U.S. patent application number 11/803039 was filed with the patent office on 2008-03-06 for heat dissipation substrate for electronic device.
This patent application is currently assigned to Polytronics Technology Corporation. Invention is credited to Kuo Hsun Chen, Fu Hua Chu, David Shau Chew Wang, En Tien Yang, Jyh Ming Yu.
Application Number | 20080057333 11/803039 |
Document ID | / |
Family ID | 39152025 |
Filed Date | 2008-03-06 |
United States Patent
Application |
20080057333 |
Kind Code |
A1 |
Chu; Fu Hua ; et
al. |
March 6, 2008 |
Heat dissipation substrate for electronic device
Abstract
A heat dissipation substrate for an electronic device comprises
a first metal layer, a second metal layer, and a thermally
conductive polymer dielectric insulating layer. A surface of the
first metal layer carries the electronic device, e.g., a
light-emitting diode (LED) device. The thermally conductive polymer
dielectric insulating layer is stacked between the first metal
layer and the second metal layer in a physical contact manner, and
interfaces therebetween include at least one micro-rough surface
with a roughness Rz larger than 7.0. The micro-rough surface
includes a plurality of nodular projections, and the grain sizes of
the nodular projections mainly are in a range of 0.1-100 .mu.m. The
heat dissipation substrate has a thermal conductivity larger than
1.0 W/mK, and a thickness smaller than 0.5 mm, and comprises (1) a
fluorine-containing polymer with a melting point higher than
150.degree. C. and a volume percentage in a range of 30-60%, and
(2) thermally conductive filler dispersed in the
fluorine-containing polymer and having a volume percentage in a
range of 40-70%.
Inventors: |
Chu; Fu Hua; (Taipei,
TW) ; Wang; David Shau Chew; (Taipei, TW) ;
Yu; Jyh Ming; (Kaohsiung City, TW) ; Yang; En
Tien; (Taipei City, TW) ; Chen; Kuo Hsun;
(Miaoli County, TW) |
Correspondence
Address: |
SEYFARTH SHAW LLP
131 S. DEARBORN ST., SUITE2400
CHICAGO
IL
60603-5803
US
|
Assignee: |
Polytronics Technology
Corporation
|
Family ID: |
39152025 |
Appl. No.: |
11/803039 |
Filed: |
May 11, 2007 |
Current U.S.
Class: |
428/612 |
Current CPC
Class: |
H05K 3/384 20130101;
H05K 2201/10106 20130101; H05K 2201/015 20130101; H05K 1/034
20130101; H05K 2203/0307 20130101; Y10T 428/12472 20150115; H05K
2201/0209 20130101; H05K 1/0393 20130101; H05K 1/0373 20130101;
H05K 2201/09309 20130101 |
Class at
Publication: |
428/612 |
International
Class: |
B21D 39/00 20060101
B21D039/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 30, 2006 |
TW |
095131947 |
Claims
1. A heat dissipation substrate for an electronic device
comprising: a thermally conductive polymer dielectric insulating
layer comprising: (1) a fluorine-containing polymer with a melting
point higher than 150.degree. C. and a volume percentage in a range
of 30-60%; and (2) thermally conductive filler dispersed in the
fluorine-containing polymer and having a volume percentage in a
range of 40-70%; a first metal layer having a micro-rough surface
which is in direct physical contact with one surface of the
thermally conductive polymer insulating layer, and consists
essentially of nodules which protrude from the surface by a
distance of 0.1 to 100 microns with roughness Rz larger than 7.0;
and a second metal layer having a micro-rough surface which is in
direct physical contact with the other surface of the thermally
conductive polymer insulating layer, and consists essentially of
nodules which protrude from the surface by a distance of 0.1 to 100
microns with roughness Rz larger than 7.0; wherein the heat
dissipation substrate has a thermal conductivity larger than 1.0
W/mK.
2. The heat dissipation substrate for an electronic device in
accordance with claim 1, wherein the first metal layer has a
thickness smaller than 0.1 mm.
3. The heat dissipation substrate for an electronic device in
accordance with claim 1, wherein the second metal layer has a
thickness smaller than 0.2 mm.
4. The heat dissipation substrate for an electronic device in
accordance with claim 1, wherein the fluorine-containing polymer
has a melting point higher than 220.degree. C.
5. The heat dissipation substrate for an electronic device in
accordance with claim 1, wherein the thermally conductive filler
has a volume percentage of 45-65%.
6. The heat dissipation substrate for an electronic device in
accordance with claim 1, wherein tensile strength between the
thermally conductive polymer dielectric insulating layer and the
first and second electrode layers is larger than 8 N/cm.
7. The heat dissipation substrate for an electronic device in
accordance with claim 1, wherein a surface of the heat dissipation
substrate neither is ruptured nor has cracks when the heat
dissipation substrate is 1 cm wide and is bent 180 degree along the
exterior circumference of a metal rod with a diameter of 5 mm.
8. The heat dissipation substrate for an electronic device in
accordance with claim 1, wherein the heat dissipation substrate has
a withstand voltage larger than 3 kV.
9. The heat dissipation substrate for an electronic device in
accordance with claim 1, wherein the fluorine-containing polymer is
selected from the group consisting of poly vinylidene fluoride and
polyethylenetetrafluoroethylene.
10. The heat dissipation substrate for an electronic device in
accordance with claim 1, wherein the fluorine-containing polymer is
selected from the group consisting of poly(tetrafluoroethylene),
tetrafluoroethylene-hexafluoro-propylene copolymer,
ethylene-tetrafluoroethylene copolymer, perfluoroalkoxy modified
tetrafluoroethylenes, poly(chlorotri-fluorotetrafluoroethylene,
vinylidene fluoride-tetrafluoroethylene copolymer, poly(vinylidene
fluoride), tetrafluoroethylene-perfluorodioxole copolymer,
vinylidene fluoride-hexafluoropropylene copolymer, vinylidene
fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, and
tetrafluoroethylene-perfluoromethylvinylether with cure site
monomer terpolymer.
11. The heat dissipation substrate for an electronic device in
accordance with claim 1, wherein the thermally conductive filler is
nitride or oxide.
12. The heat dissipation substrate for an electronic device in
accordance with claim 11 wherein the nitride is selected from the
group consisting of zirconium nitride, boron nitride, aluminum
nitride, and silicon nitride.
13. The heat dissipation substrate for an electronic device in
accordance with claim 11, wherein the oxide is selected from the
group of aluminum oxide, magnesium oxide, zinc oxide, and titanium
dioxide.
14. The heat dissipation substrate for an electronic device in
accordance with claim 1, wherein the heat dissipation substrate is
irradiated by 0-20 Mrads, so as to make the thermally conductive
polymer dielectric insulating layer cross-linked and cured.
15. The heat dissipation substrate for an electronic device in
accordance with claim 1, wherein the electronic device is a
light-emitting diode device.
16. The heat dissipation substrate for an electronic device in
accordance with claim 1, wherein the first metal layer comprises
copper.
17. The heat dissipation substrate for an electronic device in
accordance with claim 1, wherein the second metal layer comprises
aluminum.
Description
BACKGROUND OF THE INVENTION
[0001] (A) Field of the Invention
[0002] The present invention relates to a heat dissipation
substrate, and more particularly to a heat dissipation substrate
for an electronic device.
[0003] (B) Description of the Related Art
[0004] In recent years, white LEDs have become a very popular new
product attracting widespread attention all over the world. Because
white LEDs offer the advantages of small size, low power
consumption, long life, and quick response speed, the problems of
conventional incandescent bulbs can be solved. Therefore, the
applications of LEDs in backlight sources of displays,
mini-projectors, illumination, and car lamp sources are becoming
increasingly important in the market.
[0005] At present, Europe, the United States, Japan, and other
countries have a consensus with respect to energy conservation and
environmental protection, and actively develop the white LED as a
new light source for illumination in this century. Currently,
energy is imported in many countries, so it is worthwhile to
develop the white LED in the illumination market. Based on the
evaluation of experts, if all the incandescent lamps in Japan are
replaced with the white LEDs, electric power generated by two power
plants can be saved each year and the indirectly reduced fuel
consumption will be one billion liters. Furthermore, carbon dioxide
exhausted during electrical power generation is also reduced,
thereby reducing the greenhouse effect. Therefore, countries in
Europe, America, and Japan have devoted a lot of manpower to white
LED development. It is predicted that the white LEDs can be
substituted for conventional illuminating apparatuses within ten
years.
[0006] However, with regard to a high power LED for illumination,
merely 15-20% of the input power of the LED is converted into
light, and the rest of the input power is converted into heat. If
the heat cannot be dissipated into the environment in time, the
temperature of the LED device will become so high that the luminous
intensity and service life are negatively affected. Therefore, the
heat management of the LED device attracts a lot of attention.
[0007] Generally, for single conventional LED, the working current
of a single conventional LED is about 20 to 40 mA, which produces a
small amount of heat, so the heat dissipation problem is not a
serious problem. Therefore, a common FR4 printed circuit board
(PCB), which exhibits a heat dissipation coefficient of about 0.3
W/mK, is sufficient enough to dissipate heat. However, for
backlight display and bright illumination applications, a plurality
LED devices are mounted to a circuit substrate. Due to the demand
of higher current (>1 A) and the resulting much higher heat
generation from LED devices, the circuit substrate should play the
role not only as a carrier for LED devices, but also as a heat sink
for heat dissipation. The common FR4 PCB cannot satisfy the heat
dissipation requirement.
SUMMARY OF THE INVENTION
[0008] The present invention is mainly directed to providing a heat
dissipation substrate with superior heat dissipation, the ability
to withstand high voltage, and dielectric insulation, a flexible
mechanical structure, in which metal layers are well bonded with
thermally conductive polymer dielectric insulating layers, so that
it can be applied to a high power LED device, for example, a
portable mobile phone.
[0009] In accordance with the present invention, a heat dissipation
substrate for an electronic device comprises a first metal layer, a
second metal layer, and a thermally conductive polymer dielectric
insulating layer. The surface of the first metal layer carries the
electronic device such as an LED device. The thermally conductive
polymer dielectric insulating layer is in physical contact with and
stacked between the first metal layer and the second metal layer.
The interfaces between the thermally conductive polymer dielectric
insulating layer and the first and second metal layers comprise at
least one micro-rough surface with a roughness Rz larger than 7.0
according to JIS B 0601 1994. The micro-rough surface comprises a
plurality of noduar projections with a grain size mainly in a range
of 0.1-100 .mu.m. The thermally conductive polymer dielectric
insulating layer has a thermal conductivity larger than 1 W/mK, and
a thickness smaller than 0.5 mm. The thermally conductive polymer
dielectric insulating layer comprises (1) a fluorine-containing
polymer with a melting point higher than 150.degree. C. and a
volume percentage of 30-60%, and (2) thermally conductive filler
dispersed in the fluorine-containing polymer and having a volume
percentage in the range of 40-70%.
[0010] The heat dissipation substrate of this invention comprising
a thermally conductive polymer dielectric insulating layer, a first
metal layer and a second metal layer. The thermally conductive
polymer dielectric insulating layer comprises (1) a
fluorine-containing polymer with a melting point higher than
150.degree. C. and a volume percentage in a range of 30-60%; and
(2) thermally conductive filler dispersed in the
fluorine-containing polymer and having a volume percentage in a
range of 40-70%. The first metal layer has a micro-rough surface
which is in direct physical contact with one surface of the
thermally conductive polymer insulating layer, and consists
essentially of nodules which protrude from the surface by a
distance of 0.1 to 100 microns with roughness Rz larger than 7.0.
