Datasheet

GENERAL POWERPAD DESIGN
OPA211
OPA2211
SBOS377G – OCTOBER 2006 – REVISED MAY 2009 ...................................................................................................................................................... www.ti.com
example thermal land pattern mechanical drawing
CONSIDERATIONS is attached to the end of this data sheet.
3. Additional vias may be placed anywhere along
The OPA2211 is available in a thermally-enhanced
the thermal plane outside of the thermal pad area
SO-8 PowerPAD package. This package is
to help dissipate the heat generated by the
constructed using a downset leadframe upon which
OPA2211 SO-8. These additional vias may be
the die is mounted, as Figure 50 (a) and Figure 50 (b)
larger than the 13-mil diameter vias directly under
illustrate. This arrangement results in the lead frame
the thermal pad. They can be larger because
being exposed as a thermal pad on the underside of
they are not in the thermal pad area to be
the package, as shown in Figure 50 (c). This thermal
soldered; thus, wicking is not a problem.
pad has direct thermal contact with the die; thus,
excellent thermal performance is achieved by 4. Connect all holes to the internal plane that is at
providing a good thermal path away from the thermal the same voltage potential as the V – pin.
pad.
5. When connecting these holes to the internal
plane, do not use the typical web or spoke via
The PowerPAD package allows for both assembly
connection methodology. Web connections have
and thermal management in one manufacturing
a high thermal resistance connection that is
operation. During the surface-mount solder operation
useful for slowing the heat transfer during
(when the leads are being soldered), the thermal pad
soldering operations. This configuration makes
must be soldered to a copper area underneath the
the soldering of vias that have plane connections
package. Through the use of thermal paths within this
easier. In this application, however, low thermal
copper area, heat can be conducted away from the
resistance is desired for the most efficient heat
package into either a ground plane or other
transfer. Therefore, the holes under the OPA2211
heat-dissipating device. Soldering the PowerPAD to
PowerPAD package should make their
the printed circuit board (PCB) is always required,
connection to the internal plane with a complete
even with applications that have low power
connection around the entire circumference of the
dissipation. This technique provides the necessary
plated-through hole.
thermal and mechanical connection between the lead
frame die pad and the PCB. 6. The top-side solder mask should leave the
terminals of the package and the thermal pad
The PowerPAD must be connected to the most
area with its six holes exposed. The bottom-side
negative supply voltage on the device (V – ).
solder mask should cover the holes of the
1. Prepare the PCB with a top-side etch pattern.
thermal pad area. This masking prevents solder
There should be etching for the leads as well as
from being pulled away from the thermal pad
etch for the thermal pad.
area during the reflow process.
2. Place recommended holes in the area of the
7. Apply solder paste to the exposed thermal pad
thermal pad. Ideal thermal land size and thermal
area and all of the IC terminals.
via patterns for the SO-8 DDA package can be
8. With these preparatory steps in place, simply
seen in the technical brief, PowerPAD
place the OPA2211 SO-8 IC in position and run
Thermally-Enhanced Package (SLMA002 ),
the chip through the solder reflow operation as
available for download at www.ti.com. These
any standard surface-mount component. This
holes should be 13 mils (0,33mm) in diameter.
preparation results in a properly installed part.
Keep them small, so that solder wicking through
the holes is not a problem during reflow. An
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