 Welcome, myself, Mr. Giridhar Jain, Assistant Professor in Electronics and Telecommunication Engineering, Walton Institute of Technology, Singapore. Now, today, I am going to explain fundamentals of printed circuit board design. Learning outcomes. Learning outcomes of this session are, at the end of this session, students will be able to explain fundamentals of PCB design. Contents. Contents of the session are introduction and PCB layout, steps and rules. Introduction. First is PCB design softwares. So, in the market, there are so many softwares available for designing printed circuit boards, which we call as EDA tools. Now, these softwares are ORCAD, EGLE, Proteus, ECIM, Express, PCB, etc. Now, while selecting the software, we have to understand the features provided with the available software and whether these features are user-friendly and convenient to the user. Now, important features of the PCB design softwares are, so, first feature is component library. So, component library provides the design components and very important is facility to edit and create component. Now, this facility is very useful for the user when the required component is not available into the library. For example, there is a pulse transformer or miscellaneous relay. Now, these components can be created as per requirement of user by using this create component facility available in the component library. Now, next step is schematic capture. Now, this facility of the schematic capture involves facility to draw circuit diagram and link it to the PCB layout. Means, user can draw the circuit diagram using schematic capture and later on in PCB layout, this schematic can be imported. PCB layout, so, what is PCB layout? Now, PCB layout consists of component placement and making the connections as per circuit diagram by using the tracks. Now, for this PCB layout, the distances which are used are either in millimeter or in inch. Now, user can select one of the two options either in mm or in inch. Pause this video and think on the following question. Which unit of distance be preferred for PCB layout? Out of these two millimeter and the inches, the inches distance are preferred for the PCB layout because all the electronic components which are manufactured in British units that is in inch. Therefore, the distances in inch are preferred for the PCB layout. Now, in inch, the 100 mil means mil stands for milli inch. So, 100 mil is equal to 2.54 mm and this is the distance between two pins of IC for a DIL package 100 mil 2.54 mm. One library also specifies the component distances either in mm and inches. Now, figure one shows the electronic components. Now, this is a ceramic capacitor, this is electrolytic capacitor, electrolytic capacitor. For this electrolytic capacitor, distance between two pins is 100 mil, here 200 mil. Now, this is 40 pin IC, for this IC, DIL package, distance between two pins of IC is 100 mil, that is 0.1 inch. Now, in this diagram, on the background, whatever dots you are seeing, these dots are nothing but it is a grid. So, this grid is set to 100 mil, means distance between the two dots is 100 mil. Now, this can be set to 2550 100 as per user requirement. On this is 16 pin IC, this is a diode 1N 4007 having a spacing of 400 mils, this is a quarter watt resistance having a spacing of 400 mil. Now, this figure shows the selection of component from the component library. Now, here one component is selected, radial capacitor, so this is displayed here. You can see the various components can be selected from this library and the distances are mentioned. For example, here this is 0.2 inch, like that for every component, the distances are specified in inch as well as mm and the selected component is displayed on this side window. Now, PCB loud steps and rules. Before we start the PCB loud, the complete circuit diagram with all the component detail should be available. That is, complete circuit diagram without having any doubts in the circuit. And second is, the mechanical dimensions of all the components used in the circuit should be available because all these mechanical dimensions are required for designing the PCB, means appropriate space should be provided on a PCB while making PCB loud. Now, second is, import circuit diagram from the schematic to PCB loud. This is one method, if circuit diagram is drawn in a schematic capture. And second is, select the components from component library, place them and do connections as per circuit diagram. First, components requiring input and output connections or input or output connections are placed near the edge of PCB. Now, next rule, components producing heat should be placed away from temperature-sensitive components. Now, critical components requiring more connections with other components, place first and space in between, is filled with the other components, component density. Component density is nothing but the number of components per unit area of the PCB. Component density should be maximum for the portable electronics products and it should be medium for the other applications. Now, PCB layout is done manually or by auto-router. For the complex and the large circuits, auto-router is advantageous, otherwise a manual routing is better. Width of track, for the ground, supply and signal is different as per the rules given below. Width of ground should be the highest and that is equal to twice the width of supply track and width of supply track should be equal to twice the width of signal track. Unused portion of the PCB should be connected to the ground to decrease the resistance of the ground track and the width of track also depends on the current flowing through it. As the current increases, the width of track increases. Resistance of the track is given by rho L by A. To minimize the length of track, the track should be bent at the angle of 45 degrees. Now, this figure shows a shoulder side layout. So, on this layout you can see this is a ground track. So width of ground is highest. Now here you can see the bending of tracks at the angle of 45 degrees. Now here this is unused portion of the PCB which is connected to the ground. Connectors are placed at the end. This is 40 pin IC placed at the middle making the connection with other components. And here there are three switches. This is component layout. From the component layout it is clear that the connectors requiring input or output connections are placed at the edge of the PCB. This is push buttons. These are connectors. This is 40 pin IC located at the middle. This is 7805, a three terminal IC voltage regulator which is generating heat. So you can connect external heatsink here. So it should be placed away from other components. So these are the references. Printed circuit boards designed and technology by Bushard, Tata Migrahi publisher. Second is Express PCB software free download. And third is CircuitMaker PCB design software. So component layout, shoulder side layout these are taken by using the CircuitMaker PCB design software. Thank you.