APPLICATION NOTE
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Mounting Instructions for
PIM Modules (Q0, Q1, Q2,
F1, F2)
AND9867/D
Introduction

This application note covers the mounting instructions for onsemi
Power Integrated Modules (PIMs) using the following packages:
• Q0
• Q1
• Q2
• F1
• F2
This application note covers the following topics• PCB hole sizes and plating• PCB design• Heatsink and Thermal Interface Material (TIM)• Press−in process• Soldering process• Mounting module to the heatsink• Mounting heatsink and module to PCB

Figure 1. Q1 Module with PCB andHeatsink

Figure 2. Press−fit Processonsemi family of Power Integrated Modules has package options
using solder pins or press−fit pins for the connection of the module to a
Printed Circuit Board (PCB). Figure 1 shows a Q1 module withpress−fit pins as an example.
After mounting, press−fit pins provide a cold−welding connection
between pins and plated through holes (PTH) of the PCB. This easy
assembly method avoids extra heating, avoids contamination andprovides good mechanical and electrical performance. Press−fit
assembly is a well−established connection method for power
semiconductor modules. The press−fit pins provide a gas−tight metal
to metal contact between the press−fit pin and the plated through hole
(Figure 2).
Modules having solder pins are soldered into the PCB. Modules
having press−fit pins can also be soldered into the PCB, but with larger
holes than used for the standard press−fit process.
The purpose of this application note is to provide recommendations
for the PCB and to recommend mounting and dismounting methods
with proper tools to achieve the required reliability and performancewith either press−fit or solder connections.

© Semiconductor Components Industries, LLC, 2019

April, 2022 − Rev. 4

1

Publication Order Number:
AND9867/D

AND9867/D
PCB SPECIFICATION
Correct design of the plated through holes (PTH) in the
PCB is essential to obtain good quality press−fit or solder
connections.

clearance between pins should always be considered inminimum permissible spacing calculations.
Specification for Modules with Solder Pins,
Soldered to the PCB

The recommended final PCB hole diameter for solder pins
is 1.2 mm when using 1 mm pins used in F1, F2, Q0, Q1 andQ2 modules.
The pcb pad diameter is determined by the minimum
annular ring size, the production alignment tolerance (level
A, B or C) and the drilling tolerance as detailed in IPC−2222.
The effect of the pad size in reducing the creepage andclearance between pins should always be considered inminimum permissible spacing calculations.
For 1 mm diameter pin, the final pad diameter for level B
manufacturing is calculated as 1.8 mm: allowing for 50 mm
absolute minimum annular ring, 0.5 mm alignment
tolerance and 1.2 mm actual PCB hole size.

PCB Specification

The schematic structure of a plated through hole is shownin Figure 3. If the initial drilled hole diameter is too small,the press−in force into the PTH will be too high andmechanical damage on both press−fit pin and PTH will
occur. If the final hole diameter is too small, damage to thepin and the hole may also occur. If the final hole diameter is
too large, it may not provide a reliable connection between
plated through hole and press−fit pin.
The effect of the pad size in reducing the creepage andclearance between pins should always be considered inminimum permissible spacing calculations.

Table 1. PCB SPECIFICATIONS FOR F1 AND F2MODULES WITH 1.2 MM PRESS−FIT PINS −IMMERSION OR GALVANIC TIN. Pins are IEC qualified for
immersion tin plating.

Figure 3. Cross−section of PCB

Min.

Typ.

Initial Drilled Hole Diameter Ø [mm]

1.12

1.15

Cu Thickness in the Hole [mm]

25

50
1.09

15

Sn Thickness [mm] (Chemical Tin)

Tables 1−4 list the recommended PCB specification basedon the evaluation of the press−fit technology according to
the IEC 60352−5 standard.

Final Hole Ø [mm]0.98

Annular ring [mm]200

Thickness of Conductive Layer [mm]35Specification for Modules with Press−fit Pins,
Soldered to the PCB

Board Thickness [mm]1.6

It is not recommended that press−fins are just soldered
without being pressed into the PCB in mass production. If
modules with press−fit pins are reused after being removed
from the PCB, it can be soldered on the PCB to reinforce thecontact.
The pcb pad diameter is determined by the minimum
annular ring size, the production alignment tolerance (level
A, B or C) and the drilling tolerance as detailed in IPC−2222.
The effect of the pad size in reducing the creepage andFigure 4.

