U.S. patent application number 13/853073 was filed with the patent office on 2014-05-22 for heat exchanger and semiconductor module.
This patent application is currently assigned to Industrial Technology Research Institute. The applicant listed for this patent is INDUSTRIAL TECHNOLOGY RESEARCH INSTITUTE. Invention is credited to Yu-Lin Chao, Kun-Ying Liou, Chun-Kai Liu, Chi-Chuan Wang, Shu-Jung Yang.
Application Number | 20140138075 13/853073 |
Document ID | / |
Family ID | 50726814 |
Filed Date | 2014-05-22 |
United States Patent
Application |
20140138075 |
Kind Code |
A1 |
Yang; Shu-Jung ; et
al. |
May 22, 2014 |
HEAT EXCHANGER AND SEMICONDUCTOR MODULE
Abstract
A heat exchanger suitable for cooling a heat source is provided,
wherein a bypass channel formed in the heat exchanger has a width
greater than a width of other channels to reduce a flow resistance
of a fluid and a pumping power for driving a system. That is, under
the same pumping power loss, more fluid is driven to achieve a
better heat dissipation effect. By applying the heat exchanger,
electronic devices are bonded to a top of the heat exchanger
through a supporting substrate. In this way, heat generated when
the electronic devices are is transferred to the heat exchanger
through the supporting substrate and dissipated to the outside via
the heat exchanger. Since the distance of heat transfer is
decreased, the thermal resistance generated by an interface between
the devices is reduced to improve heat transfer efficiency and heat
dissipation effect.
Inventors: |
Yang; Shu-Jung; (Tainan
County, TW) ; Chao; Yu-Lin; (Hsinchu City, TW)
; Liu; Chun-Kai; (Taipei City, TW) ; Wang;
Chi-Chuan; (Hsinchu County, TW) ; Liou; Kun-Ying;
(Taichung City, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INDUSTRIAL TECHNOLOGY RESEARCH INSTITUTE |
Hsinchu |
|
TW |
|
|
Assignee: |
Industrial Technology Research
Institute
Hsinchu
TW
|
Family ID: |
50726814 |
Appl. No.: |
13/853073 |
Filed: |
March 29, 2013 |
Current U.S.
Class: |
165/185 |
Current CPC
Class: |
H01L 2924/13055
20130101; H01L 2224/48091 20130101; H01L 2924/13055 20130101; H01L
2224/73265 20130101; H01L 23/473 20130101; H01L 2224/48111
20130101; F28F 2250/06 20130101; H01L 2224/32225 20130101; H01L
23/3735 20130101; F28D 15/0233 20130101; H01L 23/427 20130101; H01L
2224/48227 20130101; H01L 2224/48137 20130101; H01L 2924/19107
20130101; H01L 2924/1305 20130101; H01L 2924/1305 20130101; F28D
2021/0028 20130101; H01L 2224/32225 20130101; H01L 2224/48227
20130101; H01L 2924/00 20130101; H01L 2924/00014 20130101; H01L
2924/00 20130101; H01L 2924/00 20130101; H01L 2224/48091 20130101;
F28F 3/12 20130101; F28F 3/02 20130101; H01L 2224/73265
20130101 |
Class at
Publication: |
165/185 |
International
Class: |
F28F 3/02 20060101
F28F003/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 19, 2012 |
TW |
101143144 |
Claims
1. A heat exchanger, comprising: a base plate having a supporting
surface and a back side opposite to the supporting surface, wherein
the supporting surface supports a heat source; a cover plate
disposed on the back side of the base plate, the cover plate and
the base plate forming a chamber, wherein the chamber has an inlet
and an outlet located at the same side of the chamber; a plurality
of first dissipation fins intervally disposed between the base
plate and the cover plate forming a plurality of first channels and
a bypass channel in the chamber, wherein each of the first channels
and the bypass channel extend from the inlet to a mixed flow area
in the chamber, and a width of the bypass channel is greater than a
width of each of the first channels; a plurality of second
dissipation fins intervally disposed between the base plate and the
cover plate forming a plurality of second channels in the chamber,
wherein each of the second channels extends from the mixed flow
area to the outlet, and the width of the bypass channel is greater
than a width of each of the second channels; and a fluid flowing
into the chamber through the inlet, wherein a portion of the fluid
passes through the first channels, another portion of the fluid
passes through the bypass channel, and the portion of the fluid and
the another portion of the fluid mix in the mixed flow area, enter
the second channels, and leave the chamber through the outlet.
2. The heat exchanger according to claim 1, wherein a flow
resistance of the fluid in the first channels is greater than a
flow resistance of the another portion of the fluid in the bypass
channel.
3. The heat exchanger according to claim 1, wherein the chamber has
a first side and a second side opposite to each other, the inlet
and the outlet are located at the first side, and the mixed flow
area is located at the second side.
4. The heat exchanger according to claim 1, wherein each of the
first dissipation fins is L-shaped, and each of the first
dissipation fins comprises: a first portion extending from the
first side to the second side along a first direction; and a second
portion connected to the first portion and extending to the mixed
flow area along a second direction, wherein the first direction
intersects the second direction.
5. The heat exchanger according to claim 4, wherein each of the
second dissipation fins is L-shaped, and each of the second
dissipation fins comprises: a third portion extending from the
first side to the second side along the first direction; and a
fourth portion connected to the third portion and extending to the
mixed flow area along a third direction, wherein the third
direction is opposite to the second direction.
6. The heat exchanger according to claim 4, wherein each of the
second dissipation fins is in a linear shape and extends from the
first side to the mixed flow area along the first direction.
7. The heat exchanger according to claim 1, further comprising a
mixed flow means disposed in the mixed flow area and being
separated from the first dissipation fins and the second
dissipation fins
8. The heat exchanger according to claim 7, wherein the mixed flow
means comprises a partition lying in a flowing path of the
fluid.
9. The heat exchanger according to claim 1, wherein the bypass
channel is located at an outermost side of the first channels and
is adjacent to an inner wall of the chamber.
10. The heat exchanger according to claim 1, wherein the base plate
comprises a vapor chamber.
11. The heat exchanger according to claim 1, wherein at least one
of a surface of the first dissipation fins, a surface of the second
dissipation fins and an inner wall of the chamber comprises a
plurality of cavities.
12. The heat exchanger according to claim 11, wherein the cavities
correspond to a location of the heat source and penetrate through
the base plate to be connected to a bottom of the heat source.
13. The heat exchanger according to claim 1, wherein a material of
the base plate comprises metals or composite materials.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the priority benefit of Taiwan
application serial no. 101143144, filed on Nov. 19, 2012. The
entirety of the above-mentioned patent application is hereby
incorporated by reference herein and made a part of this
specification.
TECHNICAL FIELD
[0002] The disclosure relates to a heat exchanger and a
semiconductor module that uses the heat exchanger to achieve a good
heat dissipation effect.
BACKGROUND
[0003] In recent years, the rapid progress of the fabricating
techniques of integrated circuits (ICs) leads to great improvements
in the functions of electronic devices. However, with the
enhancement of the processing speed and performance of the
electronic devices, the heat generated when the electronic devices
are working also increases. If the waste heat cannot be effectively
dissipated, an electronic device failure may occur, or the
electronic devices may not achieve the best performance.
[0004] Power electronic devices, such as insulated gate bipolar
transistors (IGBTs) are widely used in electric motor vehicles. The
development of the electric motor vehicles focuses on reduction of
weight, volume and power consumption. One of the key points to
achieving the above goals is the operating performance of the IGBT
power module. Since the IGBT power module is under environmental
effects of high temperature, vibration, humidity and dust pollution
and, in addition, is itself a high-voltage high-current module,
whether the heat dissipation is good has always greatly influenced
the operating performance thereof.
[0005] A conventional IGBT power module includes one or more IGBT
chips, one or more diode chips, a control chip, a direct bond
copper (DBC) substrate and a base plate, combined with a cooling
module such as a heat sink. The heat generated when the IGBT chips
and the diode chips are working is first transferred to the DBC
substrate, is spread on the DBC substrate and then is transferred
to the base plate. Thermal grease is adhered to a cooling module
such as a heat sink, and in this way the base plate of the power
module dissipates the heat to the outside through the heat sink. In
other words, the heat sink, the IGBT power module, the thermal
grease adhered to the heat sink and the base plate of the power
module generate significant thermal resistance, which limit the
heat dissipation performance of the IGBT power module.
[0006] On the other hand, because of the high heat-generating power
of the IGBT power module, liquid cooling heat sinks are also known
to be used in the heat dissipation design of the IGBT power module.
However, in addition to the above-mentioned issue of thermal
resistance, such design further requires the consumption of pumping
power to drive the fluid in the liquid cooling heat sink, which
increases energy consumption of the entire system.
SUMMARY
[0007] According to an embodiment of the disclosure, the heat
exchanger includes a base plate, a cover plate, a plurality of
first heat dissipation fins, a plurality of second heat dissipation
fins and a fluid. The base plate has a supporting surface and a
back side opposite to the supporting surface, wherein the
supporting surface supports a heat source, such as an electronic
device. The cover plate is disposed on the back side of the base
plate, and the cover plate and the base plate form a chamber. The
chamber has an inlet and an outlet located at the same side of the
chamber. The first dissipation fins are intervally disposed between
the base plate and the cover plate, forming a plurality of first
channels and a bypass channel in the chamber. Each of the first
channels and the bypass channel extend from the inlet to a mixed
flow area in the chamber, and a width of the bypass channel is
greater than a width of each of the first channels. A ratio of the
width of the bypass channel to the width of the first channels is,
for example, less than or equal to 9. The second dissipation fins
are intervally disposed between the base plate and the cover plate,
forming a plurality of second channels in the chamber. Each of the
second channels extends from the mixed flow area to the outlet, and
the width of the bypass channel is greater than a width of each of
the second channels. The fluid flows into the chamber through the
inlet, wherein a portion of the fluid passes through the first
channels, another portion of the fluid passes through the bypass
channel, and the portion of the fluid and the another portion of
the fluid mix in the mixed flow area, enter the second channels,
and leave the chamber through the outlet.
[0008] Several exemplary embodiments accompanied with figures are
described in detail below to further describe the disclosure in
details.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The accompanying drawings are included to provide further
understanding, and are incorporated in and constitute a part of
this specification. The drawings illustrate exemplary embodiments
and, together with the description, serve to explain the principles
of the disclosure.
[0010] FIG. 1A illustrates a semiconductor module according to an
embodiment of the disclosure.
[0011] FIG. 1B is a bottom view of a heat exchanger depicted in
FIG. 1A.
[0012] FIG. 1C is a perspective view of a structure of FIG. 1B.
[0013] FIG. 1D is an enlarged view of an area A of FIG. 1B.
[0014] FIG. 1E is a perspective view of a heat exchanger according
to another embodiment of the disclosure.
[0015] FIG. 2 illustrates a heat exchanger according to another
embodiment of the disclosure.
[0016] FIG. 3 illustrates a heat exchanger according to still
another embodiment of the disclosure.
[0017] FIG. 4 illustrates a semiconductor module according to
another embodiment of the disclosure.
[0018] FIG. 5A illustrates a semiconductor module according to
still another embodiment of the disclosure.
[0019] FIG. 5B is a bottom view of a heat exchanger depicted in
FIG. 5A.
[0020] FIG. 5C is an enlarged view of an area B of FIG. 5B.
[0021] FIG. 6 illustrates a semiconductor module according to still
another embodiment of the disclosure.
DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS
[0022] It should be first noted that the heat exchanger of the
disclosure may be applied in various compatible semiconductor
modules to dissipate heat generated by electronic devices in the
semiconductor module. In the following, only an arrangement in
which the heat exchanger of the disclosure is applied in an IGBT
power module is described as an example, but the disclosure is not
limited thereto.
[0023] According to a design of the heat exchanger of the
disclosure, we may integrate a base plate of the IGBT power module
with the heat exchanger (that is, the original base plate of the
IGBT power module is omitted) and directly bond a supporting
substrate that supports electronic devices to a top of the heat
exchanger. In this way, heat generated when the electronic devices
are working is transferred to the heat exchanger through the
supporting substrate and dissipated via the heat exchanger. Since
the base plate of the IGBT power module and the heat exchanger are
integrated, and the original base plate of the IGBT power module is
omitted, the number of interfaces between devices may be reduced,
thereby reducing the thermal resistance generated by the interfaces
between the devices, and heat dissipation efficiency is
improved.
[0024] FIG. 1A illustrates a semiconductor module according to an
embodiment of the disclosure. A semiconductor module 100 includes a
heat exchanger 110, a supporting substrate 120 and electronic
devices 132 and 134. The electronic devices 132 and 134 are, for
example, a diode chip and an insulated gate bipolar transistor
(IGBT) chip, respectively, and are respectively disposed on the
supporting substrate 120. The supporting substrate 120 is a ceramic
metal substrate such as a direct bond copper (DBC) substrate or a
direct plated copper (DPC) substrate, i.e. a composite substrate
that includes a ceramic core layer 122 and double-sided copper
coating layers 124 and 126. A material of the ceramic core layer
122 is, for example, aluminum oxide (Al.sub.2O.sub.3), aluminum
nitride (AlN) or aluminum silicon carbide (AlSiC). The electronic
devices 132 and 134 are bonded to the copper coating layer 124
through a first solder layer 142, and the copper coating layer 124
may be patterned to be a surface circuit 124a to provide
connections to the electronic devices 132 and 134. The electronic
devices 132 and 134 of the present embodiment are electrically
connected to each other through a solder wire 192, and the
electronic device 132 is electrically connected to the surface
circuit 124a formed by the copper coating layer 124 through a
solder wire 194.
[0025] Herein, the number, types and connection ways of the
electronic devices 132 and 134 are only used as examples. In other
embodiments of the disclosure, the number of the electronic devices
may be one or three or more, and the types of the electronic
devices 132 and 134 are not limited to a diode chip or an IGBT
chip. The electronic devices 132 and 134 may be connected to the
outside through the supporting substrate 120 or other circuit
devices or may be directly connected to the outside. In addition,
the electronic devices 132 and 134 of the present embodiment share
one supporting substrate 120, but in other embodiments, the
electronic devices may be disposed on two independent supporting
substrates or on intermediary substrates of other possible
types.
[0026] The electronic devices 132 and 134 are disposed on a base
plate 112 of the heat exchanger 110 through the supporting
substrate 120. The supporting substrate 120 and the heat exchanger
110 are bonded to each other through, for example, a second solder
layer 144.
[0027] The structure of the heat exchanger 110 is further described
below.
[0028] FIG. 1B is a bottom view of the heat exchanger 110. In order
to clearly show the inner structure of the heat exchanger 110, FIG.
1B omits a cover plate 114. FIG. 1C is a perspective view of the
structure of FIG. 1B. FIG. 1D is an enlarged view of an area A of
FIG. 1B.
[0029] Referring to FIGS. 1A to 1D, the base plate 112 of the heat
exchanger 110 has a supporting surface 112a and a back side 112b
opposite to the supporting surface 112a, wherein the supporting
substrate 120 is disposed on the supporting surface 112a of the
base plate 112. The cover plate 114 is disposed on the back side
112b of the base plate 112 and is bonded to the base plate 112 to
form a chamber 119. A plurality of first dissipation fins 116 and a
plurality of second dissipation fins 118 are disposed between the
base plate 112 and the cover plate 114 to form a plurality of
channels between the base plate 112 and the cover plate 114. In
addition, a housing 150 is disposed on the base plate 112 of the
heat exchanger 110 to cover the electronic devices 132 and 134 and
the supporting substrate 120. The surface circuit 124a is connected
to terminals 184a and 184b on a surface of the housing 150 through
conductive wires 182a and 182b.
[0030] The chamber 119 formed by the cover plate 114 and the base
plate 112 together has an inlet 119a and an outlet 119b. The
present embodiment takes into consideration the design restriction
that the inlet and the outlet allow entry and exit only at a single
side when the system is assembled and thus disposes the inlet 119a
and the outlet 119b at the same side adjacent to the chamber 119
and allow entry and exit at a side of the chamber 119.
[0031] In other embodiments of the disclosure, holes that serve as
the inlet 119a and the outlet 119b may also be selectively formed
on the cover plate 114 or the base plate 112. For example, FIG. 1E
illustrates another structure in which the disclosure disposes the
inlet 119a and the outlet 119b on the base plate 112.
[0032] Because of the design of the present embodiment in which the
inlet 119a and the outlet 119b are located at the same side of the
chamber 119, the first dissipation fins 116 and the second
dissipation fins 118 from a plurality of U-shaped channels in the
chamber 119. In detail, the first dissipation fins 116 are disposed
between the base plate 112 and the cover plate 114 side by side to
form in the chamber 119 a plurality of first channels 162 parallel
to one another and a bypass channel 164. Each of the first channels
162 and the bypass channel 164 extend from the inlet 119a to a
mixed flow area 166 in the chamber 119, and a width W1 of the
bypass channel 164 is greater than a width W2 of each of the first
channels 162. Specifically, a ratio of the width W1 of the bypass
channel 164 to the width W2 of the first channels 162 is, for
example, less than or equal to 9, so as to achieve a good balance
between heat dissipation and reduction of flow resistance.
[0033] In addition, in the present embodiment, in order for a fluid
to be uniformly distributed in the channels, a height of the first
dissipation fins 116 and the second dissipation fins 118 may be
varied, and channels of different depths may be formed
therebetween, so that the fluid has different flow resistances when
entering the channels, and a more uniform flowing distribution of
the fluid is achieved.
[0034] In the present embodiment, the inlet 119a and the outlet
119b are located at a first side S1 of the chamber 119, and the
mixed flow area 166 is located at a second side S2 of the chamber
119. Each of the first dissipation fins 116 is L-shaped, for
example, and each of the first dissipation fins 116 includes a
first portion 116a and a second portion 116b. The first portion
116a extends from the first side S1 to the second side S2 along a
first direction D1, and the second portion 116b is connected to the
first portion 116a and extends to the mixed flow area 166 along a
second direction D2. The first direction D1 intersects the second
direction D2; for example, the first direction D1 is perpendicular
to the second direction D2. In addition, the location of the bypass
channel 164 may be adjusted according to needs. For example, the
present embodiment chooses to dispose the bypass channel 164 at an
outermost side of the first channels 162 and adjacent to an inner
wall of the chamber 119.
[0035] The second dissipation fins 118 are disposed between the
base plate 112 and the cover plate 114 side by side to form a
plurality of second channels 168 parallel to one another in the
chamber 119. Each of the second channels 168 extends from the mixed
flow area 166 to the outlet 119b, and the width W1 of the bypass
channel 164 is greater than a width W3 of each of the second
channels 168.
[0036] In the present embodiment, each of the second dissipation
fins 118 is L-shaped disposed in a mirror manner to the first
dissipation fins 116, and each of the second dissipation fins 118
includes a third portion 118a and a fourth portion 118b. The third
portion 118a extends from the first side S1 to the second side S2
along the first direction D1, and the fourth portion 118b is
connected to the third portion 118a and extends to the mixed flow
area 166 along a third direction D3. The third direction D3 is
opposite to the second direction D2.
[0037] A fluid 170 flows into the chamber 119 through the inlet
119a, wherein a first portion of the fluid 172 passes through the
first channels 162, a second portion of the fluid 174 passes
through the bypass channel 164, and the first portion of the fluid
172 and the second portion of the fluid 174 mix in the mixed flow
area 166, enter the second channels 168, and leave the chamber 119
through the outlet 119b.
[0038] Based on the above, because the width W1 of the bypass
channel 164 is greater than the width W2 of each of the first
channels 162, a flow resistance experienced by the second portion
of the fluid 174 flowing in the bypass channel 164 is lower than a
flow resistance experienced by the first portion of the fluid 172
flowing in the first channels 162. In other words, pressure loss of
the second portion of the fluid 174 in the bypass channel 164 is
lower than pressure loss of the first portion of the fluid 172 in
the first channels 162. The heat generated when the electronic
devices 132 and 134 are working is transferred to the heat
exchanger 110 through the supporting substrate 120, and the base
plate 112, the cover plate 114, the first dissipation fins 116 and
the second dissipation fins 118 may exchange heat with the fluid
170, so that the fluid 170 carries the heat away.
[0039] In addition, since the second portion of the fluid 174 in
the bypass channel 164 has a lower pressure loss and a higher
flowing speed, a temperature of the second portion of the fluid 174
passing through the bypass channel 164 is lower than a temperature
of the first portion of the fluid 172 passing through the first
channels 162. Besides, an inlet temperature when the first portion
of the fluid 172 and the second portion of the fluid 174 mix in the
mixed flow area 166 and enter the second channels 168 is lower than
an inlet temperature of a structure without the design of the
bypass channel 164. In this way, the fluid 170 may provide a better
heat exchange effect in the second channels 168.
