Freescale Semiconductor MPC830x PowerQUICC II Pro Processor Evaluation Kit MPC8309-KIT MPC8309-KIT Fiche De Données
Codes de produits
MPC8309-KIT
MPC8309 PowerQUICC II Pro Integrated Communications Processor Family Hardware Specifications, Rev. 2
72
Freescale Semiconductor
Thermal
T
T
= thermocouple temperature on top of package (
°C)
Ψ
JT
= thermal characterization parameter (
°C/W)
P
D
= power dissipation in package (W)
The thermal characterization parameter is measured per JESD51-2 specification using a 40 gauge type T
thermocouple epoxied to the top center of the package case. The thermocouple should be positioned so
that the thermocouple junction rests on the package. A small amount of epoxy is placed over the
thermocouple junction and over about 1 mm of wire extending from the junction. The thermocouple wire
is placed flat against the package case to avoid measurement errors caused by cooling effects of the
thermocouple wire.
thermocouple epoxied to the top center of the package case. The thermocouple should be positioned so
that the thermocouple junction rests on the package. A small amount of epoxy is placed over the
thermocouple junction and over about 1 mm of wire extending from the junction. The thermocouple wire
is placed flat against the package case to avoid measurement errors caused by cooling effects of the
thermocouple wire.
24.1.5
Heat sinks and junction-to-case thermal resistance
In some application environments, a heat sink is required to provide the necessary thermal management of
the device. When a heat sink is used, the thermal resistance is expressed as the sum of a junction-to-case
thermal resistance and a case to ambient thermal resistance as shown in the following equation:
the device. When a heat sink is used, the thermal resistance is expressed as the sum of a junction-to-case
thermal resistance and a case to ambient thermal resistance as shown in the following equation:
R
θ
JA
= R
θ
JC
+ R
θ
CA
Eqn. 4
where:
R
θ
JA
= junction-to-ambient thermal resistance (
°C/W)
R
θ
JC
= junction-to-case thermal resistance (
°C/W)
R
θ
CA
= case-to-ambient thermal resistance (
°C/W)
R
θ
JC
is device related and cannot be influenced by the user. The user controls the thermal environment to
change the case-to-ambient thermal resistance, R
θ
CA
. For instance, the user can change the size of the heat
sink, the air flow around the device, the interface material, the mounting arrangement on printed-circuit
board, or change the thermal dissipation on the printed-circuit board surrounding the device.
board, or change the thermal dissipation on the printed-circuit board surrounding the device.
To illustrate the thermal performance of the devices with heat sinks, the thermal performance has been
simulated with a few commercially available heat sinks. The heat sink choice is determined by the
application environment (temperature, air flow, adjacent component power dissipation) and the physical
space available. Because there is not a standard application environment, a standard heat sink is not
required.
simulated with a few commercially available heat sinks. The heat sink choice is determined by the
application environment (temperature, air flow, adjacent component power dissipation) and the physical
space available. Because there is not a standard application environment, a standard heat sink is not
required.
Accurate thermal design requires thermal modeling of the application environment using computational
fluid dynamics software which can model both the conduction cooling and the convection cooling of the
air moving through the application. Simplified thermal models of the packages can be assembled using the
junction-to-case and junction-to-board thermal resistances listed in the thermal resistance table. More
detailed thermal models can be made available on request.
fluid dynamics software which can model both the conduction cooling and the convection cooling of the
air moving through the application. Simplified thermal models of the packages can be assembled using the
junction-to-case and junction-to-board thermal resistances listed in the thermal resistance table. More
detailed thermal models can be made available on request.
24.2
Heat sink attachment
When attaching heat sinks to these devices, an interface material is required. The best method is to use
thermal grease and a spring clip. The spring clip should connect to the printed-circuit board, either to the
board itself, to hooks soldered to the board, or to a plastic stiffener. Avoid attachment forces which would
lift the edge of the package or peel the package from the board. Such peeling forces reduce the solder joint
thermal grease and a spring clip. The spring clip should connect to the printed-circuit board, either to the
board itself, to hooks soldered to the board, or to a plastic stiffener. Avoid attachment forces which would
lift the edge of the package or peel the package from the board. Such peeling forces reduce the solder joint