U.S. patent application number 11/996580 was filed with the patent office on 2009-05-21 for heat transfer member, convex structural member, electronic apparatus, and electric product.
This patent application is currently assigned to SUMITOMO ELECTRIC INDUSTRIES, LTD.. Invention is credited to Tomoyuki Awazu, Akira Kuibira, Hirohiko Nakata, Masuhiro Natsuhara.
Application Number | 20090126903 11/996580 |
Document ID | / |
Family ID | 38655329 |
Filed Date | 2009-05-21 |
United States Patent
Application |
20090126903 |
Kind Code |
A1 |
Kuibira; Akira ; et
al. |
May 21, 2009 |
HEAT TRANSFER MEMBER, CONVEX STRUCTURAL MEMBER, ELECTRONIC
APPARATUS, AND ELECTRIC PRODUCT
Abstract
A heat transfer member (20) has a support (1), and columnar
bodies (2) all or some of which are disposed so as to be inclined
at an angle with respect to the support (1). The columnar bodies
(2) are in contact with a contacted body (21), and the columnar
bodies (2) elastically deform and/or plastically deform along the
shape of the contact surface with the contacted body (21) to
thereby make direct contact along the wavy and rough irregularities
of the contacted body (21), and to cause heat to move through the
columnar bodies (2).
Inventors: |
Kuibira; Akira; (Osaka,
JP) ; Natsuhara; Masuhiro; (Hyogo, JP) ;
Awazu; Tomoyuki; (Hyogo, JP) ; Nakata; Hirohiko;
(Hyogo, JP) |
Correspondence
Address: |
GLOBAL IP COUNSELORS, LLP
1233 20TH STREET, NW, SUITE 700
WASHINGTON
DC
20036-2680
US
|
Assignee: |
SUMITOMO ELECTRIC INDUSTRIES,
LTD.
OSAKA
JP
|
Family ID: |
38655329 |
Appl. No.: |
11/996580 |
Filed: |
April 18, 2007 |
PCT Filed: |
April 18, 2007 |
PCT NO: |
PCT/JP2007/058450 |
371 Date: |
January 23, 2008 |
Current U.S.
Class: |
165/67 |
Current CPC
Class: |
H01L 23/3735 20130101;
F28F 3/048 20130101; H05K 7/20963 20130101; F28F 19/02 20130101;
H01L 23/433 20130101; H01L 2924/0002 20130101; H01L 23/3677
20130101; F28F 13/18 20130101; H01L 2924/0002 20130101; H01L
2924/00 20130101 |
Class at
Publication: |
165/67 |
International
Class: |
F28F 9/00 20060101
F28F009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 24, 2006 |
JP |
2006-118660 |
Apr 27, 2006 |
JP |
2006-122892 |
Claims
1. A heat transfer member comprising: a support; and a plurality of
columnar bodies, at least a portion of said columnar bodies being
inclined at an angle with respect to said support, wherein distal
ends of the said columnar bodies contact a contact surface of a
contacted body, and said columnar bodies being dimensioned to
elastically deform such that the distal ends of the columnar bodies
conform to non-planar shapes of the contact surface of said
contacted body to thereby make heat conducting contact
therebetween.
2. The heat transfer member according to claim 1, wherein said
columnar bodies are formed at an inclined angle of 10 to 80.degree.
from a line perpendicular to said support.
3. The heat transfer member according to claim 2, wherein a ratio
.theta.1/.theta.2 is 1 or less, where .theta.1 is an angle of a
line that connects a center and a base portion of said columnar
bodies from the line perpendicular to said support, and .theta.2 is
the angle of a line that connects the center and the distal end of
said columnar bodies from the line perpendicular to said
support.
4. The heat transfer member according to claim 1, wherein a ratio
S1/S2 is 1 or less, where S1 is the cross-sectional surface area of
the distal end of said columnar bodies, and S2 is the
cross-sectional surface area of a base portion of said columnar
bodies.
5. The heat transfer member according to claim 1, wherein at least
a portion of said columnar bodies have a structure that includes a
curve.
6. The heat transfer member according to claim 5, wherein a ratio
r2/r1 is 1 or less, where r1 is the radius of curvature of a curve
defined from a base portion to the center of said columnar bodies,
and r2 is the radius of curvature of a curve from the center to the
distal end of said columnar bodies.
7. The heat transfer member according to claim 1, wherein 50% or
more of said columnar bodies are in contact with said contacted
body.
8. The heat transfer member according to claim 1, wherein 50% or
more of the columnar bodies in contact with said contacted body are
in contact with said contacted body at a side surface portion of
said columnar bodies.
9. The heat transfer member according to claim 1, wherein the force
for pressing said columnar bodies against said contacted body is
0.01 g or more per columnar body, and the total force of pressing
said columnar bodies against said contacted body is preferably 95%
or less of the breaking force of said contacted body.
10. The heat transfer member according to claim 1, wherein a
surface area of the support on which said columnar bodies are
disposed is greater than a surface area of a heat source disposed
on one side of said contacted body.
11. The heat transfer member according to claim 1, wherein a
contact heat resistance between said columnar bodies and said
contacted body is 0.3 K/mm.sup.2W or less.
12. The heat transfer member according to claim 11, wherein the
contact heat resistance between said columnar bodies and said
contacted body is 0.1 K/mm.sup.2W or less.
13. An electronic apparatus having the heat transfer member
according to claim 1.
14. An electric product having the heat transfer member according
to claim 1.
15. A convex structural member comprising a convex structural unit
composed of a plurality of convex structures, wherein all or some
of said convex structures are in contact with a contacted body and
undergo elastic and/or plastic deformation along the shape of a
contact surface of said contacted body, whereby heat is moved via
said convex structural unit that is in direct contact along wavy
and rough irregularities of said contacted body and is in direct
contact with said contacted body.
16. The convex structural member according to claim 15, further
comprising a support (1), wherein said convex structural unit is
composed of an assembly of a plurality of columnar bodies (2)
supported by said support (1).
17. The convex structural member according to claim 16, wherein all
or some the assembly of said columnar bodies is a structure that
includes a curve.
18. (canceled)
19. (canceled)
20. (canceled)
21. (canceled)
22. (canceled)
23. (canceled)
24. The convex structural member according to claim 16, wherein
said convex structural unit is a porous body disposed between said
contacted body and said support.
25. (canceled)
26. (canceled)
27. (canceled)
28. (canceled)
29. The convex structural member according to claim 15, wherein
said convex structural unit is composed of at least one of metal
and resin which includes in dispersed form a material that has
higher thermal conductivity than the main component resin.
30. (canceled)
31. (canceled)
32. The convex structural member according to claim 15, further
comprising a coated film composed of a material that is coated onto
said convex structural unit and has higher thermal conductivity
than the convex structural unit.
33. The convex structural member according to claim 15, further
comprising a coated film composed of a material that is coated onto
said convex structural unit and has higher resistance to oxidation
and/or corrosion than the convex structural unit.
34. The convex structural member according to claim 15, further
comprising a coated film that is coated onto said convex structural
unit and has a radiation rate that is greater than 0.5.
35. (canceled)
36. An electronic apparatus having the convex structural member
according to claim 15.
37. An electric product having the convex structural member
according to claim 15.
Description
TECHNICAL FIELD
[0001] The present invention relates to a heat transfer member, a
convex structural member, an electronic apparatus, and an electric
product for rapidly removing heat from required locations and
rapidly supplying heat to required locations of an electronic
apparatus, a household electric appliance, or an industrial
product.
BACKGROUND ART
[0002] The electron gun method that uses a cathode-ray tube has
conventionally been the common method for projecting an image to a
monitor in a television (TV). However, since a television that uses
this method scans the cathode-ray tube using a single electron gun,
the angle to the external periphery becomes considerable when the
size of the monitor is increased, and the ability to increase the
size is limited because the monitor becomes distorted. One method
for preventing distortions in the monitor is to curve the monitor
to maintain a constant distance between the electron gun and the
cathode-ray tube. However, a flat monitor is easier to view in
large monitor televisions in particular, and flat monitors are
highly popular even in small televisions. Curved monitors are
therefore not adopted in large-monitor televisions. Also, a
cathode-ray tube television considerably increases in thickness as
the size of the monitor increases, and such a large-monitor
television is not suitable for installation in the living room of a
common home.
[0003] For this reason, rear-projection televisions, liquid-crystal
display televisions, plasma televisions (PDP: Plasma Display
Panel), and the like are receiving attention as methods that can be
used to obtain televisions having larger monitors and thinner
profiles, and such televisions are replacing conventional
cathode-ray tube televisions. Also, methods for projecting an image
onto a large screen using a projector are becoming more widespread
in home theater applications. In addition, monitors and screens are
progressively increasing in size in order to obtain greater impact,
but there is a demand for thinner and more lightweight devices
other than monitors or screens that do not occupy indoor room
space. There is also a demand for greater brightness because light
diffuses to a greater extent and the monitor becomes darker and
more difficult to view as the size of the monitor increases.
[0004] In the rear projection television described above in which a
picture is projected from the rear surface to a screen with the aid
of a projector, one or more reflecting mirrors are used to thereby
save distance between the monitor and the projector inside a thin
case, and the configuration can thereby be made thinner. Rear
projection also conventionally projects from the rear surface to a
monitor using the CRT method, but a switch is currently being made
to MD (Micro Display) methods in order to make the configuration
thinner and more lightweight and to achieve higher picture quality.
The MD methods include those in which the transmissive
liquid-crystal method (HTPS: High Temperature Poly-Silicon) is used
as the optical device, as well as reflective DLP (Digital Light
Processing) methods and LCOS (Liquid Crystal on Silicon)
methods.
[0005] In the liquid-crystal and PDP methods, liquid-crystal
elements or small plasma electrodes are aligned as small shutters
on the monitor in a number that corresponds to the number of pixels
to form the screen itself. For this reason, the liquid-crystal and
PDP methods do not require a distance to be established for
projection, and thinner and larger configurations are more easily
achieved. Therefore, rear projection televisions together with the
above-described liquid-crystal televisions and plasma televisions
are quickly becoming the favored type of large monitor television.
On the other hand, the heat output and heat density from the
elements and monitor have increased together with the larger size
of such monitors. Also, since the luminous energy per unit area is
insufficient when display is made to a large monitor using the same
output, power consumption generally increases as the size of the
monitor increases, and heat output increases in accordance
therewith. As a result, the elements and peripheral equipment will
suffer thermal degradation if the heat is not efficiently
dissipated from the system, and there is an increasing need to
efficiently dissipate heat.
[0006] Also, MPUs, the centerpiece of desktop computers, notebook
computers, servers, as well as larger mainframe computers and other
computers, are becoming more highly integrated, and there is need
for higher clock speeds so that large amounts of information can be
processed at high speed. For this reason, the heat output of MPUs
is increasing every year. Currently, however, heat dissipation
techniques have not caught up to the considerable increase in heat
output. For this reason, a situation is coming about in which the
development of higher clock speeds must be temporarily halted
because MPU elements will malfunction due to their self-generated
heat, and there is a growing need for more efficient heat
dissipation techniques.
[0007] Japanese Laid-open Patent Application No. 2004-319942
(Patent Document 1) discloses as a resent cooling technique a heat
sink in which a metallic expanded body is used as the heat
radiation unit. However, a metallic expanded body has innumerable
holes, and if incorrectly used, the metallic expanded body, rather
than providing heat radiation properties, is liable to act as an
insulation layer due to the internal air holes, such as in highly
insulative expanded polystyrene and the like. Japanese Laid-open
Patent Application No. 2005-032881 (Patent Document 2) discloses a
porous heat-radiating body having a low-porosity area and a
high-porosity area. However, it is difficult to bring about direct
gapless contact with the heat radiation area because the
high-porosity area does not deform, as exemplified by a porous
sintered body or a ceramic fiber.
[0008] In industrial components and household appliances, heaters
are used in various locations to rapidly provide and process heat
in required locations. In semiconductor manufacturing devices, for
example, a heater and a cooling module are used in combination to
rapidly increase and reduce the temperature, and there is a need to
reduce to the extent possible the transition time from one process
to the next process in order to increase throughput. For this
reason, coolant may be made to flow inside the coolant module when
cooling is desired in a state in which the heater and the coolant
module are in a state of contact; or the cooling module may be made
movable, a product is heated by the heater alone during heating,
and the cooling module is brought into contact with the heater to
perform cooling only when rapid cooling is desired.
Patent Document 1: Japanese Laid-Open Patent Application
Publication No. 2004-319942
Patent Document 2: Japanese Laid-Open Patent Application
Publication No. 2005-032881
DISCLOSURE OF THE INVENTION
Problems which the Invention is Intended to Solve
[0009] Recent heat dissipation techniques for televisions are
described below. In liquid crystal televisions and plasma
televisions, for example, an Al sheet is affixed to the rear
surface of the monitor, heat is released to the rear surface of the
Al sheet, air is then blown against the rear surface of the Al
sheet to radiate the heat to the air, and the heat is released
through gaps in the casing to the exterior. In rear projection
televisions and reflective projectors, an Al heat sink having Al
fins is pressed against the rear surface of an optical chip, air is
fed to with the aid of the fan to perform air cooling, and heat is
dissipated through gaps in the casing to the exterior in the same
manner.
[0010] In rear projection televisions and projectors, the total
amount of heat output increase as the size of the monitors
increase, light is focused on small elements (Micro Display) that
are set at about 10 to 20 mm angles to form an image, the image is
projected onto a large screen, and the heat density concentrated in
the elements is therefore very high. For this reason, heat must be
particularly dissipated with good efficiency. In the transmissive
HTPS method, however, light passes through a liquid-crystal chip,
and the surface of a cooling module cannot be pressed against the
chip to perform cooling in the manner described above. In view of
this situation, a technique is adopted, among others, in which the
external peripheral frame of the liquid-crystal chip is composed of
a highly heat-conductive metal such as Al or Mg, the frame
transmits heat and is air-cooled with the aid of a fan, and fins
are furthermore attached to the external peripheral frame to
improve the air cooling effect.
[0011] In the DLP methods, the rear surface of the DLP chip is
water cooled, particularly large monitor projectors which are used
in movie theaters and in which a considerable amount of heat is
produced. However, using water inside an electrical device means
that the system will constantly be operating under the possibility
of short-circuiting due to moisture leaks, electrical component
degradation, and other dangers. Air-cooling techniques are
therefore preferably used to the extent possible. Also, even if the
element portions are water-cooled, it is ordinarily rare that a
disposable fluid is used, and since the fluid is circulated, the
heat must be released to the air through a separately-located heat
exchanger, and an efficient air-cooling structure is essential.
[0012] Nevertheless, with methods in which heat is taken from
elements and other components with the aid of a heat sink and fins
as described above and cooling is carried out using a fan, there is
a limit to the ability to sufficiently cool the added production of
heat associated with larger monitor sizes. Specifically, heat
transferred from elements and the like to a heat sink spreads to
peripheral members prior to being transferred to the rear surface
of the heat sink, the temperature is reduced, and only poor cooling
efficiency can therefore be obtained even when the rear surface of
the heat sink is cooled with a fan. Also, there is a problem in
that air cooling by fan disperses the heat inside the case, and
other components are easily affected. Hot air that leaves from the
gaps in the casing is blown as a hot wind onto persons nearby the
apparatus, the temperature in the room increases, and room
occupants are therefore made to feel uncomfortable. Also, the air
flow noise produced by the fan presents the greatest unpleasant
factor when enjoying the viewing of images in a quiet living
room.
[0013] Warping that accompanies sintering is unavoidably present in
the packaging, in the ceramic substrate on which elements are
mounted, and in other components. Since the warping is, e.g., about
0.1 to 0.15 mm, gaps are formed when the heat sink or the like is
pressed and mounted, and a considerable amount of heat resistance
is produced when air is left in the gaps. In view of the above, a
method is adopted in which a pliant thermal conductive sheet or a
compound resin having a thickness of 1 to 2 mm is inserted between
the heat sink and the substrate, package, or the like to mount the
heat sink without gaps. Since the thermal conductivity is about
several W/mK to 10 W/mK even if a sheet or compound having high
thermal conductivity is used, the low-thermal conductivity of the
interlayer limits the heat dissipation rate, and efficient heat
dissipation cannot be achieved even when the heat sink used is
composed of aluminum having a high thermal conductivity of 237 W/mK
or is composed of copper having a high thermal conductivity of 403
W/mK.
[0014] In desktop personal computers, servers, and the like, air
cooling techniques are adopted as MPU cooling techniques that are
substantially the same as the element cooling techniques used in
rear projection televisions and projectors. Specifically, heat is
transferred to an Al heat sink via a thermal conductive sheet or a
thermal conductive resin disposed on the rear surface of the MPU,
and air is blown from the rear surface with the aid of a fan to
dissipate the heat. Alternatively, heat from the MPU is carried
away to the vicinity of the casing with the aid of a heat pipe, and
the heat is expelled to the exterior of the casing by using large
fins and a fan. However, the problem of poor cooling efficiency
remains unresolved, and heat dissipation cannot keep up with the
increasing heat output of the MPU. Also, since a heat pipe is
simply a device for carrying away heat, the heat still needs to be
expelled to the atmosphere by large fins and a fan at the heat
delivery site, and then be expelled to the exterior of the casing.
This fact prevents the structure from being made smaller.
[0015] Heaters and cooling modules are used in various locations in
industrial products and household appliances. In semiconductor
manufacturing devices, for example, there is a need for heaters and
cooling modules to be used in combination so as to quickly increase
and reduce the temperature, to reduce to the extent possible the
time for transitioning from one process to the next process, and to
increase the throughput. However, when the area between the heater
and the cooling module is viewed microscopically, there are
problems in that gaps produced by waviness, warping, and roughness
are present, and rapid cooling is not possible because heat
resistance is higher.
[0016] The present invention was contrived in view of such prior
art problems, and an object of the present invention is to provide
a heat transfer member, a convex structural member, an electronic
apparatus, and an electric product for cooling or heating which can
be mounted in close contact with a ceramic or another contacted
body without the use of a polymer, organic sheet, or grease, and
without producing gaps that cause heat resistance; which can
immediately dissipate heat transferred from the contacted body to a
coolant or immediately supply heat to the contacted body; and in
which the heat movement efficiency is therefore higher in
comparison with contact via a conventional polymer, organic sheet,
or grease.
Means Used to Solve the Above-Mentioned Problems
[0017] In order to achieve the above-described objects, the heat
transfer member provided by the present invention has a support,
and columnar bodies all or some of which are disposed so as to be
inclined at an angle with respect to the support. The columnar
bodies are in contact with a contacted body, and the columnar
bodies elastically deform and/or plastically deform along the shape
of the contact surface with the contacted body to thereby make
direct contact along the wavy and rough irregularities of the
contacted body and to cause heat to move through the columnar
bodies.
[0018] The convex structural member provided by the present
invention has a convex structural unit composed of a plurality of
convex structures, wherein all or some of the convex structures are
in contact with a contacted body and undergo elastic and/or plastic
deformation along the shape of a contact surface of the contacted
body, whereby heat is moved via the convex structural unit that is
in direct contact along the wavy and rough irregularities of the
contacted body and is in direct contact with the contacted
body.
EFFECT OF THE INVENTION
[0019] In accordance with the heat transfer member of the present
invention, a heat transfer member can be mounted in close contact
with a cooled body without the use of a polymer, organic sheet, or
grease in a conventional manner and without producing gaps that
cause heat resistance, by using columnar body structures that have
elastic deformability and/or plastic deformability, even if
warping, roughness, and the like are present in an element, a
substrate on which the element is mounted, or another cooled body.
As a result, heat transferred from the contacted body through the
columnar body structure can be immediately radiated to a coolant,
or the contacted body can be rapidly heated.
[0020] Therefore, a contacted body can be rapidly heated or heat
can be dissipated with greater efficiency by using the heat
transfer member of the present invention in comparison with a
conventional heat sink, fins and a fan, or another cooling means
that use a polymer, an organic sheet, or grease. The recent
increase in heat output can therefore be managed in, e.g.,
televisions, projectors, personal computers, automobiles, and other
electronic apparatuses and electric products, and the high
throughput and highly uniform heating characteristics in
semiconductor manufacturing apparatuses, heaters, and the like can
be managed.
[0021] In accordance with the convex structural member of the
present invention, a heat transfer member can be mounted in close
contact with a cooled body without the conventional use of a
polymer, organic sheet, or grease and without producing gaps that
cause heat resistance, by using a convex structural unit that has
the ability to elastically deform and/or plastically deform, even
if warping, roughness, and the like are present in an element that
requires high-efficiency cooling, in a substrate on which the
element is mounted, in a component that requires rapid heating or
cooling, or in a cooled body. As a result, heat can be rapidly
taken and radiated away from the contacted body, or can be rapidly
transferred to the contacted body, and the member can be
manufactured at low cost.
[0022] Therefore, it is possible to mass produce a member in which
the heat dissipation efficiency or heat supply efficiency can be
increased by using the convex structural member of the present
invention in comparison with a conventional thermal conductive
element in which a polymer, organic sheet, or grease is used. It is
therefore possible to rapidly heat or to efficiently manage the
recent increase in the heat output of, e.g., electronic
apparatuses, household appliances, and industrial products.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1A A schematic cross-sectional view showing an example
of the heat transfer member or convex structural member of the
present invention.
[0024] FIG. 1B A schematic cross-sectional view showing another
example of the heat transfer member or convex structural member of
the present invention.
[0025] FIG. 1C A schematic cross-sectional view showing yet another
example of the convex structural member of the present
invention.
[0026] FIG. 2 A schematic cross-sectional view showing a state in
which the heat transfer member is in contact with a contacted
body.
[0027] FIG. 3 A schematic side view for describing the angle of
inclination of the heat transfer member.
[0028] FIG. 4 A schematic cross-sectional view showing an example
of the columnar bodies according to the present invention.
[0029] FIG. 5 A schematic cross-sectional view showing another
example of the columnar bodies according to the present
invention.
[0030] FIG. 6 A schematic cross-sectional view showing yet another
example of the columnar bodies according to the present
invention.
[0031] FIG. 7 A schematic cross-sectional view showing yet another
example of the columnar bodies according to the present
invention.
[0032] FIG. 8 A schematic cross-sectional view showing a foil that
is used in the formation of a heat transfer member and in which the
columnar bodies are aligned along one side.
[0033] FIG. 9 A schematic cross-sectional view showing a foil that
is used in the formation of a heat transfer member and in which
concavo-convex grooves are formed along one side.
[0034] FIG. 10 A schematic cross-sectional view showing yet another
example of the heat transfer member of the present invention.
[0035] FIG. 11 A schematic cross-sectional view showing the cooling
experiment device in which the cooling member of the present
invention is used.
[0036] FIG. 12 A schematic cross-sectional view showing the cooling
experiment device according to a comparative example.
KEY TO SYMBOLS
[0037] 1, 8 Supports [0038] 2 Columnar bodies (arch-shaped body,
S-shaped body, curve-shaped body, serpentine curve-shaped body)
[0039] 3 Rib [0040] 3a, 3b Rib end portions [0041] 4 AlN heater
[0042] 5 Al2O3 substrate [0043] 6 Cu base [0044] 7 Columnar body
assembly [0045] 8 Cu plate-like body [0046] 9 Fin [0047] 10 Fan
[0048] 11 Resin sheet [0049] 12 RTD element [0050] 13 Coated film
[0051] 14 Assembly of column units (convex structural unit) [0052]
15 Concavo-convex shape (groove) [0053] 20 Heat transfer member,
convex structural member [0054] 21 Contacted body [0055] 22 Heat
source [0056] 23 Plate-like body
BEST MODES FOR CARRYING OUT THE INVENTION
Embodiment 1
[0057] Warping, waviness, surface roughness, and other shapes that
cannot be perfectly suppressed are commonly present in a cooled
body, gaps are therefore generated in the surface of contact with
the heat sink, and the gaps have substantially no thermal
conductivity, resulting in a considerable hindrance to heat
transfer. When highly rigid components are placed in contact with
each other, for example, a perfectly flat surface cannot be formed
when viewed microscopically, no matter how much the planarity is
increased and the surface roughness is reduced. As a result, the
three most projecting points make contact, and the other parts
remain suspended. Therefore, gaps produced between components do
not contribute to heat transfer, and cooling capacity is
unavoidably reduced.
[0058] In view of this situation, it has conventionally been
necessary to use grease, an organic sheet, or a highly effective
space-filling polymer to fill in gaps between components. However,
the thermal conductivity of such polymers, organic sheets, and
greases is very poor, and even high-conductivity materials have a
thermal conductivity of about 5 W/mK at best. Therefore, the gaps
produced between the components are filled in, and areas having no
thermal conductivity are eliminated. However, a layer having poor
thermal conductivity composed of such polymers, organic sheets, and
greases forms between the components, and a layer having poor
thermal conductivity produces significant heat resistance and
becomes a hindrance to improving cooling capacity.
[0059] In contrast, the heat transfer member of the present
invention is provided with an assembly of columnar bodies acting as
heat transfer elements. The columnar structure of the heat transfer
member is not particularly limited as such, but is preferably one
in which numerous columnar bodies are disposed at an inclined angle
to the supporting body. By adopting such a columnar structure, it
is possible to easily obtain stable cushioning characteristics
without using complicated shapes, and since the shape is a simple
shape, a variety of manufacturing methods can be used and the heat
transfer member can be manufactured at very low cost.
[0060] The heat transfer member 20 is a member having a plurality
of columnar bodies 2 on a support 1, as shown in FIG. 1A, for
example, and all or some the columnar bodies 2 are inclined at an
angle with respect to the support 1 and are placed in contact with
a contacted body (not shown). Ribs 3 are disposed at the distal
ends of the columnar bodies 2, as shown in FIG. 1B, and the contact
surface area with the contacted body can be increased. The columnar
bodies 2 elastically deform and/or plastically deform along the
shape of the contact surface of with the contacted body 21 when the
heat transfer member 20 is in contact with the contacted body 21,
as shown in FIG. 2, whereby direct contact can be made along the
wavy and rough irregularities of the contacted body 21. As a
result, direct and gapless contact can be made with the contacted
body 21 even without the use of a polymer, an organic sheet, or
grease, and heat can be moved through the columnar bodies 2.
Therefore, heat is not retained in the contacted body 21 side of
the configuration because heat taken from the contacted body 21 is
rapidly transferred to the heat radiation unit via the columnar
bodies 2, for example.
[0061] The columnar bodies 2 are inclined at an angle .theta. of 10
to 80.degree. from a line perpendicular to the support 1, as shown
in FIG. 3, whereby cushioning characteristics can be more easily
obtained. When the inclination angle .theta. is greater than
80.degree., strength is reduced in relation to pressing stress,
stress is concentrated particularly at the base of the columnar
bodies 2, which are then more easily bent, and higher cushioning
characteristics cannot be achieved. When the inclination angle
.theta. is less than 10.degree., the columnar bodies 2 can no
longer flex and sufficient cushioning characteristics cannot be
obtained. The inclination angle .theta. of the columnar bodies 2 is
an angle formed between the line segment that connects the distal
end of the columnar bodies 2 to the base of the columnar bodies and
the line perpendicular to the support 1.