The second metal layer has a micro-rough surface which is in direct
physical contact with the other surface of the thermally conductive
polymer insulating layer, and consists essentially of nodules which
protrude from the surface by a distance of 0.1 to 100 microns with
roughness Rz larger than 7.0. The heat dissipation substrate has a
thermal conductivity larger than 1.0 W/mK, and the total thickness
of the substrate is smaller than 0.5 mm.
[0011] The fluorine-containing polymer is preferably selected from
poly vinylidene fluoride (PVDF) or polyethylenetetrafluoroethylene
(PETFE), and has a melting point higher than 150.degree. C., and
preferably higher than 220.degree. C. The conductive filler is
selected from thermally conductive ceramic materials such as
nitride and oxide. The filler can be pretreated with silane
coupling agent to improve the bonding with the fluorine-containing
polymer.
[0012] The fluorine-containing polymer is known for its non-stick
and lack of adhesion characteristics. The most common practice to
bond fluorine-containing polymer to the metal surface is to apply a
tie-layer between them. However, the commonly used tie-layer for
fluorine-containing polymer is not a good thermal conductive
material. Even a thin layer of the tie-layer could drastically
deteriorate the thermal conductivity of the system. It is a great
challenge to bond fluorine-containing polymer to metal substrate
and to simultaneously maintain good thermal conductivity. This
invention shows the application of nodulized metal foil to bond to
the highly filled thermal conductive fluoro-polymer without using
tie-layer to achieve good flexibility, good thermal conductivity,
and good voltage withstanding capability.
[0013] The heat dissipation substrate can be irradiated by 0-20
Mrad, so as to make the thermally conductive polymer dielectric
insulating layer cross-linked and cured, and has a favorable
thermally conductive and insulating effect. Further, if the
thicknesses of the first metal and the second metal are designed to
be smaller than 0.1 mm and 0.2 mm, respectively, and the thickness
of the thermally conductive polymer dielectric insulating layer is
designed to be smaller than 0.5 mm (preferably 0.3 mm), the heat
dissipation substrate may pass the flexural test in which a 1 cm
wide test substrate is bent to be a column with a diameter of 5 mm,
and the surface neither ruptures nor cracks, thereby being
applicable to a folded product.
[0014] Furthermore, the fluorine-containing polymer material
usually has a high melting point (for example, PVDF has a melting
point of 165.degree. C. and PETFE has a melting point of
260.degree. C.), and has the advantages of being flame retardant
and able to withstand high temperature. Therefore, the
fluorine-containing polymer is valued for safety applications.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 illustrates a heat dissipation substrate according to
an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0016] Referring to FIG. 1, an LED device 10 is carried by a heat
dissipation substrate 20. The heat dissipation substrate 20
includes a first metal layer 21, a second metal layer 22, and a
thermally conductive polymer dielectric insulating layer 23 stacked
between the first metal layer 21 and the second metal layer 22. The
LED device 10 is disposed on the surface of the first metal layer
21, and the interfaces between the first and second metal layers 21
and 22 and the thermally conductive polymer dielectric insulating
layer 23 are physically contacted, wherein at least one interface
is a micro-rough surface. The micro-rough surface has a plurality
of nodular projections with a grain size mainly in a range of
0.1-100 .mu.m, thereby increasing the tensile strength
therebetween.
[0017] The method of fabricating the heat dissipation substrate 20
is described as follows. The feeding temperature of a batch-type
blender (HAAKE-600P) is set to be 20.degree. C. higher than the
melting point (T.sub.m) of the material, and the pre-mixed
materials of the thermally conductive polymer dielectric insulating
layer 23 are added, and raw materials are placed in a steel cup and
uniformly stirred with a measuring spoon. Initially, the rotation
speed of the batch-type blender is 40 rpm, and 3 minutes later, the
rotation speed is increased to 70 rpm. The materials are blended
for 15 minutes and then taken out, thereby forming a
heat-dissipating composite material.
[0018] The heat-dissipating composite material is put into a mould
in a longitudinally symmetrical manner. The mould uses a steel
plate as an outer layer and has a thickness in the middle of, for
example, 0.15 mm. Teflon mold release cloths are disposed on the
upper and lower sides of the mould, respectively. First, the
heat-dissipating composite material is pre-heated for 5 minutes,
and then pressed for 15 minutes under a pressure of 150 kg/cm.sup.2
and a temperature equal to the blending temperature. Afterwards, a
heat dissipation sheet of a thickness of 0.15 mm is formed.
[0019] The first metal layer 21 and the second metal layer 22 are
disposed on the upper and lower sides of the heat dissipation sheet
and then pressed again, pre-heated for 5 minutes, and then pressed
for 5 minutes under a pressure of 150 kg/cm.sup.2 and a temperature
equal to the blending temperature, so as to form the heat
dissipation substrate 20, in which the thermally conductive polymer
dielectric insulating layer 23 is in the middle and the first metal
layer 21 and the second metal layer 22 are respectively attached
onto the upper and lower sides of the polymer dielectric insulating
layer 23.
[0020] Table 1 shows experimental results of the tension and
withstand voltage test of different roughness of metal layers. The
thermally conductive polymer dielectric insulating layer 23 uses
polyvinylidene fluoride (PVDF) with the melting point of
165.degree. C. as a base material, and thermally conductive fillers
Al.sub.2O.sub.3 and AlN are dispersed in the PVDF, wherein the
volume percentages of the two are 60% and 45%, respectively. In
this embodiment, the thickness of the thermally conductive polymer
material layer 23 is smaller than 0.3 mm. The adhesion test is
performed according to JIS C6481 specification for testing the
peeling strength of the interfaces.
TABLE-US-00001 TABLE 1 Thermal Conductive Metal Foil Polymer Layer
Peel Thermal Roughness Filler Filler Thickness Strength
Conductivity Withstanding Experiment Type (Rz) Type Vol % (mm)
(N/cm) (W/m K) Voltage Test Example 1 1 oz Cu 7.0 9.0
Al.sub.2O.sub.3 60 0.21 14.3 1.7 >5 kV Example 2 2 oz Cu 9.5
11.5 Al.sub.2O.sub.3 60 0.24 16.8 1.6 >5 kV Example 3 4 oz Cu
10.0 12.0 Al.sub.2O.sub.3 60 0.22 17.5 1.7 >5 kV Example 4 1 oz
Ni 9.5 11.5 AlN 45 0.21 15.4 1.2 >5 kV plated Cu Example 5 1 oz
Ni 9.5 11.5 Al.sub.2O.sub.3 60 0.23 16.9 1.7 >5 kV plated Cu
Example 6 2 oz Ni 10.0 12.0 Al.sub.2O.sub.3 60 0.23 17.8 1.6 >5
kV plated Cu Example 7 1 oz Ni 10.0 12.0 Al.sub.2O.sub.3 60 0.24
18.1 1.6 >5 kV Comparative 1 oz Cu 3.0 4.5 Al.sub.2O.sub.3 60
0.23 7.5 1.6 >5 kV Example
[0021] As shown in Table 1, the surface roughness (Rz) of the Comp.
case is in a range of 3.0-4.5, and is lower than those in the
Examples 1 to 7. The adhesion of the Comparative Example case is
7.5 N/cm, which is far less than those of the Examples 1 to 7. It
is obvious that a larger roughness can increase peeling strength
between the thermally conductive polymer dielectric insulating
layer and the first and second metal layers. Moreover, all
experimental cases can pass the withstand voltage test of 5 kV or
at least higher than 3 kV, and the thermal conductivity is larger
than 1.0 W/mK.
[0022] Table 2 shows a test comparison table of different types of
high polymers.
TABLE-US-00002 TABLE 2 Thickness of Thermal Conductive High Polymer
Thermal Peel Serial Molecular Material Conductivity Strength
Flexibility Withstanding Number Polymer Layer (mm) (W/m K) (N/cm)
(5 mm) Voltage Test Example 1 PVDF 0.22 1.6 14.5 PASS >5 kV
Example 2 PETFE 0.24 1.7 16.8 PASS >7 kV Comparative HDPE 0.21
1.7 15.7 PASS <2 kV Example 1 Comparative EPOXY 0.20 1.6 22.1
FAIL >5 kV Example 2
[0023] The experimental cases 1 and 2 use PVDF and PETFE
(Tefzel.TM.) as polymeric base materials, respectively, and the
thermally conductive filler is Al.sub.2O.sub.3. The polymers in the
Comparative Examples 1 and 2 are selected from HDPE and EPOXY
without fluorine. In the Examples and Comparative Examples, the
volume percentages of the polymers and the thermally conductive
filler are 40% and 60%, respectively, and the copper foils having
the same roughness Rz in the range of 7.0-9.0 are used as the first
metal layer and the second metal layer.
[0024] The Comparative Example of EPOXY comprises liquid EPOXY,
Novolac resin, dicyandiamide, urea catalyst, and Al.sub.2O.sub.3.
The liquid EPOXY selects Model DER331 of Dow Chemical Company, the
Novolac resin selects Model DER438 of Dow Chemical Company, the
dicyandiamide selects Dyhard 100S of Degussa Fine Chemicals, and
the urea catalyst selects Dyhard UR500 of Degussa Fine Chemicals.
The Al.sub.2O.sub.3 has a grain size in the range of 5-45 .mu.m,
and is manufactured by Denki Kagaku Kogyo Kabushiki Kaisya.
[0025] The EPOXY is prepared according to the following steps.
First, 50 phr of DER331 and 50 phr of DEN438 are mixed in a resin
kettle at a temperature of 80.degree. C. till becoming a
homogeneous solution. Then, 10 phr of Dyhard 100S and 3 phr of
Dyhard UR300 are added in the resin kettle and further mixed for 20
minutes at a temperature of 80.degree. C. Subsequently, 570 phr of
the Al.sub.2O.sub.3 filler are added into the resin kettle and
mixed till the filler is completely dispersed in the resin to form
a resin slurry. The gas contained in the resin slurry is removed in
a vacuum for 30 minutes. Then, the resin slurry is placed on a
copper foil surface, and another copper foil is laid on the surface
of the resin slurry, thereby forming a copper foil/resin
slurry/copper foil composite structure. The copper foil/resin
slurry/copper foil composite structure is placed in a metal frame
with a thickness of 3 mm. A rubber roller is used to flatten the
copper foil surface. The composite structure together with the
metal frame is placed in a furnace at a temperature of 130.degree.
C. to be pre-cured for 1 hour. Then, the composite structure
together with the metal frame is placed in a vacuum hot press
machine with a vacuum degree of 10 torr and a pressure of 50
kg/cm.sup.2 in order to be further cured for 1 hour at 150.degree.
C. The composite structure is cooled to be lower than 50.degree. C.
at a pressure of 50 kg/cm.sup.2 and is removed from the hot press
machine.
[0026] The test substrates used in the PVDF and PETFE experimental
cases and the HDPE and EPOXY Comparative cases have passed the
following tests.
[0027] 1. Flexibility: an 1 cm wide test specimen is bent 180
degree along the exterior circumference of a metal rod which has a
diameter of 5 mm, and the surface of the test specimen should has
neither ruptures nor cracks.
