U.S. patent application number 10/702085 was filed with the patent office on 2005-06-16 for heat sink in the form of a heat pipe and process for manufacturing such a heat sink.
Invention is credited to Schulz-Harder, Jurgen.
Application Number | 20050126758 10/702085 |
Document ID | / |
Family ID | 32478058 |
Filed Date | 2005-06-16 |
United States Patent
Application |
20050126758 |
Kind Code |
A1 |
Schulz-Harder, Jurgen |
June 16, 2005 |
Heat sink in the form of a heat pipe and process for manufacturing
such a heat sink
Abstract
In a heat sink designed as a heat pipe, there is an interior
space in a body of the heat sink that is closed toward the outside
with at least one vapor channel or vapor space and at least one
fluid space that is connected with the vapor space and has a porous
or capillary structure.
Inventors: |
Schulz-Harder, Jurgen;
(Lauf, DE) |
Correspondence
Address: |
HOFFMAN, WASSON & GITLER, P.C.
Suite 522
2361 Jefferson Davis Highway
Arlington
VA
22202
US
|
Family ID: |
32478058 |
Appl. No.: |
10/702085 |
Filed: |
November 6, 2003 |
Current U.S.
Class: |
165/104.21 |
Current CPC
Class: |
Y10T 29/49377 20150115;
F28D 15/04 20130101; Y10T 29/49353 20150115; H01L 2224/48091
20130101; H01L 2924/19107 20130101; Y10T 29/53113 20150115; H01L
2224/48227 20130101; H01L 2924/00014 20130101; H01L 2224/48091
20130101 |
Class at
Publication: |
165/104.21 |
International
Class: |
F28D 015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 30, 2002 |
DE |
102 61 402.4 |
Claims
1. A heat sink designed as a flat heat pipe comprising a body, at
least one interior space formed in the body and closed toward the
outside with at least one vapor channel, with at least one fluid
channel is connected to the at least one vapor channel and has a
porous or capillary structure, and with several spatially separated
posts extending through the interior and between two opposing walls
delimiting the interior, whereby the posts and the opposing walls
are made of a material with high heat conductivity, wherein each
post is connected at both ends directly with one of the opposing
walls.
2. The heat sink as claimed in claim 1, wherein the capillary or
porous structure comprises particles connected with each other by
bonding or sintering and/or with an adjacent surface in such a way
that capillary flow paths are formed between the particles.
3. A heat sink designed as a heat pipe with at least one interior
space formed in the body of the heat sink and closed toward the
outside with at least one vapor channel, with at least fluid
channel connected to the vapor channel and has a porous or
capillary structure, wherein the capillary or porous structure
comprises particles made of ceramic, connected with each other
and/or with an adjacent surface by means of bonding or sintering,
so as to form capillary flow paths between the particles.
4. The heat sink as claimed in claim 3, further comprising several
spatially separated posts extending through the interior and
between two opposing walls delimiting the interior, whereby the
posts and the opposing walls are all made of a material with high
heat conductivity, and whereby each post is connected at both ends
directly with one of the opposing walls.
5. The heat sink as claimed in claim 3, wherein particles are
connected with each other by means of metal stays, for example
copper stays (9), e.g. by means of copper stays produced through
DCB bonding.
6. A heat sink comprising a flat heat pipe having a body with at
least one interior space formed in the body and closed toward the
outside with at least one vapor channel, with at least one fluid
channel connected to the vapor channel and having a porous or
capillary structure, wherein the capillary or porous structure
comprising at least partially of a loose mass of particles in a
space separated from the fluid area by an intermediate wall.
7. A heat sink as claimed in claim 6, wherein the intermediate wall
has a plurality of openings.
8. A heat sink as claimed in claim 6, wherein the particles are
such made of metal and/or ceramic.
9. A heat sink as claimed in claim 3, wherein the capillary
structure is formed from at least one ply or layer, which is
applied at least on part of the inner surface of the wall sections
delimiting the at least one interior space, and enclosing the posts
at their respective connecting areas with these wall sections.
10. A heat sink as claimed in claim 9 wherein the layer forming the
capillary structure is applied at least on a partial area of the
surface of the posts.
