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Section 4.2

Printed Circuit Boards

Description and use of printed circuit boards — substrate, tracks, pads and vias; single, double and multilayer construction; through-hole and surface-mount components; conformal coating and ESD precautions.

Notes

Printed circuit boards — summary notes

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Main ideas
  • A printed circuit board is an insulating substrate carrying etched copper tracks that replace point-to-point wiring.
  • Features: tracks (conductors), pads (component connection points), and vias (plated holes linking layers).
  • Boards may be single-sided, double-sided or multilayer.
  • Components are fitted either through-hole (THT), with leads passing through the board, or surface-mount (SMD), soldered directly to pads on the surface.
  • Conformal coating protects against moisture, dust and vibration.
  • ESD (electrostatic discharge) precautions are essential when handling boards — wrist straps, grounded mats and antistatic bags.
  • ⚠ Exam trap: this is a Level 1 topic — recognition and purpose are examined, not detailed manufacturing processes.
Solved examples
  1. Why must ESD precautions be observed when handling an avionics circuit board?

    A static discharge far below the level a person can feel can puncture the thin oxide layers inside semiconductor devices, causing immediate failure or latent damage that shows up later in service.

Mind map

PCB concept map

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Printed Circuit Boards

Quiz

Printed circuit boards quiz

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