Editing Thermal analysis (section)

==Printed circuit boards==
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Power dissipation is an important issue in present-day PCB{{clarify|What does this abbreviation mean?|date=August 2019}} design. Power dissipation will result in temperature difference and pose a thermal problem to a chip. In addition to the issue of reliability, excess heat will also negatively affect electrical performance and safety. The working temperature of an IC should therefore be kept below the maximum allowable limit of the worst case. In general, the temperatures of junction and ambient are 125&nbsp;°C and 55&nbsp;°C, respectively.
The ever-shrinking chip size causes the heat to concentrate within a small area and leads to high power density. Furthermore, denser transistors gathering in a monolithic chip and higher operating frequency cause a worsening of the power dissipation. Removing the heat effectively becomes the critical issue to be resolved.