OPA354_16 Datasheet, PDF (25/44 Pages) Texas Instruments – 250-MHz, Rail-to-Rail I/O, CMOS Operational Amplifiers

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PowerPAD Assembly Process (continued)
OPA354, OPA2354, OPA4354
SBOS233F – MARCH 2002 – REVISED JUNE 2016
Thermal Land
(Copper)
Minimum Size
4.8mm x 3.8mm
(189 mils x 150 mils)
OPTIONAL:
Additional 4 vias outside
of thermal pad area but
under the package.
REQUIRED:
Thermal pad area 2.286mm x 2.286mm
(90 mils x 90 mils) with 5 vias
(via diameter = 13 mils)
Figure 41. 8-Pin PowerPAD PCB Etch and Via Pattern
TI recommends, but does not require, placing a small number of additional holes under the package and outside
the thermal pad area. These holes provide additional heat paths between the copper thermal land and the
ground plane. They may be larger because they are not in the area to be soldered, so wicking is not a problem.
This technique is illustrated in Figure 41.
Connect all holes, including those within the thermal pad area and outside the pad area, to the internal ground
plane or other internal copper plane for single-supply applications, and to V− for split-supply applications.
When laying out these holes, do not use the typical web or spoke via connection methodology, as shown in
Figure 42. Web connections have a high thermal resistance connection that is useful for slowing the heat transfer
during soldering operations. This feature makes soldering the vias that have ground plane connections easier.
However, in this application, low thermal resistance is desired for the most efficient heat transfer. Therefore, the
holes under the PowerPAD package must make connection to the internal ground plane with a complete
connection around the entire circumference of the plated-through hole.
Solid Via
RECOMMENDED
Web or Spoke Via
NOT RECOMMENDED
(due to poor heat conduction)
Figure 42. Via Connection
The top-side solder mask must leave the pad connections and the thermal pad area exposed. The thermal pad
area must leave the 13-mil holes exposed. The larger holes outside the thermal pad area may be covered with
solder mask.
Apply solder paste to the exposed thermal pad area and all of the package terminals.
With these preparatory steps in place, the PowerPAD IC is simply placed in position and run through the solder
reflow operation as any standard surface-mount component. This preparation and processing results in a part
that is properly installed.
For detailed information on the PowerPAD package including thermal modeling considerations and repair
procedures, please see PowerPAD Thermally Enhanced Package located at www.ti.com.
Copyright © 2002–2016, Texas Instruments Incorporated
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