Infineon PressFIT User manual

Application Note Please read the Important Notice and Warnings at the end of this document <Revision 2.4>
www.infineon.com <2019-06-17>
AN2009-01
Assembly Instructions for the Easy-PressFIT
Modules
About this document
Scope and purpose
This application note provides a guideline on how to use and implement Easy modules using PressFIT
connectors. The values and recommendations provided in this document should not be considered as
datasheet values.
Intended audience
This document is intended for all experts using Infineon Easy modules.
Table of contents
1General information....................................................................................................... 2
1.1 General information on power module handling ..................................................................................3
2Requirements for printed circuit boards........................................................................... 4
3The press-in process....................................................................................................... 6
3.1 Press-in tools...........................................................................................................................................6
3.1.1 Press-in tools for Easy modules with thermal interface material....................................................7
3.2 Press-in forces and speed .......................................................................................................................9
4The press-out process ...................................................................................................10
4.1 Press-out tools.......................................................................................................................................10
4.2 Press-out forces.....................................................................................................................................11
5Quality of PressFIT contacts...........................................................................................12
6Mounting a PCB to the module .......................................................................................14
7Condition of the heat sink for module assembly...............................................................15
8Applying the thermal grease ..........................................................................................16
9Assembling the module on heat sink ...............................................................................17
9.1 Assembling Easy1B/2B module on heat sink .......................................................................................17
9.2 Assembling Easy3B module on heat sink.............................................................................................19
10 System considerations ..................................................................................................21
10.1 Module is already pressed into the PCB before mounting ..................................................................21
10.2 Module is pressed into the PCB after mounting...................................................................................21
11 Clearance and creepage distances ..................................................................................22
12 Multi-module and automotive application.......................................................................24
12.1 Modules’ press-in process on the PCB..................................................................................................24
12.2 Modules and PCB mounting on the heat sink......................................................................................26
12.3 Press-in and mouting only Easy3B modules with PCB and heat sink.................................................28

Application Note 2 <Revision 2.4>
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Assembly Instructions for the Easy-PressFIT Modules
1General information
PressFIT is an alternative method for connecting control and load current contacts on IGBT modules to a PCB
(printed circuit board) that complies with the requirements for greater durability, the trend towards higher
temperatures, RoHS and, of course, very simple handling.
This contact technology has already been employed for years in the automotive sector under the most difficult
of conditions, and with medium-sized currents. The contacts have also been used in the telecommunications
sector for some time now for signal transmissions. This type of contact is therefore ideal for use in IGBT
modules for which the contacts have to meet the requirements for load, control and sense connections.
The PressFIT contact technology for power modules was initially developed in the EconoPIM™ and
EconoPACK™ series.
The Easy PressFIT pin provides a solution for modules without a baseplate. It should be noted in the case of the
Easy PressFIT geometry that it has been used for decades in a wide variety of applications, and has been
adapted for use in the various modules.
The Easy PressFIT contact allows solderfree assembly of the EasyPIM™, EasyPACK and Easy Automotive
modules in the EasyB series. In this assembly technology, the module can be mounted on either side of the
circuit board.
The electrical and thermal contacts with the circuit board are implemented by means of cold welding. The
contacts can be used in standard FR4 PCB with the typical tolerances of manufacturers.
Figure 1 Modules in the EasyB series featuring PressFIT contacts
Easy PressFIT contacts have an area of approximately 1.7 mm that adapts itself to the hole in the PCB during
the press-in process. The plastic is deformed as a result. This deformation is intended to accommodate the
tolerance, and provides the basis for the cold welding.
The forces resulting during the PressFIT process ensure that the welded materials on the PCB and pin exhibit a
continuously consistent –and, unlike other contact technologies –very small electrical contact resistance
(approximately 0.05 mΩ). Figure 2 shows various sections and REM images that provide a view of the gas-tight
bonded materials resulting from the press-in force.
Figure 2 Easy PressFIT contact sections

