Resistor Manufacture and Optimization - Book Report/Review Example

Resistor Manufacture and Optimization Abdlkareem Abuauref Engineering Science II: Electrical Engineering Swansea Metropolitan Dr. P. Charlton March 21, 2012 Introduction The following is an analysis of resistors, their manufacture and optimization. The paper uses literature review to create understanding of the current resistor types as well as the various manufacturing techniques in the first part of the discussion. The second part of the discussion involves analysis of resistor manufacturing output. Analyses of resistor manufacture output involves understanding of two sets of data for two identical machines that are used in production. Through development of a histogram, the available data is analyzed in order to establish the objective of the analysis. Types of Resistors and Manufacturing Techniques Resistors (R) are considered as the most fundamental and commonly applied within almost all electronic components. There is no doubt that electronic industry has experienced serious improvements and development since the classical period (Chinoy & Langlois, 2004). Contemporary electronic industry is highly characterized with many electrical appliances and components. During the last two decades, electronic industry has experienced introduction and development of new techniques and advances, which have been very effective in shrinking sizes of most of the electrical appliances (Snogren, 2003). Various devices have therefore been developed in a bid to ensuring that such electrical appliances are effective. Amongst the contemporary developed, upgraded, and modified devices that enhance performance and effectiveness of contemporary electronic appliances are the resistors (Nabatian, Brown & Durant, 2000). Resistors are a major development and advancement within the contemporary electronic industry. There is no doubt that the significance impacts of resistors have attracted interest from various electrical scholars and engineers. One of the motivating factors for modification and upgrading of resistors in the contemporary electric industry is advancement of power supply technology, which has demanded for the need to have accurate current sensing techniques, methods, or devices. Classical resistors unlike the current resistors had low power ratings. With increased power technology supply, electrical engineers have been forced into modifying and upgrading classical or traditional resistors to current resistors in a bid to improving effectiveness and performance (Snogren, 2003). The standard symbols of resistors are: Figure 1: Standard Symbol of Resistors (Taurasi & Brown-Worsham, 2007) On the other hand, a typical current resistor would resemble the following diagram (image): Figure 2: Typical Current Resistor (Taurasi & Brown-Worsham, 2007) Consequently, the quest to upgrade and modified classical resistors has resulted into different types of current resistors. Resistors can be categorized into various classes as determined by their ohms, performance, and composition amongst others. There are two broad categories of resistors; fixed and variable. Nonetheless, there are other ways of categorizing resistors as earlier on mentioned. Fixed resistors are the mostly used (Chinoy & Langlois, 2004). Fixed resistors are commonly used in electrical circuits, which are very common within the electrical industry. In most cases, the values of fixed resistors are usually determined during the circuit design phase. The reason as to why they are categorized as fixed resistors is that once their values are set during the circuit design phase, the values can never be altered or changed (Nabatian, Brown & Durant, 2000). Variable resistors on the other hand consist of a fixed resistor element in addition to a slider responsible for tapping onto the main element of the resistor. In most cases, unlike fixed resistors, variable resistors have three connections; two connections connecting the fixed element and the third connection being that of the slider. Whenever the three connections are used, then a variable potential divider is created within the resistor (Chinoy & Langlois, 2004). Variable resistors unlike fixed resistors may provide variable resistance that I, the ohm value can be varied due to the presence of the variable potential divider. Therefore, the other categories of resistors can either take the form of fixed or variable resistors. In respect to composition, resistors can be categorized into different types. For instance, categorizing by composition leads to carbon resistors, lead resistors, metal film/metal oxide resistors, and unleaded resistors (Felmetsger, 2000). Amazingly, there are resistors that combine more that two elements such as carbon and lead leading to leaded carbon resistors. Carbon resistors are associated with classical period even though they are still in use within the current electrical industry (Snogren, 2003). Carbon resistors as their names suggest are made from carbon element. In this respect, carbon granules are mixed with a binder in order to make a small rod applied as a resistor. The reason as to why carbon resistors are gradually being avoided is the fact that they cannot withstand very large power supply (Chinoy & Langlois, 2004). A typical carbon resistor looks like the following diagrams: Figure 3: Typical Carbon Resistor (Taurasi & Brown-Worsham, 2007) Figure 4: Typical Carbon Resistor, Internal Structure (Taurasi & Brown-Worsham, 2007) Other than the carbon resistor, which is currently being faced out in the industry, another type of current resistor is the metal oxide/metal film resistors. In most cases, electrical engineers would refer to metal oxide/metal film resistor as simply film resistor (Felmetsger, 2000). Film resistors, as they are widely known consist if