U.S. patent application number 11/728071 was filed with the patent office on 2008-09-25 for method of manufacturing a brazed micro-channel cold plate heat exchanger assembly.
Invention is credited to Russell Charles Anderson, Brian Leslie Barten, John Benoit, Stephan Michael Vetter.
Application Number | 20080229580 11/728071 |
Document ID | / |
Family ID | 39773268 |
Filed Date | 2008-09-25 |
United States Patent
Application |
20080229580 |
Kind Code |
A1 |
Anderson; Russell Charles ;
et al. |
September 25, 2008 |
Method of manufacturing a brazed micro-channel cold plate heat
exchanger assembly
Abstract
The invention relates to a method of making a brazed
micro-channel cold plate assembly for cooling a heat producing
electronic component. The primary components of a cold plate
assembly are a base plate, a manifold cover, and inlet/outlet
pipes; wherein the individual components are assembled and brazed
into an integral unit. The joining surfaces of the individual
components have novel features that provide for permanent bonding
of the joints by brazing and a hermetic seal along the joint seams.
The novel features also forestall excess braze alloy from
contaminating the interior surfaces of the assembled cold plate and
obstructing the engineered flow channels.
Inventors: |
Anderson; Russell Charles;
(North Tonawanda, NY) ; Barten; Brian Leslie;
(Lockport, NY) ; Benoit; John; (Lockport, NY)
; Vetter; Stephan Michael; (Lockport, NY) |
Correspondence
Address: |
DELPHI TECHNOLOGIES, INC.
M/C 480-410-202, PO BOX 5052
TROY
MI
48007
US
|
Family ID: |
39773268 |
Appl. No.: |
11/728071 |
Filed: |
March 23, 2007 |
Current U.S.
Class: |
29/890.03 ;
257/E23.098 |
Current CPC
Class: |
B23K 2101/14 20180801;
F28F 3/025 20130101; Y10T 29/4935 20150115; F28F 3/12 20130101;
H01L 23/473 20130101; F28F 9/0246 20130101; B23K 1/0012 20130101;
H01L 2924/0002 20130101; H01L 2924/0002 20130101; H01L 2924/00
20130101; B23K 2101/40 20180801 |
Class at
Publication: |
29/890.03 |
International
Class: |
B21D 53/02 20060101
B21D053/02 |
Claims
1. A method of manufacturing a heat exchanger assembly for a heat
producing component, comprising the steps of: providing a base
plate having a substantially central axis, wherein said base plate
includes: an exterior surface adapted to engage with said heat
producing component; an interior surface having substantially
parallel micro-fins and micro-channels, wherein said micro-fins
have coplanar edges; and a co-axial perimeter wall having an outer
surface, an inner surface, and an end edge, wherein said perimeter
wall is substantially parallel to said central axis; providing a
manifold cover having a substantially central axis, wherein said
manifold cover includes: an interior manifold cover surface having
a series of substantially parallel alternating inlet/outlet
channels, wherein said inlet/outlet channels have coplanar edges
adapted to engage with said coplanar edges of said micro-fins in a
crossing pattern; and a co-axial perimeter trough adapted to
cooperate with said perimeter wall, wherein said perimeter trough
has a trough first face, a trough second face, and a bottom,
wherein the width of said bottom is greater than width of said
perimeter wall; arranging said base plate and said manifold cover
so that said end edge of said perimeter wall is received in said
trough of said manifold cover, wherein said coplanar edges of
inlet/outlet channels are in intimate contact with said coplanar
edges of micro-fins, wherein said end edge of said perimeter wall
is spaced apart from said bottom of said trough defining a gap,
wherein said outer surface of said perimeter wall is spaced apart
from said trough first face defining an outboard radial clearance,
and wherein said inner surface of said perimeter wall is spaced
apart from said trough second face defining an inboard radial
clearance; positioning a first braze alloy element said onto said
outer surface of the perimeter wall proximate to said outboard
radial clearance; heating the arrangement to a temperature
effective to melt said braze alloy, where upon the melted braze
alloy is drawn into said outboard radial clearance by capillary
forces and displaced air exits via the inboard radial clearance,
thereby permitting said coplanar edges of micro-fins of base plate
and said coplanar edges of inlet/outlet channels of manifold cover
to remain in intimate contact; and cooling the arrangement to
solidify the braze alloy to bond said base plate to said manifold
cover to form said assembly.
