U.S. patent application number 12/883640 was filed with the patent office on 2011-03-17 for device for cooling semi-conductors.
This patent application is currently assigned to ESW GmbH. Invention is credited to Markus GRIMMIG, Jan WENSKE.
Application Number | 20110061849 12/883640 |
Document ID | / |
Family ID | 43603503 |
Filed Date | 2011-03-17 |
United States Patent
Application |
20110061849 |
Kind Code |
A1 |
GRIMMIG; Markus ; et
al. |
March 17, 2011 |
DEVICE FOR COOLING SEMI-CONDUCTORS
Abstract
The device serves for cooling electronic structural elements and
has a cooling body and a metal base plate constructed as a part of
the support of the structural element. The cooling body is arranged
adjacent the base plate. A connecting element is arranged at least
over areas between the base plate and the cooling body. The
connecting element is at least partially constructed of a metal
which has a melting temperature of at least 60.degree. C. The
connecting element is provided with a frame-like seal.
Inventors: |
GRIMMIG; Markus; (Ennepetal,
DE) ; WENSKE; Jan; (Radbruch, DE) |
Assignee: |
ESW GmbH
Wedel
DE
|
Family ID: |
43603503 |
Appl. No.: |
12/883640 |
Filed: |
September 16, 2010 |
Current U.S.
Class: |
165/185 |
Current CPC
Class: |
H01L 23/3736 20130101;
H01L 2924/0002 20130101; H01L 2924/00 20130101; H01L 2924/0002
20130101 |
Class at
Publication: |
165/185 |
International
Class: |
F28F 7/00 20060101
F28F007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 16, 2009 |
DE |
10 2009 042 519.5 |
Claims
1-8. (canceled)
9. Device for cooling an electronic structural element, comprising;
a cooling body; a metal base plate constructed as a part of a
support of the structural element, the cooling body being arranged
adjacent to the base plate; and a connecting element is arranged at
least over areas between the base plate and the cooling body,
wherein the connecting element is at least over areas thereof
constructed of a metal which has a melting temperature of at least
60.degree. C., and wherein the connecting element is provided with
a frame-like seal.
10. The device according to claim 9, wherein the seal is of a metal
having a melting temperature above 200.degree. C.
11. The device according to claim 9, wherein the connecting element
is constructed to be foil-like.
12. The device according to claim 9, wherein at least one recess is
arranged in the area of the connecting element.
13. The device according to claim 9, wherein at least one material
thickness reduction is arranged in the area of the connecting
element.
14. The device according to claim 9, wherein the connecting element
extends at least over areas thereof at a distance from the
seal.
15. The device according to claim 9, wherein at least one recess is
arranged in the area of the seal facing the connecting element.
16. The device according to claim 11, wherein the seal has a
greater height in a direction extending transversely of the cooling
body than a thickness of the metal foil.
Description
[0001] The invention relates to a device for cooling electronic
structural components which includes a cooling body and a metal
base plate constructed as a part of a support of the structural
element, wherein the cooling body is arranged adjacent the base
plate and wherein a connecting element is arranged at least over
certain areas between the base plate and the cooling body.
[0002] Connecting elements of this type according to the prior art
are typically constructed as so-called heat conducting pastes. As a
rule, such heat conducting pastes contain silicon and/or graphite.
It is also already known to use as connecting elements coated metal
foils or non-metal heat conducting elements. Generally, such
connecting elements serve for an improvement of the heat transfer
between the electronic structural component, typically a power
semi-conductor element, and the cooling body.
[0003] From the field of constructing computers, it is also already
known to use heat conducting foils. Such heat conducting foils have
a melting point in the range of above 58.degree. C., typically in
the range of 60.degree. C., and they are therefore not suitable for
use in the field of power electronics because in that field
frequently cooling body temperatures above 100.degree. C. are
encountered. Such cooling body temperatures may lead to the
discharge of molten heat conducting foils and, consequently, there
is the danger of short circuits.
[0004] It is the object of the present invention to construct a
device of the above-described type in such a way that an effective
cooling of electronic structural elements is made possible even at
higher cooling body temperatures.
[0005] In accordance with the invention, this object is met by
constructing the connecting element at least over areas thereof of
a metal which has a melting temperature of at least 60.degree. C.,
and the connecting element is provided with a frame-like seal.
[0006] Because of the selection of the above-mentioned melting
temperature for the metal and the use of a frame-like seal, it is
possible even at higher cooling temperatures to utilize the very
good heat transfer between the structural element to be cooled, the
metal connecting element and the cooling body, and to still prevent
the discharge of liquefied metal when the melting point of the
metal connecting element is exceeded. The frame-like seal surrounds
the metal connecting element and rests against a support side, on
the one hand, and a cooling body, on the other hand. In this
connection, it is possible to provide either a direct contact
between the connecting element and the electronic structural
element; in accordance with other embodiments, it is also possible
to position the electronic structural element on a metal support.
It is essential for effective cooling that, starting from the
ambient temperature and prior to reaching a maximum operating
temperature, the metal changes its state of aggregation.
[0007] To prevent molten metal from being discharged, it is
proposed that the seal is constructed of a metal having a melting
temperature above 200.degree. C.
[0008] In particular, it is considered to construct the connecting
element so as to be foil-like.
[0009] For compensating for increased volumes due to melting of the
metal, it is possible to arrange at least one recess in the area of
the connecting element.
