C&H Technology MTP Series Mounting Instructions - Manual

10/04/2002
A PPLICATION N OTE
I NDUSTRIAL B USINESS U NIT
Confidential 1
MTP Series Mounting Instructions
Proper mounting and exchanger surface preparation are generally very important to optimize the heat transfer from
module to heatsink. The following procedure is recommended.
Heatsink Preparation
The contact surface of the heatsink must be flat, with a recommended tolerance of < 0.03mm (1.18 mil) and a
leveling depth of < 0.02mm (0.79 mil), according to DIN/ISO 1302. In general, a milled or machined surface is
satisfactory if prepared with tools in good working condition. The heatsink mounting surface must be clean, with no
dirt, corrosion, or surface oxides. It is very important to keep the mounting surface free from particles exceeding in
thickness 0.05mm (2 mils), provided thermal compound is used
Visual Inspection
Inspect the power module to insure that the contact surface of the base is clean, that there are no lumps or bulges
on the base plate that could damage the base or reduce heat transfer across the surfaces.
Thermal Compound
Coat uniformly the heatsink mounting surfaces and power module base plate with a good quality thermal
compound. Screen printing of the compound is recommended. Data sheet’s thermal resistance refers to a 0.1mm
thick, uniform layer of thermal compound. 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.
Module Fastening
Bolt the module to the heatsink using the two fixing holes. An even amount of torque should be applied for each
individual mounting screw. M4 screws should be used with lock washers. A torque wrench, accurate in the
specified range, must be used in mounting module, in order to achieve optimum results. 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 of the screws can then be completed applying the recommended torque
(please see in the Data Sheet). Over tightening the mounting screws may lead to deformation of the package, which
would hence increase the thermal resistance and damage the semiconductors. After a period of about 3 hours,
check the torque with a final tightening in opposite sequence to allow the spread of the compound.