2. A method of manufacturing a heat exchanger assembly of claim 1
further comprising, prior to heating said assembly, the steps of:
providing at least one inlet/outlet port through said manifold
cover; providing at least one inlet/outlet pipe amendable to
brazing, wherein said inlet/outlet pipe comprises: a first exterior
surface and a second exterior surface, wherein said first exterior
surface is adapted to slidably insert into said inlet/outlet port
while providing effective inlet/outlet pipe clearance to allow for
capillary action to draw melted braze alloy, and an annular
exterior flange circumscribing said second exterior surface;
positioning a second braze alloy element on said second exterior
surface of inlet/outlet pipe between said annular exterior flange
and said first surface of inlet/outlet pipe; and assembling said
inlet/outlet pipe with said manifold cover by slidably inserting
the first surface of said inlet/outlet pipe into said inlet/outlet
port; whereupon heating the arrangement to a temperature effective
to melt said braze alloy, the melted braze alloy is drawn into said
effective inlet/outlet pipe clearance by capillary forces.
3. A method of manufacturing a heat exchanger assembly of claim 2,
wherein said first exterior surface of inlet/out pipe has an
annular notch to capture excess melted braze alloy.
4. A method of manufacturing a heat exchanger assembly of claim 1,
wherein said co-axial perimeter wall further has a rim extended
substantially perpendicular to said central axis on interface of
said outer wall and said end edge, wherein said rim retards melted
braze flow into said gap during said heating of assembly.
5. A method of manufacturing a heat exchanger assembly of claim 1,
wherein said manifold cover has an exterior manifold cover surface
and a substantially perpendicular force is applied onto said
exterior manifold cover surface to ensure said coplanar edges of
micro-fins of base plate and said coplanar edges of inlet/outlet
channels of manifold-cover are in intimate contact during said
heating and cooling of assembly.
6. A method of manufacturing a heat exchanger assembly of claim 5,
wherein a force is applied onto said inlet/outlet pipe toward said
exterior manifold cover surface during said heating and cooling of
assembly.
7. A method of manufacturing a heat exchanger assembly of claim 1,
wherein the volume of said braze element is less than the total
volume of said outboard radial clearance and said gap.
8. A method of manufacturing a heat exchanger assembly of claim 1,
wherein said perimeter wall further comprises a shoulder extending
from said outer surface and said braze element is positioned onto
said shoulder and proximal to said outboard radial clearance.
9. A method of manufacturing a heat exchanger assembly of claim 3,
wherein the volume of said second braze element is less than the
total volume of said inlet/outlet pipe clearance and said annular
notch.
