\chapter{Electronics Production, ECAD}

Electronic Computer-Aided Design (ECAD) has become a fundamental pillar of industrial production, facilitating the transition from mechanical and hydraulic systems to sophisticated electronic control. While mechanical CAD (MCAD) dominated the market for decades, ECAD systems have seen rapid growth due to the increasing complexity of miniaturized devices and the need to integrate electrical planning directly into Product Data Management (PDM) environments. The scope of ECAD spans three primary domains: the engineering of industrial machines and plants, the development of printed circuit boards (PCBs), and the design of highly integrated circuits or microchips.

In modern engineering, the primary objective of using ECAD is to decrease development durations and minimize manufacturing costs while simultaneously enhancing the quality and reliability of the final product. This is achieved through automated analysis, such as the generation of connector lists and bill of materials, and through the implementation of simultaneous engineering. By allowing electrical and mechanical designers to work in parallel, companies can achieve significant productivity gains.

\dfn{ECAD}{A category of software tools used for the computer-based planning, dimensioning, and documentation of electrical and electronic equipment across various industrial applications.}

\section{Historical Evolution and System Generations}

The development of ECAD technology is categorized into three distinct generations, each representing a leap in functionality and integration. The first generation was primarily a digital substitute for manual, paper-based drafting. While it improved the aesthetic quality of circuit diagrams, it offered limited time savings as the logical data was not yet interconnected with other systems.

The second generation introduced automated evaluation capabilities. These systems could automatically generate parts lists and terminal connection tables, significantly reducing manual clerical work. Furthermore, this era saw the integration of Production Planning and Control (PPS) and PDM systems, enabling a more cohesive data environment. The current third generation is defined by model-based electrical engineering. These systems utilize object-oriented approaches and offer Application Programming Interfaces (APIs) for deep customization, allowing companies to integrate their own specific routines and automate complex design tasks.

\dfn{Simultaneous Engineering}{A collaborative development approach where different engineering disciplines work on a project at the same time rather than in sequence, facilitated by shared databases and integrated software tools.}

\thm{Productivity Gains}{The implementation of third-generation ECAD systems within a simultaneous engineering framework can reduce overall development time by 20\% to 30\% compared to traditional sequential methods.}

\nt{Early ECAD systems failed to significantly increase productivity because they lacked the database integration necessary to prevent data locking during multi-user access.}

\section{Documentation Standards and Schematic Structures}

Unlike mechanical drawings that focus on physical dimensions and surface finishes, electrical documentation relies heavily on graphical symbols to convey logical functions. The creation of these documents is governed by international standards, such as DIN EN 61346-1, which provides a framework for the unequivocal identification of objects. This standard classifies documentation into three essential perspectives: functional, product-related, and location-related.

\subsection{The Three Aspects of Technical Documentation}

The functional aspect focuses on the purpose of the circuit, answering the question of what the system does. The product aspect identifies the specific components and assemblies used, answering how the system is constructed. Finally, the location aspect specifies where the components are physically situated within an installation. These three views ensure that any object—whether a motor, a sensor, or a relay—can be identified and serviced throughout its lifecycle.

\dfn{Object}{An entity within an electrical system that is considered during planning, design, realization, or maintenance, and is uniquely identified through its functional, product, and location aspects.}

\nt{In ECAD, the only "complete" object is the entire design itself, as individual assemblies cannot be fully understood without their logical cross-references to other parts of the system.}

\section{Machine Engineering and Plant Wiring}

Designing the wiring for complex machinery requires more than just connecting points on a diagram. It involves calculating cable diameters based on current loads, determining minimum bending radii to prevent mechanical failure, and planning for high-frequency (HF) suitability. ECAD systems of the third generation allow for the integration of MCAD data, enabling designers to place virtual cable ducts directly onto the 3D geometry of the machine.

\subsection{Harness Design and Virtual Routing}

The process typically begins with the electrical circuit diagram, which establishes the logical connectivity. However, the physical length of cables is determined by the adjustment travel of moving parts, such as a robot arm. ECAD systems use "rubber band" representations to show logical connections before an auto-router or a designer defines the final path through cable channels. This integration ensures that cable harnesses—groups of wires traveling in the same direction—are manufactured with precise lengths and correct connectors.

