\chapter{Electronic Components}

The study of electronic components is a cornerstone of modern engineering, as electronics now permeate every facet of private and professional life. From automotive systems and medical technology to domestic appliances and mobile communication, the integration of complex circuitry is a primary driver of economic and industrial value. This chapter explores the foundational elements of electronic circuits, beginning with the transition from purely mechanical systems to integrated mechatronic solutions. It details the various methods of realizing circuits—including Printed Circuit Boards (PCBs), hybrid technologies, and integrated circuits—and provides a comprehensive examination of passive components like resistors, capacitors, and inductors, as well as active semiconductor devices and quartz oscillators.

\section{Fundamental Circuit Definitions}

To understand electronic manufacturing, one must first define the structures that house and connect components. An electric circuit is not merely a collection of parts but a functional integration designed to achieve complex tasks.

\subsection{Electric Circuit}

\dfn{Electric Circuit}{An electric circuit is the systematic connection of electric and electronic components on an interconnect device, such as a printed circuit board, to perform a specific complex function.}

\thm{Realization Forms}{Depending on the manufacturing method, an electric circuit can be realized as a printed circuit board (PCB), a hybrid technology assembly, or a high-density integrated circuit (IC).}

\subsection{Printed Circuit Board (PCB)}

\dfn{Printed Circuit Board}{A PCB is a substrate consisting of an isolating carrier material with integrated conductive structures. It serves both to mechanically support components and to provide the electrical pathways required for the circuit's operation.}

\nt{Standard PCBs often use fiber-reinforced epoxy resin, known as FR4, which has a glass transition temperature of approximately 135 degrees Celsius, necessitating precise control during the soldering process.}

\section{Assembly and Hybrid Technologies}

The physical construction of a circuit involves different assembly philosophies. The choice between through-hole technology (THT) and surface-mounted technology (SMT) depends on the required component density and manufacturing efficiency. While THT involves inserting leads through the board, SMT places components directly onto the surface pads.

\subsection{Hybrid Technology}

\dfn{Hybrid Technology}{Hybrid technology represents a blend of integrated and discrete technologies, where components such as resistors and capacitors are printed onto glass or ceramic substrates, while other parts like transistors are added as discrete units.}

\thm{Integrated Circuits (ICs)}{The integrated circuit is the most compact form of micro-electronics, combining numerous discrete functional elements into a single, non-repairable unit that performs complex functions.}

\section{Passive Components: Resistors}

Resistors are fundamental passive components used to control current and voltage within a circuit. They are classified based on whether their resistance is fixed, manually adjustable, or dependent on external physical parameters.

\subsection{Linear Resistors}

\dfn{Ohmic Resistors}{Linear resistors, or Ohmic resistors, maintain a constant proportional relationship between the applied voltage and the resulting current, following Ohm’s Law.}

\nt{Fixed resistors can be constructed as film resistors, where a conductive layer's thickness defines the resistance, or wire-wound resistors, which use coiled resistive wire to handle higher power loads.}

\subsection{Temperature-Dependent Resistors}

\dfn{NTC and PTC Resistors}{Negative Temperature Coefficient (NTC) resistors see a decrease in resistance as temperature rises, whereas Positive Temperature Coefficient (PTC) resistors exhibit increased resistance with rising temperatures.}

\thm{Voltage-Dependent Resistors (Varistors)}{A varistor is a non-linear resistor whose resistance decreases significantly as the applied voltage increases, providing a critical safety mechanism for voltage limitation and protection.}

\section{Passive Components: Capacitors}

Capacitors are defined by their ability to store electric charge within an electric field. They are essential for filtering, energy storage, and signal coupling.

\dfn{Capacitance}{Capacitance is the physical property of an arrangement of conductive objects to store an electric charge of one Coulomb when a voltage of one Volt is applied. It is measured in Farads (F).}

\nt{Real capacitors are not ideal and possess internal losses, which are represented by an equivalent series resistance (ESR) and quantified by the loss factor, tan delta.}

\dfn{Electrolyte Capacitor}{An electrolyte capacitor is a polarized component where the anode is a valve metal and the dielectric is an oxide layer. They offer high capacitance but can be destroyed by incorrect polarity or excessive voltage.}

\thm{Ceramic Multi-Layer Capacitors (MLCC)}{MLCCs utilize ceramic as a dielectric medium and are characterized by high dielectric strength and small footprints, making them the most frequently used capacitor type in modern electronics.}

\section{Passive Components: Inductors}

Inductors store energy in a magnetic field generated by the flow of current. They are particularly important in alternating current (AC) circuits, where they provide inductive reactance.

\dfn{Inductance}{Inductance is the property of an inductor where a change in electric current of one Ampere per second induces a voltage of one Volt. This self-induction is measured in Henry (H).}

\nt{The resistance of an inductor, known as inductive reactance, increases proportionally with the frequency of the alternating current.}

\dfn{Ferrite Cores}{Ferrite cores are made of non-conductive ferromagnetic metal oxides. Because they are non-conductive, they prevent the formation of eddy currents, making them ideal for high-frequency applications.}

\thm{Eddy Current Suppression}{In iron-core inductors operating at lower frequencies, sheet cores consisting of isolated stacked layers are used to minimize energy losses caused by eddy currents.}

\section{Quartz Crystals and Oscillators}

Quartz crystals are used to generate precise and stable frequency oscillations. They rely on the piezoelectric effect, where mechanical deformation and electrical fields are interconnected.

\dfn{Quartz Oscillator}{A quartz oscillator is a component containing a piezoelectric crystal disk that performs deformation oscillations at its eigenfrequency when excited by an electrical field, serving as a stable clock generator for microprocessors.}

\nt{The addressing voltage of a quartz must be carefully managed to avoid excessive energy in the crystal, which can lead to the formation of micro-cracks and failure.}

\section{Active Components: Semiconductor Devices}

Semiconductors form the basis of active electronic control. Their conductivity can be precisely manipulated through the process of doping, which introduces impurities into the crystalline silicon structure.

\dfn{Doping}{Doping is the intentional introduction of specific atoms, such as Phosphorus (n-type) or Boron (p-type), into a semiconductor crystal to adjust its electrical conductivity.}

\dfn{Diode}{A diode is a semiconductor component that acts as a one-way valve for electrical current, allowing it to pass in one direction while blocking it in the other.}

\dfn{Transistor}{A transistor is an active component used for switching and amplifying signals. It acts as a "transfer resistor" whose resistance can be controlled by an external current or voltage.}

\thm{MOSFET Working Principle}{Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) operate by using an electric field generated at a gate electrode to create a conductive bridge between the source and drain, allowing for power-efficient control.}

\nt{While bipolar transistors are current-controlled, unipolar transistors like MOSFETs are voltage-controlled, making them the most important type for high-density integrated circuits.}