Application Note 3 <Revision 2.4>
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Assembly Instructions for the Easy-PressFIT Modules
1.1 General information on power module handling
This section describes forces on module housing –DCB push-out
The power module is not designed to withstand forces on the module housing as shown in the example of
Figure 3. The module pins are located here on a flat table. Forces on the module housing (Fp) are pushing the
DCB out of the housing. Therefore, forces (Fp) on the module housing have to be avoided during handling.
Please note that this is a different case compared to the normal press-in process, where the DCB is fully
supported in the press-tool, and the press-in forces affect the DCB, and not the housing.
Figure 3 Forces on the housing during module handling should be avoided to prevent a push-out of the
DCB
Some modules will have quite low DCB push-out forces (Fp), the minimum value of which is not a confirmed
property of the power module. This is not critical for real applications, because the housing is fixed later on the
cooling system by the integrated clamps. Thus, the housing cannot move in a critical way. Furthermore, the
“sealing rope” between the module frame and the DCB only serves to seal the module when the isolating gel is
filled during our production process. After the filling process, the liquid gel is heated and becomes soft but
solid. The sealing has no gluing function in the final product.

Application Note 4 <Revision 2.4>
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Assembly Instructions for the Easy-PressFIT Modules
2Requirements for printed circuit boards
The PressFIT technology used in the Easy modules has been inspected and qualified by Infineon Technologies
AG for standard FR4 PCBs with tin applied chemically (IEC 60352-5 + IEC60747-15). If other handling
technologies are to be used in the production of PCBs, they have to be tested, inspected and qualified.
Requirements for the PCB material:
Double-sided PCB according to IEC 60249-2-4 or IEC 60249-2-5.
Multilayer PCB according to IEC 60249-2-11 or IEC 60249-2-12.
Table 1 Requirements for a PCB
Minimum
Typical
Maximum
Hole drill diameter
1.12 mm
1.15 mm
Copper thickness in hole
> 25 µm
< 50 µm
Metallization in hole
< 15 µm
End hole diameter
0.99 mm
1.09 mm
Copper thickness of
conductors
35 µm
70 µm
105 µm
400 µm
Metallization of circuit
board
Tin (chemical) recommended
Metallization of pin
Tin (galvanic)
In order to ensure that the PressFIT contact sits securely in the PCB, the specification of the hole given in Table
1 must be adhered to.
If the specification of PressFIT holes is limited to only the finished dimension (i.e., the metallized hole), different
drill sizes could be used depending on the PCB manufacturer and production philosophy, and also different
metallization thicknesses could be provided. This would lead to results that would have to be rejected for
quality assurance reasons. The end hole diameter is a function of the drill hole, the copper thickness and
the metallization in the hole.
The recommendation still applies that the hole in the PCB is to be drilled during manufacture with a drill size of
1.15 mm, and should not be milled. Experience has shown that a final hole diameter between 1.12 mm and 1.15
mm is obtained under consideration of the runout tolerances of the spindles after drilling due to shrinking of
the FR4 material.
With a copper thickness of 30 µm to 50 µm in the hole and a tin layer of about 1 µm for tin applied chemically,
an end hole diameter is obtained as the test dimension. Due to the thinner tin layer thickness, this diameter is
always higher than the value of 1 mm stated in the standard (IEC 60352-5). The final hole diameter, considering
the drilling diameter, copper thickness and a chemical tin layer, is typically between 1.02 mm and 1.09 mm.

Application Note 5 <Revision 2.4>
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Assembly Instructions for the Easy-PressFIT Modules
Figure 4 Structure of a PCB
The PressFIT technology is qualified for FR4 PCB material.
After a reflow soldering process is carried out on a PCB, the module can be pressed into the board without
difficulty. The retention forces of the press-fitted pins are not diminished.
Depending on the applied press tools, a certain distance from the middle of the pins to other components must
be observed. A distance of 5 mm is recommended, similar to Infineon’s Econo PressFIT power modules.
A PressFIT module can be replaced up to two times. This means that a PCB can be used in total three times.
Correct handling of the components is essential.
A module that has been pressed in, and the contact pressed out again, can no longer be pressed back in again.
Instead, the module can only be attached to a new PCB via soldering. The plastic deformation of the PressFIT
area does not permit a further PressFIT process.
Tolerance of PCB hole pattern is suggested to be kept within:

Application Note 6 <Revision 2.4>
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Assembly Instructions for the Easy-PressFIT Modules
3The press-in process
This section deals with the necessary press-in forces and tools for the modules.
The PressFIT module is inserted in a PCB by pressing it in. PressFIT can be performed using a toggle lever press
or a machine. A press-in tool that records the necessary force and the travel distance is recommended.
Consistent quality and reproducability is assured in this way. The PressFIT speed should not be lower than 25
mm/min according to IEC 60352-5. A lower PressFIT speed can lead to increased press-in forces and to
deformation of the pins, or a non gas-tight connection.
Note that during the press-in process, the placement area of the PCB and the pressing area of the pressure
plate must be parallel to each other. The pressure plate should be mechanically fixed in position without any
tolerance. The module is then pressed into the PCB in a regular motion.
The module pins should penetrate the PCB during press-in until the four stand-offs on the module, or optional
distance keepers as described in Multi-module and automotive application, make contact with the board.
By adhering to the principles stated above, a smooth insertion process for the two components can be
achieved.
The following illustrations show the press-in process as it is implemented in the laboratory.
Figure 5 Press-in process of an Easy module
Attention! It is recommended to protect the underside of the IGBT module against damage during the press-
fitting process.
3.1 Press-in tools
The following tools that help pressing the modules in and out are recommended for the three Easy B Series
modules. Figure 6 shows these pressing tools for the two housing types, Easy 1B and Easy 2B. The pressing
tools for Easy3B housing are shown in Figure 7.

Application Note 7 <Revision 2.4>
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Assembly Instructions for the Easy-PressFIT Modules
Each of the tools has two parts. The first part presses against the underside of the module, and the second part
holds the PCB in place to be pressed against.
No components can be placed in the mounting areas of this special type of press-fitting tool. This prevents
damage during the press-fitting process.
When press-fitting multiple modules onto a PCB, arrange the press-in tool in such a way that the modules are
on the same level after pressing. In this way, the modules can be mounted on the heat sink with a good thermal
connection.
Figure 6 Press-fitting tools for Easy1B (shown left), Easy2B (shown right)
Figure 7 Press-fitting tools for Easy3B from HARTING Electronics GmbH
The drawing can be adjusted according to different requirements (e.g. module pinning and top side assembly
of other parts) and the tools produced by a manufacturer of choice.
3.1.1 Press-in tools for Easy modules with thermal interface material
If modules with pre-applied thermal interface material (TIM) are used, the press-in stamp has to be designed
with respect to the position of the TIM material on the module’s base plate. Figure 8 shows the picture of an
Easy2B module with TIM.

Application Note 8 <Revision 2.4>
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Assembly Instructions for the Easy-PressFIT Modules
Figure 8 Easy2B with TIM
The structure of the presented TIM surface is only exemplary and not fixed for all products within the Easy
family.
The stamp should not touch the TIM material during press-in. That is why the stamp only touches the substrate
areas without TIM. Figure 9 shows the geometries of the stamp for the press-in of Easy1B and Easy2B modules
with TIM.
Figure 9 Press-in stamp of Easy1B (left) and Easy2B (right)

Application Note 9 <Revision 2.4>
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Assembly Instructions for the Easy-PressFIT Modules
3.2 Press-in forces and speed
To press a module onto a PCB, a force of between approximately 60 N and 100 N must be applied for each pin in
the module. The press-in forces vary according to the diameter of the hole and copper metallization in the PCB.
Table 2 shows the PressFIT speed and the maximum PressFIT force per pin.
PressFIT speed
>25 mm/min according to IEC 60352-5 qualification
100 mm/min recommended
PressFIT forces
per pin
Typ. 85 N
<100 N max.
Table 2 PressFIT speed and forces per pin
Attention! The maximum applied force per module for Easy1B and Easy2B during pressing should not exceed 4
kN. For Easy3B the maximum applied force should not exceed 8 kN.
The press-fitting speed should not be lower than 25 mm/min according to IEC 60352-5. Infineon recommends a
press-in speed of about 100 mm/min. The typical press-in speed for automated assembly lines is up to 450
mm/min.

Application Note 10 <Revision 2.4>
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Assembly Instructions for the Easy-PressFIT Modules
4The press-out process
This section deals with the necessary press-out forces and tools for the modules.
PressFIT modules are removed with the appropriate tools as shown in Figure 10 and Figure 11. The PCB is
placed with the PressFIT module on the device tray. Force is applied with the extrusion plate on the PressFIT
pins that protrude from the PCB. The press-out tools must be aligned parallel to each other so that the
individual components (such as the PCB and module) are not damaged. Once the PressFIT zone has been lifted
from the PCB, the module falls onto the tray in the lower part of the tool, and is separated from the board.
Figure 10 Extrusion of an Easy module
4.1 Press-out tools
As already mentioned above, the press-out tools consist of two parts. The upper part of the tool presses directly
downwards on the module pins. The lower part of the tool holds the module with the PCB, and serves as a base
for the pressing operation.
The disassembly tools must be aligned parallel to each other in order to obtain an equally distributed extrusion
process.
The dimensions of the press-out tool must be considered when designing the PCB so that the components
positioned around the module will not be damaged.

Application Note 11 <Revision 2.4>
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Assembly Instructions for the Easy-PressFIT Modules
Figure 11 Press-out tools for Easy1B (left) and Easy2B (right) modules
The drawing can be adjusted according to requirements and the tools produced by a manufacturer of choice.
4.2 Press-out forces
To press a module out of a PCB, a force of approximately >40 N has to be applied for each pin in the module.
The extruding forces depend mainly on the diameter of the hole in the PCB.

Application Note 12 <Revision 2.4>
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Assembly Instructions for the Easy-PressFIT Modules
5Quality of PressFIT contacts
PressFIT is an alternative solution for connecting control and load current contacts on IGBT modules with a
PCB.
The requirements for greater durability, the trend towards higher temperatures and absence of lead, and, of
course, very simple handling, are continuously growing.
As an advanced technology on the market, the PressFIT makes it possible to improve reliability up to a factor of
100 compared to manually soldered contacts and other contact types. The results of the reliability analyses in
the Siemens norm SN 29500-5 demonstrate the factor.
The assembly process is simple, and consequently saves time and money. The process is reliable, and system
reparability is ensured.
An extract from the Siemens norm SN 29500-5 / Edition 2004-06 Part 5 shown in Table 3 illustrates the failure
rates of different contact technologies.
Table 3 Failure rates for various contact technologies Siemens norm SN 29500-5 /
edition 2004-06 Part 5
Process
Conductor diameter in
mm²
Failure rate
λref in FIT1)
Notes:
Standards/guidelines
Solder manual
Automatic
_
0.5
0.03
IPC 6102), class 2
Wire bonding for hybrid
circuits Al
Au
0.1
0.1
28 μm / wedge bond
25 μm / ball bond
Winding
0.05 to 0.5
0.002
DIN EN 60352 –1 /
IEC 60352 –1 CORR1
Crimping manual
Automatic
0.05 to 300
0.25
DIN EN 60352 –2 /
IEC 60352 –2 A 1+2
Clips
0.1 to 0.5
0.02
DIN 41611 –4
PressFIT
0.3 to 2
0.005
IEC 60352 –5
Insulation piercing
connectors
0.05 to 1
0.25
IEC 60352 –3 / IEC 60352
–4
Screws
0.5 to 16
0.5
DIN EN 60999 –1
Terminals (spring force)
0.5 to 16
0.5
DIN EN 60999 –1
1) 1 FIT = 1 x 10-9 1/h; (one failure per 109 component hours)
2) Acceptance conditions for PCBs
The PressFIT contact has been qualified in accordance with the usual standards for IGBT modules at Infineon.
Figure 12 shows a small extract of the various tests. The extract shows that the conditions in the individual tests
are to be regarded as considerably stricter than stated in the standards. For example, in a corrosive gas test, the
temperatures in scope of individual test is 15 K higher than the condition in the standard. And the H2S

Application Note 13 <Revision 2.4>
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Assembly Instructions for the Easy-PressFIT Modules
concentration is five times higher than the conditions according to the norm. The green fields show the test
conditions according to the norm, which is less critical than in the individual tests.
Figure 12 Extract from qualification test
Further details on the individual tests can be found in various publications, such as "Reliability of PressFIT
connections" at www.infineon.com.

Application Note 14 <Revision 2.4>
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Assembly Instructions for the Easy-PressFIT Modules
6Mounting a PCB to the module
For mounting a PCB onto the module, additional screws can be used if desired. These screws will be tightened
into the stand-offs of the module.
An electronically controlled, or a slowly turning electric screwdriver, with n ≤ 300 rpm, is the preferred
mounting tool.
Due to the lack of accuracy, we do not recommend the use of pneumatic screwdrivers or manual screwdrivers.
Figure 13 Detailed view of the assembly insert
The effective length of the thread in the stand-off should have a minimum of 4 mm and a maximum length of
8 mm.
The initial 1.5 mm of the mounting stand-off serves as guidance only and cannot take any force. The thread in
the plastic will form during the screwing process.
For the choice of the screw length, the given PCB thickness has to be taken into account.
The following screws are tested to fix the PCB to the module:
Ejot PT WN 1451 K25*10 A2K Mmax=0,45 Nm ±10%
Ejot DELTA PT WN 5451 K25*8 Mmax=0,4 Nm ±10%
Metric screws: M2.5*x –for example, M2.5*8 or M2.5*10 depending on the thickness of the PCB used
To avoid damage or splitting of the stand-off, straight insertion of the screw into the stand-off has to be
observed during assembly.

Application Note 15 <Revision 2.4>
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Assembly Instructions for the Easy-PressFIT Modules
7Condition of the heat sink for module assembly
The power loss occurring in the module has to be dissipated via heat sink in order not to exceed the maximum
permissible temperature Tvjop specified in the datasheets during operation.
The condition of the heat sink surface in the area where the module is mounted is of great importance, as this
interface between heat sink and module is of decisive influence on the heat transfer of the entire system.
The contact surfaces, the surface below the module and the surface of the heat sink have to be free of
degradation and contamination to prevent excess mechanical stress to the module as well as an increase in
thermal resistance.
Heat sink requirements:
Roughness: ≤ 10 µm
Flatness based on a length of 100 mm: ≤ 50 µm
Note 1: The flatness of the heat sink should not exceed the values listed above. This area includes the entire
module mounting area as well as that of the clamps.
Note 2: If the layer of thermal grease applied is too thick, e.g. as a consequence of cavities, the thermal
resistance Rth between module and heat sink will increase.

Application Note 16 <Revision 2.4>
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Assembly Instructions for the Easy-PressFIT Modules
8Applying the thermal grease
Due to the individual surface shape (e.g. roughness and flatness) of the heat sink and the module, the lower
surface of the module and the surface of heat sink do not touch across the entire area. Therefore a certain
localized separation between the two components cannot be avoided.
To dissipate the losses occurring in the module and to achieve a good flow of heat into the heat sink, all
localized cavities have to be filled with a thermal compound. When using a heat conductive paste, a
homogenous application needs to be assured.
A well-applied layer will fill all cavities, and at the same time will still allow the metallic contact between
module base and heat sink surface. A compound should be selected which shows permanently elastic features
in order to assure a continuously favorable heat transfer resistance.
Before the module is mounted onto the heat sink, an even layer of thermal grease, 80 µm thick for Easy1B/2B,
and 60 µm thick for Easy3B, is recommended be applied to the module base or to the heat sink according to the
module size and the thermal grease used. This grease can be applied using either a spatula, a roller, or by silk
screen printing. The quantity of thermal grease is sufficient if a small amount of grease is visible around the
module after assembly to the heat sink.
The recommendation is to apply the thermal grease by means of a screen print process. Apart from an
optimized and module-specific distribution of the heat conductive paste, a homogenous and reproducible
layer thickness can be achieved with this procedure. If a screen print process is used, the layer thickness could
be reduced to values under the above-mentioned numbers. The size of the module and the viscosity of the
thermal grease are important factors in this case.
Further notes regarding the application of screen print templates for the application of thermal grease can be
found in the application note AN2006-02 Application of silk screen.