11. A heat sink as claimed in claim 3 wherein the posts have a
diameter that is considerably smaller in every direction of the
diameter than the dimension of the interior in this direction of
the diameter.
12. A heat sink as claimed in claim 3 wherein between the vapor
space and the capillary structure forming the at least one fluid
channel there is an intermediate wall.
13. A heat sink as claimed in claim 12, wherein the intermediate
wall is provided with a plurality of openings or is made of a
perforated material.
14. A heat sink as claimed in claim 12, wherein, the at least one
intermediate wall is parallel to the first wall sections.
15. A heat sink as claimed in claim 12, wherein the intermediate
wall is formed from a pipe section preferably from a pipe section
pressed flat or formed in an oval profile.
16. A heat sink as claimed in claim 9, wherein at least two
capillary structures forming a fluid channel and/or at least two
vapor channels are provided for.
17. A heat sink as claimed in claim 6, wherein first and second
wall sections are each formed from plate-shaped walls, which
together with a peripheral wall delimit the interior of the heat
sink.
18. A heat sink as claimed in claim 17, wherein the first wall
sections are formed from areas of a pipe section preferably pressed
flat delimiting the interior of the heat sink.
19. A heat sink as claimed in claim 4, wherein the heat sink
comprises several plates located one above the other in the manner
of a stack and connected with each other at the surfaces, of which
plates in the inside of the stack are provided with openings so
that these openings form a channel structure through the interior
of the heat sink and that the structured plates are supplemented by
areas outside of the openings to the continuous posts, and that the
material forming the capillary structure is inserted in at least
one area of the channel structure.
20. A heat sink as claimed in claim 19, wherein the interior is
formed by at least one depression or recess in one of the plates
forming the heat sink.
21. A heat sink as claimed in claim 6, wherein the particles
forming the capillary layer or structure are provided in one layer
on the respective surface of the walls delimiting the interior.
22. A heat sink as claimed in claim 6, wherein the particles are
connected directly with the respective surface, for example by
means of DCB bonding.
23. A heat sink as claimed in claim 6, wherein the body of the heat
sink is formed from a pipe section that is closed at both ends.
24. A process for manufacturing a heat sink in the form of a heat
pipe with at least one vapor channel formed in a closed interior
and with at least one fluid channel with a porous or capillary
structure, wherein the porous or capillary structure is produced by
insertion of a mass of particles made of a heat-resistant material,
for example ceramic particles and by subsequent DCB bonding upon
heating to a bond temperature between 1065 and 1085.degree. C.
25. A process as claimed in claim 24, wherein the porous or
capillary structure is produced by insertion of a mixture or mass
of particles made of the heat-resistant material and pulverized
copper oxide or oxidized copper particles and by subsequent DCB
bonding.
26. A process as claimed in claim 25, wherein the mass or mixture
additionally contains copper particles.
27. A process as claimed in claim 25, wherein, after bonding and
cooling, the excess portion of the mass or mixture is removed.
28. A process as claimed in claim 24, wherein the capillary or
porous structure or layer is produced before sealing the interior
of the heat sink.
29. A process as claimed in claim 25, wherein the mass or mixture
forming the capillary structure is inserted in the interior through
at least one opening and is distributed there before bonding by
shaking, vibration or turning.
30. A process as claimed in claim 24, wherein during the
manufacture of the porous or capillary structure at least one part
of the interior of the heat sink forming a vapor area is filled or
kept free by means of a support medium before bonding of the
particles forming the porous or capillary structure.
31. A process as claimed in claim 30, wherein the support medium is
removed after bonding or after manufacturing the porous or
capillary structure.
32. A process as claimed in claim 30, wherein the support medium
remains in the heat sink.
33. A process as claimed in claim 30, wherein the support medium is
a particle-like medium,.
34. A process as claimed in claim 30, wherein the support medium is
formed from a wall.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a heat sink in the form of
a heat pipe.
