THS7001, THS7002

70-MHz PROGRAMMABLE-GAIN AMPLIFIERS

SLOS214B – OCTOBER 1998 – REVISED AUGUST 1999

29

POST OFFICE BOX 655303

APPLICATION INFORMATION

general PowerPAD design considerations

Although there are many ways to properly heatsink this device, the following steps illustrate the recommended

approach.

THS7002

Thermal pad area (0.12 x 0.3)

with 10 vias

(Via diameter = 13 mils)

THS7001

Thermal pad area (0.12 x 0.25)

with 8 vias

(Via diameter = 13 mils)

Figure 68. PowerPAD PCB Etch and Via Pattern

1.

Prepare the PCB with a top side etch pattern as shown in Figure 68. There should be etch for the leads as

well as etch for the thermal pad.

2.

Place the thermal transfer holes in the area of the thermal pad. These holes should be 13 mils in diameter.

They are kept 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 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 IC 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

thermal transfer holes exposed. The bottom-side solder mask should cover the thermal transfer 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 THS7001PWP/THS7002PWP 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.