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Table 2. PCB SPECIFICATIONS FOR F1 AND F2MODULES WITH 1.2 MM PRESS−FIT PINS − HAL
PLATING. Pins are IEC qualified for HAL plating but

Table 4. PCB SPECIFICATIONS FOR Q0, Q1 AND Q2MODULES WITH 1.6 MM PRESS−FIT PINS − HAL
PLATING. Pins are IEC qualified for HAL plating but

immersion/galvanic tin is recommended for more consistent
mounting.

immersion/galvanic tin is recommended for more consistent
mounting.

Min.

Typ.

Initial (Drill) Hole Ø [mm]

1.12

1.15

Cu Thickness in the Hole [mm]25

Sn Thickness [mm]Final Hole Ø [mm]0.94

Annular ring [mm]200

Thickness of Conductive Layer [mm]35

Board Thickness [mm]1.670−105

Max.

Min.

Typ.

Initial (Drill) Hole Ø [mm]

1.57

1.60

50

Cu Thickness in the Hole [mm]2540

Sn Thickness [mm]1.09

Final Hole Ø [mm]1.45

Annular ring [mm]

200

400

Max.
50
40

Thickness of Conductive Layer [mm]35

Board Thickness [mm]

1.6

1.54
70−105400

Figure 5.

Figure 7.

Table 3. PCB SPECIFICATIONS FOR Q0, Q1 AND Q2MODULES WITH 1.6 MM PRESS−FIT PINS −IMMERSION OR GALVANIC TIN. Pins are IEC qualified forTable 5. PCB SPECIFICATIONS FOR F2 MODULES
WITH EON PRESS−FIT PINS − IMMERSION ORGALVANIC TIN. Pins are IEC qualified for immersion tin

immersion tin plating.

plating. For HAL tin coating, a thicker tin thickness of up to
40 um is permitted reducing the hole size to 0.94 mm but thisrequires additional approval from onsemi.

Min.

Typ.

Initial Drilled Hole Diameter Ø [mm]

1.57

1.60

Cu Thickness in the Hole [mm]

25

Max.
50
15

Sn Thickness [mm] (Chemical Tin)
Final Hole Ø [mm]1.45

Annular ring [mm]200

Thickness of Conductive Layer [mm]35

Board Thickness [mm]

1.6

1.54
70−105Min.

Typ.

Initial Drilled Hole Diameter Ø [mm]

1.12

1.15

Cu Thickness in the Hole [mm]2550Final Hole Ø [mm]

1.02

1.09

Annular ring [mm]

200

15

Sn Thickness [mm] (Chemical Tin)

400

Thickness of Conductive Layer [mm]35

Board Thickness [mm]1.6

Figure 6.
Figure 8.

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AND9867/D
PCB DESIGN

Mounting with Distance of 12 mm

Option 1: without spacers

PCB Layout Restrictions

PCB bending during the press−in process causes
mechanical stress to other PCB components, such as
capacitors and resistors. Experiments to verify a safe
minimum distance between passive components and theplated through hole were conducted with FR4 PCB. Various
sizes (0603, 0805, 1206, 1210, 1812, and 2220) of
mechanically sensitive components were evaluated. Basedon experimental results, the recommended minimum space
between center of the plated through hole and the edge of thecomponent is 4 mm, as shown in Figure 9.

Figure 10. Mounting Height with Module as Spacer

Option 2: with spacers

Figure 11. Mounting Height with Spacer in case ofusing Recommended Press−fit Tool
Example: Q1 Module with Press−fit Pins

Figure 12 shows an example of mounting a Q1 module.
The Q1 package has its power connectors/terminals
distributed across the surface of the plastic case. Electricalconnections are made by connecting these terminals toa print circuit board (PCB) by soldering or press−fit
technology.

Figure 9. PCB Design Restriction: Distancefrom Center of PTH to Edge of Components

The minimum distance between the edge of the PCB andthe centre of the pin hole must be more than 4 mm.
The minimum distance between the center of the pin holeand a neighbored component on the PCB must be more than
4 mm.
Recommended PCB−thicknesses and Mounting
Heights by Module TypeThe distance between the top surface of the heatsink andthe bottom plane of the PCB is defined by the module heightof 12 mm for Q0, Q1, F1 and F2 packages or 17 mm for Q2
packages. PCB spacers can be used for fixing. The number
and the position of the fixing points depend on the design ofthe circuit, location of different masses like capacitors or
inductor and the environment of the system. Generalrecommendations cannot be given. The recommended
heights of these spacers are given in the following sections

Figure 12. Q1 Package Mounting Example

The PCB has four mounting holes for the spacers, two
cut−out holes for accessing the heatsink mounting screws
through the PCB and the holes for the pin connections.
The dimensions and positions of the cut−out holes, thePTH holes and mounting holes are specified in the datasheet
drawing for the specific module.
The Q0 solder pin modules have plastic mounting clips
which require different shaped cut−outs in the PCB as
specified in the datasheet.

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AND9867/D

HEATSINK AND THERMAL INTERFACE
MATERIAL
Power semiconductor modules generate heat that needs tobe dissipated to protect against overheating. In general,
module operation temperature should not exceed the
maximum allowable junction temperature (TJmax) specified
in the datasheet. Thermally conductive metal heatsinks thatabsorb and disperse heat are commonly used for coolinghigh power electronics. The thermal performance ofa module, in combination with a heatsink, can becharacterized by the thermal resistance Rqja, which is thesum of all thermal resistances in the thermal path:junction−to−case (Rqjc), case−to−heatsink (Rqcs), heatsink(Rqsink), and heatsink−to−ambient (Rqsa), as shown in
Figure 13.
Figure 14. Microscopic View of Surfaces.
A is Flatness and B is Roughness (Rz)

The interface surface of the heatsink must be free ofparticles and contamination. Avoid handling the heatsink
surface with bare hands or contacting any foreign materials.
If it is necessary to remove contamination from heatsink,cleaning can be accomplished using dry cloth soaked withsolvent, such as isopropyl or ethylene alcohol.
Figure 13. Thermal Model of Power Module &Heatsink

Thermal Interface Material (TIM)

The backside of the module and the surface of the heatsink
are not ideally smooth. TIM is used to prevent air cavities
and help the thermal dissipation. Such TIM material may be
a thermal pad, foil, grease, or any other similar material. The
material selection should consider the thermal conductivity,
drying out behavior during aging, and shape maintaining
properties during power ON/OFF cycling.
The surfaces of the heatsink and the substrate of themodule are not perfectly flat. After the module is mounted
to a heatsink, air gaps can form between these two surfaces
and the effective contact is limited to the area shown in
Figure 15. Air is a poor heat conductor with 0.03 W/m⋅K
thermal conductivity. It acts as a thermal barrier that limits
the efficiency of heat transfer from the device.

Generally, air convection is the dominant heat transfer
mechanism in electronics. The heat transfer by air
convection strongly depends on the air velocity and the areaof the heat−transferring surface. Proper contact between
module substrate and the surface of the heatsink is crucial for
managing the overall thermal efficiency of the system.
Thermal Interface Materials (TIMs) are thermallyconductive materials used to achieve good mating of the two
surfaces and improve heat transfer.
Heatsink Surface

The contact surface of a heatsink must be flat and clean tomaximize heat transfer. Rough surfaces result in large voids
between the substrate of the module and the surface of theheatsink. The following surface qualities are required for theheatsink to achieve a good thermal conductivity, according
to DIN 4768−1. Roughness (Rz) should be 10 mm or less andflatness, based on a length of 100 mm, should be 50 mm or
less. The heatsink should have no contamination,
unevenness, and burrs on the surface contacting the module.

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1. Choose one side of the surface, module substrate,or heatsink to apply thermal grease.
2. Coat a rubber roller with thermal grease.
3. Paint the surface repeatedly using the rubber roller
to create a uniform layer of thermal grease around
80–100 mm thick.

(a)Since the thermal grease has the lowest thermal
conductivity in the thermal path, a layer as thin as possible
is necessary to keep the overall thermal resistance low.
Recommended thickness of printing layer is 60–100 mm tofill the gap between two contact surfaces completely. Checkthe thermal grease thickness with thickness gauges, such as
wet film combs or wet film wheels. Because manual controlof the printing pressure and speed can be learned byexperience, training is needed to achieve a technique forgood quality printing layer in real application.
Alternatively, apply thermal paste by screen printing, forexample using a honeycomb pattern. The recommended
thermal paste thickness is 80−100 mm A thickness of the
TIM layer in excess of this recommendation will
unnecessarily increase thermal resistance.
When applying thermal grease, the material must be
applied uniformly on the whole surface which is in contact
to the module substrate surface. If the module isre−mounted, surfaces should be cleaned and TIM needs beapplied again.

(b)

Figure 15. (a) Heat Transfer, Module to Heatsink,(b) Heat Transfer with Thermal Interface Material

Thermal interface materials are widely used in theindustry to fill air gaps between contact surfaces. Thermalinterface material provides better thermal performance than
air and compensates for imperfect mating surfaces, such as
roughness and flatness shown in Figure 14. There arevarious thermal interface materials available in the market.
The right choice of material is an essential factor for theapplication. It should be selected considering the following
features:• High Thermal Conductivity• Ease of Distribution with Low Contact Pressure• Minimal Thickness• Degradation of Characteristics Over Time• Stability of Characteristics Over Time• Toxicity (Non−Toxic Optimal)• Ease in Handling during Application or Removal

Pre−applied Thermal Interface Material

As an option the module may be prepared or provided witha pre−applied PCM layer. The recommended pattern forsuch PCM layer is shown in Figure 17.

Thermal Grease

The most common thermal interface materials are thermal
greases. Thermal grease can be applied to the heatsink or themodule substrate using a rubber roller or spatula or by screen
printing. A rubber roller, as shown in Figure 16, is an easy
and fast method for applying thermal grease.
Figure 17. Printing Pattern Example for TIM Material
Modules Shipped with Pre−applied Phase−change
Material

Please refer to the application note referring to handling
modules with pre−applied TIM material.
Figure 16. Applying Thermal Grease

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AND9867/D
PRESS IN PROCESS OF MODULES WITH
PRESS−FIT PINS
The press−fit process is a cost−effective way to assemble
power modules without introducing additional thermal
stress. The press−fit connection generates a good electrical,
and also strong mechanical connection between the moduleand the PCB. This section deals with the mounting process
to achieve suitable press−fit connections.
There are several types of presses available; from simple
toggle presses to the automated pneumatic presses shown in
Figure 18. If possible, monitor the press−in/press−out
distance, speed, and force to achieve mechanical stability
and high reliability of the press−fit connection. The travel
distance during the press−in process should be controlled toensure that the press−fit zone of the pins sits properly in theplated through hole. The speed also influences the quality ofthe press−fit connection; therefore, speed recommended by
IEC standard should be applied.

Figure 19. Recommended Tooling Construction for
the Press−in Process

Figure 18. Press−in Presses
Figure 20. Press−in Tools Closed,
Module is Pressed in

Generally, a module can be pressed in until the stand−offson the four corners of the module touch the PCB. If, forexample, more than one module is mounted on a PCB atshort distances or assemblies are subjected to mechanicalshocks in the application, the press−in method as describedin Figure 23 is recommended.

Press−in Process Parameters

The total press−in force is the result of the number of pins
in a module, multiplied with the force required for a single
pin. Press−in forces lower than 60 N/pin mean that press−fit
pin may have a less secure connection in the plated throughhole. The primary reason for the low press−fit force is thatthe diameter of plated through hole is too large for thepress−fit pins. Press−in forces higher than 150 N/pin cancause mechanical damage to the press−fit terminal, the PTH,
or to the tracks on the PCB. The recommended press−in
speed ranges from 25 mm/min to 50 mm/min in accordancewith the recommendations in IEC 60352−5.

Press−in Tool Construction

The preferred method is to press the module into the PCB
from the top. Pressing multiple modules into one PCB canbe done one by one; or all at once.
Pressing multiple modules at the same time requires
a press−in tool according to the above detailed single tool.
The tool has to ensure the correct leveling of the modules
and the PCB to avoid any mechanical stress.

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The two parts of the tool need to be aligned to each other(a). In the first step of the assembly, the printed circuit board
is placed on the alignment pins of the lower part of thepress−in tool (b).
Then, the module is placed on top of the printed circuitboard using the alignment pins. It is necessary to check if themodule and the printed circuit board are in alignment (c). In
the next step, the press−in force is applied via the upper partof the press−in tool to the backside of the module evenly. The
module should be pressed−in with a speed of
25~50 mm/min until the stand−offs on the four corners ofthe module touch the surface of the printed circuit board
while press−in distance and force are monitored at the sametime (d).
It is required to adjust the traveling distance of the press
to avoid damages to the module case due to pressure being
applied. A simple manual press does not use a distancesensing system, so a distance keeper should be designed on
the press−in tool to terminate press−in process
appropriately. The next section describes the function of the
distance keeper more in detail.

The press−fit pins have to be pressed into the holes of the
PCB to the correct depth. The center of the press−fit zone has
to be at least 0.5 mm below the top surface and at least
0.5 mm above the bottom surface of the PCB (Figure 21).

Figure 21. Press−in Depth in PCB
General Press−in Process

Figure 22 shows the general sequence of the press−inprocedure. The press−in tool is comprised of two parts: theupper press−in tool is flat to contact with the module
backside evenly and the lower press−in tool has engraved
spaces to accommodate the press−fit pins.

Figure 22. Press−in Process

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Press−in Process for Multiple Modules

the PCB. If the distance keeper contacts the surface, press−inforce rises sharply and the press−in process can beterminated by reaching the limit of the press−in force. The
distance keeper should be designed to avoid the collision
with other PCB components.
The press−in process using the distance keeper is
described in Figure 23. First, the PCB should be placed on
the lower press−in tool (a). Then, a module is placed on thelower press−in tool and aligned with the PCB (b). The
press−in stroke is applied to the backside of the module until
the distance keeper touches the surface of the PCB (c).

In case multiple modules are assembled to the same PCB
and heatsink, height tolerances can result in unintended
bending of the PCB or inappropriate heatsink contact.
Therefore, if more than one module is mounted on thesame PCB, it is required to minimize the height tolerances
between those modules. This section presents a modified
press−in process related to that.
Figure 23 shows a press−in tool including distancekeepers. The distance keeper terminates the press−inprocess and limits the press−in depth.
By contacting the printed circuit board ahead of themodule case, it prevents direct contact between the case andFigure 23. Press−in Process with Distance Keepers

Figure 24. Schematic Description of the Press−in Process using Distance Keeper

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Consequently, an air gap between the top of the case andthe surface of the PCB remains. Screwing the PCB down to
the stand−offs of the module case, as shown in Section 5, is
not allowable. Instead, the assembly should use space posts
to support the PCB.

As illustrated in Figure 25, depending on the length of the
distance keeper, the contact length between press−fit pins
and the plated through hole is determined. The total heightof the module is 12.00 ±0.30 mm for Q0, Q1, F1 and F2
modules. It is recommended that the length of the distancekeeper should be 12.40 (+0.05/−0) mm to achieve a stablecontact length.

A: Package height (DBC bottom to case top) is 12.00 +0.30/−0.30 (mm)
B: Distance keeper height is 12.40+0.05/−0 (mm)
C: Air gap between case top and surface of the PCB

Figure 25. Press−in Depth in Accordance with Length of Distance Keeper
Press−in Tool Design Commentsof the component is 4 mm or more. It is also important tokeep a certain area to provide support for the PCB.

Some design options should be considered to avoid
press−in failure. First, the contact plate of the upper press−intool must be larger than the module DBC substrate size. If
the contact area of the upper press−in tool is smaller than themodule substrate and pressure is applied to the center areaof the module only, the module can be mechanicallydamaged during the press−in process. The press−in tool
design should consider the size of the module.
If other components (capacitors, resistors) are assembled
on the PCB next to the module mounting area, the press−intool design should avoid collision during the press−inprocess. As shown in Figure 20, the lower press−in tool isdesigned with engraved spaces for the press−fit pin and other
PCB Based on experimental results, components did notexhibit mechanical or electrical damages due to board
bending during the press−in process when the distance
between the center of the plated through hole and the edge

Press−out Process

In some situations, it is necessary to remove power
modules from the PCB. It is possible to disconnect thecontact between module pins and PTH. The press−out
process can be performed with the same equipment used in
the press−in process.
Careful handling in the press−out process is essential to
avoid mechanical damage to both the module and the PCB.
PCB can be re−used once with a new module.
Please note: in case a module which was pressed out of a
PCB should be used again, it is necessary to solder themodule to the PCB; this is because the press−fit zone willremain deformed after the press−out process. An additionalpress−in cycle will result in low holding forces between thepress−fit pin and PCB hole.

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Figure 26. Press−out Tools

Figure 27. Press−out Process

mounting area to avoid collision during the press−out
process. The specific tool to disassemble the modules fromthe PCBs has two parts similar to the press−in tool. The
lower part serves as a support for the PCB. It has a cavity andsupporting pins. It is important that the size of the cavity isclose to the dimensions of the module. The supporting pins
are in line with the fixing pins of the upper part. There may
be components mounted to the PCB in the area of the tool,in such case it is possible to cut out the nest.
The upper part consists of two pressing plates that areconnected by springs. The pins on the lower plate serve to
fix the PCB. With the aid of these parts, the bending of the
PCB can be prevented during pressing.
The ram fastened to the upper plate is designed according
to the positions of the parts on the PCB and the layout of thepins.
It is not possible to press the module out with a flat plateif the PCB is thicker than 2.5 mm due to the overhang of thepins. In this case, pressing sticks positioned according to thepin layout are necessary.
Recommended spring force: 25 N/mm
Recommended number of springs: 4 pcs

The press−out tool consists of an upper and a lower
press−out tool, as shown in Figure 26. The upper press−out
tool should be parallel and aligned to the lower press−out
tool (a). The assembled board should be placed on the lower
press−in tool (b). The upper press−out tool moves down andcontacts the projecting part of the pins. Press−out force
should be applied to all pins evenly within 3−12 mm/min ofpress−out speed according to IEC 60352−5 (c). The module
falls down to the lower tool as it is disassembled from the
PCB. The press−out distance should be monitored to ensure
the upper press−out tool does not apply unnecessarypressure on the PCB after the module is fully pressed−out(d).
Press−out Tool Design

The upper and lower press−out tools should be parallel toeach other to prevent stress on the module during press−out
process. Some pins may have contact with the upperpress−out tool while other pins have no contact with tool.
Pulling force can be exerted on the press−fit pins where
upper the press−out tool does not contact.
The press−out tool design should consider othercomponents assembled on the PCB next to the module

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Wave soldering profile

Figure 28. Press−out Failure Mode: Upper and Lower
Press−out Tools Not Parallel

Due to the stress relaxation between contact partners, theinitial contact force tends to reduce over time. In addition,
the press−out force varies in relation to the contact ratio
between press−fit pin and plated through hole. As shown in
Table 6, the press−out force should be higher than 40 N per
pin.

Figure 30. Wave Solder Profile

MODULE MOUNTING TO HEATSINKThis section describes how the modules are mounted tothe heatsink. The different module family members havedifferent sized mounting holes and recommendations.
It is extremely important that the contact surface ofheatsink must be flat and free of particles. Avoid handlingthe heatsink surface with bare hands or contacting with any
foreign materials. If it is necessary to remove
contaminations from heatsink, please clean it using a dry
cloth soaked with solvent such as isopropyl or ethylene
alcohol.

Table 6. PRESS−OUT FORCE AND SPEED
SPECIFICATION
Min.
Press−Out Force (per Pin)
Press−Out Speed

Typ.

Max.

40 N
3–12 mm/min

This condition is automatically fulfilled with the use of therecommended press−in tool.

Methods of Screw Clamping

There are two recommended screw clamping methods
which apply to all modules. The F1 module is used as an
example. Figure 31 describes one method for fastening themodule to the heatsink. Fasten two screws simultaneously toprevent tilting or rising of one side of module during
fastening. Electric screwdrivers can tighten the screws withthe specified torque. Additional flat or spring washers are
permissible, considering clearance and creepage distances
specified later in this section.
Screw holes on heatsink need to be countersunk.
If method 1 cannot be applied, the method as described in
Figure 32 is also acceptable. Fasten the first screw loosely
to prevent tilting or rising of the module (step 1). Then insert
the second screw with final torque so as to be fully tightenedwith the heatsink (step 2). Finally, apply full torque to thefirst screw for solid tightening with the heatsink.

SOLDERING TO PCBPCB holes with fully plated through−holes will enable
100% wetting and fillets between pin and both sides of PCB.

Figure 29. Solder Wetting of PCB Through Holewww.onsemi.com
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Mtorque
1.6−2.0 Nm

Mtorque
1.6−2.0 Nm

Figure 31. Illustration of Screw Clamping with Heatsink (Method 1)
Torque Values Apply to F1/F2 Packages. See Later Diagrams for Other Packages

Mtorque
1.6−2.0 Nm

Mtorque
1.6−2.0 Nm

Figure 32. Screw Clamping Steps (Method 2)
Torque Values Apply to F1/F2 Packages. See Later Diagrams for Other Packages
F1/F2/Q0/Q1 Modules

This has to be taken into account to prevent over−tightening
the fastener.
Due to excessive temperature fluctuations washers should
be used to prevent the loosening of the screws. After
accurate tightening of the screws the spring washer exerts
a constant force on the joint. The flat washer distributes thisforce on the plastic surface.
When using screws with pre−assembled washers:
Screws with pre−assembled washers (SEMS or kombi
screws) combine the screw and the washers into a single
component. These screws eliminate the need to slip the

When using screws with flat washers:
Metric screw: M4 (recommended screw type DIN7984)
Flat washer: D = 8 mm ISO 7092 (DIN 433)
Spring washer: D = 8 mm DIN 127 or DIN 128
Mounting torque: 1.6−2.0 Nm
Screw holes on heatsink need to be countersunk.
A torque wrench shall be used to tighten the mounting
screws at the specified torque. Excessive torque may resultin damage or degradation of the device. The inaccuracy of
torque wrench tightening method can range up to ±12%.

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MOUNTING HEATSINK AND MODULE TO PCB

washers into place by hand, boosting the speed andefficiency of the assembly process. The specifications ofthese screws are provided below:
Screw size: M4 according to DIN 6900 (ISO 10644;
JIS B1188)
Flat washer: According to DIN 6902 Type C (ISO 10673
Type S; JIS B1256)
Washer outer diameter:
8 mm diameter can be fitted onto the module
Split lock spring washer:
According to DIN 6905(JIS B1251)
Mounting torque range: 1.6−2.0 Nm
See Figure 33.

Mounting screws for attaching module to PCB

Screwing the PCB to the stand−offs on the module is oneof the assembly methods. By adding this screw connection
to the stand−offs, securing the assembly of module and PCB
can be expected. Figure 35 shows the key dimensions of thestand−off. Self−tapping screws are recommended so that thescrews form the thread in the hole.
For F1 and F2 modules, metric screws, self−tapping, withdimensions of 2.5xL or 2.6xL have been verified. The lengthof the screws (L) may differ depending on the thickness of
the PCB. Typically, an 8 mm long screw (M2.5X8) can beused with 1.6 mm−thick PCB. Recommended mounting
torque is 0.4~0.5 Nm for each screw. See Figure 30. Thisshows the recommended sequence for mounting the PCB tothe module. Straight inserting avoids mechanical damage tothe module case. An electric screwdriver helps achieve
uniform force and speed for inserting the screws.
For Q2 modules, metric screws, self−tapping, withdimensions of 2.5xL have been verified. The length of thescrews (L) may differ depending on the thickness of the
PCB. Typically, an 8 mm long screw (M2.5X8) can be usedwith 1.6 mm−thick PCB. Recommended mounting torque is0.3~0.5 Nm for each screw. See Figure 36. This shows therecommended sequence for mounting the PCB to themodule. Straight inserting avoids mechanical damage to themodule case. An electric screwdriver helps achieve uniform
force and speed for inserting the screws.
Q0 and Q1 modules do not have screw holes for mounting
onto the PCB.

Step 2: pre−mountwith 0.4−0.6N.M
Step 1: pre−mountwith 0.4−0.6N.M

Step 3: mount with
1.6−2N.M

Step 4: mount with
1.6−2N.M

Figure 33. Q0/Q1 Modules − Mounting to Heatsink
Q2 Modules

Use M5 screws with torque of 3.0–5.0 Nm.
See Figure 34.

