Metal Core Printed Circuit Board (MCPCB) Design rules (1)
The designs of electronic devices and systems are being continuously improved by becoming smaller in size and faster in communication speed. The potential risk associated with these specif ic design improvements will be an increase in power density and, consequently, a greater risk of thermal problems and failures. At the same time, the prevailing use of circuit boards integrated with power devices such as motor controllers and drivers, light emitting diode (LED) lighting modules, power supplies and amplifiers, and regulators for TV, etc., drive to the use of a proper thermal management system while designing these kinds of printed circuit board (PCB).
Importance of thermal management
Thermal management of an electronic system encompasses all of the thermal processes and technologies that must be employed to remove and transfer heat from individual components to the systems thermal sink in a controlled manner. The objective of thermal management is to ensure that the temperature of all components is maintained within functional and absolute maximum limits. The functional temperature limit is the range within which the electrical circuits can be expected to meet their specified performance or cause logic errors. The absolute maximum temperature limit is the temperature that a portion of the component may be safely exposed to. Temperatures exceeding the limits can cause physical destruction or may result in earlier failure of electronic components in the system.
The failure rate F of an electronic component is directly proportional to heat and can be described by the Arrhenius equation:
where A = constant
F = failure rate
EA= activation energy in electron volts (eV)
K = Boltzmann's constant (8.63 x 10-5eV/K)
T = junction temperature in Kelvin
If a device with activation energy EA = 0.65eV were operating at50℃and its temperature raised to60℃, the failure rate would increase by a factor of 2.
Hence, efficient thermal management is crucial to:
● increase the shelf-life of systems
● reduce failure rates
● increase thermal durability
● enable the design of high circuit density
● enable the use of higher power density
Thermal conductivity is a material property that describes the ability of a material to conduct heat after the heat has entered the material. As shown in Table 1, conventional PCB materials such as FR4 and PI share the lowest thermal conductivity and are not capable of meeting the continuously increasing demand of the thermal requirement of the high power dissipation PCB. One of the current approaches to address this thermal dissipation problem is the use of a Metal Core PCB (MCPCB).