10. A method of manufacturing a heat exchanger assembly for a heat
producing component, comprising the steps of: providing a base
plate having a substantially central axis, wherein said base plate
includes: an exterior surface adapted to engage with said heat
producing component; and an interior surface having substantially
parallel micro-fins and micro-channels, wherein said micro-fins
have coplanar edges; and providing a manifold cover having a
substantially central axis, wherein said manifold cover includes:
an interior manifold cover surface having a series of substantially
parallel alternating inlet/outlet channels, wherein said
inlet/outlet channels have coplanar edges adapted to engage with
said coplanar edges of said micro-fins in a crossing pattern;
wherein one of said base plate or said manifold cover further
comprises a co-axial perimeter wall having an outer surface, an
inner surface, and an end edge, wherein said perimeter wall is
substantially parallel to said central axis; and wherein the other
of said base plate or said manifold cover further comprises a
co-axial perimeter trough adapted to cooperate with said perimeter
wall, wherein said perimeter trough has a trough first face, a
trough second face, and a bottom, and wherein the width of said
bottom is greater than width of said perimeter wall; arranging said
base plate and said manifold cover so that said end edge of said
perimeter wall in received in said trough of said manifold cover,
wherein said coplanar edges of inlet/outlet channels are in
intimate contact with said coplanar edges of micro-fins, wherein
said end edge of said perimeter wall is spaced apart from said
bottom of said trough defining a gap, wherein said outer surface of
said perimeter wall is spaced apart from said trough first face
defining an outboard radial clearance, and wherein said inner
surface of said perimeter wall is spaced apart from said trough
second face defining an inboard radial clearance; positioning a
first braze element said onto said outer surface of the perimeter
wall proximal to said outboard radial clearance, wherein said braze
element is formed of a braze alloy; heating the arrangement to a
temperature effective to melt said braze alloy, where upon the
melted braze alloy is drawn into said outboard radial clearance
including portion of said gap by capillary forces and displaced air
exits via inboard radial clearance, thereby permitting said
coplanar edges of micro-fins of base plate and said coplanar edges
of inlet/outlet channels of manifold cover to remain in intimate
contact; and cooling the arrangement to solidify the braze alloy to
bond said base plate to said manifold cover to form said assembly.
Description
TECHNICAL FIELD OF INVENTION
[0001] The invention relates to a method of making a brazed
micro-channel cold plate assembly for cooling a heat producing
electronic component.
BACKGROUND OF INVENTION
[0002] Recirculating closed-loop liquid cooling systems are used
for cooling heat generating electronic components such as computer
processing units (CPU). Shown in FIG. 1 is a typical recirculating
closed-loop liquid cooling system 10 known in the art that includes
a reservoir tank 15, a coolant pump 22, a cold plate 25, a radiator
35, and a fan 40, wherein the cold plate 25 is in thermal contact
with a heat generating electronic component 30.
[0003] In reference to FIG. 1, the coolant pump 22 transfers a
liquid coolant from the reservoir tank 15 to the cold plate 25.
Within the cold plate 25 are engineered channels through which the
coolant flows for optimized transfer of excess heat from the
electronic component 30 to the coolant. After exiting the cold
plate 25, the hot coolant continues to the radiator 35 where the
heat is released to the ambient air by convection with the aid of a
fan 40 blowing a stream of cooler air across the radiator 35. The
cooled coolant then returns to the reservoir tank 15 to repeat the
heat transfer process.
[0004] U.S. patent application Ser. No. 11/221,526 discloses a cold
plate assembly with engineered flow channels. The disclosed cold
plate assembly includes a base plate of
[0005] U.S. patent application Ser. No. 11/221,526 discloses a cold
plate assembly with engineered flow channels. The disclosed cold
plate assembly includes a base plate of copper having a flat
exterior surface that is adapted to thermally bond to a heat
generating electronic component. On the interior surface of the
base plate is a series of micro-channels and micro-fins, wherein
the micro-fins have coplanar surfaces. The base plate is assembled
to a manifold cover, wherein the interior surface of the manifold
cover has larger alternating channels with co-planer edges that
cooperate with the smaller coplanar surfaces of the micro-fins.
Inlet/outlet pipes are also joined to inlet/outlet ports on the
manifold cover.
[0006] When the manifold cover is engaged to the base plate, the
coplanar edges of the alternating channels of the manifold cover
come in intimate contact with the coplanar edges of the micro-fins
of the base plate forming a checkerboard pattern for fluid flow
resulting in more effective and efficient heat extraction. The
multiple crossing interfaces between the bottom coplanar edges of
the manifold channels and the top coplanar edges of the micro-fins
have to be held to very close tolerances to prevent any bypass flow
of coolant, which would cause reduced heat transfer efficiency.
