21ECC101J
Electronic system and PCB
design
Unit 5
, Unit 5
` Topic Reference Page no
1. Environmental Factors on PCB design 136-137
Raghbir Singh Khandpur, Printed Circuit Boards: Design, Fabrication, and Assembly,
McGraw Hill Education; 1st edition
2. Cooling and Packaging of PCB Raghbir Singh Khandpur, Printed Circuit Boards: Design, Fabrication, and Assembly, 139-140
McGraw Hill Education; 1st edition
3. Layout Design of PCB and checklist Raghbir Singh Khandpur, Printed Circuit Boards: Design, Fabrication, and Assembly, 142-151
McGraw Hill Education; 1st edition
4. Design rules for Analog PCB Raghbir Singh Khandpur, Printed Circuit Boards: Design, Fabrication, and Assembly, 155-162
McGraw Hill Education; 1st edition
5. Design rules for Digital PCB Raghbir Singh Khandpur, Printed Circuit Boards: Design, Fabrication, and Assembly, 162-164
McGraw Hill Education; 1st edition
6. Problems in Digital PCB (reflections, cross-talk, signal Raghbir Singh Khandpur, Printed Circuit Boards: Design, Fabrication, and Assembly, 164-168
noise and interference) McGraw Hill Education; 1st edition
7. PCB Design for high frequency circuits Raghbir Singh Khandpur, Printed Circuit Boards: Design, Fabrication, and Assembly, 169-170
McGraw Hill Education; 1st edition
8. PCB Design for fast pulse circuits Raghbir Singh Khandpur, Printed Circuit Boards: Design, Fabrication, and Assembly, 171-172
McGraw Hill Education; 1st edition
9. PCB Design for microwave circuits Raghbir Singh Khandpur, Printed Circuit Boards: Design, Fabrication, and Assembly, 174-181
McGraw Hill Education; 1st edition
21ECC101J
, 1.Environmental Factors on PCB design
The reliability of an equipment, to a large extent, would depend upon the reliability of the basic print
board. It is therefore, expected that the PCB should withstand exposure to the environmental requiremen
either physical damage or change in operating characteristics. The important environmental factors in the d
printed circuit boards are detailed below
Thermal Considerations
The PCB designer should keep in view the following points to ensure proper cooling of the electronicpac
Use of high temperature components, where possible;
Thermal isolation of temperature-sensitive components from high heat-emitting sources;and Ensuring pro
conductive cooling;
the heat removal can be achieved by all the three modes of heat transfer, i.e. conduction, convection and
21ECC101J
, Contd…..
• Contamination
Printed circuit boards must be protected against dust, dirt, contamination, humidity, salt spray and mechanical abuse. The
many insulating compounds that can be applied as protective coatings.
The commonly used compounds are polyurethanes, silicones, acrylics, polystyrenes and varnishes.
The following are the broad technical considerations involved in the selection of protective coating:
i) Ability to prevent corrosion and provide protection to the board;
ii) Flexibility — resistance to cracking during shock;
iii) Easy application and processing;
iv) Transparency — to enable viewing of the board’s component marking; and
v) Easily removable for repairing the printed wiring assembly — minimum effect due to its
thickness on important electrical properties such as dissipation factor, dielectric constant
21ECC101J
Electronic system and PCB
design
Unit 5
, Unit 5
` Topic Reference Page no
1. Environmental Factors on PCB design 136-137
Raghbir Singh Khandpur, Printed Circuit Boards: Design, Fabrication, and Assembly,
McGraw Hill Education; 1st edition
2. Cooling and Packaging of PCB Raghbir Singh Khandpur, Printed Circuit Boards: Design, Fabrication, and Assembly, 139-140
McGraw Hill Education; 1st edition
3. Layout Design of PCB and checklist Raghbir Singh Khandpur, Printed Circuit Boards: Design, Fabrication, and Assembly, 142-151
McGraw Hill Education; 1st edition
4. Design rules for Analog PCB Raghbir Singh Khandpur, Printed Circuit Boards: Design, Fabrication, and Assembly, 155-162
McGraw Hill Education; 1st edition
5. Design rules for Digital PCB Raghbir Singh Khandpur, Printed Circuit Boards: Design, Fabrication, and Assembly, 162-164
McGraw Hill Education; 1st edition
6. Problems in Digital PCB (reflections, cross-talk, signal Raghbir Singh Khandpur, Printed Circuit Boards: Design, Fabrication, and Assembly, 164-168
noise and interference) McGraw Hill Education; 1st edition
7. PCB Design for high frequency circuits Raghbir Singh Khandpur, Printed Circuit Boards: Design, Fabrication, and Assembly, 169-170
McGraw Hill Education; 1st edition
8. PCB Design for fast pulse circuits Raghbir Singh Khandpur, Printed Circuit Boards: Design, Fabrication, and Assembly, 171-172
McGraw Hill Education; 1st edition
9. PCB Design for microwave circuits Raghbir Singh Khandpur, Printed Circuit Boards: Design, Fabrication, and Assembly, 174-181
McGraw Hill Education; 1st edition
21ECC101J
, 1.Environmental Factors on PCB design
The reliability of an equipment, to a large extent, would depend upon the reliability of the basic print
board. It is therefore, expected that the PCB should withstand exposure to the environmental requiremen
either physical damage or change in operating characteristics. The important environmental factors in the d
printed circuit boards are detailed below
Thermal Considerations
The PCB designer should keep in view the following points to ensure proper cooling of the electronicpac
Use of high temperature components, where possible;
Thermal isolation of temperature-sensitive components from high heat-emitting sources;and Ensuring pro
conductive cooling;
the heat removal can be achieved by all the three modes of heat transfer, i.e. conduction, convection and
21ECC101J
, Contd…..
• Contamination
Printed circuit boards must be protected against dust, dirt, contamination, humidity, salt spray and mechanical abuse. The
many insulating compounds that can be applied as protective coatings.
The commonly used compounds are polyurethanes, silicones, acrylics, polystyrenes and varnishes.
The following are the broad technical considerations involved in the selection of protective coating:
i) Ability to prevent corrosion and provide protection to the board;
ii) Flexibility — resistance to cracking during shock;
iii) Easy application and processing;
iv) Transparency — to enable viewing of the board’s component marking; and
v) Easily removable for repairing the printed wiring assembly — minimum effect due to its
thickness on important electrical properties such as dissipation factor, dielectric constant
21ECC101J
