OPA1632 Datasheet, PDF (16/30 Pages) Texas Instruments – High-Perfomance, Fully-Differential AUDIO OP AMP

OPA1632
SBOS286C – DECEMBER 2003 – REVISED OCTOBER 2015
10 Layout
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10.1 Layout Guidelines
1. The PowerPAD is electrically isolated from the silicon and all leads. Connecting the PowerPAD to any
potential voltage between the power-supply voltages is acceptable, but it is recommended to tie to ground
because it is generally the largest conductive plane.
2. Prepare the PCB with a top-side etch pattern, as shown in Figure 17. There should be etch for the leads as
well as etch for the thermal pad.
3. Place five holes in the area of the thermal pad. These holes should be 13 mils (0,03302 cm) in diameter.
Keep them small so that solder wicking through the holes is not a problem during reflow.
4. Additional vias may be placed anywhere along the thermal plane outside of the thermal pad area. These vias
help dissipate the heat generated by the OPA1632 IC, and may be larger than the 13-mil diameter vias
directly under the thermal pad. They can be larger because they are not in the thermal pad area to be
soldered so that wicking is not a problem.
5. Connect all holes to the internal ground plane.
6. When connecting these holes to the plane, do not use the typical web or spoke via connection methodology.
Web connections have a high thermal resistance connection that is useful for slowing the heat transfer during
soldering operations. This makes the soldering of vias that have plane connections easier. In this application,
however, low thermal resistance is desired for the most efficient heat transfer. Therefore, the holes under the
OPA1632 PowerPAD package should make their connection to the internal plane with a complete connection
around the entire circumference of the plated-through hole.
7. The top-side solder mask should leave the terminals of the package and the thermal pad area with its five
holes exposed. The bottom-side solder mask should cover the five holes of the thermal pad area. This
prevents solder from being pulled away from the thermal pad area during the reflow process.
8. Apply solder paste to the exposed thermal pad area and all of the IC terminals.
With these preparatory steps in place, the IC is simply placed in position and runs through the solder reflow
operation as any standard surface-mount component. This results in a part that is properly installed.
Single or Dual
68mils ´ 70mils (0,1727cm ´ 0,1778cm)
(via diameter = 13mils (0,03302cm)
Figure 17. PowerPAD PCB Etch and Via Pattern
10.1.1 PowerPAD Design Considerations
The OPA1632 is available in a thermally-enhanced PowerPAD family of packages. These packages are
constructed using a downset leadframe upon which the die is mounted (see Figure 18(a) and Figure 18(b)). This
arrangement results in the lead frame being exposed as a thermal pad on the underside of the package (see
Figure 18(c)). Because this thermal pad has direct thermal contact with the die, excellent thermal performance
can be achieved by providing a good thermal path away from the thermal pad.
DIE
(a) Side View
DIE
(b) End View
Thermal
Pad
(c) Bottom View
Figure 18. Views of the Thermally-Enhanced Package
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