[0007] Providing a permanent bond and a hermetic seal at the
joining surfaces of the cold plate assembly while maintaining
intimate contact between the coplanar edges of the micro-fins with
the coplanar edges of the alternating channels is critical. Any
liquid coolant leakage from the cold plate assembly will severely
damage the electronic component for which it is designed to cool,
as well as any other components which the coolant may come into
contact with. Also, any air introduced into the closed-loop system
may risk lowering the performance of the coolant pump 22, creating
unacceptable noise during the operation of the pump, and lowering
heat transfer efficiency. In addition, the presence of air in the
system would reduce the volume of the initial coolant charge,
resulting in reduced heat transfer efficiency. Known methods of
permanently bonding and hermetically sealing the base plate and
inlet/outlet pipes to the manifold cover have been known to fail
over prolonged use or can be too complex and expensive to be
manufactured.
[0008] One known method to permanently bond and hermetically seal
the base plate and inlet/outlet pipes to the manifold is by welding
joining surfaces of the components. Due to the compact size of a
typical cold plate required for cooling electronic components,
typically in the neighborhood of 40 mm to 50 mm in diameter, the
heat required to weld diminutive metal components may warp the cold
plate assembly causing the coplanar edges of the micro-fins and the
coplanar edges of the alternating channels to lose intimate contact
and results in a non-functional unit.
[0009] Another method known is to use an elastomer seal to bond and
hermetically seal the base plate and inlet/outlet pipes to the
manifold. A draw back to using elastomer is the change in thickness
of the elastomer as it cures or after it is exposed to the working
fluid. Furthermore, the use of elastomer has proven to be
unreliable where the elastomer along the joining surfaces has
failed after prolonged temperature cycling.
[0010] Still another method known to permanently bond and
hermetically seal the base plate and inlet/outlet pipes to the
manifold cover is by resistance welding the components after
assembly which is also disclosed in U.S. patent application Ser.
No. 11/221,526. Resistance welding provides for a permanent bond
and hermetic seal for the usable life of the cold plate; however,
resistant welding may not be cost effective. Resistance welding
requires the use of highly pure, oxygen free copper that is both
electronically and thermally conductive. Besides the suitable
material, the joining surfaces of the base plate, inlet/outlet
pipes, and manifold cover have to be precision machined to exact
specifications resulting in complexity and cost of
manufacturing.
[0011] There exists a need for a micro-channel cold plate heat
assembly wherein the joints of the base plate, manifold cover, and
inlet/outlet pipes can be permanently bonded and hermetically
sealed by conventional means that is predictable, easy to
manufacture, and cost effective.
SUMMARY OF THE INVENTION
[0012] The invention relates to a brazed micro-channel cold plate
assembly for cooling electronic components. The instant invention
provides a novel combination of features and method steps that
allow a micro-channel cold plate assembly to be brazed without
clogging or jeopardizing the coolant flow in the micro-channels and
with the assurance of a hermetic seal between joining components. A
hermetic seal is critical to exclude the intrusion of air into the
closed loop system and prevent the leakage of coolant onto the
electronic component that the cold plate assembly is in contact
with.
[0013] The primary components of a cold plate assembly are a base
plate, a manifold cover, and inlet/outlet pipes; wherein the
individual components are assembled and brazed into an integral
unit. The joining surfaces of the components have novel features
that provide for a permanent bond of the joining surfaces and a
hermetic seal along the joining surfaces. The novel features also
forestall excess braze alloy from contaminating the interior
surfaces of the assembled cold plate and obstructing the engineered
flow channels.
[0014] The base plate has an interior surface with substantially
parallel micro-channels and corresponding micro-fins having
coplanar edges. About the perimeter of the interior surface of the
base plate is a wall with an end edge. The interior of the manifold
cover has a series of substantially parallel alternating
inlet/outlet channels with coplanar edges. About the perimeter of
the manifold cover interior surface is a trough that is adapted to
join with the wall of the base plate to form features that are
conducive to brazing. Manifold cover also has inlet/outlet ports to
accept inlet/outlet pipes for coolant flow into and out of the cold
plate assembly.
[0015] When the manifold cover is engaged with the base plate, the
alternating channels coplanar edges on the manifold cover come into
intimate contact with the micro-fins coplanar edges on the base
plate. The perimeter trough on the manifold cover cooperates with
the wall of the base plate to define an outboard radial clearance,
an inboard radial clearance, and a gap in between; wherein all
three spatial voids are in hydraulic communication with each other.
Fitted between the base plate and manifold cover is a first braze
element formed of a braze alloy.
[0016] The inlet/outlet pipe has an annular flange, a joining
surface, and an annular notch on the joining surface. The joining
surface of the inlet/outlet pipe is inserted into the inlet/outlet
port of the manifold. Fitted between the annular flange and the
manifold cover is a second braze element formed of a braze
alloy.
[0017] The cold plate assembly is heated to a temperature effective
to melt the first and second braze elements. Once the braze alloy
enters a liquid state, the liquid alloy is drawn into the outboard
radial clearance and portion of the gap by capillary forces. Air
displaced by the braze alloy exits to the ambient atmosphere
through the inboard radial clearance. The inboard radial clearance
is essential to prevent air from being trapped in the gap.
Otherwise, during the brazing process, trapped air in the gap will
increase in pressure, thereby separating the manifold cover from
the base plate causing the multiple crossing interfaces between the
alternating channel coplanar edges and micro-fins coplanar edges to
lose intimate contact.
[0018] The arrangement is then cooled at a predetermined rate,
solidifying the braze alloy to bond the base plate to the manifold
cover, and the inlet/outlet pipe to the manifold cover to form the
cold plate assembly.
[0019] An advantage of the present invention allows the individual
components of a micro-channel cold plate to be assembled,
permanently bonded, and hermetically sealed by conventional means
that is predictable and cost effective.
[0020] Another advantage of the present invention is that the
combination of novel features on the joining surfaces of the base
plate, manifold cover, and inlet/outlet pipes allows a
micro-channel cold plate to be permanently bonded by brazing
without braze alloy clogging or jeopardizing the coolant flow in
the micro-channels.
[0021] Still another advantage of the present invention is that the
combination of novel features on the individual components provides
for a robust hermetic seal along the joining surfaces for the
designed life of the micro-channel cold plate.
[0022] Further features and advantages of the invention will appear
more clearly on a reading of the following detail description of
the preferred embodiment of the invention, which is given by way of
non-limiting example only and with reference to the accompanying
drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0023] This invention will be further described with reference to
the accompanying drawings in which:
[0024] FIG. 1 is a schematic diagram of a prior art recirculating
closed-loop liquid cooling system for a heat producing electronic
component.
[0025] FIG. 2 is an exploded view of the various components of the
brazed all metal micro-channel heat exchanger plate assembly.
[0026] FIG. 3 is a cross sectional view of the assembled present
invention prior to heat being applied for brazing.
[0027] FIG. 4 is an enlarged circle section of FIG. 3 prior to heat
being applied for brazing.
[0028] FIG. 5 is an enlarged circle section of FIG. 3 after
brazing.
[0029] FIG. 6 is an enlarged perspective view of a portion of the
bottom surfaces of the manifold channels crossing the top edges of
the micro fins.
DETAILED DESCRIPTION OF INVENTION
[0030] Shown in FIG. 2, is an exploded view of a preferred
embodiment of the current invention, a brazed all metal
micro-channel cold plate assembly which is indicated generally at
20. The primary components of the cold plate assembly 20 are a base
plate 100, a manifold cover 200, and inlet/outlet pipes 300. The
components are assembled and brazed into an integral unit. Base
plate 100, manifold cover 200, and inlet/outlet pipes 300 have
novel features that provide for a permanent hermetic seal and bond
of the joining surfaces when brazed. The novel features also
forestall excess braze alloy from obstructing the engineered flow
channels within cold plate assembly 20, an advantage that will
become more apparent as the invention is further described.
