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Electromechanical Drawing Chapter 4 - Drawings: Show Me a Plan Copyright © 2004 by Janna B. Gallaher

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Page 1: Electromechanical Drawing - ssucet.orgjgallaher/download/etem130/ETEM130Chapter… · Design Drawings System (functional) diagram Conceptual circuit design Packaging plan Conceptual

Electromechanical Drawing

Chapter 4 - Drawings: Show Me aPlan

Copyright © 2004 by Janna B. Gallaher

Page 2: Electromechanical Drawing - ssucet.orgjgallaher/download/etem130/ETEM130Chapter… · Design Drawings System (functional) diagram Conceptual circuit design Packaging plan Conceptual

Drawings: The Language of EngineeringElectronic Fabrication Drawings (The 10Drawing Set)

Design DrawingsWorking Schematic DrawingConceptual DesignPC Board Design Layout DrawingPC Board Artwork & Fabrication DrawingsPC Assembly DrawingWiring (Interconnect) DiagramSheet Metal or Packaging DrawingFinal Packaging Drawing

Page 3: Electromechanical Drawing - ssucet.orgjgallaher/download/etem130/ETEM130Chapter… · Design Drawings System (functional) diagram Conceptual circuit design Packaging plan Conceptual

Design Drawings

System (functional) diagramConceptual circuit designPackaging plan

Conceptual Design Sketch

These drawings represent the “top level” design of a system. They show the functionality of the product. Only thefunctions are shown and their relationships. These drawings represent the “form, fit, and function.”

System Diagram

Page 4: Electromechanical Drawing - ssucet.orgjgallaher/download/etem130/ETEM130Chapter… · Design Drawings System (functional) diagram Conceptual circuit design Packaging plan Conceptual

Conceptual Electrical Design

Conceptual design contains all the electricalrequirements.

Note the sketches of thecomponent packagesand pin-outs.

Importantcalculationsshow designintent.

Page 5: Electromechanical Drawing - ssucet.orgjgallaher/download/etem130/ETEM130Chapter… · Design Drawings System (functional) diagram Conceptual circuit design Packaging plan Conceptual

Working Schematic DrawingDrafted schematic with all detailsContains all of the electronic and electrical design informationon a circuitContains a representation of all parts and their values, theirinterconnection, and may contain test points or other waveformdescriptionsMost important document because it describes how a circuitworks

Page 6: Electromechanical Drawing - ssucet.orgjgallaher/download/etem130/ETEM130Chapter… · Design Drawings System (functional) diagram Conceptual circuit design Packaging plan Conceptual

Working Schematic Drawing (continued)

Rules for Drafting SchematicsFlow should be from left to right, top to bottomLines should be evenly spaced apartLines between components should take the shortest path(but not diagonally)Connecting lines should have a minimum of crossovers andjogglesArrange long parallel lines in groupsAvoid 4 way tie points or 4 way junctionsPower supply lines should go up and ground lines should godownNegative voltages should be positioned below ground

Page 7: Electromechanical Drawing - ssucet.orgjgallaher/download/etem130/ETEM130Chapter… · Design Drawings System (functional) diagram Conceptual circuit design Packaging plan Conceptual

Working Schematic Drawing (continued)

Poor Spacing Good Spacing

Good Emphasis

Three examples of how to handlejoggled,crossover and parallel lines.Note the difference in readabilitybetween the upper left diagram andthe other two.

Page 8: Electromechanical Drawing - ssucet.orgjgallaher/download/etem130/ETEM130Chapter… · Design Drawings System (functional) diagram Conceptual circuit design Packaging plan Conceptual

Working Schematic Drawing (continued)Connection

Crossover, no connection

Connection

Connection of four lines

Crossover

No connection

Dot was forgotten

OutdatedMethod

Most PreferredMethod

A

B

C

D

Four methods ofdrawing junctions andcrossovers. Note thatmethod “C” is the mostpreferred.

Page 9: Electromechanical Drawing - ssucet.orgjgallaher/download/etem130/ETEM130Chapter… · Design Drawings System (functional) diagram Conceptual circuit design Packaging plan Conceptual

Working Schematic Drawing (continued)

Component Designations

Notes

Component ReferenceDesignations are required for allcomponents. They aresequentially numbered startingat the upper left andproceeding left to right and topto bottom. Locate eachreference as close to thecomponent as possible andcentered around it.

Notes give specific instructions,clarify issues, or define generalspecifications on the drawing.

Typical component designations: C = capacitor, L = inductor, R = resistor, CR = diode, VR = zener diode, Q = bipolartransistor, U = integrated circuit, SW = switch, F = fuse

Page 10: Electromechanical Drawing - ssucet.orgjgallaher/download/etem130/ETEM130Chapter… · Design Drawings System (functional) diagram Conceptual circuit design Packaging plan Conceptual

Working Schematic Drawing (continued)

Page 11: Electromechanical Drawing - ssucet.orgjgallaher/download/etem130/ETEM130Chapter… · Design Drawings System (functional) diagram Conceptual circuit design Packaging plan Conceptual

Conceptual Design Sketch

Conceptual Design Sketch

Conceptual designs start out as sketches on whatever is handy (paper, napkin, table cloth, hand, etc.). Theycontain as much detail as possible about how the designer thinks it should look, operate, feel, and work. Usuallythese drawings are cluttered with thoughts and are usually sloppy and almost, but not quite, to scale. They willoften be significantly revised as the project progresses. Generally, the sketches that contain a lot of clutterednotes and details are the most successful at being implemented.

Page 12: Electromechanical Drawing - ssucet.orgjgallaher/download/etem130/ETEM130Chapter… · Design Drawings System (functional) diagram Conceptual circuit design Packaging plan Conceptual

PC Board Design Layout Drawing

Printed Wiring Assembly drawingshows all components mounted onthe printed circuit board along withnotes clarifying assembly techniquesand general specifications.

Printed Circuit Board drawing definesall of the parameters andrequirements for the vendor tomanufacture the p.c. board.

Page 13: Electromechanical Drawing - ssucet.orgjgallaher/download/etem130/ETEM130Chapter… · Design Drawings System (functional) diagram Conceptual circuit design Packaging plan Conceptual

PC Board Artwork

The artwork is used to make a photo-tool used inmanufacturing the printed circuit board. (Modern vendors usethe output of a p.c. design program to directly create “Gerber”files that plot directly on film to make the photo-tool.)

Page 14: Electromechanical Drawing - ssucet.orgjgallaher/download/etem130/ETEM130Chapter… · Design Drawings System (functional) diagram Conceptual circuit design Packaging plan Conceptual

Wiring Diagram

The Wiring Diagram defines off-board componentinterconnections along with any connections to the printedwiring assemblies.

Page 15: Electromechanical Drawing - ssucet.orgjgallaher/download/etem130/ETEM130Chapter… · Design Drawings System (functional) diagram Conceptual circuit design Packaging plan Conceptual

Sheet Metal or Packaging Drawing

Page 16: Electromechanical Drawing - ssucet.orgjgallaher/download/etem130/ETEM130Chapter… · Design Drawings System (functional) diagram Conceptual circuit design Packaging plan Conceptual

Final Packaging Drawing

The packaging drawing defines how all of the assemblies and off-board components fit inside the enclosure.