Microelectronics Case Study

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1-1 CHAPTER 1 MICROELECTRONICS LEARNING OBJECTIVES Learning objectives are stated at the beginning of each topic. These learning objectives serve as a preview of the information you are expected to learn in the topic. The comprehensive check questions are based on the objectives. By successfully completing the OCC-ECC, you indicate that you have met the objectives and have learned the information. The learning objectives are listed below. Upon completion of this topic, you will be able to: 1. Outline the progress made in the history of microelectronics. 2. Describe the evolution of microelectronics from point-to-point wiring through high element density state-of-the-art microelectronics. 3. List the advantages and disadvantages of point-to-point…show more content…
As more was learned by designers, they began to increase both the size and complexity of circuits. Component limitations were soon identified as this technology developed. 1-3 VACUUM-TUBE EQUIPMENT Vacuum tubes were found to have several built-in problems. Although the tubes were lightweight, associated components and chassis were quite heavy. It was not uncommon for such chassis to weigh 40 to 50 pounds. In addition, the tubes generated a lot of heat, required a warm-up time from 1 to 2 minutes, and required hefty power supply voltages of 300 volts dc and more. No two tubes of the same type were exactly alike in output characteristics. Therefore, designers were required to produce circuits that could work with any tube of a particular type. This meant that additional components were often required to tune the circuit to the output characteristics required for the tube used. Figure 1-1 shows a typical vacuum-tube chassis. The actual size of the transformer is approximately 4 × 4 × 3 inches. Capacitors are approximately 1 × 3 inches. The components in the figure are very large when compared to modern microelectronics. Figure 1-1.—Typical vacuum tube…show more content…
The reductions in size, weight, and power use were impressive. Circuits that earlier weighed as much as 50 pounds were reduced in weight to just a few ounces by replacing bulky components with the much lighter solid-state devices. The earliest solid-state circuits still relied on point-to-point wiring which caused many of the disadvantages mentioned earlier. A metal chassis, similar to the type used with tubes, was required to provide physical support for the components. The solid-state chassis was still considerably smaller and lighter than the older, tube chassis. Still greater improvements in component mounting methods were yet to come. One of the most significant developments in circuit packaging has been the PRINTED CIRCUIT BOARD (pcb), as shown in figure 1-3. The pcb is usually an epoxy board on which the circuit leads have been added by the PHOTOETCHING process. This process is similar to photography in that copper-clad boards are exposed to controlled light in the desired circuit pattern and then etched to remove the unwanted copper. This process leaves copper strips (LANDS) that are used to connect the components.

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