CAD Rev PDF - Engineering Drawing Standards & Abbreviations

Importance of Designations, Standards, Standards and Abbreviations Definition: Developing, promoting, and Engineering Drawing Abbreviations & mandating compatible technologies & Symbols...

Importance of Designations, Standards, Standards and Abbreviations Definition: Developing, promoting, and Engineering Drawing Abbreviations & mandating compatible technologies & Symbols processes o Communicate & detail Focus Areas: characteristics of drawings o Quality o Consistency o Used in manufacturing & inspection o Compatibility Technical Standards o Interoperability o Provide glossaries of abbreviations, o Safety acronyms & symbols Purpose: o Define terms & symbols (corporate- o Normalization of processes & specific) technology Drawing Standards Manual o Establishes rules, guidance & templates o Establishes conventions for o Ensures conformity & quality across engineering & drafting activities o Sets minimum requirements for GSFC drawings o Ensures standardization & uniform Abbreviations interpretation Definition: Standardized symbols & System, Payload, or Component abbreviations in engineering drawings Assembly Definition Used in: o Defined through drawings, lists, o Mechanical schematics, wiring diagrams & specs o Electrical o Ensures fabrication follows design o Piping & Plumbing o Serves as permanent record o Civil o Structural Designations Purpose: o Saves time Definition: Unique ID/reference for part, o Improves accuracy & clarity component, or feature o Simplifies complex information Includes: o Reduces costs 1. Part Number/Code – Alphanumeric o Ensures standardization across identifier engineering industries 2. Component Name – Description of Examples: the part o AC – Alternating Current 3. Material Specification – o DC – Direct Current Material/grade info o FAB – Fabrication 4. Drawing Number – Unique ID for o LD – Load the drawing Purpose: Electronic Symbol System o Ensures clarity & proper identification Different Standard Systems: o Prevents confusion in assemblies 1. IEC 60617 – International o Maintains accuracy in Electrotechnical Commission (based on manufacturing, assembly & BS 3939) inspection ▪ Contains ~1750 circuit symbols 2. ANSI Y32 (IEEE Std 315) – American Standard for circuit symbols  3. Australian Standard AS 1102 – o Pin numbers → Outside symbol Australian electronic component graphics standard o Sheet connection symbols → Extreme Widely Used Standards: left or right edge o IEC & ANSI/IEEE are globally recognized Title Block Placement o Both have similarities & some o Lower right corner of first sheet differences o Should include: o Essential for international circuit 1. Title diagrams & electronics engineering 2. Part number 3. Revision (if any) Circuit Notation & Reference Designators Additional Pages o Block diagram page for circuit overview Purpose: o History page to track schematic o Identifies components in circuit changes diagrams & schematics o Cross-references with parts lists or Bill Circuit Layout/Design Keywords: of Materials (BOM) o Aids in repair & troubleshooting on Circuit Diagram: Graphical representation of printed circuit boards electrical/electronic circuits; simplifies circuit Circuit Reference Designator: structure. o Format: One/two letters + number Electrical/Electronic Diagram: Alternate names (e.g., R13, C45) for a circuit diagram. o Letters: Indicate component type Elementary Diagram: Basic representation of o Numbers: Identify specific component circuit components and their connections. Standardization: Electronic Schematic: Detailed graphical tool o IEEE 200-1975 – Original standard for for circuit design, construction, and reference designations maintenance. o ASME Y14.44-2008 – Current standard Components & Symbols: Standard for electrical/electronics parts representations of circuit elements. identification Interconnections: Connections between circuit components depicted in the diagram. Rules & Guidelines for Drawing Good Design, Construction, and Maintenance: Schematics (Continued) Purposes of circuit diagrams for electricians/technicians/engineers. Electrical Connections o Lines represent connections between Circuit Layout/Design components o Intersecting lines must have a node to Connections: Focus on clarity and simplicity of indicate connection connections in circuit diagrams. o Max 3 lines per node for clarity Wire Layout: Wires drawn neatly and straight Net Naming for clarity. o Assign names to nets in complex Component Positioning: Actual physical layout circuits often differs from circuit diagram o Nets with same name are connected representation. automatically Beginner Focus: New users should focus on Text & Orientation understanding connections, not positions of o Pin numbers, polarity, values, and net components. names → Horizontal o Inputs → Left, Outputs → Right Circuit Diagram & Stripboard Layout Schematic Organization o Use functional blocks for clarity Circuit Diagram: Helps in testing and understanding circuit functionality.  Stripboard/PCB Layout: Physical layout Types: Bare wire (soldering), terminals, representation used to build the circuit. clips, jacks, plugs. Soldering vs. Mechanical: Soldering for Drawing Circuit Diagram Tips permanent, mechanical for removable connections. Correct Symbol Usage: Use accurate symbols for components (resistors, capacitors, etc.). Wiring Diagram Labels Straight Lines: Draw wires neatly with straight lines (preferably using a ruler). Required: Wire size/type, insulation Junctions: Mark junctions with a 'blob' to type/color, connection method. indicate connections. Component Labeling: Label resistors, Wiring Diagram Construction capacitors, etc., with their respective values for clarity. Rough Sketch: Initial layout for space and Power Supply Orientation: Place the positive component relationships. supply (+) at the top and the negative (-) at the Component Representation: Shows bottom. physical characteristics, proportions. 