3M™ Thermally Conductive Adhesive Tape 8940 / 8943
Product Information Sheet
11.04.2007
Supersedes Version 01.10.2005
Product Description
3M
TM
Thermally Conductive Adhesive Tapes 8940 / 8943 are
designed to provide an efficient heat transfer path between heat
generating components and heat sinks or other cooling devices.
The tapes consist of a carrier, highly loaded with thermally conductive
fillers, coated on either one side (3M
TM
8943) or both sides (3M
TM
8940) with a high temperature resistance acrylic pressure sensitive
adhesive.
The specialized construction securely bonds the heat generating
components to heat sinks and offer both, good thermal conductivity
and excellent electrical insulation properties.
Product Construction
3M 8940
Color
Carrier
Adhesive type
Tape type
Tape Thickness
Liner Thickness
3M 8943
Beige
Filled Copolymer
Modified Acrylic Adhesive
Double coated
Single coated
0.170 mm
0.190mm
0,075 mm
The film liner is a double sided siliconized Polyester Film with a
differential release system.
Typical Applications
Applications requiring good thermal transfer and thin bonding.
Typical applications are assembling of power devices as bare dies in
chip on board technique or flip chip assemblies with a directly
mounted heat sink.
The tape performance properties have been primarily adapted to fit
thermal requirements in applications such as Engine Control Units
bonding, ABS Systems, High power LED’s, and other electronic
increased power devices.
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3M™ Thermally Conductive Adhesive Tapes 8940 / 8943
Typical Properties
and Performance
Characteristics
Thermal Properties
Note: The following technical information for 3M
TM
Thermally Conductive
Tape 8940 / 8943 should be considered representative or typical only and
should not be used for specification purposes.
Test
Thermal Conductivity at 25 °C
Coefficient of Thermal Expansion
(-40 to 150°C)
Test
Unit
W/m*K
mm/°C
Value
0,9
140 E -06
Test Method
ASTM D 5470
TMA
Electrical
Properties
Unit
kV
kV/mm
Ω*cm
Value
8940 8943
10.3
9.8
55
52
2,5 x 10
13
Test Method
IEC 60243-1
IEC 60243-1
ASTM D257
Breakdown Voltage typical value *
Dielectric Strength typical value *
Volume Resistivity
* Average value (not for specification purposes)
Mechanical
Properties
90° Peel Adhesion to
Aluminium Substrate
(AlMg
3
; R
a
: 0,48 µm; R
z
: )µm)
Test
20 min dwell time at room temp.
24 h dwell time room temp.
at 150 °C
at 180 °C
Unit
N/cm
N/cm
N/cm
N/cm
MPa
MPa
MPa
MPa
Minutes
Minutes
N/mm²
%
cN/25,4
mm
Visual
Value
5,0
6,0
4,9
2,4
5,3
9,0
6,8
9,0
10000+
10000+
6-7
80-120
15
Test Method
AFERA 5001
AFERA 5001
AFERA 5001
AFERA 5001
ASTM D 1002
ASTM D 1002
ASTM D 1002
ASTM D 1002
Overlap Shear
20 min dwell time at room temp.
24 h dwell time room temp.
After 24 h @ 150 °C
After 24 h @ - 40 °C
1000 g load @ room temp.
500 g load @ 70 °C
Tensile Strength
Elongation at break
Liner release
Holding Power
AFERA 4012
AFERA 4012
EN ISO 527-2
EN ISO 527-2
FINAT TM3
Tensile strength
Liner properties
Temperature
Performance
Thermal Stability
225 °C Dwell @ 60 min
(Tape was applied between a glass
and an aluminium panel)
Solder Reflow process according
to JEDEC J-STD-020C (Level 1)
Continuous Operating Temperature
Range
No Change
3M
Visual
°C
Test in
process
- 40 up to
150
3M
3M
2/4
3M™ Thermally Conductive Adhesive Tapes 8940 / 8943
Test
Unit
Value
Test Method
Thermal
Resistance
Properties
Thermal Gravimetric Analysis *
Mass loss at 200 °C
Mass loss at 150 °C after 4 h
%
%
< 0,2
< 0,3
3M
Flame Class:
UL 94 V-0, File E253171, Flame rating applies to adhesive film (3M
TM
Thermally
conductive Tape 8940) bonded to 3.0 mm minimum thickness aluminium on one side and
0.86 mm minimum thickness FR-4 laminate on other side.
Application
Guidelines
1.) Substrate surfaces should be clean and dry prior to tape application. Isopropyl alcohol
(isopropanol) applied with a lint-free wipe or swab should be adequate for removing
surface contamination such as dust or finger prints. Do not use “denatured alcohol” or glass
cleaners which often contain oily components. Allow the surface to dry for several minutes
before applying the tape. More aggressive solvents (such as acetone, methyl ethyl ketone
(MEK) or heptane) may be required to remove heavier contamination (grease, machine oils,
solder flux, etc.) but should be followed by a final isopropanol wipe as described above.
Note:
Be sure to read and follow the manufacturers’ precautions and directions when using
primers and solvents.
2) Apply the tape to one substrate at a modest angle with the use of a squeegee, rubber roller
pressure to help reduce the possibility of air entrapment under the tape during its
application. The liner can be removed after positioning the tape onto the first substrate.
3) Assemble the part by applying compression to the substrates to ensure a good wetting of
the substrate surfaces with the tape. Proper application of pressure (amount of pressure,
time applied, temperature applied) will depend upon design of the parts. The preferred pressure at
room temperature is a minimum of 1 kg/cm
2
for 5 seconds. For fragile parts lower pressure may be
needed.
Rigid substrates are more difficult to bond without air entrapment as most rigid parts are not flat.
Flexible substrates can be bonded to rigid or flexible parts with much less concern about air
entrapment because one of the flexible substrates can conform to the other substrate.
Shelf Life
Product shelf life is 2 years from date of manufacture when stored at room temperature
conditions 22°C and 50% r.h. in the products original packaging.
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3M™ Thermally Conductive Adhesive Tapes 8940 / 8943
Important Notice
All statements, technical information and recommendations herein are based on tests we believe to be reliable, but the accuracy or completeness
thereof is not guaranteed. User is responsible for determining whether the 3M product is fit for a particular purpose and suitable for user’s
method of application. Please remember that many factors can affect the use and performance of a 3M product in a particular application. The
materials to be bonded with the product, the surface preparation of those materials, the product selected for use, the conditions in which the
product is used, and the time and environmental conditions in which the product is expected to perform are among the many factors that can
affect the use and performance of a 3M product. Given the variety of factors that can affect the use and performance of a 3M product, some of
which are uniquely within the user’s knowledge and control, it is essential that the user evaluate the 3M product to determine whether it is fit
for a particular purpose and suitable for the user’s method of application. All questions of liability relating to the 3M product are governed by
the terms of the sale subject, where applicable, to the prevailing law.
3M is a registered trademark of 3M Company.
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3M Deutschland GmbH
Electronics Markets and Materials Division
Carl-Schurz-Straße 1, 41453 Neuss
Telefon 0 21 31 / 14 33 30
Telefax 0 21 31 / 14 38 17
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