Resistor Manufacture and Optimization - Assignment Example

Introduction Resistors are very essential in electronics. They are the most generally used electronic component. The main function of resistors is to resist or block electrons movement. A part from resisting electrons flow, resistors do also divide voltage in a circuit. Several types of resistors and manufacturing techniques do exist. Resistors are manufactured in different forms. Their formation range from small surface mount chip to huge wire wound power resistors. The way resistors are formed depends a lot with the work they are supposed to do. This paper therefore seeks to evaluate various studies done on current types of resistors and the techniques used when being manufactured. Current types of resistors and manufacturing methods Krishnamurthy argues that there are many types of resistors that are usually employed in electronics. According to him the most common types of resistors are power wire wound resistor, carbon composition resistors, carbon film resistors, metal film resistors and metal oxide resistors (14). Singmin suggest that current resistors can be manufactured through application of various modern technologies. Current resistors can be manufactured through application of thick-film network. Film-thick network is away of manufacturing resistors by making use of valuable metal inks, printed screen and alumina substrates. Resistors can also be manufactured through employment of thin-film deposition technique. The manufacturing techniques entail decomposition and reaction of gases on heated substrate’s surface (230). According to Ballou, carbon composition resistors are not only the most common type of resistors but also the cheapest resistors that are widely employed in electronic and electrical circuits (207). Carbon composition resistors are the most common resistors in electronics markets. Their prices are very competitive. These resistors are manufactured by accurately cutting carbon rods in the required length and then molding them when attached with leads. The combination of carbon can be altered so as to change the resistivity to the values that are desired. High values are always very easy to attain than low values. Therefore, manufacturing resistors with a 5% tolerance is usually done through measuring and choosing of values. According to Krishnamurthy, carbon composition resistors do have voltage coefficient. The resistances of carbon composition resistors do always change when voltage is applied. The change will be greater if the voltage is greater. Apart from power rating, carbon composition resistors do also have voltage rating (18). The voltage rating of this type of resistors is usually determined by considering the physical size, value and wattage rating. Carbon composition resistors do always produce noise. This is usually the case because of their manufacturing technique. The level of noise, produced by carbon composition resistors, is determined by physical size and value. The power ability as compared to physical size is far beyond the precision wire wounds and less than power wire wounds. Ballou argues that Carbon film resistors are similar to carbon composition resistors. Both carbon film resistors and carbon composition resistors have noise and voltage coefficient. Similar to carbon composition resistors, carbon film resistors have voltage coefficient. The TCR of carbon film resistors is lower than that of carbon composition (170). The difference in TCR is due to different formulas that are usually employed to obtain it. Different manufacturing processes are usually employed when developing Carbon composition and film resistors. This therefore normally makes the tolerance of carbon film resistors to be very tight than that of carbon composition resistors. Carbon film resistor is usually manufactured by using carbon materials mixture to coat ceramic rods. The materials are usually employed on the rods in a number of ways. According to Ballou, the most common ways are rolling, printing, dipping and spraying the rods with the required solution. The most appropriate way of determining the size of the coating is through the use of solution’s viscosity. By doing this, it is easy to determine ohms. According to Erjavec, carbon film resistors have the best frequency response as compared to wire wounds and carbon composition resistors. It is believed that at very low frequencies and values, wire wound resistors are inductive. At very high frequencies, carbon film resistors are believed to be capacitive (30). Metal film resistors are more precise than carbon film. Metal film resistors have low noise if well manufactured. Of all resistors, Metal Film resistors are the outstanding compromise. They are not as firm as Precision Wirewounds and are not as exact and posses a higher coefficient of temperature resistance. They do not possess a coefficient of voltage; have a lesser coefficient of temperature compared to Carbon Film. TCRs of 50 to 100 pppm can be attained. When properly produced, their level of noise is low. Actually a number of the processes of screening measure the level of noise to establish if there are issues in a specific batch of resistors. Metal film resistors are produced through the process of evaporation or deposition. That is the support metal vaporized in a space and placed on a ceramic bar or wafer. Various trials have been made for TCR vaporization materials and place on these substrates, in vain. This is because of dissimilar boiling points of the different support metals in the alloys. The materials with very small TCR resistive are treated by heat to attain the resistivity and small TCR. The process of evaporation is not compatible with this. The characteristics of frequency of this kind are outstanding and enhanced than Carbon Films. The maximum value is the area that carbon films exceed metal films. Carbon films can attain greater maximum values compared to any other group. Metal oxide resistors are more reliable than metal film resistors. They are made up of metal oxides and causes high temperature and huge stability. Power wire wound resistors are very effective when a lot of power is needed to pass through electrical circuits. Ballou highlights that Power wire wound resistors do sometimes resembles heater elements. When it is required to manage loads of power, Power