[0062] The ratio .theta.1/.theta.2 is preferably 1 or less, wherein
.theta.1 is the inclination angle of a line that connects the
center and the base of the columnar bodies 2 from the line
perpendicular to the support 1, and .theta.2 is the inclination
angle of a line that connects the center and the distal end of the
columnar bodies 2 from the line perpendicular to the support 1, as
shown in FIG. 3. The ratio .theta.1/.theta.2 of the inclination
angle .theta.1 on the base side of the columnar bodies 2 and the
inclination angle .theta.2 on the distal end side of the columnar
bodies 2 is set to 1 or less, whereby the distal ends of the
columnar bodies 2 are provided with sufficient cushioning
characteristics, and all of the columnar bodies 2 can be held
securely at the base and can be in flexible contact with the
contacted body. Including cases in which the columnar bodies form
curved lines, the inclination angle .theta.1 of the base side is an
angle formed by the line segment that connects the center and base
of the columnar bodies 2 and the line perpendicular to the support
1. The inclination angle .theta.2 of the distal end side is an
angle formed by the line segment that connects the center and
distal end of the columnar bodies and the line perpendicular to the
support 1.
[0063] The thickness of the columnar bodies 2 is preferably
determined by setting the ratio S1/S2 of the cross-sectional area
S1 of the distal end and the cross-sectional area S2 of the base to
be 1 or less. The distal ends of the columnar bodies 2 thereby make
contact with the contacted body while maintaining sufficient
cushioning characteristics, the base portion securely holds all of
the columnar bodies 2, and flexible contact can be made with the
contacted body. Preferably, the diameter of the individual columnar
bodies 2 is set to 500 .mu.m or less and the aspect ratio is set to
be 5 or higher, whereby sufficient deformability as well as heat
radiation characteristics can be achieved. The surface area of heat
dissipation from the columnar bodies 2 can be increased, fluid flow
can be disturbed, and heat dissipation can be more easily achieved
by furthermore forming branched bodies on the surface of the
columnar bodies 2.
[0064] The columnar bodies 2 can be placed in contact with the
cooled body at a side surface of the columnar bodies 2 by using a
structure in which all or some of the columnar bodies 2 are curved,
and the columnar bodies can thereby be pressed against the cooled
body with good cushioning characteristics because the surface area
can be increased and the elasticity produced by the curved portions
can be utilized. Stress is concentrated at the base or midway along
the curvature of the columnar bodies 2 when the columnar bodies 2
are pressed against the contacted body and the stressed portions
can undergo complete plastic deformation to prevent the loss of
cushioning characteristics.
[0065] When a curvature is provided to all or some of the columnar
bodies 2, the ratio r2/r1 between the radius of curvature r1 of a
curve L1 from the base to the center of the columnar bodies 2 and
the radius of curvature r2 of a curve L2 from the center to the
distal end of the columnar bodies 2 is preferably set to 1 or less.
Such a ratio of the radii of curvature allows the distal end of the
columnar bodies 2 to be placed in contact with the contacted body
while maintaining sufficient cushioning characteristics, and the
base portion to securely hold all of the columnar bodies 2 and make
flexible contact with the contacted body.
[0066] Examples of the columnar bodies 2 all or some of which have
curves are shown in FIGS. 4 and 5. Specifically, only one side 3a
of the curved portion of the columnar bodies 2 may be fixed to the
support 1, as shown in FIG. 4, and two sides 3a and 3b of the
curved portion of the columnar bodies 2 may be fixed to the support
to form an arch, as shown in FIG. 5. In particular, the columnar
bodies can be pressed against the cooled body while maintaining
stable and good cushioning characteristics by using the structure
shown in FIG. 5. Also, all or some the columnar bodies 2 may be
shaped to include a plurality of curves or helical shapes, as shown
in FIG. 6. The columnar bodies 2 may furthermore be S-shaped, as
shown in FIG. 7.
[0067] In the heat transfer member 20 of the present invention as
shown in FIG. 2, the heat-transfer effect can be increased by
placing 50% or more of all of the columnar bodies 2 in contact with
the contacted body 21, and the cooling and heating capacity can be
enhanced. Even more preferably 70% or more of the total number of
columnar bodies are kept in contact with the contacted body 21
because the cooling and heating speed can be dramatically
increased. Among the columnar bodies 2 that are in contact with the
contacted body 21, 50% or more of the columnar bodies 2 are
preferably placed in contact with the contacted body 21 on the side
surface, whereby sufficient cushioning characteristics can be
obtained because the bending elasticity of the columnar bodies 2
can be effectively used, and a greater contact surface area can be
obtained when the contact is made on the side surface rather than
at the distal end of the columnar bodies 2. When contact is made
with the contacted body at the distal end of the columnar bodies 2,
there is an area in which only the edge of the border between the
distal and the side surface makes contact at a certain level of
pressure as the level of pressure is increased, and the contact
heat resistance increases rapidly because such a situation results
in a point contact. For this reason, the cooling and heating
capacity can be increased if side contact is used from the
beginning because stable contact can be obtained and point contact
is not liable to occur in the process of increasing the level of
pressure.
[0068] The stress used to press the columnar bodies 2 against the
contacted body 21 is preferably 0.01 g or higher per columnar body.
Each of the columnar bodies 2 is thereby sufficiently pressed
against the contacted body 21, and the total stress of pressing
against the contacted body 21 is preferably 95% or less of the
breaking stress of the contacted body 21 because the contacted body
21 is damaged by the pressing force if excessive force is applied
with the intention of providing enough pressing force.
[0069] The surface area on which the columnar bodies 2 is disposed
is preferably greater than the surface area of the range in which
the heat source 22 on the side of the contacted body 21 is
disposed. The reason is that the heat-spreading effect can be used
in which heat is transferred while the heat generated by the heat
source 22 spreads in the horizontal direction in FIG. 2, and highly
efficient cooling can therefore be carried out. Contact heat
resistance between the columnar bodies 2 and the contacted body 21
is set to be 0.3 K/mm.sup.2W or less, whereby heat is transferred
with high efficiency via a conventional thermal conductive sheet or
grease, and cooling and heating can therefore be carried out with
good efficiency. Furthermore, heat can be transferred at even
higher efficiency by setting the contact heat resistance between
the columnar bodies 2 and contacted body 21 to be 0.1 K/mm.sup.2W
or less, and cooling and heating can therefore be carried out with
even better efficiency.
[0070] Other preferred structures of the columnar bodies 2 include
a metallic porous body and a honeycomb structure body. A metallic
porous body can be manufactured at low cost by plating a resinous
expanded body, for example, and then burning off the resin expanded
body. In addition, a structure having a relatively uniform space is
easily obtained. A honeycomb structure body has an axis that is
disposed parallel to the contact surface with the cooled body,
whereby relatively uniform and stable rigidity and cushioning
characteristics are obtained. In addition, a structure having an
internal space can be easily obtained.
[0071] Other preferred structures of the columnar bodies 2 include
a structure in which metal wires are intertwined, and a structure
in which carbon fibers are intertwined. A low-cost structure can be
obtained in which the assembly of columnar bodies 2 is pressed
against the contacted body 21 by pressing the columnar bodies 2
against the contacted body 21 with the aid of the support 1.
Columnar bodies 2 having a structure of intertwined metal wires can
be applied to mostly all metals, and carbon fibers can be provided
with a high thermal conductivity of 500 to 800 W/mK in axial
direction "c" in accordance with manufacturing conditions. Since a
relatively low cost, a structure in which columnar bodies are
pressed against a contacted body can easily be obtained. For this
reason, a structure of intertwined metal wires or a structure of
intertwined carbon fibers is preferred.
[0072] The columnar bodies 2 may be formed by electrical discharge
machining, nanoimprinting, LIGA (Lithograph Galvanoformung
Abformug), etching foil lamination, MEMS, or another method.
Electrical discharge machining is a method in which a wire to which
voltage has been applied or an electrode machined in a reverse
pattern of the desired shape is brought close to an
electroconductive material to thereby generate an electric
discharge and to induce vaporization or melting to process the
electroconductive material. Nanoimprinting is a method in which,
e.g., a workpiece is heated and pressed using a metal mold to
thereby impart the shape of the metal mold. This method is suitable
for mass production at low cost.
[0073] When, for example, the assembly 14 of numerous columnar
bodies 2 shown in FIG. 1A is manufactured using LIGA, a resist is
coated and dried on a metal substrate acting as the support 1, a
mask of the pattern that corresponds to the cross section of the
columnar bodies 2 is then mounted, and X-rays are irradiated from
an oblique 45.degree. direction, for example. Next, the substrate
is washed using a developing solution to remove the resist in
locations exposed to the X-rays, metal is embedded in the form of
columns by electroplating in the spaces from which the resist has
been removed, and the remaining resist is then removed using oxygen
plasma. Also, metal foil is placed on the distal ends of the
numerous columnar bodies 2 via silver solder or the like, the
assembly is heated and joined, and the metal foil is thereafter cut
away in squares using a laser to thereby dispose ribs 3 at the
distal ends of the columnar bodies 2 in the manner shown in FIG.
1B. Columnar bodies can thus be obtained in which the contact
surface area with the contacted body is increased.
[0074] In the etching foil lamination method described above,
columnar bodies 2 that measured 0.1.times.0.1 mm and were aligned
on one side of the Cu foil can be obtained as shown in FIG. 8 by
etching in which 0.1 mm intervals are left along one side of a Cu
foil having a thickness of 0.1 mm, for example. Therefore, the Cu
foil is etched at intervals of 0.3 mm, for example, and columnar
bodies 2 are aligned at intervals of 0.3 mm on one side of the Cu
foil, resulting in a configuration in which Cu foil having a
thickness of 0.3 mm is disposed between the columnar bodies 2,
whereby an assembly of columnar bodies 2 can be obtained in which
the columnar bodies 2 are aligned at intervals of 0.3 mm in the
form of a plane. The foils may be perfectly joined to each other by
fusing or the like, or may be tightened using screws or the like
and fixed in place at low cost.
[0075] The heat transfer member can be easily mass produced using
injection molding or the like by using resin as the columnar bodies
2. A resin is preferably a material having high thermal
conductivity. A resin having a high thermal conductivity of 30 W/mK
or higher has been developed in recent years, and such a material
is preferred as the heat transfer member 20 of the present
invention. However, since the thermal conductivity is still lower
than that of a metal that contains Cu or Al, it is also possible to
subject the resin to injection molding and then to coat the surface
with an inorganic substance or metal that has high thermal
conductivity to supplement the thermal conductivity. Examples of
the metal in such a case include Ni plating, Cu plating, and Au
plating; and Ni, Cu, Au, or another metal that has been sputtered,
sprayed, or applied in another manner. The method is not
particularly limited, and it is possible to coat an organometallic
slurry and to precipitate the metal by heat decomposition, or to
precipitate the metal by dissociative induction or another method
when the resin has sufficient electroconductivity.
[0076] In the heat transfer member 20 described above, a metal that
is highly resistant to oxidation and corrosion may be coated onto
the surface of the columnar bodies 2 to improve resistance to
oxidation, corrosion, and the like and to assure long-term contact
reliability in the case that the columnar bodies 2 are formed from
a highly thermal conductive metal that has low resistance to
oxidation, corrosion, and the like.
[0077] With the heat transfer member 20 of the present invention,
the flow of air or another coolant is preferably disturbed to
promote heat radiation when the structure is one in which
concavo-convex grooves are formed between the columnar bodies 2.
For example, foil in which numerous columnar bodies 2 are aligned
on the surface of the support 1 in the manner shown in FIG. 8, as
well as the heat transfer member 20 obtained by layering the
support 1 in which concavo-convex grooves 15 are formed on the
surface of the support 1 in the manner shown in FIG. 9, are
preferred because the flow of air or another coolant is disturbed
to promote heat radiation. However, when the depth of the
concavo-convex grooves 15 is ten times greater than the thickness
of the columnar bodies 2, fabrication becomes difficult, costs
increase, and the effect of disturbing the coolant flow is no
longer significant. Therefore, the depth of the concavo-convex
grooves is preferably a magnitude of 10 or less in relation to the
thickness of the columnar bodies.
[0078] It is also preferable to disturb the flow of air or another
coolant and to promote the radiation of heat by forming a
plate-like body 23 having a thickness that is equal to or less than
the thickness d of the columnar bodies 2 between the columnar
bodies 2, as shown in FIG. 10. The air or another coolant is
disturbed by solid/gas friction with the coolant by setting the
surface roughness Ra of the plate-like body 23 to be 0.01 .mu.m or
more, and the effect is considerably magnified at 0.1 .mu.m or
more. The air or another coolant is disturbed by solid/gas friction
with the coolant by setting the surface roughness Rmax of the
plate-like body 23 to be 0.1 .mu.m or more to facilitate heat
dissipation, and the effect is considerably magnified at 0.5 .mu.m
or more.
[0079] The thickness d of the assembly of columnar bodies 2 is
preferably 0.01 mm or more and 50 mm or less in the direction
perpendicular to the contact surface of the contacted body. It is
difficult to machine the thickness d to less than 0.01 mm, and
since a machine tool with high-feed precision is required, the cost
is excessively high. When the thickness d of the assembly of
columnar bodies exceeds 50 mm, the machining cost during
manufacture is excessively high and the demand for a thinner
apparatus cannot be satisfied.
[0080] The thickness d of the assembly of columnar bodies 2 is more
preferably 0.3 mm or more and 5 mm or less in the direction
perpendicular to the contact surface of the contacted body. When
the thickness d is less than 0.3 mm, sufficient deformability
cannot be obtained, and since gapless contact with the cooled body
is not possible, cooling efficiency is reduced. When the thickness
d exceeds 5 mm, the columnar bodies 2 are excessively thick, heat
transfer to the heat radiation unit disposed on the rear surface
side can no longer be rapidly carried out, and cooling efficiency
is reduced.
[0081] The heat transfer member of the present invention can have a
heat radiator disposed on a surface other than the contact surface
with the cooled body when the contacted body is the cooled body.
