THS4051 Datasheet, PDF (21/36 Pages) Texas Instruments – 70-MHz HIGH-SPEED AMPLIFIERS

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THS4051
THS4052
SLOS238D − MAY 1999 − REVISED AUGUST 2008
APPLICATION INFORMATION
GENERAL POWERPAD DESIGN CONSIDERATIONS (CONTINUED)
DIE
Side View (a)
Thermal
Pad
DIE
End View (b)
NOTE A: The thermal pad is electrically isolated from all terminals in the package.
Bottom View (c)
Figure 51. Views of Thermally Enhanced DGN Package
Although there are many ways to properly heatsink this device, the following steps illustrate the recommended approach.
Thermal pad area (68 mils x 70 mils) with 5 vias
(Via diameter = 13 mils)
Figure 52. PowerPAD PCB Etch and Via Pattern
1. Prepare the PCB with a top side etch pattern as shown in Figure 52. There should be etch for the leads as well
as etch for the thermal pad.
2. Place five holes in the area of the thermal pad. These holes should be 13 mils in diameter. Keep them small so
that solder wicking through the holes is not a problem during reflow.
3. Additional vias may be placed anywhere along the thermal plane outside of the thermal pad area. This helps
dissipate the heat generated by the THS405xDGN IC. These additional vias 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.
4. Connect all holes to the internal ground plane.
5. When connecting these holes to the ground 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 THS405xDGN package should make their connection to the internal ground plane with a complete
connection around the entire circumference of the plated-through hole.
6. 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.
7. Apply solder paste to the exposed thermal pad area and all of the IC terminals.
8. With these preparatory steps in place, the THS405xDGN IC is simply placed in position and run through the
solder reflow operation as any standard surface-mount component. This results in a part that is properly installed.
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