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SBAS308A− MAY 2004 − REVISED MARCH 2005
Assembly Process
5. Do not use the typical web or spoke via connection
pattern when connecting the thermal vias to the
ground plane. The spoke pattern increases the
thermal resistance to the ground plane.
1. Prepare the PCB top-side etch pattern including
etch for the leads as well as the thermal pad as
illustrated in the Mechanical Data section.
6. The top−side solder mask should leave exposed
the terminals of the package and the thermal pad
area.
2. Place a 5-by-5 array of thermal vias in the thermal
pad area. These holes should be 13 mils in
diameter. The small size prevents wicking of the
solder through the holes.
7. Cover the entire bottom side of the PowerPAD vias
to prevent solder wicking.
3. It is recommended to place a small number of 25 mil
diameter holes under the package, but outside the
thermal pad area to provide an additional heat path.
8. Apply solder paste to the exposed thermal pad area
and all of the package terminals.
4. Connect all holes (both those inside and outside the
thermal pad area) to an internal copper plane (such
as a ground plane).
For more detailed information regarding the PowerPAD
package and its thermal properties, please refer to
either Application Brief SLMA004B (PowerPAD Made
Easy), or Technical Brief SLMA002 (PowerPAD
Thermally Enhanced Package), both available for
download at www.ti.com.
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BB [ BURR-BROWN CORPORATION ]