Application Note 17 <Revision 2.4>
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Assembly Instructions for the Easy-PressFIT Modules
9Assembling the module on heat sink
9.1 Assembling Easy1B/2B module on heat sink
The module is mounted onto the heat sink using M4 screws. It is also possible to use an additional flat washer.
The heat sink has to be provided with threaded holes as shown in Figure 14.
Figure 14 Spacing of the threaded holes
Note: If the module is first pressed in to the PCB, or if a later disassembling of the module is desired, the PCB
must contain suitable through-holes. The hole size depends on the screwdriver size or the screw’s head
diameter or washer.
The module should be positioned onto the heat sink in such a way that the holes of the screw clamps are
exactly above the threaded holes of the heatsink. The mounting surface must be clean and free of
contamination.
The module can be fastened by screwing in and tightening both screws at the same time (Figure 15a) or by
holding down the module during the mounting process with a force of approximately 10 N so that the module
cannot rise up (Figure 15b).

Application Note 18 <Revision 2.4>
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Assembly Instructions for the Easy-PressFIT Modules
Figure 15 Module fastening options
Alternatively, one screw can be applied initially. It is important that the module does not lift up. To prevent this,
tighten the first screw loosely to avoid a press force to the clamp (Figure 16a). Then, tighten the second screw
completely (Figure 16b). Finally, tighten the first screw completely (Figure 16c).
Figure 16 Fasten the module by tightening both screws at the same time

Application Note 19 <Revision 2.4>
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Assembly Instructions for the Easy-PressFIT Modules
Table 4 Technical data of the mounting screw
Description
Values
Mounting screw
M4
Recommended mounting torque
Ma = 2.0 –2.3 Nm
Recommended thread engagement for screws with property class 4.8 to
6.8 for different materials
Aluminium cast alloy
Aluminium alloy hardened
Aluminium alloy not hardened
2.2 x d = 8.8 mm 1)
1.2 x d = 4.8 mm 1)
1.6 x d = 6.4 mm 1)
Washer acc. to DIN 125
D = 9 mm
1) As per technical literature
9.2 Assembling Easy3B module on heat sink
For the assembly of the Easy3B module to the heatsink, Infineon recommends the use of DIN M5 screws, in
combination with a M5 washer.
Position the module correctly to the heat sink, so that the mounting area of the module is congruent with the
threaded holes in the heat sink. Make sure that there are no foreign objects between the module and the heat
sink.
The module can be fixed by screwing and tightening both screws at the same time (see Figure 17Figure 14).
Figure 17 Steps for alternative fastening of the module
Alternatively, the module can be mounted to the heat sink in several steps (see Figure 18):
Step 1: The first screw can be screwed in slightly. Do not fully tighten it, so that no pressure is exerted.
Step 2: The second screw needs to be firmly screwed to the heat sink.
Step 3: Finally, the first (loose) screw needs to be screwed on firmly to the heat sink.
Note: If the module is first pressed in to the PCB, or if a later disassembling of the module is desired, the PCB
must contain suitable through-holes. The hole size depends on the screwdriver size or the screw’s head
diameter or washer.

Application Note 20 <Revision 2.4>
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Assembly Instructions for the Easy-PressFIT Modules
Step 1
Step 2
Step 3
Figure 18 Module fastening steps
The following values are recommended for the mounting process:
Table 5 Recommended parameters for heat sink mounting
Description
Values
Mounting screw
M5
Recommended mounting torque
Mamax = 1.5 Nm
Recommended property class of
bolt
4.6 –5.6
Minimal thread length into the
heatsink
2 x d = 10 mm
Pre-tightening torque
0.3 –0.5 Nm
Tightening torque Ma
1.3 –1.5 Nm
Screw velocity (pre-tightening)
U ≤ 250 U/min
Screw velocity (tightening)
U ≤ 20 U/min
Recommended washer
M5