I347-AT4 Datasheet, PDF (136/148 Pages) Intel Corporation – Intel® Ethernet Network Connection I347-AT4 Datasheet

I347-AT4 — Thermal Design Recommendations
7.4
Thermal Management Importance
The objective of thermal management is to ensure that all system component temperatures are
maintained within their functional limits. The functional temperature limit is the range in which the
electrical circuits are expected to meet specified performance requirements. Operation outside the
functional limit can degrade system performance, cause logic errors, or cause device and/or system
damage. Temperatures exceeding the maximum operating limits can result in irreversible changes in
the device operating characteristics. Also note that sustained operation at a component maximum
temperature limit might affect long-term device reliability. See Section 7.6.2 for more details.
7.5
Terminology and Definitions
The following is a list of the terminology that is used in this section and their definitions:
TFBGA — Thin Profile Fine Pitch Ball Grid Array: A surface-mount package using a BGA structure whose
PCB-interconnect method consists of a Pb-free solder ball array on the interconnect side of the package
and is attached to a near chip-scale size substrate.
2s2p — A 4-layer board with two signal layers on the outside and two internal plane layers.
Thermal Resistance — The resulting change in temperature per watt of heat that passes from one
reference point to another.
Junction — Refers to a P-N (diode) junction on the silicon. In this section, it is used as a temperature
reference point (for example, Θ_JA refers to the junction-to-ambient thermal resistance).
Ambient — Refers to the local ambient temperature of the bulk air approaching the component. It can
be measured by placing a thermocouple approximately 1 inch upstream from the component edge.
Lands — The pads on the PCB to which BGA balls are soldered.
PCB — Printed Circuit Board.
Printed Circuit Assembly (PCA) — A PCB that has components assembled on it.
Thermal Design Power (TDP) — The estimated maximum possible/expected power generated in a
component by a realistic application. TDP is a system design target associated with the maximum
component operating temperature specifications. Maximum power values are determined based on
typical DC electrical specification and maximum ambient temperature for a worst-case realistic
application running at maximum use.
LFM — A measure of airflow velocity in Linear Feet per Minute.
Θ_JA (Theta JA) — Thermal resistance from component junction to ambient, °C/W.
Ψ_JT (Psi JT) — Junction-to-top (of package) thermal characterization parameter, °C/W. Ψ_JT does not
represent thermal resistance, but instead is a characteristic parameter that can be used to convert
between T_j and T_case when knowing the total TDP. Ψ_JT is easy to characterize in simulations or
measurements and is defined as follows:
This parameter can vary with environmental conditions, such as airflow, thermal solution presence, and
design.
126