\thm{Cable Rigidity and Space}{The physical volume required for wiring is heavily influenced by cable shielding and rigidity; ECAD systems must account for these parameters to ensure that assembly is physically possible within the mechanical constraints.}

\section{Design of Control Cabinets}

The control cabinet serves as the convergence point for almost all electrical information in a plant. Modern ECAD modules for cabinet design have replaced the need for physical prototypes by offering 3D collision detection and thermal simulation. Designers can arrange components based on their logical identifiers or by component type to optimize space and clarity.

\dfn{Back-Annotation}{The process of automatically updating the original circuit diagram and database with modifications made during the physical layout or cabinet design phase to ensure data consistency.}

\thm{Thermal Distribution Verification}{By utilizing 3D models within an ECAD environment, engineers can simulate heat dissipation and air flow within a control cabinet, preventing component failure due to overheating.}

\nt{Precise documentation of every cable within a control cabinet is mandatory to guarantee access for maintenance and to prohibit unauthorized manipulation of sensitive technology.}

\section{Printed Circuit Board Generation}

The path from a schematic to a finished PCB involves several critical verification steps. Once the circuit design is finalized, it often undergoes simulation (such as pSpice) to verify behavior before any physical layout begins. The transition to the board layout requires defining the board size, the number of layers, and the "footprints" of the components.

\dfn{Footprint}{The physical dimensions and pin arrangement of an electronic component on a printed circuit board, which determines the required space and solder point locations.}

\subsection{Verification Procedures: ERC and DRC}

Before manufacturing, two types of checks are performed. The Electrical Rule Check (ERC) identifies logical errors in the schematic, such as open inputs or short-circuited outputs. The Design Rule Check (DRC) focuses on the physical layout, ensuring that conductive paths maintain minimum distances and widths, and that they follow predefined geometric constraints.

\thm{Auto-Router Limitations}{While auto-routers can handle the majority of connections, complex boards often require manual intervention to place vias, route difficult paths, or integrate 0-Ohm resistors as bridges.}

\nt{The final output for PCB manufacturing is typically a Gerber file, which provides the precise geometric data required by CAM systems for drilling, milling, and etching.}

\section{Microelectronics and Integrated Circuit Design}

The design of highly integrated circuits (ICs) represents the most complex application of ECAD. Unlike PCBs, an IC cannot be modified once manufactured, making "first-time-right" design imperative. This field is driven by Moore's Law, which observes that the number of transistors on a chip doubles approximately every 18 to 24 months.

\subsection{The Top-Down Design Philosophy}

Modern chip design follows a top-down approach, moving from abstract system specifications to detailed transistor-level layouts. This systematic approach reduces error-proneness by allowing developers to verify the logic at high levels of abstraction (Register Transfer Level) before committing to a physical layout. This hierarchy is often visualized using the Gajski Diagram (or Y-Chart), which maps the design across three domains: behavioral, structural, and physical.

\dfn{Gajski Diagram}{A visualization tool for IC design that describes the transition of a circuit through various levels of abstraction across behavioral, structural, and physical dimensions.}

\thm{Design Regularity}{The efficiency of an IC design is measured by its regularity factor, which promotes the reuse of identical cells (like NAND gates) to simplify the layout and reduce potential errors.}

\section{Data Representation and Manufacturing Prep}

As chips now contain billions of transistors, the amount of data required to describe the layout is staggering. A traditional polygon-based description of 10 million transistors could require over 3 gigabytes of data. To manage this, ECAD systems have moved away from surface-based polygons toward more efficient edge-based representations.

\subsection{Physical Realization and Artwork}

The final stage of IC design is the preparation of "artwork," which involves transferring design layers to production layers. This process accounts for manufacturing distortions through the expansion or contraction of surfaces. The data is then used to create a "reticle"—a glass pane with a chromium structure—which acts as a negative for the photochemical exposure of the silicon wafer.

\dfn{Reticle}{A high-precision master mask used in semiconductor manufacturing to project the circuit pattern onto a silicon wafer through a photochemical process.}

\nt{Edge representation is currently the standard for layout data because it allows for local modifications without reloading entire complex polygons and facilitates faster Design Rule Checks.}

\thm{Moore's Law and Power Density}{As transistor counts increase, the power density of high-performance processors has surpassed that of an industrial oven plate, necessitating advanced thermal management strategies during the ECAD phase.}