AN3232

Mounting base surface conditions

Doc ID 17594 Rev 3

11/26

5

Mounting base surface conditions

The mounting base, or the surface of the core to which the backside of the package is

mounted, must be flat, clean, and free of tool marks. Recommended specifications for the

surface conditions are shown in Table 2.

Flatness and roughness values can be achieved on the above mentioned materials with

standard machining processes, such as milling. Improved flatness and lower roughness

values reduce both electrical and thermal resistance.

Table 2.

Surface conditions

Flatness

400 µin / in (0.4 µm/mm)

< 30 µin (0.8 µm)