[0028] 2. Peel Strength Test: a 180 degree T-peel strength
measurement is applied to the test specimen (1.0 cm.times.12 cm) by
clamping the upper and lower metal foil at one end of the specimen,
and testing the sample under a constant tensile speed of 3 cm/min
in a tensile testing machine.
[0029] 3. Dielectric Strength (insulation withstanding voltage)
Test: it is a withstanding voltage test using Kikusui Model TOS5101
Withstanding Voltage Tester by applying 1 kV on the upper and lower
electrodes of the 1'' diameter specimen for 30 seconds and applying
a step increase 0.5 kV for each consecutive tests until the applied
voltage exceeds the withstanding voltage of the insulation layer of
the specimen.
[0030] As shown in Table 2, the Example 1 and Example 2 cases of
the fluorine-containing polymers PVDF and PETFE have superior
flexibility, and pass the withstanding voltage test since these two
could withstand a voltage higher than 5 kV. On the contrary, the
Comparative Example 1 using HDPE as the polymer passes the
flexibility test, however, fails the withstanding voltage test
since the HDPE system could only withstand a voltage lower than 2
kV, which is obviously lower than those in the Example 1 and
Example 2. Comparative Example 2 using EPOXY as the polymer passes
the withstanding voltage test, however, fails the flexibility
test.
[0031] Furthermore, the fluorine-containing materials such as PVDF
and PETFE are not easily caught on fire and do not support
combustion (meeting UL 94 V-0), and are much more suitable for
safety applications in comparison with HDPE or EPOXY.
[0032] The volume percentages of the fluorine-containing polymer
and the thermally conductive filler can be adjusted to some extent
and still have the same characteristics. The volume percentage of
the fluorine-containing polymer is preferably in the range of
30-60%; the volume percentage of the thermally conductive filler is
in the range of 40-70%, and more preferably in the range of
45-65%.
[0033] In addition to the aforementioned materials, the thermally
conductive high molecular polymer can be selected from the group of
poly(tetrafluoroethylene) (PTFE),
tetrafluoroethylene-hexafluoro-propylene copolymer (FEP),
ethylene-tetrafluoroethylene copolymer (ETFE), perfluoroalkoxy
modified tetrafluoroethylenes (PFA),
poly(chlorotri-fluorotetrafluoroethylene (PCTFE), vinylidene
fluoride-tetrafluoroethylene copolymer (VF-2-TFE), poly(vinylidene
fluoride), tetrafluoroethylene-perfluorodioxole copolymers,
vinylidene fluoride-hexafluoropropylene copolymer, vinylidene
fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, and
tetrafluoroethylene-perfluoromethylvinylether with cure site
monomer terpolymer.
[0034] The thermally conductive filler can be nitride and oxide,
wherein the nitride includes zirconium nitride (ZrN), boron nitride
(BN), aluminum nitride (AlN), and silicon nitride (SiN) and the
oxide includes aluminum oxide (Al.sub.2O.sub.3), magnesium oxide
(MgO), zinc oxide (ZnO), and titanium dioxide (TiO.sub.2).
[0035] Furthermore, in order to be used in the high power
light-emitting devices such as LEDs, the first metal layer 21
carrying the LED device 10 can be made of copper so as to fabricate
a relevant circuit of the LED device 10 thereon. The second metal
layer 22 on the bottom can be made of copper, aluminum, or an alloy
thereof.
[0036] The heat dissipation substrate of the present invention has
the advantages of high thermal conductivity, high withstanding
voltage, high tensile strength, and flexibility, so that it can be
applied in an LED module for illumination to dissipate heat.
Furthermore, the heat dissipation substrate can further be used in
more compact size portable devices, e.g., a notebook or a mobile
phone, in which higher efficiency of heat dissipation is
required.
[0037] The above-described embodiments of the present invention are
intended to be illustrative only. Numerous alternative embodiments
may be devised by those skilled in the art without departing from
the scope of the following claims.
* * * * *