All or part of the heat radiation unit may have the same structure
as the assembly of columnar bodies described above, or may be a
finned radiation unit in which known fins or a plurality of
plate-like bodies are aligned. The heat dissipation efficiency from
the cooled body can be further enhanced by causing heat to radiate
from the radiation unit.
[0082] The thickness of the heat radiation unit, i.e., the
thickness of the heat radiation unit composed of an assembly of a
plurality of columnar bodies, or the thickness of the space
occupied by the finned heat radiation unit in which a plurality of
plate-like bodies are aligned, is preferably 0.01 mm or more and 50
mm or less. It is difficult to machine the heat radiation unit to a
thickness less than 0.01 mm, a machine tool with high-feed
precision is therefore required, and the cost is excessively high.
When the thickness of the heat radiation unit exceeds 50 mm, the
machining cost during manufacture is excessively high, the demand
for a thinner apparatus cannot be satisfied, and such a situation
is therefore not preferred.
[0083] The thickness of the heat radiation unit is more preferably
0.3 mm or more and 5 mm or less. When the thickness of the heat
radiation unit is less than 0.3 mm, a sufficient heat radiation
surface area cannot be obtained and cooling efficiency is reduced.
Conversely, when the thickness of the heat radiation unit exceeds 5
mm, the heat radiation distance is excessively long, and heat
transfer to the entire heat radiation unit can therefore no longer
be rapidly carried out. It is difficult for air to penetrate to the
base of the fins in a finned heat radiation unit, and cooling
efficiency is therefore reduced.
[0084] The heat transfer member 20 of the present invention can be
configured using a material that has high thermal conductivity,
such as cooper at 403 W/mK or aluminum at 236 W/mK, for example,
and the heat resistance can therefore be reduced in comparison with
a heat transfer sheet that has considerable heat resistance because
such a conventional sheet has a thermal conductivity of only 5 W/mK
at best. Therefore, a high cooling effect can be obtained by using
the heat transfer member 20 in place of a conventional heat
transfer sheet and feeding air to perform cooling from the rear
surface of the support 1 of the columnar bodies 2. It is also
possible to use a columnar body structure as the heat radiation
fins on the rear surface to obtain a thin cooling device.
[0085] In the heat transfer member of the present invention, air or
another coolant is fed to the rear surface of the support 1 and/or
the assembly of columnar bodies 2 to perform cooling, whereby the
surface area for radiating heat can be increased, and the cooling
efficiency can therefore be improved. For example, holes that allow
air or another coolant to pass through to the support 1 are formed,
and air or another coolant flows through the holes from the rear
surface, whereupon the cooling efficiency can be improved without
providing particularly large auxiliary equipment. In order improve
cooling efficiency, air or another coolant may be fed via a pump,
compressor, or the like to the columnar bodies in contact with the
heat source, and air or another coolant may be fed to the rear
surface with the aid of a fan.
[0086] When pressure loss inside the assembly of columnar bodies 2
increases and an area of reduced pressure of the air or another
coolant is generated during evacuation or pressurization, cooling
efficiency is reduced because the heat-receiving molecular density
in this area is reduced. For this reason, it is preferred that a
coolant flow be formed in which the pressure loss inside the
assembly of columnar bodies 2 does not increase so that cooling
efficiency is improved. For example, when coolant is pumped away
from the rear surface at a single point in the center, the pressure
is lowest in the vicinity of the center outlet, and cooling
efficiency is reduced in the center area. For this reason, pressure
loss is reduced and cooling efficiency is improved when auxiliary
holes are provided to disperse the pressure in the center vicinity,
for example. Pressure loss is further reduced and cooling
efficiency is improved by alternately forming air inlets and pump
outlets or by handling pressure loss in another manner.
[0087] With the heat transfer member 20 of the present invention,
the ratio between the surface area (facing surface area) of the
contacted body 21 facing the columnar bodies 2 and the surface area
(contact surface area) of the portion in which the plurality of
columnar bodies 2 are in contact with the contacted body 21 is
preferably 0.01% or higher. The efficiency for taking heat away
from the contacted body 21 by contact can be kept high by setting
the ratio of the contact surface area to the facing surface area to
0.01% or higher. However, when the ratio of the contact surface
area and the facing surface area is less than 0.01%, the contact
heat resistance becomes excessively high, and such a situation is
therefore not preferred.
[0088] The gap ratio of the assembly of columnar bodies 2, which
are heat transfer elements, is preferably 50% or higher. When the
gap ratio of the assembly of columnar bodies 2 is 50% or higher,
cooling efficiency is further improved in a preferred manner
because heat can also be radiated from the columnar bodies 2. The
amount of elastic deformation and/or the amount of plastic
deformation of the columnar bodies 2 is preferably 50 .mu.m or more
in the direction perpendicular to the contact surface of the
contacted body 21. One or both of the amount of elastic deformation
and the amount of plastic deformation is 50 .mu.m or more, whereby
sufficient capacity is provided for absorbing the warping and
waviness of the contacted body 21. This approach is therefore
preferred.
[0089] The columnar bodies 2 are preferably composed of a material
having a Young's modulus of 70 GPa or higher. This is due to the
fact that when the columnar bodies 2 are pressed against the
contacted body 21, stable contact can be obtained by the elastic
force of the columnar bodies 2 that is generated when the columnar
bodies are firmly pressed against the contacted body 21. The
temperature of the columnar bodies 2 increases above normal
temperature when the bodies are used for cooling and heating. When
the temperature increases, the Young's modulus tends to be reduced
and the Young's modulus at 60.degree. C. or higher is preferably 60
GPa or greater.
[0090] Ideally, the columnar bodies 2 have high elasticity overall,
plastically deform under low stress at the distal ends that make
contact with the contacted body 21, and are compressed along the
contacted body, making it possible to obtain a sufficient contact
surface area in each of the columnar bodies 2. The material
requires what appear to be contradictory characteristics. To
satisfy such requirements, a hybrid form of the columnar bodies is
preferably obtained, a material having a high Young's modulus is
used for the columnar bodies 2 themselves, and the surface of the
distal ends thereof is preferably coated with a soft material
having high thermal conductivity. For example, it is possible to
plate or deposit silver (Ag) and gold (Au) onto the surface of the
columnar bodies 2 composed of Cu.
[0091] The columnar bodies 2 are preferably composed of a material
having a thermal conductivity of 100 W/mK or higher. The thermal
conductivity of the columnar bodies is set to 100 W/mK or higher
because the heat transferred to the columnar bodies 2 can be
rapidly transferred to the rear surface side. Also, the heat is
transferred through the contact area more efficiently by coating
the surface of the columnar bodies 2 with a material that has
higher thermal conductivity than the columnar body material. For
example, it is possible to plate or deposit a coating of silver
(Ag), gold (Au), carbon (C), diamond, or the like onto the surface
of the columnar bodies composed of Cu.
[0092] The purity of constituent material of the columnar bodies 2
is preferably 90% or higher. When a large amount of impurities,
i.e., 10% or higher, is contained, the original thermal
conductivity of the material is rapidly reduced and the contact
heat resistance increases because of a reduction in the ability of
the columnar bodies to spread in order to increase the actual
contact surface area when the columnar bodies are pressed to the
heat source.
[0093] The air or another coolant is disturbed by solid/gas
friction with the coolant, and heat radiation is more easily
promoted by setting the surface roughness Ra of the columnar bodies
2 to be 0.01 .mu.m or more, and the effect is considerably
magnified at 0.1 .mu.m or more. The air or another coolant is
disturbed by solid/gas friction with the coolant, and heat
radiation is more easily promoted by setting the surface roughness
Rmax of the columnar bodies 2 to be 0.1 .mu.m or more, and the
effect is considerably magnified at 0.5 .mu.m or more. Since the
columnar bodies 2 have a narrow diameter, it is difficult to
measure surface roughness using a stylus-based profilometer. A
three-dimensional SEM (3D SEM) that can measure surface roughness
and waviness is suitable for measuring the surface roughness of the
columnar bodies because the surface roughness can be measured at
high magnification in a non-contact manner.
[0094] When the strength of the columnar bodies 2 is greater than
350 MPa, the cushioning characteristics and the ability of the
columnar bodies to spread in order to increase the actual contact
surface area when the columnar bodies are pressed to the heat
source are reduced, and such a situation is not preferred because
the contact heat resistance increases. When the surface roughness
Ra of the contact area of the columnar bodies 2 is 10 .mu.m or
more, the contact surface area with the heat source is reduced, and
such a situation is not preferred because heat resistance is
increased. Therefore, the surface roughness Ra is preferably kept
to 1 .mu.m or less if possible.
[0095] The stress applied to the columnar bodies 2 against the
contacted body 21 is preferably 1 g or more per columnar body. When
the stress is less than 1 g, the columnar bodies 2 are not
sufficiently pressed against the contacted body, and the cushioning
characteristics and the contact produced by surface deformation are
insufficient. The maximum pressing value must be 95% or less of the
total stress that would break the contacted body. This is because
the possibility that the contacted body 21 will break is increased
when such a level is exceeded.
[0096] The columnar bodies 2 in the heat transfer member 20 are
preferably composed of at least copper or aluminum, or a material
that contains these metals. For example, copper has a Young's
modulus of 120 GPa, and aluminum has a Young's modulus of 80 GPa,
which provide sufficient deformability. Copper has a high thermal
conductivity of 403 W/mK, and aluminum has a high thermal
conductivity of 237 W/mK, and these metals are therefore preferred.
Other preferred materials include gold (Au) and silver (Ag), which
also have high thermal conductivity and deformability, but such
metals are expensive and are therefore not preferred from a
commercial viewpoint.
[0097] The heat radiation unit in the heat transfer member 20
preferably has a surface radiation rate of 0.1 or higher. Heat
radiation as well as convection can be sufficiently carried out by
setting the surface radiation rate of the heat radiation unit to be
0.1 or higher, and cooling efficiency can therefore be further
enhanced. Furthermore, contact heat transfer and heat transfer by
radiation can also be utilized in portions that are in contact with
the contacted body 20 by setting the surface radiation rate of the
heat transfer member 20, including the heat radiation unit, to be
0.1 or higher. Such a situation is therefore preferred in that
contact heat resistance is reduced and heat is more readily
transferred, thus contributing to improved cooling efficiency.
[0098] In the heat transfer member 20 of the present invention,
heat radiation efficiency can be considerably improved in
comparison with natural convection by forcing coolant to flow to
the heat radiation unit. For example, the heat is more easily
circulated in an apparatus by using a coolant gas, and such a
configuration is preferred. Air is particularly preferred as the
coolant gas in that a tank or the like for supplying a gas does not
need to be provided or exchanged, the air can be taken in from the
area around the apparatus and used in a simple manner, and there in
no effect on the human body if the gas were to leak.
[0099] Liquid is preferably used as the coolant in the particular
case that greater cooling ability is desired because heat capacity
is increased when a liquid is used as a coolant. Cooling water is
particularly preferred as the liquid coolant in that cooling water
is inexpensive and is easy to replace. Although more costly, the
use of Galden is also effective as a liquid coolant when freezing
is liable to occur in cold regions and when an even higher cooling
ability is desired.
[0100] The heat transfer member 20 of the present invention can be
mounted on the contacted body 21 by merely pressing the heat
transfer member 20 against the contacted body, but when the heat
transfer member 20 can withstand brazing, soldering, or the like,
the components may be perfectly joined by brazing or soldering. In
such a case, the columnar bodies 2 easily deform to form a cushion
against the contacted body 21, and heat stress can be absorbed.
Therefore, priority can be given to the coefficient of thermal
expansion in order to match the coefficient of thermal expansion in
relation to the contacted body 21, there is no need to sacrifice
thermal conductivity and Young's modulus, and there is no need to
join components via a compound resin or the like in order to
alleviate stress. For this reason, high cooling characteristics can
be achieved because heat resistance produced by unnecessary gaps
and a stress-reducing layer is eliminated.
[0101] The heat transfer member 20 of the present invention as
described above may be used to cool televisions, projectors,
computers, and other electronic apparatuses and electric products,
whereby the heat of a cooled body can be radiated and cooling can
be provided with very good efficiency in comparison with
conventional heat sinks, fans, and other cooling means.
Heat-induced malfunctions, reduced life, damage to chips, or the
like can be prevented. Recent increases in heat output can
therefore be managed and thinner electronic apparatuses can be
designed. The heat transfer member of the present invention can
provide uniform heating with high efficiency when used in electric
products or electronic apparatuses that have heaters.
Embodiment 2
[0102] The convex structural member of the present invention is a
member having a plurality of convex structures supported on a
support, wherein all or some of the convex structures are in
contact with a contacted body and undergo elastic and/or plastic
deformation along the shape of a contact surface of the contacted
body. Heat is therefore moved via the convex structural unit
because the convex structure can be in direct contact along the
wavy and rough irregularities of the cooled body and is in direct
contact with the contacted body. In other words, direct gapless
contact can be made with a contacted body, and the heat of the
contacted body can be taken away or be supplied to the contacted
body. A contacted body can be rapidly brought to a prescribed
temperature because heat is rapidly transferred from a
higher-temperature region to a lower-temperature region via a
convex structural unit that is in contact with the contacted
body.
[0103] In one mode of the convex structural member according to the
present invention, the convex structural unit is preferably an
assembly of a plurality of columnar bodies. Since a plurality of
columnar bodies can be aligned in an orderly fashion to form a
convex structural unit, and a plurality of columnar bodies can be
uniformly aligned in the convex structural unit overall, the
movement of heat can be accurately designed by heat simulation or
the like. In some cases, the density of the columnar bodies in
areas where heat transfer is desired can be increased, and other
situations can be easily managed. Therefore, the convex structural
member is suitable for use in locations that require rigorous heat
control.
[0104] All or some the assembly of the columnar bodies is a
structure that includes a curve, whereby elasticity of the bending
of the columnar bodies overall can be used in a preferred manner to
cause sufficient contact across the entire surface of the contacted
body. Branched bodies can be formed on the columnar bodies, whereby
the surface area for heat radiation can be increased, and the flow
of coolant supply can be disturbed to increase heat radiation
efficiency. Cooling efficiency can therefore be improved because
heat can be transferred from the contacted body through the
columnar bodies, and heat radiation from the surface of the
columnar bodies can also be facilitated.
[0105] A method for fabricating the columnar bodies can be one in
which plate-like bodies are worked so that a plurality of grooves
are formed in the plate-like bodies, and the remainder of the
plate-like bodies is left to act as the columnar bodies to thereby
form the columnar bodies in a simple manner. For example, a
plurality of grooves can be formed by machining plate-like bodies
using a movable grinder so that a plurality of columnar bodies
supported on a support are formed in a simple manner. A blade for
slicing and dicing, a wire in which abrasive grains are embedded,
or a wire for machining while dropping abrasive grains may be used
as the movable grinder. These are commercially available, and
machining can be carried out in a simple manner by introducing such
devices and movable grinders.
[0106] The plurality of grooves may be formed by electrical
discharge machining. Since a wire can be used to carry out
machining by a non-contact electric discharge, a subsequent
columnar body can be machined without applying mechanical pressure
to an adjacent machined columnar body when the columnar bodies are
formed by groove machining. There is therefore an advantage in that
the completed columnar bodies are fabricated as designed.
Electrical discharge machining is a method in which a live wire is
brought into proximity with an electroconductive material to
thereby generate an electric discharge and vaporize or fuse and
machine the electroconductive material.
[0107] The blade or wire used in the movable grinder machining
described above, or the wire for generating an electric discharge,
may be designed as a set of blades or wires for simultaneous
machining. In accordance with this method, the machining time per
machine can be reduced when numerous grooves are machined to form
the columnar bodies. Such an approach is commercially preferred
from the viewpoint of mass production and reducing costs.
[0108] The plurality of grooves may be formed as a whole in a
single groove machining process by electrical discharge machining
with an electrode that has convexities that correspond to the
groove shape. For example, when columnar bodies are fabricated on a
surface that measured 30.times.30 mm by forming grooves in the
entire surface at a pitch 300 .mu.m, the machining must be carried
out 1,000 times in the X direction and 1,000 times in the Y
direction, and a considerable amount of machining time is required
to machine one columnar body at a time, resulting in higher costs.
In view of the above, an electrode is fabricated having convexities
in a reverse pattern of the target shape of the columnar bodies,
and electrical discharge machining is carried out in a single
operation to a prescribed depth while the electrode is moved closer
to the plate-like electroconductive material. The machining time
can thereby be considerably reduced. This method is one in which an
electrode having a reverse pattern of the desired shape to be
machined via the application of voltage is brought close to the
electroconductive material to which another electrode is
electrically connected, and an electrical discharge is thereby
generated to vaporize or fuse and machine the electroconductive
material.
[0109] An assembly of columnar bodies can be formed by making use
of the plastic deformation of the plate-like body. Running costs
can be markedly reduced by this method. For example, the use of a
mold to machine a plate-like body by pressing requires cost and
time to design, fabricate, and set the press conditions for a mold.
However, once the mold has been completed, machining can be carried
out in sequential fashion. Among machining methods that use the
plastic deformation of the plate-like body, nanoimprinting can be
used to form a plurality of very small columnar bodies in a single
process, and numerous narrow columnar bodies can be formed in
contact with the contacted body. For this reason, the number of
contact points can be increased, heat transfer can be facilitated,
and the specific surface area can be increased. This approach is
therefore advantageous when heat is to be radiated from the surface
of columnar bodies.
[0110] Since machining can be rapidly performed in the pressing and
nanoimprinting processes described above, machining is facilitated
in a preferred manner when the plate-like body as the workpiece is
heated, softened, and machined. The problem encountered during
nanoimprinting is that when a mold is pressed against the workpiece
to perform precision machining and the mold is then removed,
columnar bodies that have been meticulously machined with good
precision adhere to the mold and may be damaged. For this reason,
the mold is preferably removed after having applied vibrations to
separate the mold and the columnar bodies, and nanoimprinting can
thereby be carried out with good precision.
[0111] The assembly of columnar bodies may be formed by patterning
and layering a metal. Such a method is preferred because it can be
used to fabricate columnar bodies in accordance with a designed
shape by heat simulation. LIGA (Lithograph Galvanoformung Abformug)
is one such methods that is used when a convex structural unit
composed of an assembly of columnar bodies is manufactured, wherein
a resist is coated and dried on a metal substrate acting as the
base, a mask of the pattern that corresponds to the cross section
of the columnar bodies is then mounted, and X-rays are irradiated
from an oblique 45.degree. direction, for example. The substrate is
washed using a developing solution to remove the resist in
locations exposed to the X-rays, metal is embedded in the form of
columns by electroplating in the spaces from which the resist has
been removed, and the remaining resist is then removed using oxygen
plasma, whereby a convex structural unit 14 is obtained in which
numerous diagonally inclined columnar bodies 2 are assembled on a
support 1, as shown in FIG. 1A. Also, metal foil is placed on the
distal ends of the numerous columnar bodies 2 via silver solder or
the like, the assembly is heated and joined, and the metal foil is
thereafter cut away in squares using a laser. Ribs 3 can thereby be
disposed at the distal ends of the columnar bodies 2 in the manner
shown in FIG. 1B, and a convex structural unit can be obtained in
which the contact surface area with the cooled body is
increased.
[0112] The assembly of columnar bodies 2 can be fabricated by
etching one or more foils and layering a plurality of foil layers.
A foil can be etched with error precision on the order of +10 .mu.m
using conventional techniques, and etching can be carried out in
accordance with a designed shape by heat simulation. For example,
columnar bodies 2 having a cross section of 0.1.times.0.1 mm can be
obtained by etching a Cu foil having a thickness of 0.1 mm, and
leaving intervals of 0.1 mm. When the interval of the columnar
bodies 2 is 0.3 mm, for example, the columnar bodies 2 can be
etched at intervals of 0.3 mm, the columnar bodies 2 can be layered
by inserting foil having a thickness of 0.3 mm between the columnar
bodies, and a convex structure can be obtained in which the
columnar bodies 2 are aligned in intervals of 0.3 mm in the planar
direction. The plurality of layered foils can be fixed in place in
a simple manner by tightening with screws, brazing, or soldering.
Therefore, reliability can be improved because the layered foils
can be handled without subsequently becoming offset from each
other. For example, concavo-convex shapes can be formed in the foil
on the spacer side in the plurality of layered foils, whereby the
flow of coolant can be disturbed to generate stirring effect when
the coolant flows in the vicinity of the columnar bodies 2, and
heat can be radiated to the coolant with high efficiency.
[0113] The assembly of columnar bodies 2 described above can be
formed by applying heat and/or vibrations to the plate-like body to
realign the molecules, and columnar bodies having complex shapes
can easily be formed in accordance with this method. When heat,
vibrations, or a combination of the two is applied to the
plate-like body, molecular motion in the plate-like body is
facilitated. Therefore, in this state, a mold having an inverted
shape relative to the desired shape is pressed against the
plate-like body, whereby molding can be performed along the
inverted shape mold and an assembly of columnar bodies can be
molded in a very simple manner. Vibrations are applied to the
plate-like bodies and the mold when the plate-like body described
above is machined to form columnar bodies, whereby molecular motion
of the constituent molecules of the plate-like body and/or the mold
is facilitated, machining is made easier, and separation from the
mold can be improved.
[0114] The assembly of columnar bodies 2 described above can be
manufactured with high mass productivity by forming the columnar
bodies using injection molding. In the case of a metal, metal
particles are kneaded into a resin as the binder to form a compound
that is injected into a mold for injection molding, whereby a
molded article in the form of an assembly of columnar bodies can be
obtained with good mass productivity. Since a microstructure is
involved, mass productivity is considerably increased when a resin
with low viscosity is used, the temperature is increased to improve
fluidity, air bleeder holes are formed in the direction parallel to
the support so that burrs are not formed at the distal ends of the
columnar bodies, and other measures can be taken to facilitate the
flow of the compound into the structure. Separation from the mold
is improved when vibrations, for example, are applied during
separation. The molded article is degreased by heating or the like,
and the article is then baked at a prescribed temperature, whereby
assemblies of columnar bodies can be fabricated in large quantities
in a single cycle. Also, in the case that a thermoplastic resin is
used, the temperature is increased until the resin itself softens
and injection molding is carried out, whereby mass production can
be achieved in a very simple manner because the resin hardens when
cooled and returned to room temperature. In the case that a
thermoplastic resin is used, the temperature is increased to, e.g.,
50.degree. C. to achieve softening, and the resin is injected into
a mold that has been heated to 150.degree. C., whereby heat curing
is accomplished.
[0115] The assembly of columnar bodies 2 described above can be
fabricated by pre-fabricating each of the columnar bodies 2 one
body at a time, and then embedding these in the support 1.
Ordinarily, the assembly of columnar bodies 2 must be formed in
units of several thousand, for example, and manually embedding the
columnar bodies 2 is not preferred from a commercial standpoint.
However, it is possible to achieve mass production in a simple
manner by, for example, opening holes using a press or the like in
locations in which the columnar bodies 2 of the support 1 are to be
embedded, mechanically transferring the columnar bodies 2 into the
holes using a transfer machine, and pouring brazing material into
the holes to fix the bodies in place. The columnar bodies 2 can be
fabricated with high precision by foil etching or LIGA in
accordance with a designed shape obtained by heat simulation.
[0116] The convex structural member 20 of the present invention may
also be formed by inserting a porous body having a convex structure
between the contacted body and the support 1, and is not limited to
a member in which an assembly of columnar bodies 2 is formed on the
support 1 in the manner described above. In this case, since there
are two contact areas, i.e., between the contacted body and the
convex structural member 20, and between the convex structural
member 20 and the support 1, it is possible that the heat
resistance will increase in comparison with the assembly of the
columnar bodies 2 in which the convex structural member 20 and
support 1 can be integrally fabricated. However, the porous body
can be composed of metal, resin, metal/metal compounds, resin/resin
compounds, metal/resin compounds, and various other materials, and
since expanded articles having these as main components are already
commercially available, very inexpensive members having suitable
heat resistance can be obtained through the use of these articles.
The porous body and the support 1 may be integrated by fusing or
brazing in order to improve characteristics.
[0117] The porous body can be a structure composed of intertwined
metal wires. It is difficult to strictly and uniformly control the
contact area between the contacted body and the convex structural
member 20, and between the convex structural member 20 and the
support 1, but since inexpensive metal wool can also be used, lower
costs can be assured. The convex structural member 20 may also be
formed by inserting, into the area on one side of the joined body,
a structure endowed with cushioning characteristics in which
grooves having coils or wavy metal wires formed on the support 1
are aligned, or a structure endowed with cushioning characteristics
in which coils or wavy metal wires are joined using solder, brazing
material, or another joining material on the support 1. A porous
body can be formed in a simple manner by intertwining fibers,
whiskers, or a combination of the two, and molding these by
moderate pressing or the like. Mostly any metal can be used in the
porous body having a structure of intertwined metal wires. Carbon
fibers and whiskers may also be molded in the manner described
above to form a porous body. Carbon fibers in particular are
advantageous in that they are relatively inexpensive despite the
use of a material that has very high thermal conductivity of 500 to
800 W/mK in the axial direction "c" depending on the manufacturing
conditions.
[0118] The porous body may also be a honeycomb structure. Such a
structure is preferred because the cushioning characteristics to
can be precisely adjusted in a simple manner by setting the
material and shape of the honeycomb. Honeycombs are commercially
available, and can therefore be used as inexpensive porous bodies
in a simple manner by obtaining a honeycomb having suitable
characteristics and inserting the honeycomb between the support and
the contacted body. Also, the cushioning characteristics can be
used more effectively by disposing an axis of the honeycomb
structure parallel to the plane direction of the support.
[0119] The convex structural member 20 of the present invention
described above is composed of metal, resin, metal/metal compounds,
resin/resin compounds, or metal/resin compounds, whereby the
thermal conductivity and cushioning characteristics can be
enhanced, and an inexpensive convex structural member can be
obtained. Many resins usually have a low thermal conductivity of 1
W/mK or less, but resins having a high thermal conductivity of 30
W/mK or higher have been developed in recent years, and such
materials are preferred for the convex structural member 20 of the
present invention.
[0120] Aluminum or copper are preferably used as the main component
of the metal described above. These metals have high thermal
conductivity and cushioning characteristics, as well as high
plastic deformation when pressed against a contacted body.
Therefore, contact can be easily improved and the metals can be
easily obtained with little expense. Gold, silver, and the like
have superior characteristics such as high thermal conductivity and
high cushioning characteristics, but are often unsuitable
commercially because of their high cost.
[0121] On the other hand, the thermal conductivity of resins is
generally inferior to that of metals, and resins are often
unsuitable as thermally conductive materials. However, resins have
excellent moldability and are usually inexpensive. The thermal
conductivity of a compound can be improved by dispersing a material
having higher thermal conductivity than the main component resin.
Resins can by softened by heat and readily formed into complicated
shapes by injection molding or the like. High thermal conductivity
characteristics can be obtained while keeping mass productivity
high in the production of such convex structural members.
[0122] In the convex structural member 20 of the present invention
described above, heat transfer through a surface can be utilized by
providing the surface of the convex structural unit 14 with a
coated film 13 composed of a material having higher thermal
conductivity than the convex structural unit 14, as shown in FIG.
1C. For example, the resin may be endowed with higher thermal
conductivity by the addition of a dispersed material having high
thermal conductivity, and the lower thermal conductivity can still
be kept below that of a metal in which copper or aluminum is the
main component. Therefore, a resin can be injection molded to
manufacture the convex structural unit 14, and a metal or inorganic
matter having high thermal conductivity can be coated onto the
surface to supplement the thermal conductivity. The metallic coated
film 13 may be obtained by Ni plating, Cu plating, and Au plating,
or using Ni, Cu, Au, or another metal that has been sputtered,
sprayed, diamond coated, or applied in another manner. The method
is not particularly limited. Alternatively, an inorganic metal
slurry may be coated and the metal may be precipitated using
thermal decomposition, or the metal may be precipitated using
electric induction or the like when the resin has sufficient
electroconductivity.
[0123] In the case that the convex structural unit 14 has poor
oxidation resistance, poor corrosion resistance, or both, a coated
film 13 composed of a material having higher oxidation resistance,
corrosion resistance, or both in comparison with the convex
structural unit 14 may be formed on the surface of the convex
structural unit 14, making it possible to overcome the
aforementioned problem. A coated film 13 having a radiation rate of
0.5 or higher is formed when the surface of the convex structural
unit 14 is to be used to radiate heat. Radiation can thereby be
used in addition to convection in order to radiate heat from the
surface of the convex structural unit 14, and highly efficient heat
radiation is therefore made possible. Carbon or ceramics, which
have a high radiation rate, or a compound composed of these, are
preferably used for the high-radiation coated film 13.
[0124] The convex structural member 20 of the present invention can
be applied to electronic apparatuses, electric products, or
industrial products to rapidly take away or provide heat, making it
possible to perform high-efficiency or high-speed cooling or
heating. An advantage is therefore obtained for managing heat by
the high-efficiency cooling of silicon semiconductor chips and
other parts that have poor resistance to heat. Industrial products
can be obtained at high throughput because of the ability to induce
rapid temperature changes.
EXAMPLE 1
[0125] An AlN heater 4 having longitudinal, horizontal, and
thickness dimensions of 20.times.20.times.1 mm was used in place of
a semiconductor element, as shown in FIG. 11, and the AlN heater 4
was bonded to an Al.sub.2O.sub.3 substrate 5 having a purity of 92%
and longitudinal, horizontal, and thickness dimensions of
40.times.40.times.2.5 mm, respectively, by using Ag grease (thermal
conductivity: 9 W/mK). The contact area in the center of the
reverse side of the Al.sub.2O.sub.3 substrate 5, which was a
contacted body, had a length of 20 mm and a width of 20 mm and was
concavely warped by 0.05 mm.
[0126] A columnar body assembly 7 composed of an assembly of
numerous Cu columnar bodies on one side of a Cu base 6, which was a
support, were also formed by electrical discharge machining to
serve as the heat transfer member 20. A Cu plate-like body 8 for
radiating heat was disposed on the other surface of the Cu base 6,
and fins 9 were formed by integral machining on the rear surface of
the Cu plate-like body 8. The columnar bodies of the columnar body
assembly 7 were pressed against the contact area in the center of
the reverse surface of the Al.sub.2O.sub.3 substrate 5, and the
Al.sub.2O.sub.3 substrate 5 and Cu plate-like body 8 were tightened
using SUS screws to fix and complete the assembly, as shown in FIG.
11. Air was furthermore made to flow in an ordinary manner to the
fins 9 on the rear surface of the Cu plate-like body 8 using a fan
10.
[0127] The heat transfer member 20 was formed using electrical
discharge machining to produce a Cu support, wherein the angle
.theta. (see FIG. 3) formed by the columnar bodies and a line
perpendicular to a Cu base 6 (support) that measured
50.times.50.times.3 mm was varied for each sample. Samples having
different slopes were fabricated, i.e., 0.degree. (sample 1),
5.degree. (sample 2), 10.degree. (sample 3), 20.degree. (sample 4),
45.degree. (sample 5), 70.degree. (sample 6), 80.degree. (sample
7), and 85.degree. (sample 8). The columnar body assembly 7 of each
sample had a structure in which numerous columnar bodies having a
cross section of 0.1.times.0.1 mm were regularly arrayed at
intervals of 0.3 mm between each other on the Cu base 6, which was
a support.
[0128] The cooling systems of samples 1 through 8 described above
were placed into casings having longitudinal, horizontal, and
thickness dimensions of 300.times.300.times.600 mm. In a state in
which external factors had no effect, the room temperature was kept
at 20.degree. C. by air conditioning, the power supplied to the AlN
heater 4 was set to 7 W, and cooling experiments were carried out.
In this case, atmospheric air was not particularly allowed to flow
inside the columnar body assembly 7, and was fed by a fan from the
rear surface side provided with fins 9 to carry out cooling. A
configuration was used in which the fins 9 on the rear surface side
were integrated with the support 8, and in which 14 fins that
measured 20.times.50.times.1 mm were erected.
[0129] The samples 1 through 8 described above were subjected to
the above-described cooling experiment, and the temperatures as
measured by embedding an RTD element 12 in the AlN heater 4 were
found to be 40.degree. C. for sample 1, 39.degree. C. for sample 2,
35.degree. C. for sample 3, 31.degree. C. for sample 4, 30.degree.
C. for sample 5, 31.degree. C. for sample 6, 36.degree. C. for
sample 7, and 40.degree. C. for sample 8.
COMPARATIVE EXAMPLE 1
[0130] A smooth Cu board without columnar bodies was used in place
of the heat radiation member fabricated in example 1 described
above. In other words, other than inserting and fixing a resin
sheet 11 (thickness: 1.5 mm) having a thermal conductivity of 5
W/mK in place of the columnar body assembly between the smooth Cu
base 6 and the Al.sub.2O.sub.3 substrate 5, sample 9 as a
comparative example was fabricated in the same manner as in example
1 described above, as shown in FIG. 12.
[0131] Sample 9 as a comparative example was used in a cooling
experiment under the same conditions as those used in example 1
described above, and the temperature was 52.degree. C., as measured
by embedding an RTD element 12 in the AlN heater 4.
EXAMPLE 2
[0132] A heat transfer member 20 was fabricated in the same manner
as in example 1 described above. In the present example, an angle
.theta.1 (see FIG. 3) formed by a line that connects the center and
the base of the columnar bodies 2 and the line perpendicular to the
Cu base 6 (support), and an angle .theta.2 (see FIG. 3) formed by a
line that connects the center and the distal end of the columnar
bodies 2 and the line perpendicular to the Cu base 6 (support) were
varied to obtain the following ratios (.theta.1/.theta.2) of the
two angles: 0.1 (sample 10), 0.3 (sample 11), 0.6 (sample 12), 0.8
(sample 5), 0.95 (sample 13), 1.0 (sample 14), 1.5 (sample 15), and
2.0 (sample 16).
[0133] The heat transfer members of samples 10 to 16 of the present
invention described above were used in a cooling experiment under
the same conditions as those used in example 1 described above, and
the temperatures were, as measured by embedding an RTD element 12
in the AlN heater 4, 30.degree. C. for sample 10, 31.degree. C. for
sample 11, 33.degree. C. for sample 12, 35.degree. C. for sample 5,
35.degree. C. for sample 13, 39.degree. C. for sample 14,
40.degree. C. for sample 15, and 42.degree. C. for sample 16.
EXAMPLE 3
[0134] A Cu foil that measured 20.times.5.times.0.1 mm was etched
to form a columnar body assembly 7 in which columnar bodies having
a curve on one side were aligned. The Cu foil having the columnar
body assembly 7 on one side and a Cu foil that measured
20.times.4.times.0.1 mm and was devoid of the columnar bodies were
layered in alternating fashion to fabricate a heat transfer member
having external dimensions of 20.times.20.times.5 mm.
[0135] In the columnar bodies 2 (see FIG. 3) having the
above-described curve, the curvature radius r1 of the curve from
the base to the center of the columnar body was varied, as was the
curvature radius r2 of the curve from the center to the distal end,
so that the ratios r2/r1 of the two were 0.1 (sample 17), 0.3
(sample 18), 0.6 (sample 19), 0.8 (sample 20), 0.95 (sample 21),
1.0 (sample 22), 1.5 (sample 23), and 2.0 (sample 24). In these
heat transfer members, Ag was brazed on a pure Cu base 6 (support)
having a shape in which the columnar bodies of example 1 described
above were removed, and each of the members formed a cooling system
in the same manner as in example 1 described above.
[0136] The heat transfer members of samples 17 to 21 of the present
invention described above were used in a cooling experiment under
the same conditions as those used in example 1 described above, and
the temperatures were, as measured by embedding an RTD element 12
in the AlN heater 4, 24.degree. C. for sample 17, 26.degree. C. for
sample 18, 27.degree. C. for sample 19, 29.degree. C. for sample
20, 29.degree. C. for sample 21, 30.degree. C. for sample 22,
33.degree. C. for sample 23, and 35.degree. C. for sample 24.
EXAMPLE 4
[0137] Samples were fabricated in which the probability of the
number of columnar bodies in contact with the Al.sub.2O.sub.3
substrate 5, which was the contacted body, was varied using Cu
boards with varying warping levels prior to electrical discharge
machining in a case in which the columnar body assembly 7 was
fabricated in the same manner as in example 1 described above.
Specifically, the probabilities of the number of columnar bodies in
contact with the Al.sub.2O.sub.3 substrate 5 were 10% (sample 25),
30% (sample 26), 50% (sample 27), 80% (sample 28), and 95% (sample
29).
[0138] The heat transfer members of samples 25 to 29 described
above were used in a cooling experiment under the same conditions
as those used in example 1 described above, and the temperatures
were, as measured by embedding an RTD element 12 in the AlN heater
4, 42.degree. C. for sample 25, 39.degree. C. for sample 26,
33.degree. C. for sample 27, 27.degree. C. for sample 28, and
25.degree. C. for sample 29, in contrast to 30.degree. C. for
sample 5 described above in which the probability of the number of
contacting columnar bodies was 70%.
EXAMPLE 5
[0139] Several columnar body assemblies 7 were fabricated in the
same manner as in example 1 described above, clamped against a
Al.sub.2O.sub.3 substrate 5, and used to fabricate heat transfer
members having different probabilities of contact with the columnar
body side surface (number of side surface contacts/(number of side
surface contacts+number of distal end contacts)), with the
Al.sub.2O.sub.3 substrate 5 acting as a contacted body.
Specifically, the probabilities that the columnar bodies would come
into side surface contact with the Al.sub.2O.sub.3 substrate 5 were
20% (sample 30), 40% (sample 31), 50% (sample 32), 60% (sample 33),
80% (sample 34), and 90% (sample 35).
[0140] The heat transfer members of samples 30 to 35 described
above were used in a cooling experiment under the same conditions
as those used in example 1 described above, and the temperatures
were, as measured by embedding an RTD element 12 in the AlN heater
4, 30.degree. C. for sample 30, 29.degree. C. for sample 31,
27.degree. C. for sample 32, 26.degree. C. for sample 33,
25.degree. C. for sample 34, and 25.degree. C. for sample 35.
EXAMPLE 6
[0141] The tightening stress used in the configuration of the
cooling systems in example 1 described above was varied and the
pressing stress levels per columnar body in which the columnar
bodies were clamped against the Al.sub.2O.sub.3 substrate 5 of the
contacted body were 5 mg per columnar body (sample 36), 9 mg per
columnar body (sample 37), 10 mg per columnar body (sample 38), 15
mg per columnar body (sample 39), 500 mg per columnar body (sample
40), 1,000 mg per columnar body (sample 41), 5,000 mg per columnar
body (sample 42),
[0142] The heat transfer members of samples 36 to 42 described
above were used in a cooling experiment under the same conditions
as those used in example 1 described above, and the temperatures
were, as measured by embedding an RTD element 12 in the AlN heater
4, 42.degree. C. for sample 36, 40.degree. C. for sample 37,
36.degree. C. for sample 38, 35.degree. C. for sample 39,
29.degree. C. for sample 40, 28.degree. C. for sample 41, and
26.degree. C. for sample 42, in contrast to 30.degree. C. for
sample 5 described above in which the above-described pressing
stress was 100 mg per columnar body.
EXAMPLE 7
[0143] The tightening stress used in the configuration of the
cooling systems in example 1 described above was varied and the
total stress levels for clamping the columnar bodies against the
Al.sub.2O.sub.3 substrate 5 of the contacted body were 50% (sample
43), 70% (sample 44), 95% (sample 45), 97% (sample 46), and 100%
(sample 47), in contrast to the breaking strength of the
Al.sub.2O.sub.3 substrate 5 acting as the contacted body.
[0144] The breaking probabilities for the 20 samples after clamping
were calculated for the heat transfer members of samples 43 to 47
described above, and the breaking probabilities were 0/20 for
sample 43, 0/20 for sample 44, 1/20 for sample 45, 7/20 for sample
46, and 20/20 for sample 47, in contrast to 0/20 for sample 5 in
which the total stress was 30%.
EXAMPLE 8
[0145] A columnar body assembly 7 was fabricated in the same manner
as in example 1 described above, and the surface area occupied by
the columnar bodies was varied, whereby the ratios S2/S1 of the
surface area S2 occupied by the columnar bodies with respect to the
surface area S1 occupied by the AlN heater 4 were 0.5 (sample 48),
0.9 (sample 49), 1.0 (sample 50), and 1.5 (sample 51).
[0146] The cooling systems of samples 48 to 51 described above were
used in a cooling experiment under the same conditions as those
used in example 1 described above, and the temperatures were, as
measured by embedding an RTD element 12 in the AlN heater 4,
38.degree. C. for sample 48, 37.degree. C. for sample 49,
34.degree. C. for sample 50, and 27.degree. C. for sample 51, in
contrast to 30.degree. C. for sample 5 in which the above-described
surface area ratio was 1.2.
EXAMPLE 9
[0147] The contact heat resistance was varied after the heat
transfer member and Al.sub.2O.sub.3 substrate 5 had been clamped
together as in example 1 described above, and the contact heat
resistances were 0.01 K/mm.sup.2W (sample 52), 0.05 K/mm.sup.2W
(sample 53), 0.2 K/mm.sup.2W (sample 54), 0.3 K/mm.sup.2W (sample
55), 0.4 K/mm.sup.2W (sample 56), and 0.5 K/mm.sup.2W (sample
57).
[0148] The cooling systems of samples 52 to 57 described above were
used in a cooling experiment under the same conditions as those
used in example 1 described above, and the temperatures were, as
measured by embedding an RTD element 12 in the AlN heater 4,
25.degree. C. for sample 52, 27.degree. C. for sample 53,
32.degree. C. for sample 54, and 35.degree. C. for sample 55,
39.degree. C. for sample 56, and 40.degree. C. for sample 57, in
contrast to 30.degree. C. for sample 5 in which the contact heat
resistance was 0.1 K/mm.sup.2W.
EXAMPLE 10
[0149] An AlN heater having longitudinal, horizontal, and thickness
dimensions of 20.times.20.times.1 mm, respectively, was used in
place of a semiconductor chip, and the AlN heater was bonded to an
Al.sub.2O.sub.3 substrate having a purity of 92% and longitudinal,
horizontal, and thickness dimensions of 40.times.40.times.2.5 mm,
respectively, by using Ag grease (thermal conductivity: 9 W/mK).
The cooling area in the center of the reverse side of the
Al.sub.2O.sub.3 substrate, which was a cooled body, had a length of
20 mm and a width of 20 mm and was concavely warped by 0.05 mm.
[0150] A convex structural member was also formed as a cooling
member using a method to be described below. The convex structural
member had the following components: a pure copper fin in which 14
fins having dimensions of 50.times.20.times.1 mm were
perpendicularly formed on one side of an oxygen-free Cu plate that
measured 50.times.50.times.2 mm, and a protruding portion that
measured 20.times.20.times.6 mm was formed in the center of the
opposite surface of the Cu plate; and an assembly of Cu columnar
bodies that measured of 0.1.times.0.1.times.1.0 mm and were set at
a 45.degree. angle in 0.3 mm intervals on the surface of the
protruding portion. The pure Cu fin was prepared using an
oxygen-free copper plate in an ordinary machining process.
[0151] Specifically, the protruding portion of the Cu plate was
placed facing upward, the Cu fins were tilted at a 45.degree. angle
on the dicing machine stage and fixed in place using wax, and the
Cu plate was cut to a depth of 1.0 mm from the upper surface using
a blade having a thickness of 0.3 mm, and fed at a pitch of 0.4 mm
to form 50 grooves. Next, the stage was rotated 90.degree., the Cu
plate was thereafter reset parallel to the stage, and the Cu plate
was perpendicularly cut to a depth of 1.0 mm from the upper surface
and fed at a pitch of 0.4 mm to form 50 grooves, whereby 2,500
columnar bodies having dimensions of 0.1.times.0.1.times.1.0 mm
were formed and used as the convex structural member of sample
101.
[0152] The convex structural member acting as the cooling member
was pressed against the cooling area in the center of the reverse
surface of the Al.sub.2O.sub.3 substrate described above, and the
Al.sub.2O.sub.3 substrate and the convex structural member were
tightened and fixed in place using a SUS screw. The cooling system
of sample 101 was placed in a casing having longitudinal,
horizontal, and height dimensions of 300.times.300.times.600 mm, in
a state in which external factors had no effect, the room
temperature was kept at 20.degree. C. by air conditioning, the
power supplied to the AlN heater 4 was set to 7 W, and cooling
experiments were carried out.
[0153] In this case, atmospheric air was not provided to the
assembly of columnar bodies 2 (convex structural unit) on the side
in contact with the cooled body, but was fed by a fan from the rear
surface side provided with Cu fins to carry out cooling. The
temperature of the AlN heater was 32.degree. C., as measured by
embedding an RTD element in the AlN heater.
COMPARATIVE EXAMPLE 2
[0154] A smooth Cu base without a convex structural unit was used
as the cooling member in place of the convex structural member
having an assembly of columnar bodies (convex structural unit) in
the sample 101 of example 10 described above. Other than inserting
and fixing a resin sheet (thickness: 1.5 mm) having a thermal
conductivity of 5 W/mK between the smooth Cu base and the
Al.sub.2O.sub.3 substrate, sample 101a as a comparative example was
fabricated in the same manner as in example 10 described above.
[0155] Sample 101a as a comparative example was used in a cooling
experiment under the same conditions as those used in example 10
described above, and the temperature was 52.degree. C., as measured
by embedding an RTD element in the AlN heater.
EXAMPLE 11
[0156] A convex structural member having the same shape as that in
example 10 was fabricated using the following method. Specifically,
the Cu fins of the Cu plate described in example 10 were fixed
using wax to the stage of a wire machining apparatus. The wire had
a mechanism in which the cutting angle could be freely modified.
The protruding portion of the Cu plate was cut using a wire having
a diameter of 0.3 mm to a depth of 1.0 mm at an angle of 45.degree.
from the upper surface of the Cu plate, and fed at a pitch of 0.4
mm to form 50 grooves.
[0157] Next, the stage was rotated 90.degree., the cutting angle of
the wire was then set to 90.degree., and the Cu plate was cut to a
depth of 1.0 mm from the upper surface and fed at a pitch of 0.4 mm
to form 50 grooves, whereby 2,500 columnar bodies having dimensions
of 0.1.times.0.1.times.1.0 mm were fabricated as the convex
structural member of sample 102.
[0158] The convex structural member of sample 102 was used in a
cooling experiment under the same conditions as those used in
example 10 described above, and the temperature was 33.degree. C.,
as measured by embedding an RTD element in the AlN heater.
EXAMPLE 12
[0159] A convex structural member having the same shape as that in
example 10 was fabricated using the following method. Specifically,
the Cu fins of the Cu plate described in example 10 were fixed
using wax to the stage of a wire machining apparatus. The wire had
a mechanism in which the cutting angle could be freely modified. 50
wires having a diameter of 0.3 mm were set on the protruding
portion of the Cu plate at a pitch of 0.4 mm, and 50 grooves were
formed by cutting the protruding portion of the Cu plate at a
45.degree. angle to a depth of 1.0 mm from the upper surface.
[0160] Next, the stage was rotated 90.degree., the cutting angle of
the wires was then set to 90.degree., the Cu plate was cut to a
depth of 1.0 mm from the upper surface, and 50 grooves were formed
at a pitch of 0.4 mm, whereby 2,500 columnar bodies having
dimensions of 0.1.times.0.1.times.1.0 mm were fabricated as the
convex structural member of sample 103. The cutting velocity was
reduced and the actual machining time was 1/20 of that of sample
102 of example 11.
[0161] The convex structural member of sample 103 was used in a
cooling experiment under the same conditions as those used in
example 10 described above, and the temperature was 33.degree. C.,
as measured by embedding an RTD element in the AlN heater.
EXAMPLE 13
[0162] A convex structural member having the same shape as that in
example 10 was fabricated using the following method. Specifically,
the Cu fins of the Cu plate described in example 10 were fixed
using wax to the stage of an electrical discharge machining
apparatus, and electrically connected to the lower electrode. The
wire had a mechanism in which the cutting angle could be freely
modified. Voltage was applied to the Cu plate via the stage while
an electric discharge was generated between the lower electrode and
the wire having a diameter of 0.3 mm, and 50 grooves were formed by
machining from the upper surface of the Cu plate to a depth of 1.0
mm at a pitch of 0.4 mm.
[0163] Next, the stage was rotated 90.degree., the cutting angle of
the wires was then set to 90.degree., the Cu plate was cut to a
depth of 1.0 mm from the upper surface, and the plate was fed at a
pitch of 0.4 mm to form 50 grooves, whereby 2,500 columnar bodies
having dimensions of 0.1.times.0.1.times.1.0 mm were fabricated as
the convex structural member of sample 104.
[0164] The convex structural member of sample 104 was used in a
cooling experiment under the same conditions as those used in
example 10 described above, and the temperature was 32.degree. C.,
as measured by embedding an RTD element in the AlN heater.
EXAMPLE 14
[0165] The convex structural member of sample 105 in which only the
material was changed to aluminum was fabricated in the same shape
as the convex structural member of sample 104 using the same method
as in example 13.
[0166] The convex structural member of sample 105 was used in a
cooling experiment under the same conditions as those used in
example 10 described above, and the temperature was 35.degree. C.,
as measured by embedding an RTD element in the AlN heater.
EXAMPLE 15
[0167] A convex structural member having the same shape as that in
example 13 was fabricated using the following method. Specifically,
2,500 columnar bodies having the dimensions of
0.1.times.0.1.times.2.0 mm were formed on a Cu plate that measured
20.times.20.times.20 mm to a wire cutting depth of 2.0 mm using the
same method as for sample 103 of example 12. The columnar bodies
were used as the upper electrode for electric discharge, the Cu
plate that measured 20.times.20.times.20 mm was electrically
connected to the lower electrode to perform electric discharge
machining, and an article was fabricated having 2,500 holes that
measured 0.1.times.0.1.times.1.0 mm.
[0168] Next, this article was used as an upper electrode, the upper
surface of the Cu plate described in example 11 was subjected to
electric discharge machining using the same conditions as those
used for sample 104 of example 13, and an assembly of columnar
bodies that were the same as in sample 104 of example 13 were
formed in a single process. The cutting velocity was reduced and
the actual machining time was 1/50 of that of sample 104.
[0169] The convex structural member of sample 106 was used in a
cooling experiment under the same conditions as those used in
example 10 described above, and the temperature was 32.degree. C.,
as measured by embedding an RTD element in the AlN heater.
EXAMPLE 16
[0170] A convex structural member having the same shape as that in
example 10 was fabricated using the following method. Specifically,
an article was fabricated in which 2,500 columnar bodies having the
dimensions of 0.1.times.0.1.times.1.5 mm were formed on the Cu
plate that measured 20.times.20.times.20 mm to a wire cutting depth
of 1.5 mm using the same method as for sample 106 of example 15.
The columnar bodies were used as the upper electrode for electric
discharge, a SUS plate that measured 20.times.20.times.20 mm was
electrically connected to the lower electrode to perform electric
discharge machining, and an article was fabricated having 2,500
holes that measured 0.1.times.0.1.times.1.5 mm.
[0171] This article was used as a mold, and the protruding portion
of the Cu plate described in example 10 was press-machined to form
the same assembly of columnar bodies as in sample 106 in a single
process. However, with this sample 107, the plastic deformation of
the Cu plate during machining was not very good and it was
necessary to set the press time for a single cycle to 5 minutes
because the columnar bodies 2 would collapse.
[0172] In view of the above, a heater and a vibrator were set on
the machining stage, the Cu plate was heated to 150.degree. C. and
vibrated while the pressing process was carried out, and the convex
structural member of sample 108 was fabricated without particularly
any collapsed columnar bodies, even when the press time for a
single cycle was set to 1 minute.
[0173] The convex structural members of samples 107 and 108 were
used in a cooling experiment under the same conditions as those
used in example 10, and the temperature was 32.degree. C. for both
samples 107 and 108, as measured by embedding an RTD element in the
AlN heater.
EXAMPLE 17
[0174] A mold having numerous holes that measured
0.02.times.0.02.times.0.10 mm was fabricated for nanoimprinting
using the method described below. Specifically, a resist was coated
and dried on the surface of an Ni plate measuring
20.times.20.times.20 mm, a mask was placed thereon, X-rays were
irradiated from an oblique direction at 45.degree., and the surface
was washed using a developing solution to remove the resist in
locations exposed to the X-rays. Ni was embedded in the form of
columns by electroplating in the spaces from which the resist had
been removed, and the remaining resist was then removed using
oxygen plasma. The mold fabricated in this manner had an inverted
pattern relative to the assembly of columnar bodies, and a
structure in which numerous holes that had a cross section of
0.02.times.0.02 mm and were diagonally inclined 45.degree. were
arrayed in regular fashion at intervals of 0.06 mm.
[0175] The Cu fins of the Cu plate described in example 10 was set
on the stage of a nanoimprinting machine, the protruding portion of
the upper surface of the Cu plate was press-machined while being
heated to 150.degree. C., and the convex structural member of
sample 109 was fabricated. However, since the member tended to
adhere to the mold during separation from the mold, the member was
required to be slowly removed over a time of 3 minutes. In view of
this situation, vibrations were imparted to the stage only during
release from the mold in the same manner as described above in
order to improve mold release characteristics, and sufficient
machining was achieved even with a release time of 30 seconds and
the convex structural member of sample 110 was obtained.
[0176] The convex structural members of samples 109 and 110 were
used in a cooling experiment under the same conditions as those
used in example 10, and the temperature was 38.degree. C. for both
samples 109 and 110, as measured by embedding an RTD element in the
AlN heater.
EXAMPLE 18
[0177] A convex structural member having the same shape as that in
example 10 was fabricated using LIGA as described below.
Specifically, a resist was coated and dried on the surface of the
Cu plate described in example 10, a mask in which numerous
square-shaped holes measuring 0.1.times.0.1.times.1.0 mm were
formed at intervals of 0.3 mm was placed thereon, X-rays were
irradiated from an oblique 45.degree. direction, and the surface
was washed using a developing solution to remove the resist in
locations exposed to the X-rays. Cu was embedded in the form of
columns by electroplating in the spaces from which the resist had
been removed, and the remaining resist was then removed using
oxygen plasma to fabricate the convex structural member of sample
111.
