Application Note
24
<Revision 2.4>
<<2019-06-17>>
Assembly Instructions for the Easy-PressFIT Modules
12
Multi-module and automotive application
An increasing number of applications require the mounting of several power modules on the PCB. Furthermore,
new power module applications, like automotive hybrid electrical vehicles and full electric vehicles (H)EV, have
high requirements on vibration and mechanical shock robustness. In such applications the height tolerance of
the modules has to be considered in the mounting concept in order to avoid a mechanical deformation of the
PCB or unwanted forces on the modules and PressFIT pins.
Please note that the following instructions shall be regarded as additional information to the general mounting
instructions. The chapter focuses on mounting concepts of the module, taking into account the height
tolerance. General recommendations like PCB requirements, press speed, heat sink requirements, etc. are
unaffected by the following instructions.
12.1
Modules’ press-in process on the PCB
Figure 22 shows the press-in process of the power modules on the PCB. This process is quite similar to that of
Chapter 3.
Figure 22a shows the bottom side of the press-tool with guiding domes, which are useful for pre-alignment. In
Figure 22b, the PCB is placed into the press-tool, whereby the correct placement is obtained by the guiding
domes of the press-tool.
Figure 22c shows the press-tool with the PCB ready for module assembly.
In Figure 22d the module is placed on the guiding elements. The module is released and the module pins are
inserted into the PCB.
Figure 22e shows the state where the module pins are inserted into the PCB. The module is now placed flush
with the press-tool, and the pin touches the PCB at the beginning of the active press zone, which starts at about
2.5 mm from the pin top. If the module is not flush with the press-tool or pins are not inserted (module about
2.5 mm higher than the normal case shown here), then mounting should be corrected before the pins are
damaged in the later press-in process.
In Figure 22f, the top press-tool with the distance keeper is shown.
Figure 22g shows the controlled path-force press-in process. The press process stops by the increasing force
between the PCB and this distance keeper. It is correct if the press-in process is stopped before the PCB is on
the module housing. Thus, the distance of the module backside to the PCB is independent of the module
height.
Please note: It is possible to press the module tighter to the PCB than the maximum 12.45 mm. This will
increase the overlapping zone in the active press zone (contact area: pin to PCB). Please do not forget to lower
the fixing elements of the cooling system (Figure 23b) accordingly if the modules are pressed tighter to the PCB!
The value (H) of Figure 23b must not be higher than the module-to-PCB height of Figure 23a! A force of the PCB
on the module in the direction to the cooling system is uncritical and is desired, as it improves the thermal
contact.
