5/5
Application note
APT0501
December 2011
www.microsemi.com
5.
Mounting instruction without using the plastic post.
For important temperature variations, extremely
low and high temperatures or strong shock and
vibration environment, screwing the PCB onto
the plastic posts is not recommended. The plastic
expansion leads to some mechanical stress that
can damage the tracks or the components on the
PCB.
On the other hand, the plastic posts may break
under strong shock and vibration stress.
In order to avoid these phenomenons, the
utilization of metallic spacer 18
±0.2
mm high is
recommended to screw the PCB on top of the
power module. (See fig 8).
Fig 8: PCB screwed onto the metallic spacers.
6.
Connection push-pull forces.
When the PCB is mounted onto the power
module and the terminals soldered to it, some
mechanical forces may be applied to the
terminals. Such push or pull forces must not
exceed 10N (2.25lbf) maximum per individual
connector. This acceptable maximum value of
push-pull force may vary depending on the
mounting and operating conditions.
Conclusion:
This application note gives the main
recommendations regarding the mounting of SP4
modules. Applying these instructions will help
decreasing the mechanical stress both on PCB
and power module and therefore will ensure long
term operation of the system. Mounting
instructions to the heat sink must also be
followed to achieve the lowest thermal resistance
from the power chips down to the cooler. All
these operations are essential to guarantee the
best system reliability.
SP4 POWER MODULE
Heat sink
Spacer
Spacer
PCB
18
±0.2
mm