[0010] Moreover, it is also being considered to arrange at least
one material thickness reduction in the area of the connecting
element.
[0011] It is also possible that the connecting element extends at
least over areas thereof at a distance from the seal.
[0012] In accordance with another embodiment, it is provided that
at least one recess facing the connecting element is arranged in
the area of the seal.
[0013] Moreover, it is also possible that the seal has in a
direction extending transversely of the cooling body a greater
height than a thickness of the metal foil.
[0014] In the drawings, embodiments of the invention are
schematically illustrated. In the drawing:
[0015] FIG. 1 is a partial representation of a cross-section
through a support for an electronic structural element which is in
contact to a cooling body through a metal connecting element;
[0016] FIG. 2 is a top view of a metal connecting element which is
surrounded by a frame-like seal;
[0017] FIG. 3 is an embodiment modified in comparison to FIG. 2,
with expansion spaces;
[0018] FIG. 4 is a further modified embodiment with a differently
constructed expansion space.
[0019] In accordance with the embodiment of FIG. 1, an electronic
structural element 1, typically a chip, is positioned in the area
of a support 2, typically a module. The support 2 has a metal base
plate 3 which is coupled through a connecting element 4 to a
cooling body 5. The cooling body 5 has for supporting its heat
transfer to the ambient air cooling ribs 6 which extend preferably
in a direction which is modified as compared to the structural
element 1. Alternatively or as a supplement to the use of cooling
ribs 6, it is also possible to use liquid cooling. In particular,
it is intended to conduct an appropriate cooling medium through
assigned cooling ducts.
[0020] In accordance with the embodiment of FIG. 2, the connecting
element 4 is composed of a metal foil 7 which is surrounded by a
frame-like seal 8. In the mounted state illustrated in FIG. 1, the
seal 8 is clamped between the base plate 3 and the cooling body 5
in order to ensure a necessary tightness.
[0021] In accordance with the embodiment of FIG. 3, one or more
recesses 9 are arranged in the area of the metal foil 7. The
recesses 9 ensure a sufficient tightness of the frame 8 even when
the metal foil 7 melts as a result of temperature influence and, as
a result, a volume increase of the material of the metal foil 7 is
caused. Thus, the recesses 9 constitute expansion spaces in the
event of a corresponding volume increase.
[0022] In accordance with the embodiment of FIG. 4, the metal foil
7 has a smaller thickness than a height of the seal 8. In this
case, the height of the seal 8 corresponds to a distance between
the base plate 3 and the cooling body 5. The appropriate
dimensioning of the seal 8 ensures that above the metal foil 7 an
expansion space 10 is arranged which can compensate for the
corresponding volume increases of the material of the metal foil 7
in the case of liquefication. In particular, the metal foil 7 can
in a liquefied state compensate even for different distances
between the base plate 3 and the cooling body 5 which are caused by
the fact that the base plate 3 assigned to the module typically has
an arched shape.
[0023] A preferred use of the metal connecting element 4 according
to the invention takes place in connection with electronic
structural elements 1 which are constructed as power
semi-conductors. They are used in stationary as well as in mobile
fields. Such mobile uses refer in particular to power electric
devices or components. The improved cooling effect can be utilized
for achieving different advantages. For example, it is possible to
increase the power density as a result of the improved cooling
effect. Also, it is possible to facilitate an operation with
increased cooling agent temperatures and/or at increased ambient
temperatures. Generally, it is also possible to increase the
service life of the structural elements 1 by reducing the operating
temperatures.
[0024] When the structural elements are constructed as power
semi-conductors, especially considered are realizations as IGBT or
MOSFET. These may be present in discrete construction or in modular
construction.
[0025] The metal connecting elements 4 according to the invention
reduce the DIE temperature by about 4 to 6.degree. K. Also,
compared to a use of heat conducting pastes, a markedly reduced
assembly work is required. The reproducibility of the achieved
cooling effect is improved and, as a result, quality requirements
of the production process can be safely adhered to.
[0026] Used as material for the metal foil 7 are typically suitable
alloys. The melting point can be influenced through the composition
of the alloy. A typical alloy consists of indium, tin and bismuth.
As necessary, indium can be replaced fully or partially by
gallium.
[0027] Used as the material for the seal 8 can be tin, aluminum or
copper or an alloy which contains one or more of the aforementioned
elements.
[0028] A typical thickness of the metal foil 7 is about 30
micrometers. However, also usable are metal foils 7 with a
thickness in the range of 20 micrometers up to 40 micrometers. A
typical thickness of the seal 8 is about 60 micrometers. Basically,
also usable are material thicknesses in the range of 40 micrometers
up to 80 micrometers.
[0029] The metal foil 7 used has during assembly a solid state of
aggregation. In a conventional operation, the metal foil 7 has a
liquid state of aggregation and a discharge of the molten metal is
prevented by the seal 8. During each longer interruption of
operation, the metal foil 7 returns into the solid state of
aggregation. The changes from the liquid state into the solid state
as well as from the solid state into the liquid state take place
completely reversibly.
[0030] FIG. 5 once again illustrates the arched configuration of
the base plate 3 as already described above and the limitation of
the expansion space 10 resulting therefrom. After a liquefication
of the metal foil 7, the latter fills out the expansion space 10
and leads to a large area contact between the base plate 3 and the
cooling body 5 which is not illustrated.
* * * * *