STEVAL-TDR009V1

SD2932 mounting recommendations

Doc ID 17347 Rev 1

9/13

6

SD2932 mounting recommendations

6.1

Mounting recommendations

●

Ensure holes in heatsinks are free from burrs;

●

Minimum depth of tapped holes in heatsinks is 6 mm;

●

Use 4-40 UNC-2A cheese-head screws with a flat washer to spread the joint pressure;

●

The minimum flatness of the mounting area is 0.02 mm;

●

Mounting area roughness should be less than 0.5 µm (micro);

●

Avoid, as much as possible, use of flux or flux solutions because flux can penetrate

even when hermetically sealed ceramic-capped transistors. Tin and wash the printed-

circuit board BEFORE mounting the power transistors, then solder the transistor leads

without using flux;

●

Transistor leads may be tinned by dipping them full-length into a solder bath at a

temperature of about 230 °C. No flux should be used during tinning;

●

Recommended heatsink compounds: WPSII (silicon free) from Austerlitz Electronics,

340 from dow corning etc.

6.2

Mounting sequence

●

Apply a thin layer of evenly distributed heatsink compound to the flange;

●

Position the device with flat washers in place;

●

Tighten the screws until finger tight (0.05 Nm);

●

Further tighten the screws until the specified torque is reached;

●

For M174, M177 and M244 type of packages, torque should be minimum 0.6 Nm and

0.75 Nm max.

Table 4.

DMOS packages - list of materials

Package

Type

Description

Flange

Leadframe

Ceramic

insulator

Plating

Torque (Nm)

Leads

Flange

Min

Max

M174

0.500 dia 4l non

herm w/flange

Cu

Alloy 42

(Fe58 /

Ni42)

BeO

(99.5%

min)

Au (100 µ min)

over Ni (100 µ

min / 350 µ max)

Ni(100 µ min) +

Pd (10 µ min)

0.6

0.75

M174

(Moly

disk)

0.500 dia 4l non

herm w/flange

(moly disk)

Cu-Mo-

Cu

Alloy 42

(Fe58 /

Ni42)

BeO

(99.5%

min)

Au (100 µ min)

over Ni (100 µ

min / 350 µ max)

Ni(100 µ min) +

Pd (10 µ min)

0.6

0.75

M177

0.550 dia 4l non

herm w/flange

Cu-Mo-

Cu

Alloy 42

(Fe58 /

Ni42)

BeO

(99.5%

min)

Au (60 µ min)

over Ni (100 µ

min / 350 µ max)

Au (100 µ min)

over Ni (100 µ

min / 350µ max)

0.6

0.75

M244

2 x 0.400x0.425

wide 2l lap n/h

flange

W (85%)

- Cu

(15%)

Alloy 42

(Fe58 /

Ni42)

BeO(99.5

% min)

Au (60 µ min)

over Ni (100 µ

min / 350µ max)

Au (60 µ min)

over Ni (100 µ

min / 350µ max)

0.6

0.75