SOLDERING RECOMMENDATION

The

soldering process causes

considerable

thermal stress to a semiconductor component.

This has to be minimized to assure a reliable and

extended lifetime of the device. The PowerSO-10

package can

be

exposed to

a

maximum

temperature of 260

°C for 10 seconds. However a

proper soldering of the package could be done at

215

°C for 3 seconds. Any solder temperature

profile should be within these limits. As reflow

techniques are most common in surface mounting,

typical heating profiles are given in Figure 1,either

for mounting on FR4 or on metal-backed boards.

For each particular board, the appropriate heat

profile has to be adjusted experimentally. The

present proposal is just a starting point. In any

case, the following precautions have to be

considered :

- always preheat the device

- peak temperature should be at least 30

°C

higher than the melting point of the solder

alloy chosen

- thermal capacity of the base substrate

Voids pose a difficult reliability problem for large

surface mount devices. Such voids under the

package result in poor thermal contact and the

high thermal resistance leads to component

failures. The PowerSO-10 is designed from

scratch to be solely a surface mount package,

hence symmetry in the x- and y-axis gives the

package excellent weight balance. Moreover, the

PowerSO-10 offers the unique possibility to control

easily the flatness and quality of the soldering

process. Both the top and the bottom soldered

edges of the package are accessible for visual

inspection (soldering meniscus).

Coplanarity between the substrate and

the

package can be easily verified. The quality of the

solder joints is very important for two reasons : (I)

poor quality solder joints result directly in poor

reliability

and (II) solder thickness affects the

thermal resistance significantly. Thus a tight

control of this parameter results in thermally

efficient and reliable solder joints.

Fig. 1 : Typical reflow soldering heat profile

Time (s)

Temperature ( C)

0

40

80

120

160

200

240

280

320

360

0

50

100

150

200

250

o

215 C

o

Soldering

Preheating

Cooling

245 C

o

Epoxy FR4

board

Metal-backed

board

®

RBO08-40G / RBO08-40M / RBO08-40T

9/14