EV1380QI Datasheet, PDF (14/16 Pages) Enpirion, Inc. – 8a synchronous highly integrated dc-dc

Design Considerations
Exposed Metal on Bottom of Package
Package lead frames offer advantages in
thermal performance, in reduced electrical lead
resistance, and in overall foot print. They do,
however, require some special considerations.
In the assembly process, lead-frame
construction requires-for mechanical support-
that some of the lead-frame cantilevers be
exposed at the point where wire-bonds or
internal passives are attached. Because of this
EV1380 Datasheet Rev A
lead frame requirement, several small pads are
exposed on the bottom of the package. Only
the large thermal pad and the perimeter pads
should be mechanically or electrically
connected to the PC board. The PCB top layer
under the EV1380 should be clear of any metal
except for the large thermal pad. The “grayed-
out” area in Figure 8 represents the area that
should be clear of all metal (traces, vias, or
planes) on the top layer of the PCB.
Figure 8: Lead-Frame Exposed Metal. Gray area highlights exposed metal below which there
should not be any metal (traces, vias, or planes) on the top layer of the PCB
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