# Package Thermal Data

The management of thermal energy due to a microelectronic device’s power dissipation is important to receive the best possible performance out of any electronic product.  The temperature at which a microelectronic device operates determines among other things the speed and reliability of the product. IDT actively enhances its products and packages to generate the fastest and most reliable devices possible. However, since product performance is often affected by its implementation, careful consideration of the factors affecting the device’s operating temperature is recommended to achieve the best possible results.

The most important factors affecting device operating temperature are power dissipation, air temperature, package construction, and cooling mechanisms.  The combination of these factors determine at what temperature the product will operate.  The current method for determining the operating temperature is to use the following equations:
QJA = (TJ - TA)/P
QJC = (TJ - TC)/P
QCA = (TC - TA)/P
QJA = QJC + QCA
TJ = TA + P [QJA ]
TC = TA + P [QCA ]
QJA =  Package thermal resistance from the die to the ambient air (degree Celsius per watt)
QJC =  Package thermal resistance from the die to the package case (degree Celsius per watt)
QCA = Package thermal resistance from the package case to the ambient air (degree Celsius per watt)
TJ =     Average die temperature (degree Celsius)
TC =    Package case temperature (degree Celsius)
TA =    Ambient air temperature (degree Celsius)
P =      Power (watts)

These equations are the current models which determine package temperatures.  More precise and complex models are sometimes used in the industry, but these require more information regarding the mounting conditions and cooling mechanisms of the part.  Due to the difficulty in compiling this information, these simple models are generally used to give a comparison of thermal performance of a part in varying packages and an estimate of the operating temperature.

View Thermal Data - (Excel file; Jan. 2012)