Printed Circuit Board BasicsBy - Creative Hi-tech Ltd.www.creativehitech.com

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.

History of PCBs

PCBs were first developed during the Second World War.

The revolutionary invention was made by an Austrian Engineer, Paul Eisler.

Since 1929, PCBs have been mass produced for commercial applications.

They were first used in transformers and capacitors.

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.

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.

Parts of a PCBThe 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.

Parts of a PCB

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.

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.

Manufacturing/Assembly StepsFollowing 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.

Manufacturing/Assembly Steps

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:14. Component missing15. Component replacement16. Trace or pad repair17. Cuts and Jumps

PCB Material Options When it come to manufacturing PCBs, there are several material options available. 1. Substrate Material

Epoxy imprinted fiberglass Polyester (PET) Polyimide

2. Conductor Materiel Electro-deposited copper foil Rolled copper foil

3. Adhesives Polyimide Adhesives Polyester Adhesives Acrylic Adhesives Epoxies

4. Protective Coating Polyimide Adhesives Cover Lays - Polyester or polyimide is combined with a suitable adhesive. Cover Coat - A thin coating of liquid acrylated epoxy and acrylated polyurethane.

PCB Material Options

Substrate Material

Conductor Materiel

Adhesives Protective Coating

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.

Applications

Automotive - Electronic control module, transmission controls, LCD displays, comfort control units, air conditioning systems, music systems.

Manufacturing - Test equipment, electrical switches, industrial automation systems, control panels, industrial air conditioners, and CCTV surveillance systems.

Consumer Appliances - Oven, TV remote controllers, washing systems, lighting systems, solar power systems, UV water purifiers.

Contact Us710 Cooper Ct.Schaumburg, IL 60173phone 224.653.4000fax 224.653.4100Email: sales@creativehitech.com