[0040] In other words, the bypass channel 164 of the present
embodiment reduces pressure loss of the fluid 170 in the channels,
effectively decreases a flow resistance that drives the fluid 170
to flow, and decreases a pumping power required to drive the
system, or the bypass channel 164 of the present embodiment,
compared with a conventional design, provides a greater fluid flow
and heat transfer amount and achieves a better heat dissipation
effect under the same pumping power consumption. In addition, the
semiconductor module 100 of the present embodiment, when serving as
an IGBT power module of an electric motor vehicle, lowers a power
consumption of the electric motor vehicle and prolongs a traveling
time and distance of the electric motor vehicle.
[0041] In the manufacturing process, the heat exchanger 110 may be
manufactured by techniques such as machining, welding and sealing.
First, machining such as computer numerical control (CNC) is used
to manufacture the channels, the mixed flow area, and the
dissipation fins on a metal plate. That is, the base plate 112, the
first dissipation fins 116 and the second dissipation fins 118 are
integrally formed. Furthermore, the cover plate 114 is manufactured
by machining and then combined to the base plate 112 by ways of
welding and sealing, for example, to form the heat exchanger 110.
In the present embodiment, the chosen metal plate may be a copper
plate or other metal materials with good heat conductivity. In
addition, a composite material may replace the metal plate for the
manufacture of the heat exchanger 110.
[0042] Multiple embodiments are described below to illustrate
possible varied examples of the semiconductor module and the heat
exchanger of the disclosure. The parts described in the previous
embodiment are omitted, and the description focuses on major
differences, and the same or similar reference numerals are adopted
to represent similar elements.
[0043] FIG. 2 illustrates a heat exchanger according to another
embodiment of the disclosure. FIG. 2 omits the cover plate to
clearly show the inner structure of the heat exchanger.
[0044] As shown in FIG. 2, a heat exchanger 210 of the present
embodiment is similar to the heat exchanger 110 shown in FIG. 1B,
and the difference between the two mainly lies in that the present
embodiment changes structures of second heat dissipation fins 218
to adjust a shape of a mixed flow area 266. To be more specific,
the present embodiment omits the fourth portion 118b (as shown in
FIG. 1B) of the second heat dissipation fins 118 in the heat
exchanger 110 of the previous embodiment, so that the mixed flow
area 266 of the present embodiment is expanded by leaving
unoccupied an area where the fourth portion 118b is originally
disposed. Each of the second heat dissipation fins 218 is in a
linear shape and extends from the first side S1 to the mixed flow
area 266 along the first direction D1.
[0045] Indeed, the shape, size and location of the mixed flow area
266 may be adjusted according to actual needs. In response to the
design of the mixed flow area 266, structures of first dissipation
fins 216 and the second dissipation fins 218 may be changed
correspondingly.
[0046] In addition, the disclosure may choose to dispose an
additional turbulence structure in the mixed flow area to improve a
mixing effect of the fluid in the mixed flow area. A heat exchanger
310 of another embodiment of the disclosure as shown in FIG. 3
illustrates a design with a mixed flow means 367 additionally
disposed in a mixed flow area 366. Herein, the mixed flow means 367
is a partition, for example, and the mixed flow means 367 is
separated from first dissipation fins 316 and second dissipation
fins 318 and lies in a flowing path of a fluid 370. Furthermore,
the disclosure does not limit the number, shape, location and
height of the mixed flow means 367. In other embodiments, the
number, shape, location and height of the mixed flow means 367 may
be changed to achieve an expected flow mixing effect.
[0047] FIG. 4 illustrates a semiconductor module according to
another embodiment of the disclosure. As shown in FIG. 4, a
semiconductor module 400 of the present embodiment is similar to
the semiconductor module 100 shown in FIG. 1A, and the difference
between the two mainly lies in that a base plate 412 of the present
embodiment is a vapor chamber. That is, a chamber 412a having a
capillary structure 490 and a low vacuum level is formed inside the
base plate 412, and when heat is transferred to the base plate 412
from a heat source, a liquid working substance in the chamber 412a
absorbs the heat and vaporizes in the environment with a low vacuum
level. At this time, the working substance absorbs the heat and
then it phase changes to form the vapor, and the vapor working
substance quickly fills the whole chamber 412a. When the vapor
working substance is exposed to an area of a lower temperature, the
vapor working substance condenses to release the heat absorbed in
vaporization. The condensed liquid working substance returns to
where evaporation has occurred through capillarity of the capillary
structure. In this way, the above-described cycle is repeated so
that the heat generated by the heat source is spread to each part
of the base plate 412 rapidly. In other words, the base plate 412
of the present embodiment is a flat heat pipe structure having good
two-phase flow characteristics and providing an excellent lateral
heat conduction effect. Even if the base plate 412 carries a
distributed heat source with a high working temperature, the base
plate 412 is able to spread the heat generated by the heat source
rapidly to prevent a hot spot from forming in a localized area and
to extend life of the product.