0V Label: Negative supply usually labeled as 0V Identification: Includes tabs, slots, and for clarity. polarity for multi-lead components. Science vs. Electronics: Understand the differences between drawing for science and Categories of Wiring Diagrams electronics-specific contexts. Continuous Line Diagram: Shows all Wiring and Cabling Diagram connections and the location or travel of the wire from one point to another. This Wiring Diagram diagram is convenient for simple circuits not containing an excessive number of parts, Definition: Diagram for assembling where the actual assembly can be done one electronic/electrical packages, showing wire at a time. physical relationships between components Interrupted Line Diagram: Used for and wiring. complex wiring diagrams, with placement of lines that may have very little to do with the Wire actual routing of the wires. All wires go into one mainline no matter where they terminate Types: Copper, aluminum for low or what path they take to get there. This type resistance. of diagram may not be very convenient for Structure: Single or multiple strands. production or assembly, since components Insulation: Non-conductive (nylon, rubber, are not drawn in their true physical polyester), color-coded for identification. relationships. Size/Gauge: AWG, smaller numbers = Tabular Form: A lineless diagram, where larger wire. all connections are listed in tabular form. This table should include some means of Insulation identifying each wire and should define the destination or endpoints. Purpose: Prevents electrical contact and short circuits. Types of Wiring Diagrams Materials: Varies based on use, often color- coded. Point to Point: The oldest type of wiring drawing. The figure shows a pictorial form Method of Termination of the diagram in which each part and terminal are drawn about as they appear to the viewer. It shows the drawing with the  most specific details as it uses an individual management. Uses fans, heat sinks, thermal line for every wire. vias, or materials with high thermal Trunkline or Highways: This type differs conductivity to eliminate extra heat. from the point-to-point style in that Prolongs the life of equipment by ensuring conductors (conductor paths might be better) they run within safe temperature ranges. are merged into long lines called highways Signal Distribution: Facilitates efficient (or trunklines) instead of being drawn as transmission of signals between components separate, complete lines from terminal to through PCBs, connectors, and cables. terminal. Minimizes noise, signal degradation, or Baseline or Airline: These wiring drawings, interference during transmission. Maintains with a rather misleading name, are similar in signal integrity for high-speed or complex some ways to highway diagrams. The circuits. airline, or baseline, as it is sometimes called, Power Distribution: Effectively and is an imaginary, usually horizontal or consistently distributes power to every vertical, line conveniently located so that component. Includes regulators, traces, and short feed lines may be drawn from power planes for appropriate voltage and component terminals to it. current delivery. Guarantees steady Straight Line: Instead of drawing the operation free from power outages or components or terminals as rectangles, overloads. circles, etc., each component number is listed at the top with a vertical line directly Electronic Packaging Levels underneath. Conductors that go to each component are shown with a connection dot Level 0: "Chip," protecting a bare and the terminal number close to the dot. semiconductor die from contamination and damage. Electronic Packaging Level 1: Component, such as semiconductor package design and the packaging of other Definition discrete components. Level 2: Etched wiring board (printed circuit Electronic packaging is defined as an electronic board). structure that serves to protect an Level 3: Assembly, one or more wiring electronic/electrical element from its environment boards, and associated components. and the environment from the electronic/electrical Level 4: Module, assemblies integrated in element. It involves housing and interconnection of an overall enclosure. integrated circuits to form electronic systems. It is Level 5: System, a set of modules combined the method of closing, protecting, or providing for some purpose. physical structure to either electronic components, assemblies of components, or finished electronic Materials Used in Electronic Packaging devices. Semiconductors Function of Electronic Packaging o Si, GaAs Metals Circuit Protection: Shields parts from o Solders for interconnects (Sn-Pb, Sn- environmental elements such as dust, Ag; gold wirebonds; copper moisture, vibrations, and physical harm. leadframes (Kovar, CuBe, Alloy 42); Protects circuits from electrostatic discharge copper traces in substrates; tungsten, (ESD) and electrical interference. May molybdenum traces in co-fired consist of grounding, fuses, or surge ceramics; Ag, Au, Pd for thin/thick protectors. films on ceramics; and nickel Heat Dissipation: Prevents component diffusion barrier metallizations. overheating by using appropriate thermal Ceramics  o V₂O₅ substrates modified with BaO, ▪ Select flame-retardant SiO₂, CuO, etc.; SiN dielectrics; materials (e.g., UL 94 V-0 diamond heat sinks. rated) for housings. Polymers ▪ Ensure safe thermal o Epoxies (overmold); filled epoxies management and electrical (overmold); silica-filled anhydride insulation. resin (underfills); conductive ISO Standards (International adhesives (die bonding, Organization for Standardization) interconnects); laminated o Focus: Quality management and epoxy/glass substrates; polyimide reliability. dielectric; benzoylclobutene; o Application: silicones; and photosensitive ▪ Establish design processes to polymers for photomasks. minimize defects and ensure Glasses regulatory compliance. o SiO₂ fibers for optoelectronics; silicate glasses for sealing; borosilicate glass substrates; and glass fibers for epoxy/glass substrates (F4-4). Standards IPC Standards (Association Connecting Electronics Industries) o Focus: PCB design, assembly, and quality assurance. o Application: ▪ Ensure proper material selection for heat dissipation and reliability. ▪ Design for manufacturability and inspectability. IEC Standards (International Electrotechnical Commission) o Focus: Safety, performance, and electromagnetic compatibility (EMC). o Application: ▪ Ensure enclosures meet IP ratings for environmental protection. ▪ Validate designs for electromagnetic compatibility in signal and power distribution. UL Standards (Underwriters Laboratories) o Focus: Product safety for electronic devices. o Application: