U.S. patent application number 09/925272 was filed with the patent office on 2002-02-28 for heat sink and process and molding tool for production of same.
Invention is credited to Bock, Uwe, Graf, Werner.
Application Number | 20020023732 09/925272 |
Document ID | / |
Family ID | 26006834 |
Filed Date | 2002-02-28 |
United States Patent
Application |
20020023732 |
Kind Code |
A1 |
Graf, Werner ; et
al. |
February 28, 2002 |
Heat sink and process and molding tool for production of same
Abstract
A heat sink of metal material, in particular a light metal
alloy, for semi-conductor elements or similar components, has
plate-like cooling ribs projecting from a base plate at intervals
(f) and approximately parallel to each other, protrude with a
connection strip into the base plate in which they are cast. A
molding tool designed for production of the heat sink includes a
casting mold with a mold chamber for the base plate. The mold
chamber contains an area to receive the connection strips of the
cooling ribs. Two parallel side walls of the casting mold and
intermediate layers arranged parallel between them, each defining a
receiver gap, are arranged displaceably on at least one shaft
passing through them. The walls can be moved to produce the compact
casting mold after insertion of the cooling ribs in the receiver
gaps.
Inventors: |
Graf, Werner; (Engen,
DE) ; Bock, Uwe; (Singen, DE) |
Correspondence
Address: |
Gregory P. LaPointe
BACHMAN & LaPOINTE, P.C.
Suite 1201
900 Chapel Street
New Haven
CT
06510-2802
US
|
Family ID: |
26006834 |
Appl. No.: |
09/925272 |
Filed: |
August 9, 2001 |
Current U.S.
Class: |
165/80.3 ;
165/185; 257/E23.102; 257/E23.103 |
Current CPC
Class: |
F28F 1/32 20130101; H01L
2924/0002 20130101; H01L 2924/0002 20130101; H01L 21/4882 20130101;
F28D 15/0275 20130101; H01L 23/3672 20130101; H01L 23/367 20130101;
H01L 2924/00 20130101; F28F 3/02 20130101 |
Class at
Publication: |
165/80.3 ;
165/185 |
International
Class: |
F28F 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 28, 2000 |
DE |
100 42 124.5 |
Oct 26, 2000 |
DE |
100 53 240.3 |
Claims
1. A heat sink having a base plate; a plurality of cooling ribs
extending from the base plate, the cooling ribs being spaced from
each other a distance f and each cooling rib having a connection
strip which protrudes into the base plate, the improvement which
comprises: the base plate and cooling ribs are a cast structure
wherein the base plate is cast onto the connection strips of the
cooling ribs.
2. A heat sink according to claim 1, wherein the base plate is
provided with at least one insert of highly heat-conductive
material.
3. A heat sink according to claim 2, wherein the insert is a heat
pipe.
4. A heat sink according to claim 3, wherein a plurality of heat
pipes are provided which run substantially parallel to each other
and to end faces of the base plate.
5. A heat sink according to claim 2 including a plurality of
inserts wherein the inserts extend between parallel sides of the
base plate.
6. A process for the production of a heat sink comprising the steps
of: providing a mold having a plurality of space apart intermediate
layers which define therebetween a plurality of receiver gaps of
width f, the mold having a chill mold chamber and the receiver gaps
opening into the mold cavity; positioning cooling ribs into the
plurality of receiver gaps wherein a portion of each cooling rib
extends into the chill mold chamber a distance n to form connection
strips; and casting molten metal into the chill mold chamber around
the connection strips and cooling the metal to form a base plate
cast to the cooling ribs.
7. A process according to claim 6, wherein the mold includes two
face walls parallel to the intermediate layers and the process
includes moving the two face walls toward each other after the
positioning and prior to the casting.
8. A process according to claim 6, wherein prior to casting,
inserts of heat conductive material are located in the chill mold
chamber.
9. A molding tool for the production of a heat sink having a base
plate and cooling ribs projecting approximately parallel from the
base plate comprising a casting mold having a chill mold chamber
for forming the base plate and this chill mold chamber includes
means to receive connection strips of height (n) of the cooling
ribs, wherein (n) is less than a height (e) of the chill mold
chamber.
10. A molding tool according to claim 9, wherein the casting mold
further includes two parallel side walls and intermediate layers
arranged parallel between the side wall wherein the side walls and
intermediate layers are arranged displaceably on at least one shaft
passing through them.
11. A molding tool according to claim 10, wherein the chill mold
chamber has a bore which is substantially formed by edges of the
intermediate layers.
12. A molding tool according to claim 10, wherein the shaft form a
stop for the cooling ribs inserted in the receiver gaps an
insertion depth (t) is less than the height (h1) of the cooling
ribs.
Description
BACKGROUND OF THE INVENTION
[0001] The invention concerns a heat sink of metallic material, in
particular a light metal alloy, for semi-conductor elements or
similar components, with cooling ribs projecting from a base plate
parallel to each other and spaced apart, with approximately rodlike
cross section, and which protrude into the base plate with a
connection strip. The invention also comprises a process for the
production of these and a molding tool for these.
[0002] DE 35 18 310 C2 discloses a heat sink with a base plate of
an AlMgSi alloy extruded in an extrusion die as a molding tool, in
the surface of which body are formed insert grooves for the
plate-like cooling ribs made from a sheet or profile. The ribs have
a base which, after insertion in one of the grooves, is distorted
by a caulking process. With very close rib spacing and deep cooling
ribs, the load on the caulking chisel is so great that it quickly
kinks. In other known cooling bodies the cooling ribs can be glued
or soldered in place. Gluing has the disadvantage that the glue
causes a deterioration in the heat transmission from the base plate
or plinth to the cooling rib. For soldering, again costly
preliminary treatment is required.
[0003] For another heat sink according to DE 25 02 472 C2, the base
plate is also produced with grooves, the walls of which in their
longitudinal direction are fitted with pressed-out wall ribs.
Cooling ribs with vertical fluting are pressed in these grooves by
means of cold pressure welding. The necessary high forces which
must be applied in the cold pressure welding process greatly limit
the length of the cooling bodies to be produced, and a minimum
thickness of cooling ribs is required in order to avoid their
kinking during the cold pressure welding process.
[0004] It is not only the forces occurring which limit the length
of the cooling body. The vertical fluting of the cooling ribs
limits their length measured along the base plate due to the
dimensions of the extrusion tool as the pressing direction is the
same as the fluting direction.
[0005] Accordingly, it is an object of the present invention to
provide a cooling body which does not have the defects described.
Also, the heat conductivity or control of heat conduction is
improved.
SUMMARY OF THE INVENTION
[0006] The foregoing object is achieved wherein, the base plate
consisting of metal material is cast onto the metallic cooling ribs
in the area of their connection strips, i.e. no subsequent
insertion and deformation processes are required. The casting
process also allows integration of inserts of heat conductive
material to increase the conductivity and to control the heat
conduction.
[0007] According to a further feature of the invention, at least
one insert of good conductive material is cast into the base plate;
as inserts, preferably heat pipes to control the heat conduction
can be used.
[0008] Favourably, several heat pipes are used as inserts which run
parallel to each other and to the faces of the base plate. Also,
the inserts extend between the parallel sides of the base
plate.
[0009] The scope of the invention includes a process for production
of such a cooling body in which, to form cooling ribs, plate-like
moldings are arranged at intervals in a mold, approximately
parallel to each other so that their connection strips of specific
height protrude into the chill mold chamber for the base plate, and
this mold chamber is filled with the metallic material as a casting
compound; when this hardens, the connection strips are held firmly
by the base plate and subsequently form a unit with this.
[0010] To simplify the casting process, by the use of intermediate
layers parallel to each other receiver gaps for the plate-like
moldings are produced and the latter inserted in the receiver gaps,
whereupon two side walls parallel to the intermediate layers are
brought together under pressure in order to create a compact mold
for preparation of the casting.
[0011] According to a further feature of the invention, before
filling with the hot casting compound, inserts of heat conductive
material are arranged in the mold chamber in order to be cast into
the base plate.
[0012] As a molding tool according to the invention, a casting mold
is used with a mold chamber for the base plate or plinth, to which,
before the actual casting process, are allocated the parallel
cooling ribs made from a sheet or profile so that their foot edges
and adjacent connection strips protrude into the area established
for the casting compound and are there held by the latter during
the casting process; after hardening of the casting compound, the
cooling body with metal constituents connected internally is then
ready for use.
[0013] In the molding tool according to the invention, two parallel
side walls, and intermediate layers between them and also parallel,
are arranged displaceably on at least one shaft passing through
them; the plate-like moldings are pressed into the receiver gaps
bordered by the intermediate layers until they contact the
shaft(s), the side walls are then compressed in the shaft direction
until a compact casting mold is achieved. Its mold base is
substantially determined by the foot edges of the intermediate
layers.
DRAWINGS
[0014] Further advantages, features and details of the invention
arise from the description of preferred design examples below and
using the drawing; these show:
[0015] FIG. 1: a perspective view onto a cooling body with parallel
cooling ribs protruding from a base plate;
[0016] FIG. 2: a top view onto a mold as a device for production of
the cooling body;
[0017] FIG. 3 to FIG. 5: a perspective view under the base plate of
three different embodiments of the cooling body;
[0018] FIG. 6: a perspective view onto the mold for production of
the cooling body;
[0019] FIG. 7: an enlarged section of FIG. 6 in front view.
DETAILED DESCRIPTION
[0020] A longitudinally approximately comb-like cooling body 10 of
an aluminium alloy, for example an AlMgSi alloy, for semiconductor
elements, not shown further in the drawings for the sake of
clarity, has a base plate 12 of length a, width b and height e with
plate-like cooling ribs 20 of free height h projecting above the
surface 14 of base plate 12 at close intervals f. The distance
between a plane E determining the surface 14 of the base plate 12
and the upper contour of a shaft 19 visible in FIG. 2 in the
casting position shown, and which runs parallel to the base plate
12, is marked t.
[0021] The two end cooling ribs 20e each run to the adjacent end
face 16 of the base plate 12 at distance i, the length of which
corresponds almost to plate height e. The side edges 22 of the
cooling ribs 20, 20e align with the side surface 18 of the base
plate 12.
[0022] To produce the cooling body 10, the cooling ribs 20, 20e
made from sheets or profiles and of total height h1 and in between
intermediate layers 28 (See FIG. 6 and FIG. 7) determining their
rib spacing f (see FIG. 7), are laid in a mold 30 of steel so that
in each case a short connection strip 24 of height n starting from
the foot edge 23 of cooling ribs 20, 20e protrudes into a mold
chamber 32 of the mold 30, the base of which is determined by the
said plane E and the height of which e1 corresponds to a multiple
of the height n of the said connection strip 24.
[0023] FIGS. 6 and 7 show particularly clearly that the mold 30 has
two side walls 34 and several parallel intermediate layers 28
bordering between them receiver gaps 29 of width f, where the
number of intermediate layers is lower than the number of cooling
ribs 20, 20e. The side walls 34 and the intermediate layers 28 can
be displaced on the shaft 19 passing through them so that thickness
tolerances of the cooling ribs 20, 20e can be compensated. The
latter, starting from the top in FIGS. 6, 7, are pressed between
the intermediate layers 28 until their crest edges 26 lie on the
shafts 19. The mold or chill mold 30 is then compressed in the
shaft direction by pressure means, arrow FIG. 7, i.e. closed
downwards. At the free face ends cover plates 36 are applied as
bordering walls. Molding strips 34a, 36a of one piece with the side
walls 34 and the face walls or cover plates 36 form the border of
the fully enclosed chill mold chamber 32 of a base plate or plinth
mold into which, as stated, the cooling ribs 20, 20e protrude by
the said dimension n, where in contrast the adjacent foot edges 27
of the intermediate layers 28 run in the said plane E i.e. they
form the substantial part of the mold base. When this mold chamber
32 is evacuated, the cooling ribs 20, 20e are firmly connected with
the base plate 12.
[0024] The chill mold chamber 32 is shown in the upper part of FIG.
2 within the molding strips 34a, 36a of the mold 30 which determine
it. The height q at least of the side walls 34 is dimensioned such
that in the casting position sketched in FIG. 2 these extend with
their wall face edges 38 beyond the crest edges 26 of the cooling
ribs 20, 20e. The evacuation of the chill mold chamber 32, as shown
in particular in FIG. 7, produces the base plate 12 of the valve
body 10 in which are cast--and subsequently established after
hardening--the cooling ribs 20, 20e with their feet sections or
connection strips 24.
[0025] Depending on the arrangement of the electronic components,
before the casting process, plate-like--flat or curved--parts 40 or
40a of particularly good heat conduction material can be laid in
the mold chamber 32 which increase the conductivity or control the
heat distribution; these inserts 40, 40a are cast into the the
plate 12 according to FIGS. 3, 4.
[0026] Instead of the plate-like inserts 40, 40a heat pipes 42 can
be inserted to control the heat conduction. In FIG. 5 heat pipes 42
run in the base plate 12 parallel to each other and to the faces 16
of the base plate 12. Like the plate-like inserts 40, 40a, they
extend between the parallel side surfaces 18 of the base plate
12.
* * * * *