AUTOMATIC LAYOUT DESIGN FOR POWER MODULE
IEEE Student Member
IEEE Senior Member
Oak Ridge National Laboratory
Power Electronics & Electric Machinery
Knoxville, TN 37932 USA
Department of Electrical Engineering
and Computer Science
The University of Tennessee
Knoxville, TN 37996 USA
Center for Power Electronics Systems
Bradley Department of Electrical and
Virginia Polytechnic Institute and State
Blacksburg, VA 24061 USA
—The layout of power modules is one of the most
important elements in power module design, especially for high
power densities, where couplings are increased. In this paper, an
automatic design process using a genetic algorithm is presented.
Some practical considerations are introduced in the optimization
of the layout design of the module.
—Layout, genetic algorithms, parasitic parameters
Parasitic parameters in a module have a detrimental effect on
the switching loss and dynamic behavior . They cause
voltage overshoot, affect blocking voltage requirements of the
power devices, and influence device switching losses. These
phenomena are exaggerated when the density increases. In
addition, power integration decreases distances, resulting in a
bigger impact on the coupling of the current conduction path.
To ensure high efficiency and high performance of a
high-density power module, efforts are required in the layout
There are basically two important layout design
considerations. First, when the switching frequency is high,
large voltage spikes result due to the high di/dt. By reducing the
parasitic parameters, the magnitude of these voltage spikes can
be reduced . Second, the parasitic parameters between
paralleled devices need to be balanced. This helps to achieve
equal current distribution in parallel devices, consequently
affecting the performance of the whole module.
As described in Fig.1, the layout design procedure is usually
based on design iterations. Each cycle can generate a layout
design result, which can then be compared with other design
results. After several iterations the best layout can be chosen
from the design candidates. Usually even the best layout
candidate is not the best selection for the whole design space.
The final selected result still requires a superior layout and will
be beneficial in achieving power loss reduction.
During the design iterations, devices and power terminals,
which are the basic components in layout design, first are
geometrically placed by considering the electrical connections.
The second step is the routing process, in which the dies and the
pads are connected with the copper traces and the wire bonds.
Then the parasitic parameters in the designed layout can be