[0031] Cold plate assembly 20 is comparable in size to, and in
thermal contact with a heat generating electronic component. Base
plate 100 is approximately 34 mm in outer diameter with a thickness
of approximately 1.0 mm. Manifold cover 200 outer-diameter is
greater than outer-diameter of base plate 100 in order to overlay
base plate 100. Manifold cover 200 thickness is approximately 5 mm
and is largely determined by the hydraulic flow requirements for
the desired cooling needs. Inlet/outlet pipes 300 are approximately
9.5 mm in outer diameter, excluding the enlarged tapered diameters
for hose retention, which would be approximately 10.8 mm in outer
diameter, and are approximately 25 mm in length. Preferably, base
plate 100, manifold cover 200, and inlet/outlet pipes 300 are
formed of copper; however, the components can be formed of any
elemental metals, metal alloys, or combinations thereof that are
thermal conductive and amendable to brazing.
[0032] In reference to FIGS. 2 and 3, cold plate assembly 20 has a
substantially central axis 110 passing through base plate 100 and
manifold cover 200. Inlet/outlet pipes 300 extend substantially
parallel to central axis 110 from manifold cover 200.
[0033] In reference to FIGS. 4 and 6, base plate 100 has an
exterior plate surface 130 adapted to engage with a heat producing
component (not shown) that is to be cooled and a planar interior
plate surface 135. Located on the interior plate surface 135 are
substantially parallel micro-fins 140 and corresponding
micro-channels 145. The micro-channels 145 are approximately 350 to
450 microns deep, and are extremely narrow, approximately 60
microns, while the micro-fins 140 are narrower, approximately 50
microns. Each of micro-fins 140 has micro-fins coplanar edges 150
that are substantially parallel with interior plate surface 135.
Circumscribing the perimeter of base plate 100 is a perimeter wall
155 extending substantially parallel to central axis 110.
[0034] In reference to FIG. 4, perimeter wall 155 has a wall outer
surface 160, a wall inner surface 165, and a wall end edge 170.
Wall outer surface 160 and wall inner surface 165 are substantially
parallel to central axis 110, and wall end edge 170 is
substantially perpendicular to central axis 110. Wall outer surface
160 has a retainer shoulder 175 that is substantially perpendicular
to central axis 110. Protruding outward, perpendicular to central
axis 110, from interface of wall outer surface 160 and wall end
edge 170 is rim 180.
[0035] Perimeter wall 155, rim 180, and retainer shoulder 175 of
perimeter wall 155 cooperate with novel features of manifold cover
200, which are described below, during the brazing process to form
a permanent bond and hermetic seal along the joining surfaces, as
well as to prevent excess metal braze alloy from contaminating
micro-fins 140 and micro-channels 145.
[0036] Also shown in FIG. 4 is manifold cover 200 having a manifold
interior surface 205 engaged with base plate 100. In reference to
FIG. 6, shown is a series of substantially parallel alternating
inlet/outlet channels 230 that resembles a sinuous wall 237,
wherein alternating inlet/outlet channels 230 extend from manifold
interior surface 205. For clarity, manifold interior surface 205 is
not shown attached to alternating inlet/outlet channels 230.
Alternating inlet/outlet channels 230 have coplanar edges 235
capable of being oriented and intimately engaged over micro-fins
coplanar edges 150 in a crossing pattern.
[0037] Co-axially located with central axis 110 on manifold cover
200 is a perimeter trough 250 having a trough first face 255, a
trough second face 260, and a trough bottom 265. Trough first face
255 and trough second face 260 are substantially parallel with wall
outer surface 160 and wall inner surface 165 of base plate 100,
respectively. Trough bottom 265 is substantially parallel with wall
end edge 170 and rim 180 of perimeter wall 155.
[0038] Perimeter trough 250 is sufficient in width to accommodate
wall end edge 170 and rim 180. Ultimately, perimeter wall 155 of
base plate 100 is inserted into and cooperates with perimeter
trough 250 of manifold cover 200 to define an inboard radial
clearance 280 between trough second face 260 and wall inner surface
165, and an outboard radial clearance 275 between trough first face
255 and wall outer surface 160.
[0039] Perimeter trough 250 is also sufficient in depth to allow
alternating channel coplanar edges 235 of manifold cover 200 to
come into intimate contact with micro-fins coplanar edges 150 of
base plate 100 without interference between trough 250 and
perimeter wall 155, while also defining gap 270 between wall end
edge 170 and trough bottom 265, when base plate 100 is assembled
with manifold cover 200.
[0040] The spatial distance between trough first face 255 and wall
outer surface 160 is effective for capillary forces to draw melted
braze alloy into outboard radial clearance 275. Outboard radial
clearance 275 is in hydraulic contact with gap 270, which in turn
is in hydraulic contact with inboard radial clearance 280. In
reference to FIGS. 4 and 5, as melted braze alloy is drawn into
outboard radial clearance 275 and partially into gap 270, displaced
air escapes via inboard radial clearance 280. The displaced air is
then vented out through the inlet/outlet pipes 300. Without inboard
radial clearance 280, displace air would be trapped in gap 270 and
expand due to the heat required of brazing. The increase in
pressure and volume of the heated air would separate base plate 100
from manifold cover 200 resulting in loss of intimate contact
between alternating channel coplanar edges 235 and micro-fins
coplanar edges 150.
[0041] In reference to FIGS. 3 through 5, located through manifold
cover 200 is inlet/outlet port 225. Inlet/outlet pipe 300 has first
pipe exterior surface 305 and a second exterior pipe surface 310.
First exterior pipe surface 305 is adapted to be slidably inserted
into inlet/outlet port 225 while providing effective inlet/outlet
pipe clearance 315 to allow for capillary action to draw melted
braze alloy. Located on first exterior pipe surface 305 is annular
notch 330. Separating first exterior pipe surface 305 from second
exterior pipe surface 310 is exterior pipe edge 325. Circumscribing
second exterior pipe surface 310 is annular flange 320. Annular
flange 320 and exterior edge 325 are substantially parallel with
manifold exterior surface 207 in the assembled state.
[0042] Prior to assembly of the individual components, the joining
surfaces of base plate 100, manifold cover 200, and inlet/outlet
pipe 300 are prepared and cleaned in a manner known to those
skilled in the art of brazing. After proper preparation, the
components are assembled and brazed as described next.
[0043] Base plate 100 is firmly secured in a fixture. First braze
element 120 is positioned onto retainer shoulder 175 of base plate
100. Base plate 100 and manifold cover 200 are then arranged so
that wall end edge 170 is receivable in perimeter trough 250 of
manifold cover. Perimeter wall 155 of base plate 100 is inserted
into perimeter trough 250 of manifold cover 200 until alternating
channels coplanar edges 235 of manifold cover 200 are in intimate
contact with micro-fins coplanar edges 150 of the base plate 100
forming a checkerboard pattern. It is critical that alternating
channels coplanar edges 235 are maintained in intimate contact with
micro-fins coplanar edges 150 during and after the brazing process;
otherwise, coolant will by pass the engineered flow pathways
resulting in less efficient heat transfer.
[0044] As described herein above, perimeter trough 250 is
sufficient in depth, wherein alternating channels coplanar edges
235 are in intimate contact with micro-fins coplanar edges 150 and
wall end edge 170 is spaced apart from trough bottom 265 defining
gap 270. Gap 270 provides a mean to capture excess melted braze
alloy. Wall outer surface 160 and trough first face 255 are spaced
apart defining outboard radial clearance 275. Wall inner surface
165 is spaced apart from trough second face 260 defining inboard
radial clearance 280. Outboard radial clearance 275, gap 270,
inboard radial clearance 280, and interior plate surface 135 are
all in hydraulic communication.
[0045] Inlet/outlet pipe 300 is arranged so that first exterior
pipe surface 305 is receivable in inlet/outlet port 225. Second
braze element 125 is positioned on second exterior pipe surface 310
of inlet/outlet pipe 300 between the annular flange 320 and the
first exterior pipe surface 305 of inlet/outlet pipe along exterior
edge 325. First exterior pipe surface 305 of inlet/outlet pipe 300
is slidably inserted into inlet/outlet port 225. Second braze
element 125 is held in position by annular flange 320 and manifold
exterior surface 207.
[0046] The components as described are clamped onto the fixture, a
sufficient force substantially parallel to central axis 110 is then
applied on manifold exterior surface 207 to ensure micro-fins
coplanar edges 150 of base plate 100 and alternating channel
coplanar edges 235 of manifold-cover 200 remain in intimate
contact. The force could be applied to the manifold exterior
surface 207 by means of applying pressure on the fixture or
directly onto the manifold exterior surface 207.
[0047] The multiple crossing interfaces between the alternating
channel coplanar edges 235 and micro-fins coplanar edges 150 have
to be maintained in intimate contact during the heating and cooling
cycle of the brazing process. Were it not for the maintenance of
intimate contact between the surfaces throughout the entire brazing
cycle, the faying surfaces would spread apart during the cooling
down period from liquiduis temperature to room temperature
resulting in a spatial separation that would be highly detrimental
to heat transfer efficiency.
[0048] Referring to FIG. 5, cold plate assembly 20 is heated to a
temperature effective to melt braze alloy in first braze element
120 and second braze element 125. As capillary forces draw melted
braze alloy from first braze element 120 from retainer shoulder 175
into outboard radial clearance 275 and a portion of gap 270,
displaced air from outboard radial clearance 275 and a portion of
gap 270 travels through inboard radial clearance 280 and exits
inlet/outlet port 225. Inboard radial clearance 280 is essential to
prevent air from being trapped in gap 270; otherwise, during the
brazing process, air pressure from trapped air in gap 270 will
increase and separate manifold cover 200 from base plate 100
causing the multiple crossing interfaces between the alternating
channel coplanar edges 235 and micro-fins coplanar edges 150 to
lose intimate contact.
[0049] When manifold cover 200 is assembled with base plate 100,
rim 180 of perimeter wall 155 constricts outboard radial clearance
275 and thereby retards the flow of liquid braze alloy into gap
270. Following the path of less resistance, excess braze alloy will
drip off retainer shoulder 175 rather than further flowing past the
constriction between rim 180 and trough first face 255. It is
preferred that the volume of braze alloy in first braze element 120
is less than the sum of the volume of outboard radial clearance 275
and gap 270 to ensure that excess braze alloy does not exit inboard
radial clearance 280 onto interior plate surface 135 and
contaminate micro-channels 145.
[0050] When inlet/out pipe 300 is inserted into inlet/outlet port
225 on manifold cover 200, annular notch 330 together with
inlet/outlet pipe clearance 315 forms an effective spatial
clearance to contain excess braze alloy. It is also preferred that
the volume of braze alloy in second braze element 125 is less than
the sum of the volume of inlet/outlet pipe clearance 315 and
annular notch 330 to ensure excess braze alloy does not enter
interior plate surface 135 and contaminate micro-channels 145. Any
excess braze alloy will drip off of manifold exterior surface 207
due to the path of least resistance.
[0051] The arrangement is then cooled at a predetermined rate
depending upon the type of brazing process used, the section
thickness of the parts being brazed, and the purity of the
materials being brazed, to solidify the braze alloy to bond the
base plate to the manifold cover to form the assembly.
[0052] While this invention has been described in terms of the
preferred embodiments thereof, it is not intended to be so limited,
but rather only to the extent set forth in the claims that follow.
Dimensions are only presented to illustrate the actual size of cold
plate assembly 20 and are not intended to be limiting. Those
skilled in the art can adjust the dimensions of cold plate assembly
20 to accommodate the specific heat transfer needs.
[0053] Furthermore, variation in the disclosed embodiment could be
made. The perimeter wall 155 could be formed on the manifold cover
200 and the perimeter trough 250 could be formed on the base plate
100.
[0054] Still furthermore, the function of cold plate assembly 20
has been described as removing excess heat from a heat generating
component; those skilled in the art can recognize that cold plate
assembly 20 can also function as adding heat to a component by
pumping preheated coolant through the cold plate assembly 20.
Therefore, it will be understood that it is not intended to limit
the method of the invention to just the embodiment disclosed.
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