[0178] The convex structural unit of the convex structural member
fabricated in this manner had a microstructure in which numerous
columnar bodies that measured 0.1.times.0.1.times.1.0 mm and were
diagonally inclined at 45.degree. were arrayed in regular fashion
at intervals of 0.3 mm in a serrated manner.
[0179] The convex structural member of sample 111 was used in a
cooling experiment under the same conditions as those used in
example 10, and the temperature was 32.degree. C., as measured by
embedding an RTD element in the AlN heater.
EXAMPLE 19
[0180] A Cu foil that measured 20.times.3 mm and had a thickness of
0.1 mm was etched and a Cu foil A1 (see FIG. 1) was fabricated in
which columnar bodies that measured 0.1.times.0.1.times.1.0 mm and
were diagonally inclined at 45.degree. were aligned at intervals of
0.3 mm. Fifty sets of the Cu foil A1 and a flat Cu foil B that
measured 20.times.2 mm and had a thickness of 0.3 mm were
alternately overlaid and then tightened using screws in sample 112,
fusing in sample 113, and Ag--Cu brazing in sample 114 to fabricate
a convex structural member with external dimensions of
20.times.20.times.3 mm that had an assembly of columnar bodies
(convex structural unit).
[0181] These convex structural members were brazed using Ag--Cu on
the protruding portion of the Cu plate described in example 10 to
fabricate cooling systems in the same manner as sample 10 described
above.
[0182] The convex structural members of samples 112, 113, and 114
were used in a cooling experiment under the same conditions as
those used in example 10, and the temperatures were 33.degree. C.
for sample 112, 33.degree. C. for sample 113, and 33.degree. C. for
sample 114, as measured by embedding an RTD element in the AlN
heater.
EXAMPLE 20
[0183] When the Cu foil of example 19 was etched, branched bodies
measuring 0.05.times.0.1 mm were etched in the side surface of the
columnar bodies so as to add four columnar bodies each to the left
and right. A Cu foil A2 provided with an assembly of columnar
bodies having the branched bodies on the side surfaces, and a flat
Cu foil B that measured 20.times.2.times.0.3 mm were alternately
layered and fused to fabricate the convex structural member of
sample 115 measuring 20.times.20.times.3 mm.
[0184] When the Cu foil of example 19 was etched, Cu ribs 3
measuring 0.3.times.0.1.times.0.1 mm were formed so as to be
mounted in parallel on the distal ends of the columnar bodies (see
FIG. 1B). A Cu foil A3 provided with an assembly of columnar bodies
having the ribs 3 at the distal ends, and a flat Cu foil measuring
20.times.2.times.0.3 mm were alternately layered and fused to
fabricate the convex structural member of sample 116 having the
dimensions of 20.times.20.times.3 mm.
[0185] When the Cu foil of example 19 was etched, curve-shaped
bodies 2 were formed at intervals of 0.35 mm having a curved shape
in which the width was 100 .mu.m, the outside diameter was 1 mm,
one end thereof was integrated into the support 1, and the other
end was positioned 0.8 mm from the support 1, as shown in FIG. 4.
The Cu foil B and a Cu foil A4 having a large number of these
curve-shaped bodies 2 were alternately layered and fused to
fabricate the convex structural member of sample 117 having the
dimensions of 20.times.20.times.3 mm.
[0186] When the Cu foil of example 19 was etched, arch-shaped
bodies 2 were formed at intervals of 0.2 mm having an arched shape
in which the width was 100 .mu.m, the outside diameter was 1 mm,
and both ends were integrated into the support 1, as shown in FIG.
5. The Cu foil B and a Cu foil A5 having a large number of these
arch-shaped bodies 2 were alternately layered and fused to
fabricate the convex structural member of sample 118 having the
dimensions of 20.times.20.times.3 mm.
[0187] When the Cu foil of example 19 was etched, serpentine
curve-shaped bodies 2 were formed having a width of 100 .mu.m, an
end-to-end distance of 1 mm, a plurality of semicircular curves
with an outside diameter of 250 .mu.m, and a center pitch of 700
.mu.m, as shown in FIG. 6. The Cu foil B and a Cu foil A6 having a
large number of these serpentine curve-shaped bodies 2 were
alternately layered and fused to fabricate the convex structural
member of sample 119 having the dimensions of 20.times.20.times.3
mm.
[0188] When the Cu foil of example 10 was etched, S-shaped bodies 2
were formed having a width of 100 .mu.m, an end-to-end distance of
1 mm, an outside diameter of 250 .mu.m, and a center pitch of 700
.mu.m, as shown in FIG. 7. The Cu foil B and a Cu foil A7 having a
large number of these S-shaped bodies 2 were alternately layered
and fused to fabricate the convex structural member of sample 120
having the dimensions of 20.times.20.times.3 mm.
[0189] A Cu foil A8 that measured 20.times.4.times.0.1 mm and had
numerous columnar bodies 2 disposed on the surface in the manner
shown in FIG. 1A, and a Cu foil A9 that measured
20.times.3.times.0.1 mm and had been etched to form concavo-convex
shapes 15 having a radius (R) of 1 mm on the surface, were
alternately layered and fused to fabricate the convex structural
member of sample 121 having the dimensions of 20.times.20.times.3
mm.
[0190] The convex structural members of the samples 115, 116, 117,
118, 119, 120, and 121 were used in a cooling experiment under the
same conditions as those used in example 11, and the temperatures
were, as measured by embedding an RTD element in the AlN heater,
27.degree. C. for sample 115, 30.degree. C. for sample 116,
29.degree. C. for sample 117, 28.degree. C. for sample 118,
28.degree. C. for sample 119, 28.degree. C. for sample 120, and
29.degree. C. for sample 121.
EXAMPLE 21
[0191] A convex structural member having the same shape as that of
example 10 was fabricated by injection molding. Specifically, Cu
powder having a particle diameter of 1.0 .mu.m was kneaded into a
binder for injection molding to form a compound, and pellets were
formed from the compound. The pellets were heated to 50.degree. C.,
and then injected into an injection mold set at 150.degree. C. and
injection molded. The resulting molded article was heated to
800.degree. C. in nitrogen gas to remove the binder, and the
article was then baked at 950.degree. C. in nitrogen gas to
fabricate the convex structural member of sample 122. The thermal
conductivity of the Cu convex structural member of sample 122 was
80 W/mK.
[0192] Resin pellets in which Ni had been kneaded into PPS resin
were injection-molded under the same conditions to fabricate the
convex structural member of sample 123. The thermal conductivity of
the convex structural member of sample 123 was 20 W/mK.
Furthermore, the surface of the convex structural member of sample
116 in example 20 was Cu-plated to a thickness of 5 .mu.m to
fabricate the convex structural member of sample 124.
[0193] The convex structural members of the samples 122, 123, and
124 were used in a cooling experiment under the same conditions as
those used in example 10, and the temperatures were, as measured by
embedding an RTD element in the AlN heater, 31.degree. C. for
sample 122, 39.degree. C. for sample 123, and 36.degree. C. for
sample 124.
EXAMPLE 22
[0194] A convex structural member having the same shape as that in
example 10 was fabricated using the following method. Specifically,
an article was fabricated in which 2,500 columnar bodies having the
dimensions of 0.1.times.0.1.times.1.5 mm were formed on a Cu plate
measuring 20.times.20.times.20 mm to a wire cutting depth of 1.5 mm
using the same conditions as sample 106 of example 15. The article
was used as the upper electrode for electric discharge, an SUS
plate measuring 20.times.20.times.20 mm was electrically connected
to the lower electrode to perform electric discharge machining, and
a mold was fabricated having 2,500 holes that measured
0.1.times.0.1.times.1.5 mm. SiO.sub.2 for mold release was
vapor-deposited on the surface of the mold.
[0195] A Cu plate having the Cu fins described in example 10 was
heated to 200.degree. C. and vibrations were applied while the mold
described above was pressed against the protruding portion of the
Cu plate. The same vibrations were applied to the mold during mold
release to remove the mold, and the convex structural member of
sample 125 was fabricated.
[0196] The convex structural member of the sample 125 was used in a
cooling experiment under the same conditions as those used in
example 10, and the temperature was 34.degree. C., as measured by
embedding an RTD element in the AlN heater.
EXAMPLE 23
[0197] A Cu foil having a thickness of 0.1 mm was etched to
fabricate 2,500 pins measuring 0.1.times.0.1.times.2.0 mm. Holes
having dimensions of 0.15.times.0.15.times.0.5 mm and inclined at
an angle of 45.degree. were opened at intervals of 0.3 mm on the
surface of the protruding portion of the Cu plate having the Cu
fins described in example 10, and the pins were transferred into
the holes using a vibrating transfer apparatus. Brazing material
was then poured into the holes from the edge of the Cu plate and
the holes and pins were joined to fabricate the convex structural
member of sample 126.
[0198] The convex structural member of the sample 126 was used in a
cooling experiment under the same conditions as those used in
example 10, and the temperature was 32.degree. C., as measured by
embedding an RTD element in the AlN heater.
EXAMPLE 24
[0199] A commercially available Cu metal porous body (PPI=50)
measuring 20.times.20.times.1 mm was prepared as the convex
structural member of sample 127. Other than inserting the convex
structural member between the Al.sub.2O.sub.3 substrate and the
protruding portion of the Cu plate having the Cu fins described in
example 10, and then tightening and fixing these in place using SUS
screws, the cooling system of sample 127 was fabricated in the same
manner as in example 10.
[0200] A porous tetrafluoroethylene (PTFE) body that measured
20.times.20.times.1 mm and was Cu-plated to a thickness of 1 .mu.m
was prepared as the convex structural member of sample 128. The
convex structural member was fixed between the Al.sub.2O.sub.3
plate and the protruding portion of the Cu plate in the same manner
as described above to fabricate the cooling system of sample
128.
[0201] The convex structural members of samples 127 and 128 were
used in a cooling experiment under the same conditions as those
used in example 10, and the temperatures were 35.degree. C. for
sample 127 and 39.degree. C. for sample 128, as measured by
embedding an RTD element in the AlN heater.
EXAMPLE 25
[0202] Commercially available Cu wires having a diameter of 0.1 mm
were intertwined in the amount of 0.36 g and set to dimensions of
20.times.20.times.1 mm to act as the convex structural member of
sample 129. The cooling system of sample 129 was fabricated in the
same manner as that in example 24, except that the convex
structural member having a porosity of 90% was inserted between the
Al.sub.2O.sub.3 substrate and the protruding portion of the Cu
plate having the Cu fins described in example 10, and then these
were tightened and fixed in place using SUS screws.
[0203] Carbon whiskers in which the average dimensions were a
diameter of 0.5.times.10 .mu.m were intertwined in the amount of
0.09 g and set to dimensions of 20.times.20.times.1 mm to act as
the convex structural member of sample 130. The convex structural
member having a porosity of 90% was fixed between the
Al.sub.2O.sub.3 substrate and the protruding portion of the Cu
plate in the same manner as in example 10 to fabricate the cooling
system of sample 130.
[0204] The convex structural members of samples 129 and 130 were
used in a cooling experiment under the same conditions as those
used in example 10, and the temperatures were 37.degree. C. for the
two samples 129 and 130, as measured by embedding an RTD element in
the AlN heater.
EXAMPLE 26
[0205] A Cu honeycomb having a thickness of 3.0 mm and a honeycomb
diameter of 0.5 mm was prepared as the convex structural member of
sample 131. The cooling system of sample 131 was fabricated in the
same manner as that in example 24, except that the convex
structural member was disposed and fixed between the
Al.sub.2O.sub.3 substrate and the protruding portion of the Cu
plate having the Cu fins described in example 10 so that the
honeycomb axis was set in a direction parallel to the contacted
body.
[0206] The convex structural member of the sample 131 was used in a
cooling experiment under the same conditions as those used in
example 10, and the temperature was 37.degree. C., as measured by
embedding an RTD element in the AlN heater.
EXAMPLE 27
[0207] The surface of the convex structural member of sample 104 in
example 13 was plated with Ni to a thickness of 5 .mu.m to
fabricate the convex structural member of sample 132. The convex
structural member of the sample 132 was used in a cooling
experiment under the same conditions as those used in example 10,
and the temperature was 33.degree. C. for sample 132, as measured
by embedding an RTD element in the AlN heater, in contrast to
32.degree. C. for the sample 104 described above in which
Ni-plating was not performed.
[0208] The convex structural member of the samples 104 and 132 were
exposed for 100 hours to a temperature of 80.degree. C. and a
humidity of 80% in a high temperature humidity test machine and
thereafter evaluated in the same manner as described above. There
was no change in the characteristics in that the temperatures were
34.degree. C. for sample 104 and 33.degree. C. for sample 132.
EXAMPLE 28
[0209] Carbon was vapor-deposited to a thickness of 5 nm on the
surface of the convex structural member of sample 104 in example 13
to fabricate the convex structural member of sample 133. The
radiation rate of the surface was 0.92. The convex structural
member of sample 133 was used in a cooling experiment under the
same conditions as those used in example 10, and the temperature
was 28.degree. C. for sample 133, as measured by embedding an RTD
element in the AlN heater, in contrast to 32.degree. C. for the
sample 104 described above in which carbon was not vapor-deposited
on the surface.
EXAMPLE 29
[0210] Al.sub.2O.sub.3 was vapor-deposited to a thickness of 0.1
.mu.m on the surface of the convex structural member of sample 104
in example 13 to fabricate the convex structural member of sample
134. The radiation rate of the surface was 0.7. The convex
structural member of sample 134 was used in a cooling experiment
under the same conditions as those used in example 10, and the
temperature was 30.degree. C. for sample 134, as measured by
embedding an RTD element in the AlN heater, in contrast to
32.degree. C. for the sample 104 described above in which
Al.sub.2O.sub.3 was not vapor-deposited on the surface.
* * * * *