts. Solid St. Technol. p. 59 (October 1977)

The Development of Precision Thin Film Resistors for Submerged Repeater Applications

The paper describes development of a low inductance thin film resistor series with a stability of ±0.15% change in resistance, over a 25 year life, in a submerged repeater environment. (40% RH maximum and 0 to 30℃ ambient temperature).It was first necessary to establish an appropriate mathematical model relating resistor stability with time and temperature. This was devised from experimental data based on measured resistor drift at various temperatures, and enabled acceleration of resistor drift to be carried out to ensure that each resistor possessed the required stability.Deposition of a secondary nichrome layer protects the gold/nichrome interface and promotes SiO2adhesion. This results in an improvement in the basic elevated temperature resistor stability by minimising diffusion effects of nichrome into the conductor, and protection against electrochemical corrosion as demonstrated by 10,000 hours life test at 83% RH @ 28℃ on 5 mW load and by elevated temperature tests under electrical loading.

Factors Affecting Laser-Trim Stability of Thick Film Resistors

Various factors affecting precision of trim and resistor stability are considered. The influence of machine operating parameters (beam power, pulse frequency and trim speed) on resistor performance are examined and quantified through statistically designed experiments for aQ-switched YAG laser system. Laser kerf quality is examined by scanning electron microscopy and related to kerf isolation resistance measurements. A relatively simple, production oriented, quality control test is proposed for rapid determination of kerf electrical stability. In addition, the effect of cut design and extent of trim on precision and stability are discussed.

Flight quality nickel-chromium films with sheet resistances up to 420 ohms per square

Nickel-chromium films have been deposited with good reproducibility and reasonable uniformity of sheet resistance using a rudimentary evaporation technique. A standardized process flow has resulted in circuit yields of approx. 99 per cent for design values of sheet resistance up to 200 Ω/sq. and yields of 89 and 79 per cent for 260 and 325 Ω/sq., respectively. Circuits stabilized with (a minimum of) 2 hr air bake at 320°C have shown excellent resistor stability and reliability through packaging and environmental testing for design values up to 420 Ω/sq.

The Long-Term Stability of Fixed Resistors

The causes of long-term failure under practical conditions of use or storage of different types of fixed resistors commonly used in electronic equipment have been investigated. Some reported life tests have proceeded without interruption for almost four years. Carbon-composition (grade 2) resistors under load fail by slow thermal degradation of the resistive material. Drift of value may also occur if unloaded resistors of this type are stored in a damp atmosphere. Vitreous-enamelled wire-wound resistors made with fine wire may fail during tropical exposure both unloaded and especially when lightly loaded with direct current. This is owing to electrochemical corrosion taking place at faults in the vitreous coating. High-stability cracked-carbon (grade 1) resistors may fail rapidly under light dc load by electrochemical action if moisture condensation occurs and the protective paint or varnish coating is inadequate. Tests for long-term resistor stability are critically discussed.

The long-term stability of fixed resistors

The causes of long-term failure under practical conditions of use or storage of different types of fixed resistors commonly used in electronic equipment have been investigated. Some reported life tests have proceeded without interruption for almost four years. Carbon-composition (grade 2) resistors under load fail by slow thermal degradation of the resistive material. Drift of value may also occur if unloaded resistors of this type are stored in a damp atmosphere. Vitreous-enamelled wire-wound resistors made with fine wire may fail during tropical exposure both unloaded and especially when lightly loaded with direct current. This is owing to electrochemical corrosion taking place at faults in the vitreous coating. High-stability cracked-carbon (grade 1) resistors may fail rapidly under light d.c. load by electrochemical action if moisture condensation occurs and the protective paint or varnish coating is inadequate.Tests for long-term resistor stability are critically discussed.

The long-term stability of fixed resistors

The causes of long-term failure under practical conditions of use or storage of different types of fixed resistors commonly used in electronic equipment have been investigated. Some reported life tests have proceeded without interruption for almost four years. Carbon-composition (grade 2) resistors under load fail by slow thermal degradation of the resistive material. Drift of value may also occur if unloaded resistors of this type are stored in a damp atmosphere. Vitreous-enamelled wire-wound resistors made with fine wire may fail during tropical exposure both unloaded and especially when lightly loaded with direct current. This is owing to electro-chemical corrosion taking place at faults in the vitreous coating. High-stability cracked-carbon (grade 1) resistors may fail rapidly under light d.c. load by electro-chemical action if moisture condensation occurs and the protective paint or varnish coating is inadequate.Tests for long-term resistor stability are critically discussed.