[0048] FIG. 5A illustrates a semiconductor module according to
still another embodiment of the disclosure. FIG. 5B is a bottom
view of a heat exchanger of FIG. 5A. In order to clearly show the
inner structure of the heat exchanger, FIG. 5B omits a cover plate.
FIG. 5C is an enlarged view of an area B of FIG. 5B. As shown in
FIGS. 5A to 5C, a semiconductor module 500 of the present
embodiment is similar to the semiconductor module 100 shown in
FIGS. 1A to 1D, and the difference between the two mainly lies in
that the present embodiment disposes electronic devices 532 and 534
on a first supporting substrate 520a and a second supporting
substrate 520b, respectively, and that the present embodiment
chooses to form a plurality of cavities 502 on a surface of first
dissipation fins 516, a surface of second dissipation fins 518 or
in an inner wall of a chamber 519. To be more specific, the
electronic devices 532 and 534 of the present embodiment are, for
example, an IGBT chip and a diode chip, respectively, and may be
connected to an external circuit in the ways introduced in the
previous embodiments or in any known feasible way. The cavities 502
may be selectively formed on surfaces of a base plate 512, a cover
plate 514, the first dissipation fins 516, or the second
dissipation fins 518 by machining, for example, at the same time
when a heat exchanger 510 is manufactured, and the cavities 502 are
preferably located closer to the front of the place where a fluid
570 enters the dissipation fins In this way, the cavities 502 may
change laminar flow characteristics of the fluid 570 in the chamber
519 because the cavities result in a sinking phenomenon in an
original thermal boundary layer and in a boundary layer of a flow
field when the fluid 570 flows through the cavities. Therefore, the
thermal boundary and the boundary of the flow field are thinned.
When the thermal boundary layer is thinned, the heat transfer
effect is naturally improved (due to a lower thermal resistance).
When the boundary layer of the flow field is thinner, a separation
phenomenon is unlikely to occur, so that the resistance of the
fluid 570 is reduced, and the heat dissipation ability of the fluid
570 is enhanced.
[0049] FIG. 6 illustrates a semiconductor module according to still
another embodiment of the disclosure. As shown in FIG. 6, a
semiconductor module 600 of the present embodiment is similar to
the semiconductor module 500 shown in FIG. 5A, and the difference
between the two mainly lies in that the present embodiment chooses
to form cavities 602 on locations corresponding to heat sources
(electronic devices 632 and 634) and make the cavities 602
penetrate through a base plate 612 to be connected to bottoms of
the heat sources. To be more specific, the cavities 602 may
penetrate through the base plate 612 and reach bottoms of
supporting substrates 620a and 620b directly, so that a fluid cools
the supporting substrates 620a and 620b under the electronic
devices 632 and 634 directly to improve a heat dissipation effect.
In addition, if the supporting substrates 620a and 620b are bonded
to the base plate 612 through a solder layer 644, bubbles may be
generated on a bonding surface. The bubbles may be discharged by
the cavities 602 in the manufacturing process, and the reliability
and heat dissipation ability between the supporting substrates 620a
and 620b and the base plate 612 are enhanced. Indeed, the present
embodiment may incorporate the design of the cavities 502 of the
embodiment shown in FIGS. 5A to 5C. That is, the present embodiment
may form cavities on surfaces of the base plate 612, the cover
plate 614 and the dissipation fins 616 of the heat exchanger
610.
[0050] It will be apparent to those skilled in the art that various
modifications and variations can be made to the structure of the
disclosed embodiments without departing from the scope or spirit of
the disclosure. In view of the foregoing, it is intended that the
disclosure cover modifications and variations of this disclosure
provided they fall within the scope of the following claims and
their equivalents.
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