ON Semiconductor Q0, Q1, Q2, F1, F2 User Manual
Mounting Instructions for
PIM Modules (Q0, Q1, Q2,
F1, F2)
AND9867/D
Introduction
This application note covers the mounting instructions for
ON Semiconductor 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
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APPLICATION NOTE
ON Semiconductor 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 with press−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 and
provides 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 performance
with either press−fit or solder connections.
Figure 1. Q1 Module with PCB and
Heatsink
Figure 2. Press−fit Process
© Semiconductor Components Industries, LLC, 2019
January, 2021 − Rev. 2
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.
PCB Specification
The schematic structure of a plated through hole is shown
in Figure 3. If the initial drilled hole diameter is too small,
the press−in force into the PTH will be too high and
mechanical damage on both press−fit pin and PTH will
occur. If the final hole diameter is too small, damage to the
pin 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 and
clearance between pins should always be considered in
minimum permissible spacing calculations.
Figure 3. Cross−section of PCB
Tables 1−4 list the recommended PCB specification based
on the evaluation of the press−fit technology according to
the IEC 60352−5 standard.
Specification for Modules with Press−fit Pins,
Soldered to the PCB
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 the
contact.
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 and
clearance between pins should always be considered in
minimum 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 and
Q2 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 and
clearance between pins should always be considered in
minimum 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.
Table 1. PCB SPECIFICATIONS FOR F1 AND F2
MODULES WITH 1.2 MM PRESS−FIT PINS −
IMMERSION OR GALVANIC TIN. Pins are IEC qualified for
immersion tin plating.
Min. Typ. Max.
Initial Drilled Hole Diameter Ø [mm] 1.12 1.15
Cu Thickness in the Hole [mm]
Sn Thickness [mm] (Chemical Tin)
Final Hole Ø [mm] 0.98 1.09
Annular ring [mm]
Thickness of Conductive Layer [mm]
Board Thickness [mm] 1.6
Figure 4.
25 50
15
200
35 70−105 400
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AND9867/D
Table 2. PCB SPECIFICATIONS FOR F1 AND F2
MODULES WITH 1.2 MM PRESS−FIT PINS − HAL
PLATING.
immersion/galvanic tin is recommended for more consistent
mounting.
Initial (Drill) Hole Ø [mm] 1.12 1.15
Cu Thickness in the Hole [mm]
Sn Thickness [mm]
Final Hole Ø [mm] 0.94 1.09
Annular ring [mm]
Thickness of Conductive Layer [mm]
Board Thickness [mm] 1.6
Pins are IEC qualified for HAL plating but
Min. Typ. Max.
25 50
40
200
35 70−105 400
Table 4. PCB SPECIFICATIONS FOR Q0, Q1 AND Q2
MODULES WITH 1.6 MM PRESS−FIT PINS − HAL
PLATING.
immersion/galvanic tin is recommended for more consistent
mounting.
Initial (Drill) Hole Ø [mm] 1.57 1.60
Cu Thickness in the Hole [mm]
Sn Thickness [mm]
Final Hole Ø [mm] 1.41 1.56
Annular ring [mm]
Thickness of Conductive Layer [mm]
Board Thickness [mm] 1.6
Pins are IEC qualified for HAL plating but
Min. Typ. Max.
25 50
40
200
35 70−105 400
Figure 5.
Table 3. PCB SPECIFICATIONS FOR Q0, Q1 AND Q2
MODULES WITH 1.6 MM PRESS−FIT PINS −
IMMERSION OR GALVANIC TIN.
immersion tin plating.
Initial Drilled Hole Diameter Ø [mm] 1.57 1.60
Cu Thickness in the Hole [mm]
Sn Thickness [mm] (Chemical Tin)
Final Hole Ø [mm] 1.41 1.56
Annular ring [mm]
Thickness of Conductive Layer [mm]
Board Thickness [mm] 1.6
Pins are IEC qualified for
Min. Typ. Max.
25 50
15
200
35 70−105 400
Figure 7.
Table 5. PCB SPECIFICATIONS FOR F2 MODULES
WITH EON PRESS−FIT PINS − IMMERSION OR
GALVANIC TIN.
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 this
requires additional approval from ON Semiconductor.
Initial Drilled Hole Diameter Ø [mm] 1.12 1.15
Cu Thickness in the Hole [mm]
Sn Thickness [mm] (Chemical Tin)
Final Hole Ø [mm] 1.02 1.09
Annular ring [mm]
Thickness of Conductive Layer [mm]
Board Thickness [mm] 1.6
Pins are IEC qualified for immersion tin
Min. Typ. Max.
25 50
15
200
35 70−105 400
Figure 6.
Figure 8.
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AND9867/D
PCB DESIGN
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 the
plated through hole were conducted with FR4 PCB. Various
sizes (0603, 0805, 1206, 1210, 1812, and 2220) of
mechanically sensitive components were evaluated. Based
on experimental results, the recommended minimum space
between center of the plated through hole and the edge of the
component is 4 mm, as shown in Figure 9.
Mounting with Distance of 12 mm
Option 1: without spacers
Figure 10. Mounting Height with Module as Spacer
Option 2: with spacers
Figure 11. Mounting Height with Spacer in case of
using 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. Electrical
connections are made by connecting these terminals to
a print circuit board (PCB) by soldering or press−fit
technology.
Figure 9. PCB Design Restriction: Distance
from Center of PTH to Edge of Components
The minimum distance between the edge of the PCB and
the centre of the pin hole must be more than 4 mm.
The minimum distance between the center of the pin hole
and a neighbored component on the PCB must be more than
4 mm.
Recommended PCB−thicknesses and Mounting
Heights by Module Type
The distance between the top surface of the heatsink and
the bottom plane of the PCB is defined by the module height
of 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 of
the circuit, location of different masses like capacitors or
inductor and the environment of the system. General
recommendations 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, the
PTH 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 to
be dissipated to protect against overheating. In general,
module operation temperature should not exceed the
maximum allowable junction temperature (T
in the datasheet. Thermally conductive metal heatsinks that
absorb and disperse heat are commonly used for cooling
high power electronics. The thermal performance of
a module, in combination with a heatsink, can be
characterized by the thermal resistance R
sum of all thermal resistances in the thermal path:
junction−to−case (R
), and heatsink−to−ambient (R
(R
sink
q
), case−to−heatsink (R
jc
q
sa
q
Figure 13.
) specified
Jmax
, which is the
ja
q
), heatsink
cs
q
), as shown in
Figure 14. Microscopic View of Surfaces.
A is Flatness and B is Roughness (Rz)
The interface surface of the heatsink must be free of
particles 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 with
solvent, such as isopropyl or ethylene alcohol.
Figure 13. Thermal Model of Power Module &
Heatsink
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 area
of 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 thermally
conductive 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 to
maximize heat transfer. Rough surfaces result in large voids
between the substrate of the module and the surface of the
heatsink. The following surface qualities are required for the
heatsink to achieve a good thermal conductivity, according
to DIN 4768−1. Roughness (Rz) should be 10 mm or less and
flatness, 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.
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 the
module 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.
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AND9867/D
(a)
(b)
Figure 15. (a) Heat Transfer, Module to Heatsink,
(b) Heat Transfer with Thermal Interface Material
Thermal interface materials are widely used in the
industry to fill air gaps between contact surfaces. Thermal
interface material provides better thermal performance than
air and compensates for imperfect mating surfaces, such as
roughness and flatness shown in Figure 14. There are
various thermal interface materials available in the market.
The right choice of material is an essential factor for the
application. 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
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.
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 to
fill the gap between two contact surfaces completely. Check
the thermal grease thickness with thickness gauges, such as
wet film combs or wet film wheels. Because manual control
of the printing pressure and speed can be learned by
experience, training is needed to achieve a technique for
good quality printing layer in real application.
Alternatively, apply thermal paste by screen printing, for
example 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 is
re−mounted, surfaces should be cleaned and TIM needs be
applied again.
Pre−applied Thermal Interface Material
As an option the module may be prepared or provided with
a pre−applied PCM layer. The recommended pattern for
such 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 the
module 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 16. Applying Thermal Grease
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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.
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