Wirewound Resistors are employed. They will manage a lot of power per unit volume compared to any other resistor. Like heater constituents, a number of these resistors are free wound. So as to manage any substantial quantity of power, some type of cooling is needed. While some are immersed in different kinds of liquid varying from mineral oil to silicone liquid of high density, others are cooled by fans. Majority are coiled on some form of coiling form. These coiling form differ. For instance; there are ceramic tubes, fiberglass mandrels, profoundly anodized aluminum, and ceramic rods. The center on which the windings are created need to have a material with great conductivity of heat to attain the highest power rating in the slightest package size. Examples include Steatite, Beryllium Oxide, Alumina, or heavily anodized Aluminum in a number of cases. Hypothetically, there is a better conductivity of heat by anodized Aluminum core than any other material which is insulated, closely following is Beryllium Oxide. A number of definite problems have been linked with anodized Aluminum cores. These include managing the anodized thickness, nicks in the covering, and abrasion in the process of capping. Various shapes are structured to optimize dissipation of heat. The shapes include cylindrical, flat, and oval. More power can be carefully applied when more heat can be emitted from the resistor. Chasis Mounted Resistors are normally power resistors which are cylindrical twisted on a ceramic core shaped and compressed to an aluminium heat sink and normally with heat emitting fins. These are intended to be added to a chassis or metal plates for further heat conduction. This outcome in a scale is nearly five times or more its usual rating. The resistors come in an assortment of accuracy’s and TCRs. They can be specially made a mixture of a Precision Resistor and a Power Resistor; able to manage additional power than the usual Precision Wirewound although not as perfect. Basically speaking, apart from the parts covered with Vitreous Enamel and small values, tolerances of one per cent and coefficients of temperature of twenty ppm can be attained on all. The healing process for Vitreous a form of glass needs very great heat and contracts when pressure to the twisting is applied. Tolerances of ten per cent with a TCR of 100ppm/oC will be run by this specific group. The ratings of Power Resistors come in variety. Majority are scaled at +25oC and descaled linearly to +275oC or +350oC. Additionally if the ambient temperature of function is +275oC, no application of power and at +125ooC power which is rated half is applied. The rating of power is determined by raising the resistor in open air with the leads stopped at the suggested point. For example, it is 3/8 of an inch from the body on axial lead constituents. If they can be raised closer, the resistor will operate cooler or a little more power can be applied and if mounting is done further out, there should be power reduction. The warning is that, the heat radiating from the resistor can burn the circuit board that is printed when complete power is applied, if mounted straight over and in touch with the printed board. It is not clear about any PC Boards that are connected at +275oC. Other ways of raising the quantity if power that can be applied include; connecting the resistor to the chassis or different metal parts, mounting vertically to get the effects of chimney (this is very effective when using twisted ceramic tubes), close termination to the body as realistic, and oil submersion (warning in this is that a some forms of resistor coating, mainly coatings with silicone will break up when heated or dipped in oil). Conclusion From the discussion, it is clear that there are several types of resistors and manufacturing methods. The most common types include power wire wound resistor, carbon composition resistors, carbon film resistors, metal film resistors and metal oxide resistors. Carbon composition resistors are not only the most common type of resistors but also the cheapest resistors that are widely employed in electronic and electrical circuits. They are the most common resistors in the market, with highly competitive price. Carbon compositions resistors are manufactured by accurately cutting carbon rods in the required length and then molding them when attached with leads. Carbon film resistors are similar to carbon composition resistors. Both carbon film resistors and carbon composition resistors have noise and voltage coefficient. Similar to carbon composition resistors, carbon film resistors have voltage coefficient. The TCR of carbon film resistors is lower than that of carbon composition resistors. Metal film resistors are more precise than carbon film. Metal film resistors have low noise if well manufactured. Power wire wound resistors are very effective when a lot of power is needed to pass through electrical circuits. Metal oxide resistors are more reliable than metal film resistors. They are made up of metal oxides and causes high temperature and huge stability. Work Cited Ballou, Glen. Handbook for sound engineers. New York, Gulf Professional Publishing, 2005. Print. Erjavec, Jack. NATEF Standards Job Sheets/Electrical and Electronic Systems (A6). New York, Cengage Learning, 2009. Print. Krishnamurthy. Electrical, Electronics And Computer Engineering For Scientists And Engineers. New York, New Age International, 2007. Print. Meade, Russell. Foundations of Electronics. New York, Cengage Learning, 2002. Print. Singmin, Andrew. Modern Dictionary of Electronics Technology. Indianapolis, IN: Prompt Publications, 1999. Print. Part two Histogram for machine 1 Case 1 represent 110 Machine 2 Mean 434.7826087 Median 262 Mode 12 Range 1130 Minimum 12 Maximum 1142 Sum 10000 Count 23 The values are normally distributed, that is, they have a normal spread. Histogram for machine 2 Case 1 represent 110 Machine 1 Mean 434.7826087 Median 262 Mode 83 Range 1141 Minimum 1 Maximum 1142 Sum 10000 Count 23 The values are normally distributed, that is, they have a normal spread. The two machines therefore are working well and no machine requires recalibration. The two sets of data show that the process of production increases with an increase in resistor value up to some optimal point where an increase in resistor value decreases production. Read More