MIC45212-1 Datasheet, PDF (26/35 Pages) Micrel Semiconductor – 26V/14A DC-to-DC Power Module

Micrel, Inc.
MIC45212
Simplified PCB Design Recommendations
1. Periphery I/O Pad Layout & Large Pad for Exposed Heatsink
The board design should begin with copper/metal pads that sit beneath the periphery leads of a mounted QFN. The board
pads should extend outside the QFN package edge a distance of approximately 0.20mm per side.
Total pad length = 12.00mm + (0.20mm per side x 2 sides) = 12.40mm.
After completion of the periphery pad design, the larger exposed pads will be designed to create the mounting surface of
the QFN exposed heatsink. The primary transfer of heat out of the QFN will be directly through the bottom surface of the
exposed heatsink. To aid in the transfer of generated heat into the PCB, the use of an array of plated through-hole vias
beneath the mounted part is recommended. The typical via hole diameter is 0.30mm to 0.35mm, with center-to-center
pitch of 0.80mm to 1.20mm.
Note: Exposed metal trace is the “mirror image” of package bottom view.
March 5, 2015
26
Revision 1.1