AIC1573_06 Datasheet, PDF (1/3 Pages) –

Thermal Design Considerations of Exposed Pad IC
As the miniaturization of electronic devices, the small area and close proximity of ICs
in these modules demands small packages with excellent thermal properties. Thermal
performance is a system level concern, impacted by IC packaging as well as PCB design.
This application note addresses the thermal considerations for the exposed pad package.
The introduction of the exposed pad helps to reduce package size and improve the thermal
characteristics of the device.
The exposed pad on ICs is intended to provide significant power dissipation, and the
PCB designer should add vias from the exposed pad's land area to a copper polygon on the
other side of the PCB. This provides lower thermal impedance from the IC to the ambient
air. An example of increasing thermal performance by proper PCB layout of the exposed
pad will also be provided.
General Descriptionj
Most of the heat generated by an IC is conducted to the PCB and then radiates from the
PCB to the ambient. Heat is transferred to the PCB from the leads and package. An
exposed pad package improves the heat transfer efficiency by creating a low thermal
resistive path to the PCB. This will increase the maximum power dissipation of packages.
When an exposed pad is offered as an option, it is specifically to increase the power
dissipation capabilities of the IC package.
Bonding Wire Die
Exposed Pad
Soldering
Lead Frame
Top Layer Thermal Pad
PCB
Ground Plane
Power Plane
Thermal Vias
Bottom Layer Thermal Pad
Fig.1 Heat transfer