its all about printed circuit boards widely used in electronics circuit making

1. Printed Circuit Board
Basics
By Suhail Ahmed
BSAMT02161001
Submitted to:
Engr Hamza waseem
1

2. What are PCBs?
PCBs are the backbone of electrical devices.
They are non-conductive board that holds all electronic
components through a circuit embossed over it.
PCBs are built to last for a wide range of industrial,
commercial, and domestic applications.
They can be customized to any specifications to users’
requirements.
2

3. PCB
• In order to minimize the wiring and space required, the
components that make up an electronic circuit(such as
resistors, capacitors, diodes, transistors and integrated
circuits) are assembled on printed circuit boards (PCBs).
3

4. PCB Design
• PCBs comprise copper tracks bonded to an epoxy glass or
synthetic resin bonded paper (SRBP) board.
• Once designed and tested, printed circuits are easily
duplicated and the production techniques are based on
automated component assembly and soldering.
• A number of considerations must be taken into account
when a PCB is designed, including the current carrying
capacity of the copper track conductors and the maximum
voltage that can be safely applied between adjacent
tracks.
4

5. PCB Types
• Single Sided – Base material (rigid laminate with a woven glass
epoxy base material) clad with copper on one side.
• Double Sided - The assembly encompasses a base material with
copper on its both sides.
• Multi Layered – Encompasses several layers of substrates. Each
layer is separated by an insulation.
5

6. The current rating of a PCB track depends on three factors:
• the width of the track.
• the thickness of the copper coating.
• the maximum permissible temperature rise.
6

7. Properties
• The laminate material used to construct a PCB must have the
following properties
• • very high resistivity;
• • very high flexural strength;
• • ability to operate at relatively high temperatures(e.g. up to
125◦C);
• • High dielectric breakdown strength.
7

8. Board Styles
• The most common board styles are:
• Rigid – Solid construction.
• Flex – Flexible circuits.
• Rigid-flex –Multi-circuit boards.
• Hybrid – Very small circuit. Can be integrated as part of a
larger circuit.
8

9. Parts of a PCB
• The assembly consists the following parts.
• Components – Actual devices in the board.
• PCB components can be categorized as active and passive.
• Active components include:
• • Diode – Allows current to flow in one direction.
• • Transistor – Amplifies and switches electrical power and
electronic signals.
• • Integrated Circuits (ICs) – Responsible for several signal
processing functions.
• Passive components include:
• • Capacitor – Stores and discharge electricity.
• • Resistor – Limits the power of electrical current.
• • Inductor – Responsible for creating magnetic field. 9

10. • Pads – Location where components connect/solder to.
• Traces – Connect pads together.
• Vias – Responsible for making electrical connection between the
layers of PCB.
• Top metal layer – The layer where most of the components are
assembled. Fewer traces in this top metal layer.
• Bottom metal layer – Fewer components in bottom layer and many
traces.
10

11. Package Types
PCB components can be mounted onto the board in two ways.
• Surface Mount – PCB components are mounted directly onto
the board.
• Through-Hole – Components with leads are inserted through
mounting holes, hence the name through hole.
11

12. Manufacturing/Assembly Steps
• Following are the step involved in PCB manufacturing.
PCB Manufacturing Steps
• 1. Following are the steps involved in PCB fabrication.
• 2. Base Material Preparation – Clean the laminate, containing copper foil.
• 3. Cutting the Base Material – Post the cleaning process, cut the laminate
to required specifications.
• 4. Apply Adhesive on the Laminate - Choose between epoxy or acrylic
adhesives to get the job done.
• 5. Generate Circuit Pattern –Desired circuit patterns can be generated by
screen printing or
• photo imaging.
• 6. Etch the Circuit Pattern – Etch the copper laminate containing the circuit
pattern.
• 7. Drilling – Drill holes, pads, and vias by using high speed drilling tools.
• 8. Through-Hole Plating – Deposit the holes with copper and must be
chemically plated.
• 9. Apply Cover lay – Protect the top and bottom side of the board by
applying suitable cover lay.
• 10.Cutting Flex - Cut individual flex from the production panel.
12

13. • 11. Cleaning – Clean flux residues that are left behind during the
• manufacturing process. Use water solution or active cleaning
agents to get
• the job done.
• 12. Testing – This Includes Automated Optical Inspection (AOI),
flying probe
• test, functional test, and burn-in test.
• 13. Rework – Rework may be done on the PCB in case of:
Component missing, Component replacement ,Trace or pad
repair,Cuts and Jumps
13

14. Applications
• Medical - Pacemakers, imaging equipment, drug delivery
systems, wireless controllers.
• Military - Weapons guidance systems, communication systems,
GPS, aircraft missile-launch detectors.
• Aerospace - Radar equipment, GPS, radio communication
systems, control tower systems, sensors.
• Telecommunication - Base stations, handheld units,
communication satellites, wireless communication systems,
signal processing systems.
14

15. THANK YOU
15