BACKGROUND OF THE INVENTION
[0002] A heat sink designed as a flat, plate-shaped heat pipe is
known in the art (U.S. Pat. No. 3,680,189). The known heat sink
consists essentially of a cuboid or plate-shaped hollow body, the
interior of which is delimited by two walls forming the top and
bottom and by one peripheral wall. On each of the inner surfaces of
the wall sections forming the top and bottom is a layer forming a
capillary or porous structure. These layers are held to their
respective walls by several posts located in the interior of the
hollow body in a staggered pattern. The interior of the hollow body
serves to contain an easily vaporizable heat-transporting medium.
This medium vaporizes in order to cool, for example, an electric,
heat loss producing component located on the heat pipe in a
vaporization area, i.e. where the component is located and
condenses in a condensation area spatially distant from the
vaporization area, i.e. where the heat is dissipated and can then
flow back to the vaporization area in the capillary structures.
[0003] Also known in the art is the so-called DCB (direct copper
bond) technology. This technology, described for example in U.S.
Pat. No. 3,744,120 or DE-PS 23 19 854, makes it possible to bond
metal surfaces, for example copper, or metal and ceramic surfaces,
whereby the metals have a layer or coating (melt layer) on their
surfaces of a chemical compound made of the metal and a reactive
gas, preferably oxygen. This melt layer forms a eutectic with a
melting temperature below the melting temperature of the metal
(e.g. copper), so that after joining the materials to be bonded,
they can be bonded by heating, in particular by melting the melt
layer. The processing temperature in this DCB technology is between
approximately 1025 and 1083.degree. C.
[0004] The object of the invention is to provide a heat pipe
featuring improved efficiency.
SUMMARY OF THE INVENTION
[0005] A special feature of the invention consists in the fact that
between the first two opposing wall sections or walls that delimit
the interior of the hollow body to form the heat pipe there are
several spatially separated posts, which are directly connected
with these walls and, like these wall sections, are made of a
material with high heat conductivity, for example of metal, such as
copper.
[0006] Corresponding to further embodiments of the invention, the
at least one capillary or porous area (fluid area) is formed by a
plurality of particles that are connected with each other by means
of bonding and/or sintering and/or form a loose mass, so as to form
capillary flow paths between the particles. The particles are
thereby preferably made of ceramic, for example of an aluminum
oxide ceramic, and by means of DCB bonding technology are bonded
together and also with adjacent surfaces of the body of the heat
pipe to form the capillary structure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The invention is described in more detail below referring to
the drawings based on exemplary embodiments.
[0008] FIG. 1 shows a simplified representation of a longitudinal
cross section of a heat sink in the form of a heat pipe according
to the invention;
[0009] FIG. 2 shows a cross section corresponding to the line 1-1
of FIG. 1;
[0010] FIGS. 3 and 4 show an enlarged view of the particles forming
the porous layer or capillary layer;
[0011] FIGS. 5 and 6 show cross sections similar to FIG. 1 of
further possible other embodiments of the invention;
[0012] FIG. 7 shows a simplified partial side view of a further
embodiment of the invention;
[0013] FIG. 8 shows an enlarged view of a partial cross section of
the heat sink in FIG. 7;
[0014] FIGS. 9 and 10 show a simplified view of cross sections of
further possible other embodiments of the invention:
[0015] FIG. 11-14 each show a longitudinal cross section (partial
view) and a cross section of two further embodiments of the
invention;
[0016] FIG. 15 shows an electric circuit using a heat pipe.
DETAILED DESCRIPTION OF THE INVENTION
[0017] In FIGS. 1 and 2, 1 generally designates a heat sink
designed as a heat pipe. This heat sink 1 has a flat, plate-shaped
design and comprises a flat, cuboid or plate-shaped hollow body
1.1, the interior 2 of which is delimited on the two opposing sides
with the larger surfaces by walls 3 and 4 and on the perimeter by a
peripheral wall 5. In the interior 2 there is a plurality of
spatially separated posts 6, the axes of which are perpendicular to
the planes of the walls 3 and 4 and each of which is connected at
one end directly with the inside of the wall 3 and at the other end
directly with the inside of the wall 4.
[0018] The walls 3 and 4 have, for example, a rectangular or square
shape. The posts 6 each have a diameter which is only a fraction of
the width and length of the interior 2, i.e. none of the posts 6
extends throughout the entire length or width of the interior
2.
[0019] The walls 3 and 4, the peripheral wall 5 and the posts 6 are
made of a material that conducts heat very well, for example metal,
such as copper, whereby the DCB technology known to those skilled
in the art is preferably used for manufacturing the heat sink 1,
i.e. to bond the walls 3 and 4, the peripheral wall 5 and the posts
6.
[0020] In the depicted embodiment, the insides of the walls 3 and
4, and also partially the inside of the peripheral wall 5 and the
posts 6 are provided with a capillary or porous layer 7 forming a
capillary layer or space. The latter is comprised of a plurality of
particles 8 as seen in FIG. 3, which are connected in a suitable
manner with each other and with the respective adjacent surface 10,
for example of the walls 3 and 4, the peripheral wall 5 and the
posts 6. The particles 8 are for example made of aluminum oxide,
aluminum nitride and/or silicon nitride that are connected with
each other by means of copper or copper bridges or stays 9 and with
the adjacent surface 10 possessing the layer 7. The particles 8
have a grain size for example between 0.5 and 250 m. In the
embodiment in FIG. 3 the particles 8 form two layers or rows. It is
also possible, however, to provide the particles 8 in only one
layer on the surface 10.
[0021] The layer 7 is applied in such a manner that after
manufacturing the hollow body 1.1, a mixture of the particles 8 and
a pulverized copper oxide, possibly also with copper powder added,
is inserted into the interior 2 through at least one fill opening
1.2. Afterwards, the hollow body is heated to a temperature at
which the copper/copper oxide eutectic is transformed into a melted
state, i.e. to a temperature between 1065 and 1085.degree. C., so
that the melting of the copper/copper oxide eutectic causes the
formation of the copper stays 9 connecting the particles 8 with
each other and with the surface 10 possessing the layer 7.
[0022] By means of a suitable movement, for example shaking, of the
hollow body, the layer 7 is formed in the desired manner on all
required inner surfaces of the hollow space 2. After cooling of the
hollow body and therefore after bonding of the layer 7, the
non-bonded particles 8 are removed from the interior 2.
[0023] Generally it is also possible to use particles 8 already
coated with copper instead of a mixture of particles 8, the copper
powder and the copper oxide powder, whereby the copper layer
encompassing these particles 8 is oxidized on the outer surface, so
that upon heating to the bond temperature between 1065 and
1085.degree. C. the copper stays 9 are formed.
[0024] It was already mentioned above in connection with FIG. 3
that the particles 8 for forming the layer 7 can be provided on the
surface 10 in multiple layers or multiple row. If the particles 8
are provided in a single layer on the surface 10, then the
thickness of the layer 7 is approximately equivalent to the grain
size of these particles and in the case of multiple layers
equivalent or approximately equivalent to a multiple of the grain
size of the particles 8.
[0025] FIG. 4 shows as a possible further embodiment for the
formation of the porous layer 7 in the manner that the particles 8
are directly connected with the surface 10 by means of DCB bonding,
and there is no connection of the particles 8 with each other, so
that the corresponding copper stays or bridges 9 do not exist. This
produces a structure by means of the porous layer 7 in which the
particles 8 are provided in a single layer, but resulting in a very
distinct capillary structure between the particles 8 in which the
effective diameter of the capillaries can be adjusted by changing
the grain size of the particles 8.
[0026] Moreover, it is also possible to produce the layer 7 before
the heat sink 1 or the hollow body forming this heat sink is closed
or sealed. In this case, the upper wall 3, for example, is not
connected with the peripheral wall 5 and the posts 6 until after
the layer 7 has been provided on the inner surface of the lower
wall 6 and possibly also on part of the inner surface of the
peripheral wall 5 and on part of the height of the posts 6.
[0027] After completion of the layer 7 an easily vaporizable,
heat-transporting medium is inserted into the interior 2 through
the opening 1.2 and then the interior 2 is completely sealed at the
opening 1.2. The heat-transporting medium may be a medium which is
liquid at room temperature and is in a vaporized phase at
temperatures higher than room temperature, for example alcohol.
[0028] In FIG. 1, 11 designates a heat loss producing electric
component, which is located on top of the heat sink 1, i.e. on the
outer surface of the wall 3, and is electrically insulated from the
wall 3 by means of a layer 12 made of an electrically insulating
material, for example of ceramic. The layer 12 contains structured
metallizations 12.1 and 12.2, of which the metallization 1.2 forms
conductors, contact surfaces, etc. and the metallization 12.2
serves as a connection with the heat sink. For reasons of symmetry,
a layer with metallizations corresponding to the layer 12 is
likewise applied to the bottom surface of the heat sink 1, i.e. on
the outer surface of the wall 4, both layers 12 being applied for
example by means of DCB technology.
[0029] In the depicted embodiment the component 11 is located on
one narrow side of the heat sink 1, which is rectangular when
viewed from the top. On the opposite narrow side of the heat sink,
coolers 13 are located on the top and bottom, each consisting for
example of a passive cooling element or active coolers through
which a heat transporting medium flows as part of a cooling
circuit.
[0030] The heat dissipated from the component 11 causes
vaporization of the heat transporting medium in the interior 2 in
the vicinity of this component or the vaporization area generally
designated 14 in FIG. 1. In the area of the cooler 13, i.e. at the
condensation area generally designated 15 in FIG. 1, the heat
transporting medium condenses due to cooling and then flows back to
the vaporization area 14 with the layers 7 in the liquid phase.
This produces a circuit in the interior of the heat sink, in
particular in the area of the interior 2 not occupied by the layers
7 which can also be referred to as a vapor space or vapor channel.
The circuit is formed by the flow of the vaporized heat
transporting medium in the direction of the arrow A from the
vaporization area 14 to the condensation area 15 parallel to the
planes of the walls 3 and 4 and within the layers 7 or within the
capillary space formed by these layers in the direction of the
arrow B from the condensation area 15 back to the vaporization area
14, likewise parallel to the planes of the walls 3 and 4.
[0031] The posts 6, each of which is connected directly with the
walls 3 and 4, produces a high degree of stability, in particular
pressure resistance, for the heat sink 1. Furthermore, optimum heat
transfer is achieved between the top wall 3 and bottom wall 4,
resulting in optimum functioning of this heat sink.
[0032] FIG. 5 shows a simplified cross section of a heat sink 1a
designed as a heat pipe that differs from the heat sink 1
essentially by the fact that instead of the fluid channels formed
by the layers 7 along the top wall 3 and the bottom wall 4, there
is one fluid channel 16 respectively, each of which is separated by
a wall 17 from the vaporization channel 18 formed between the two
fluid channels 16 or between the two walls 17. The top and bottom
walls 3 and 4 are likewise directly connected with each other by
means of several spatially separated posts 6, which also extend
through the intermediate walls 17 and a partial length of which
extend within the two fluid channels 16. A suitable material for
the intermediate walls is a perforated flat material, for example a
perforated metal plate or foil, e.g. a perforated plate or foil
made of copper. However, other materials can also be used for the
intermediate wall 17, for example a grid-like flat material or a
mesh material or metal, etc.
[0033] The intermediate walls 17 are parallel to the top and bottom
walls 3 and 4 and are located at a distance from these walls,
respectively. The fluid channels are likewise filled with a porous,
capillary material, for example with the particles 8, e.g. of
aluminum oxide, whereby these particles 8 are also connected with
each other and with the inner surfaces of the respective fluid
channel 16 by means of the copper stays 9 in the fluid channels 16.
This produces a connection between the outer walls 3 and 4 and the
respective intermediate wall 17 at least by means of the particles
8 bonded to the posts 6 and the intermediate walls 17.
[0034] The heat sink 1a and its hollow body are likewise
manufactured using DCB technology, whereby for execution of the
fluid channels 16, the mixture for example of the particles 8 and
copper oxide powder, possibly with additional pulverized copper is
inserted in the recesses forming these channels and then heated to
the bond temperature between 1065-1085.degree. C. Excess material
that is not bonded is then removed.
[0035] In the embodiment in FIG. 5 the heat loss producing electric
component 11 is not on a narrow side of the likewise cuboid or flat
plate heat sink 1a, but rather in the center of this heat sink.
Coolers corresponding to the coolers 13 are located on both ends of
the heat sink. This results in two circuits in the interior of the
heat sink 1a for the heat transporting medium and two vapor streams
corresponding to the arrows A each extending in the vapor channel
18 from the vaporization area 14 in the middle of the heat sink 1a
to one end of the heat sink 1a or to one condensation area 15,
respectively, and in the fluid channels 16 the fluid flowing
corresponding to the arrows B, extending from each condensation
area 15 back to the vaporization area 14.
[0036] FIG. 6 shows a heat sink 1b designed as a flat, plate-like
heat pipe that differs from the heat sink 1a only in that the vapor
channel 18 of the heat sink 1a is further divided into two vapor
channels 18.1 by a further fluid channel 16.1 extending parallel to
the top and bottom of the heat sink 1b. The posts 6 also extend
through this additional fluid channel 16.1. The two vapor channels
18.1 are then both delimited by an intermediate wall 17 of the
adjacent fluid channel 16 and an intermediate wall 17.1 of the
adjacent vapor channel 16.1. The intermediate walls 17.1, which are
likewise parallel to the plane of the top wall 3 and the bottom
wall 4, also are made of the perforated flat material.
[0037] FIG. 7 shows in a very schematic cross section view a
further heat sink 1c designed as a flat heat pipe that has a
plurality of plates 19 located between the top wall 3 and the
bottom wall 4 and connected at the surfaces in a stack-like
manner.
[0038] The plates 19 are structured or perforated, i.e. provided
with openings, so as to produce a plurality of flow channels
through the openings 20 of the plates within the volume of the heat
sink 1c formed by the plates 19. Furthermore, the plates 19 are
structured so as to form continuous posts 6 in areas outside of the
openings 20. The posts extend between the top wall 3 and the bottom
wall 4. The plates 19 are made of a material that conducts heat
well, for example of metal and especially of copper. The surfaces
of the plates 19 are connected with each other by means of DCB
technology or a soldering process.
[0039] Suitable structures for the plates 19 are described for
example in DE 197 10 783 A1. In the embodiment depicted in FIG. 7,
the openings 20 and the flow channels formed by these openings are
filled with the capillary material in an area 21 adjacent to the
top wall 3 and in an area adjacent to the bottom wall 4. The
capillary material comprise the particles 8 connected with the
copper stays 9 and with adjoining surfaces of the plates 19. The
areas 21 then form the fluid channels for the heat transporting
medium. In a middle area 21 the openings 20 of the plates 19
without the particles 8 form a vapor channel for the vaporized heat
transporting medium.
[0040] Through the openings 20 and the structures produced by these
openings the plates 19 not only form the continuous posts 6, but
also stays 19.1 extending between these posts within the fluid
channels for the heat transporting medium. The stays 19.1 formed
respectively by a plate 19 are located opposite of openings 20 in
adjacent plates 19, as represented schematically in FIG. 8. In this
Figure, 7 designates the porous or capillary layer, for example,
particles 8. This layer covers all bare surfaces in this embodiment
in the areas 21 and on the plates 19.
[0041] It goes without saying that the heat sink 1c can also be
modified to contain several areas 21 forming fluid channels, in
alternation with an area 22 forming a vapor channel.
[0042] FIG. 9 shows a heat sink 1d in a cross section view
perpendicular to the direction of flow of the heat transporting
medium. This heat sink consists of two plates 23 and 24 made of a
material that conducts heat well, for example of copper, connected
with each other on one surface. In each plate there is a
trough-shaped depression or recess 25. With the plates 23 and 24
connected, the two recesses 25 form a closed, elongated channel 26
within the body of the heat sink 1d. The inner surfaces of the
channel 26 are provided with the capillary layer 7, so as to
produce the fluid channel within this layer and the vapor channel
in the space of the channel 26 not occupied by the layer 7.
[0043] FIG. 10 shows in a variation of FIG. 9 a heat sink 1e
designed as a flat heat pipe, in which the plate 24 with the recess
25 is likewise used, but instead of the plate 23, a plate 27
without the recess is used. The plate 27 is connected on the
surface with the side of the plate 24 that has the recess 25,
resulting in the closed channel 28 corresponding to the channel 26.
Surfaces of the recess 25 are provided with the layer 7. The plate
27 is for example a metal plate, e.g. a copper plate or copper
foil. Generally it is also possible to manufacture the plate 27
from an electrically insulating material, for example from ceramic,
such as an aluminum oxide or aluminum nitride ceramic.
[0044] The component 11 to be cooled is located in the heat sink 1d
and 1e at an area of the outer surface of the heat sink directly
adjacent to the channel 26 or 28, likewise electrically insulated
from the body of the heat sink 1d or 1e by the insulating layer 12
provided with the electric contact surfaces.
[0045] If the plate 27 is made of an electrically insulating
material, namely of ceramic, then the conductors and/or contact
surfaces for the component 11 can be located directly on the top
side of the plate 27 facing away from the channel 28.
[0046] FIGS. 11 and 12 show as a further possible embodiment of a
heat sink designed as a heat pipe, the hollow body of which
consists of a pipe section 29 closed at both ends and manufactured
from a material with high heat conductivity, for example copper. In
the depicted embodiment the pipe section 29 has a regular
cylindrical inner and outer profile. Generally it is also possible
for the heat sink 1f to have a flat design, in particular by
pressing the pipe section 29 flat into an oval profile.
[0047] The porous or capillary layer 7 is formed on the inner
surface of the pipe section 29. This layer is produced in the
manner that the material forming the layer 7, for example the
mixture consisting of the particles 8 and the pulverized copper
oxide and copper, is inserted into the pipe section 29. The
material forming the layer 7 is inserted in such a way that it
forms a ring or hollow cylinder-shaped first mass in contact with
the inner surface of the pipe section 29. Further inward and in
this embodiment surrounded by the first mass is a support medium
30, for example in the form of a second mass made of a suitable
particle-like material, for example particles made of ceramic
without the addition of copper oxide and copper.
[0048] After heating this structure to the bond temperature and
after subsequent cooling, only the particles 8 of the first mass
are connected by means of the copper bridges or copper stays 9 with
the inner surface of the pipe section 29 and with each other to
form the porous layer 7, while the particles forming the second
mass or the support medium 30 can be removed after bonding.
[0049] FIGS. 13 and 14 show as a further possible embodiment a heat
sink 1g designed as a heat pipe. In this heat sink 1g the hollow
body is again formed from the pipe section 29 closed at both ends
and made of the material with high heat conductivity, for example
copper. Inside the pipe section 29 is a further pipe section 31
made of a perforated or sieve-like material, such that a ring space
32 is formed between the outer surface of the pipe section 31 and
the inner surface of the pipe section 29. This space forms the
fluid channel in this heat sink 1g. The interior of the pipe
section 31 forms the vapor channel. The ring space 32 is filled
with a mass consisting of the particles 8 and/or of corresponding
particles forming a capillary structure, which are connected by
means of bonding or sintering with each other and possibly also
with the inner surface of the pipe section 29 and the outer surface
of the pipe section 31, for example by means of the copper stays 9
or by means of corresponding metal or copper stays. Generally it is
also possible that the ring space 32 contains the particles forming
the porous or capillary structure as a loose mass. The pipe section
31 is perforated, for example, provided with a plurality of
openings or manufactured from a perforated flat material, in
particular of a material with high heat conductivity, for example
of metal, e.g. copper. Other materials are also conceivable for the
pipe section 31, for example screen-like, weave-like or mesh
material. Furthermore it is also possible to use the pipe section
31 on as a support body during production, i.e. during bonding of
the particles 8 contained in the ring space 32, after which it is
removed again.
[0050] FIG. 15 shows a simplified representation of the use of the
heat sink or heat pipe according to the invention in an electric
circuit. The heat sink is designated 1 in FIG. 15. It goes without
saying that every other heat sink according to the invention can
also be used for this application, one of the heat sinks 1a-1g.