metal film, carbon film, as well as metal oxide in their manufacture. In order to achieve this type of resistor, pure metals such as nickel or their oxides such as tin-oxide are deposited within the device (Chinoy & Langlois, 2004). In this type of resistor, the ohm or resistivity value of the electrical appliance is controlled by changing the thickness of the deposited film. The manufacturing section of this paper provides a detailed overview of the depositing technique in a bid to achieving a given or desired resistivity within the device. A typical film resistor will look like the following diagram: Figure 5: Typical film Resistor (Taurasi & Brown-Worsham, 2007) Figure 6: Typical film Resistor, Internal Structure (Taurasi & Brown-Worsham, 2007) The last type of resistor in this category is the wirewound type. Wirewound resistor as the name suggests is manufactured through winding of a thin metal allows wire, which is usually Nichrome or similar wire with the same resistivity on an insulating ceramic. The winding of such wire is usually done in spiral helix form (Felmetsger, 2000). Unlike the other forms of resistors, the wirewound contemporary resistors are usually found in very low ohmic high precision values that may range from 0.01 to approximately 100kΩ (Chinoy & Langlois, 2004). Wirewound resistors may take different forms such as chassis mounted resistors, power wirewound resistors, and non-inductive resistance wire that is spirally wound around ceramic porcelain tune, which is then given a proper cover with mica in order to prevent movement of alloy ways especially at high temperatures. A diagram of a wirewound resistor would be as represented below: Figure 7: Typical Wirewound Resistor (Snogren, 2003) Figure 8: Internal Structure of a Wirewound film Resistor (Snogren, 2003) With respect to leaded resistors, they are also becoming extinct. Leaded resistors have been used for a long period since the first electronic component was established during the classical time. In most cases, leaded resistors contain lead in them and in some cases they may contain more that one element (Nabatian, Brown & Durant, 2000). For instance, leaded resistors may contain carbon as an additional element hence forming the leaded carbon resistor. The following diagram illustrates how leaded carbon resistors resemble: Figure 9: Typical Leaded Carbon Resistor (Taurasi & Brown-Worsham, 2007) Other forms of current resistor applicable within the contemporary electrical industry include the NIST standard, fused resistors, foil, and filament resistors. NIST resistors, developed by the National Institute of Standards and technology have an accuracy of almost 0.001% with an almost equal value of TCR with precision wirewound resistors (Felmetsger, 2000). In most cases, the NIST resistors are a benchmark in evaluating and establishing accuracy of resistivity of other forms of resistors. In any laboratory, NIST are the standards of measurement for accuracy in resistivity. The following diagrams represent the images of NIST resistors. Figure 10: Typical NIST Resistor (Snogren, 2003) Figure 11: Typical NIST Resistor (Snogren, 2003) In a different perspective, fuse resistors are those that serve the dual purpose of being a resistor as well as a fuse. In most cases, the manufacturing of fuse resistors is such that it allows the devices to open up with large current. Fuse resistors normally run hotter than normal precision or power resistor due to their duality (Felmetsger, 2000). Fuse resistors are a perfect example of developments and advancements taking place within the electrical industry. In manufacturing these electronic devices, electronic engineers have identified the fact that combing two properties within a single device may not only be cost effective and efficient but also will enhance performance of other devices (Nabatian, Brown & Durant, 2000). Consequently, electric engineers have ended up designing fuse resistors to be able to combine two properties, fuse and resistivity, which are very vital within electronic appliances. The following diagram illustrates how a normal fuse resistor would resemble. Figure 12: Fuse Resistor (Schaeffer, 2002) Manufacturing process of resistors is highly determined by the type of the resistor as discussed above. The type of a resistor is determined by the function that the electronic appliance is made to perform at the end of production. Consequently, there are different processes applied in manufacturing process with respect to the type of resistor that the manufacturer desires. For instance, in the process of manufacturing wirewound resistors, the wire under compression is wound around the outer surface, which is placed under tension. The manufacturing process then aims at achieving permanent deformation with reference to comparable elasticities of the elements or materials involved. During this process, there are usually permanent mechanical changes that are unpredictable (Felmetsger, 2000). It is this unpredictable permanent mechanical changes that cause random changes within the electrical parameters of the applied or used wire as well as its resistance. The resulting feature in this case is the wirewound resistor. This is how wirewound resistors are manufactured. The following diagram illustrates how foil resistors are manufactured, which divers from the manufacturing process of the wirewound resistors. Figure 13: Manufacturing Process for Foil Resistor (Schaeffer, 2002) Notably, manufacturing processes of resistors vary from one resistor to another. It should be however noted that any form of these resistors can either take the form of a fixed or a variable resistor, which to a significant extent determines the manufacturing process of the resistors in questions (Felmetsger, 2000). It is worthwhile to note that there have been tremendous