C&H Technology MTP Modules Mounting Instructions - Manual (Page 2)

Mounting Instructions for MTP Modules
Application Note AN-0801
Vishay High Power Products
www.vishay.com For technical support, contact [email protected] Document Number: 95002
2 Revision 02-Jul-08
APPL
ICATION NOTE
Mounting Operation Steps
Inspect the module to insure that the contact surface of the
base is clean, and that there are no lumps or bulges on the
baseplate that could damage the base or reduce heat transfer
across the surfaces.
Make a uniform coat on the heatsink mounting surfaces and
module baseplate with a good quality thermal compound.
Screen printing of the compound, or direct application with
a roller or spatula, is recommended. The test conditions for
thermal resistance values on the datasheet specify a uniform
layer of thermal compound with a thickness of 0.08 mm.
The thermal conductivity of the compound should not be
less than 1.5 W/mK. Apply uniform pressure on the package
to force the compound to spread over the entire contact area
and check the device bottom surface to verify that coverage
is full and uniform.
Bolt the module to the heatsink using the two fixing holes.
An even amount of torque should be applied for each
individual mounting screw. An M4 screw should be used
with lock washers. A torque wrench, accurate in the
specified range, must be used to achieve optimum results
when mounting the module. The first mounting screw
should be tightened to one third of the recommended torque,
the second screw should then be tightened to the same
torque. Full tightening of both the screws can then be
completed applying the recommended torque (see data in
bulletins). Over-tightening the mounting screw may result in
deformation of the package, which would hence increase the
thermal resistance and damage the semiconductors. After a
period of three hours, check the torque with a final
tightening in opposite sequence to allow the spread of the
compound.
The convexity of the module baseplate ranges from 0.02 to
0.10 mm (0.787 to 3.937 mils) when measured between the
two fixing holes. This provides for an optimal contact area
with the heatsink (Figure 2).
Fig. 2 - Description of “module convexity”
Solder to PCB
The PCB must be designed with appropriate tolerances on
its hole diameters.
Soldering operations must be done so as to avoid inducing
any mechanical stress from pulling or tensioning the module
pins. The module stand-off can be used to help align the
PCB and keep proper distance.
MTP modules can be soldered to the PCB using hand iron or
wave soldering processes. To prevent overheating of the
device, we suggest that soldering time not exceed 8 to 10
seconds at a temperature of 260 °C.
The mounting of the module on the heatsink can be done
either before or after soldering the module pins onto the
PCB.