[0051] A copper-ceramic substrate 33 is applied to the top of the
flat heat sink 1 as the basis for the electric components, which
are designated 11 and 11.1 in this drawing. This substrate consists
of a ceramic layer 34, which is provided on both sides with a
copper layer or copper foil 35 and 36, preferably using DCB
technology. The substrate 33 is connected by means of the copper
layer 36 with the top surface of the heat sink 1, by soldering or
some other suitable method. The copper layer 35 facing away from
the heat sink 1 is structured for forming conductors, contact
surfaces, etc. The components 11 and 11.1 are fastened, for example
soldered, whereby the component 11 is a power component and the
components 11.1 are control components.
[0052] In the embodiment in FIG. 15 the substrate 33 is located
with the components 11 and 11.1 in the area of one narrow side of
the long heat sink 1. The coolers 13 are located in the area of the
other narrow side. For reasons of symmetry and to prevent the
bi-metal effect and the deformation of the structure upon changes
in temperature, a substrate 33.1 corresponding to the substrate 33
is applied to the bottom of the heat sink 1, however without the
components 11 and 11.1.
[0053] The invention was described above based on sample
embodiments. It goes without saying that further modifications or
alterations are possible, without abandoning the underlying
inventive idea of the invention. For example, it is possible to
provide components on both sides of the flat or plate-shaped heat
sink, e.g. on the second substrate 33.1 of the embodiment in FIG.
15.
[0054] Furthermore, it is possible to use other materials to
manufacture the porous, capillary structure, for example particles
made of a different ceramic or another suitable material, e.g.
silicon oxide. Furthermore, it is also possible to produce these
structures for example by sintering of a suitable material, for
example a suitable metal.
[0055] In deviation from the manufacturing method described in
connection with FIGS. 11 and 12 it is also possible in the
manufacture of the heat sink 1f to insert the particles 8 made of
ceramic or another heat-resistant material in the pipe section made
of metal, for example of copper and oxidized at least on the inner
surface, as a mass that completely fills the pipe section 29 and
then to heat the structure to the bond temperature between
1065-1085.degree. C., after which the structure is allowed to cool.
The outer particles, i.e. those in contact with the inner surface
of the pipe section are then bonded with the inner surface of the
pipe section 29. The remainder of the mass can then be removed from
the pipe section 29, resulting in a porous, capillary structure in
the form of a single layer 7.
[0056] Furthermore, it was assumed in the depiction in FIG. 8 that
the openings forming the flow channels in the heat sink 1c are only
partially filled with the porous or capillary layer 7 or the
particles 8 forming this layer. Of course, it is also possible to
completely fill the openings or the flow channels formed by these
openings with the particles 8 in the areas 21.
Reference Numbers
[0057] 1-1g heat sink or heat pipe
[0058] 1.1 hollow body
[0059] 1.2 opening
[0060] 2 interior
[0061] 3, 4 top and bottom wall of the flat heat pipe
[0062] 5 peripheral wall
[0063] 6 post
[0064] 7 porous or capillary layer
[0065] 8 particle
[0066] 9 copper stay
[0067] 10 surface
[0068] 11, 11.1 component
[0069] 12 insulating layer with structured metallization
[0070] 12.1, 12.2 metallization
[0071] 13 cooler
[0072] 14 vaporization area
[0073] 15 condensation area
[0074] 16 fluid channel
[0075] 17, 17.1 intermediate wall
[0076] 18, 18a vapor channel
[0077] 19 plate or foil
[0078] 20 opening
[0079] 21, 22 area of heat sink 1c
[0080] 23, 24 plate
[0081] 25 recess
[0082] 26 channel
[0083] 27 plate
[0084] 28 channel
[0085] 29 pipe section
[0086] 30 support medium
[0087] 31 pipe section
[0088] 32 ring space
[0089] 33, 33.1 metal ceramic substrate, for example copper ceramic
substrate
[0090] 34 ceramic layer
[0091] 35, 36 metal layer, for example copper layer
* * * * *