developments and advancements with respect to contemporary electrical industry. The results of such advancements and developments have led to upgrading and modifications of existing electrical appliances and devices as well as inventing newer electronic appliances and devices as determined by different dynamic technologies. Analysis of Resistor Manufacturing Output This section involves analyses of resistor manufacturing output. Two sets of data for two identical machines used for a production run or 10,000 100Ω resistor each, all measured to the nearest whole number of Ohms are provided. In this data set, it is worth noting that not all resistors produced are sold as a single product but are graded into 4 possible types depending upon their tolerance. The sales value per resistor for each tolerance band is given in the data sets. By using a histogram, this part will be able to analyze the data whilst discussing some specific concerns as regards the data. The following table provides the data: Resistor Value Number of Components < 90 1 12 90 3 19 91 8 41 92 19 83 93 41 154 94 83 262 95 154 410 96 262 593 97 410 790 98 593 969 99 790 1096 100 969 1142 101 1096 1096 102 1142 969 103 1096 790 104 969 593 105 790 410 106 593 262 107 410 154 108 262 83 109 154 41 110 83 19 > 110 72 12 Total 10,000 10,000 The following histograms have been developed from the above data. The two histograms give various depictions of the two forms of machines and their components with respect to the resistors used. From the two histograms, a lot of information and analyses can be drawn as explained in the following discussion. Figure 14: Machine 1 Figure 15: Machine 2 Observing the two histograms, it is obvious that machine 2 requires recalibration. This is because the calibration used in the resistors yield to vary high value and a bigger spread from the mean values of the resistors. A wide dispersion from the medium, also known as variance should be as small as possible in order to depict effectiveness and efficiency of the machine. Therefore, with a bigger spread in the values from the mean, it is obvious that machine 2 needs serious calibration to reduce the bigger dispersion from the mean. From the two histograms, there is some information that can be acquired in respect to how the machines are functioning. The production process taking place in machine one is more effective than the production taking place in machine two. This is depicted by the fact that there is a bigger dispersion of the resistors from the mean in machine two indicating not only poor calibration but inefficiency in respect to resistivity. Therefore, machine one’s production process is more effective when compared to the production process going on in machine two. This explains why machine two requires better calibration in order to attain a better performance in respect to the resistivity of the resistance. The unit prices are given to one-thousandth of a pound. This is possible especially with respect to resistors. The Ohms, which measure the resistivity extends to as low as one-thousandth hence the reason as to why the unit process are given in form of one-thousandth of a pound. There are various resistors with varying resistivity, which may be measured in terms of kilo Ohms. A kilo ohm is equivalent to one-thousand resistivity hence the reason as to why the company has decided to use such kind of calibration (Felmetsger, 2000). Therefore, it is possible for the calibration process to be as the company has indicated without violating any electrical rules and requirements in respect to measures of electrical devices and appliances such as resistivity. The following formula can be used to calculate the total sales value and establish rejection rate for each machine for each of the 10,000 component of production runs: For machine 1, the following are the production runs for each range: Range Production Runs < 90 4 91-95 305 96-100 3024 101 – 105 5093 106 – 110 1502 > 110 72 For machine two, the following are the production runs for each range: Range Production Runs < 90 32 91-95 950 96-100 4590 101 – 105 3858 106 – 110 559 > 110 12 From the provided information, 1% regarded as premium has a unit sales value of 0.016, 2% high has a unit sale value of 0.012; 5% standard has a unit sales value of 0.005; 10% low has a unit sales of 0.001; and above 10% rejected has no unit sales value. Therefore, the following provides the rejected rate for each machine: For machine 1: Rejected rate = 0.76% For Machine 2 Rejected rate = 0.42% Hence, the unit sales for machine I will be 0.005 while the unit sales for machine 2 will be 0.012 Conclusion There is no doubt that electrical industry continues to experience tremendous growth and development. With such developments there are possibilities that many more electrical appliances and devices will not only be invented by upgraded and modified to meet specific requirements in as far as increasing and changing technology is concerned. Bibliography Chinoy, P. & Langlois, M. 2004, "Thin-folm embedded resistor and capacitor technologies", Circuit World, vol. 30, no. 1, pp. 16-19. Felmetsger, V.V. 2000, "Controlled sputtering enables better SiCr films", Semiconductor International, vol. 23, no. 12, pp. 181-184. Nabatian, D.J., Brown, O.W. & Durant, J.E. 2000, "Thick-film resistors", Printed Circuit Design, vol. 17, no. 5, pp. 46-50. Schaeffer, R. 2002, "Embedded resistor trimming", CircuiTree, vol. 15, no. 6, pp. 78-78. Schake, J. 2007, "Mass Reflow Assembly of 01005 Resistors", Circuits Assembly, vol. 18, no. 6, pp. 38-45. Snogren, R. 2003, "Designing with ceramic thick-film embedded passives: Bridging the gaps", CircuiTree, vol. 16, no. 12, pp. 52-57. Taurasi, E.M. & Brown-Worsham, S. 2007, "Best of the Engineering Marketplace", Design News, vol. 62, no. 9, pp. 22. Read More