Figure 34. Q2 Modules − Mounting to Heatsink
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Figure 35. Q2 Screw Clamping on Stand−offs and Key Dimensions of Screw HoleNOTE: Do not screw the PCB down to the stand−offs of
the module if an air gap remains between case
top and PCB after press−in. This can lead to
deformation of the PCB or other mechanicaldamage.

multiple modules are applied to the same PCB, heighttolerance between modules can result in the mechanicalstresses on the board and modules. To reduce stress, spaceposts should be added on the heatsink, as illustrated in toprevent movement of the PCB.
The recommended height of the space posts is 12.4(+0/−0.1) mm. The effective distance between center ofstand−off and the space post (= X) is 50 mm minimum. If
distance keepers are used during the press−in process,resulting in tighter height tolerances; distances between the

Assembly of the PCB and Heatsink

The overall structure of the mounted module should beconsidered.
If the PCB is large and heavy with other components
assembled to it, there is some risk the PCB can bend, creating
mechanical stress to the module and the PCB. When

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tolerances between module and PCB is important. Next, thethermal interface material is applied. Then the modules andthe PCB are placed on the heatsink (a).
Then the module is mounted onto the heatsink via themodule’s metal or plastic clamp. Refer to Section “Q2Modules” for instructions of screw clamping (b). Finally, the
PCB needs to be fixed on the space posts, as described in (c).

stand−off of the case and the space post (= X) smaller than
50 mm can be used.
Figure 36 shows the assembly procedure when spaceposts are used and the overall assembly structure:
Modules are first pressed into the PCB following therecommendations introduced in Section “Heatsink Surface”
before heatsink mounting. Maintaining tight height

Figure 36. Space Posts for Assembly of PCB to Heat Sink

Figure 37. Example of Whole Assembly Process for PCB and Heatsink with Space Posts

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HANDLING OF PCM PRE−APPLIED MODULES

During the assembly process, a single pin is not allowed
to be drawn or pushed inwards or outwards from substrate
more than ±0.2 mm or loaded with a force greater than 35 N
(except during pressing−in of press−fit pins). The special
design of press−fit pins prevents a deformation of pins
greater than 0.1 mm during the press−in process. The tensionof the pin must not exceed ±5 N at a maximum substratetemperature of 100°C.

Transport and Storage

During transport and storage of the modules extreme
thermal and mechanical shock should be avoided. The tray
box is designed to prevent direct contact to the PCM layerof the module substrate. PCM−pre applied modules should
be stored in this tray box. Table 7 shows optimum storage
conditions. Please note that storage of PCM pre−applied
modules above its phase change temperature (45°C) is notrecommended.

Creepage and Clearance Considerations

The spacing of the assembly between the module and PCB
must meet the clearance and creepage distance required by
the relevant standards. After F1 or F2 modules are mounted
to the PCB and heatsink, the minimum clearance is the
distance between the screw head and the bottom surface of
the PCB. The size (height) of the screw head and potential
use of an additional washer, as well as the air gap between
PCB and top side of the module, influence the creepage
distance between the screw and the PCB and the module
pins. F1 and F2 modules are mounted on the heatsink using
M4 hexagon socket head screws, according to ISO 4762.
Additional washers, according to ISO 7089, can be used.
A distance of 6.8 mm between the screw and the PCB, as
shown in Figure 38, can be maintained.

Table 7. PCB RECOMMENDED STORAGE
CONDITIONSStorage Temperature

10 − 40°C

Humidity Conditions

10 < RH < 55%

Storage Duration

Max. 12 months

Handling

PCM printing layer should be treated as a functional areaof the module and be protected from damage or removing
during handling or mounting process. PCM pre−applied
module is delivered in a tray box with a tight cover. It is
recommended to open the cover carefully side−by−side toprevent mechanical damage to the PCM layer. During theassembly process attention is needed not to touch the PCM
layer directly. If the PCM layer is contaminated or more than
10% of the entire printed area is damaged, it isrecommended to remove the PCM layer according to theguidance provided below, and to apply thermal grease
instead.
Disassembly, Cleaning, and Rework

In case of a failure or if rework is required it may benecessary to disassemble the module. In case of rework prior
to operation of modules, standard PCB / heat sinkdisassembly process can be applied. If the module wasoperated and the PCM melted and distributed already, thenbond strength between heat sink and the module may bestrong, and the module cannot be easily removed from theheatsink. In such cases it is recommended to use a knife todetach the module or apply some heat (45−60°C) to re−melt
PCM to detach the module easily. Use a soft plastic scraper
to remove the PCM layer from the module back side and heatsink. For the removal of remaining PCM residues it isrecommended to use microfiber cloth.

Figure 38. Distance between PCB and Screw

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