7.1.2 Thermal Considerations

The CSD88599Q5DC power block device has the ability to utilize the PCB copper planes as the primary thermal path. As such, the use of thermal vias included in the footprint is an effective way to pull away heat from the device and into the system board. Concerns regarding solder voids and manufacturability issues can be addressed through the use of three basic tactics to minimize the amount of solder attach that will wick down the via barrel.

• Intentionally space out the vias from one another to avoid a cluster of holes in a given area.
• Use the smallest drill size allowed by the design. The example in Figure 23 uses vias with a 10-mil drill hole and a 16-mil solder pad.
• Tent the opposite side of the via with solder-mask. Ultimately the number and drill size of the thermal vias should align with the end user’s PCB design rules and manufacturing capabilities.

To take advantage of the DualCool thermally enhanced package, an external heatsink can be applied on top of the power block devices. For low EMI, the heatsink is usually connected to GND through the mounting screws to the PCB. Gap pad insulators with good thermal conductivity should be used between the top of the package and the heatsink. The Bergquist Sil-Pad 980 is recommended which provides excellent thermal impedance of 1.07°C/W @ 50 psi.