U.S. patent application number 10/117547 was filed with the patent office on 2003-10-02 for heat sink and method of removing heat from power electronics components.
Invention is credited to Makaran, John.
Application Number | 20030183369 10/117547 |
Document ID | / |
Family ID | 28453950 |
Filed Date | 2003-10-02 |
United States Patent
Application |
20030183369 |
Kind Code |
A1 |
Makaran, John |
October 2, 2003 |
Heat sink and method of removing heat from power electronics
components
Abstract
A heat sink 28 is provided for removing heat from a component 30
on a circuit board 22. The heat sink 28 includes a base 12 having a
top 14, a bottom 16, and opposing sides 18 and 20. The top is
generally planar for being adhered to a circuit board. Each of the
opposing sides has a cutout defining a stepped shoulder 26. The
heat sink also includes a plurality of fins 24 extending from the
bottom of the base. Locating structure 50 is provided on the top of
the heat sink for locating the heat sink with respect to the
circuit board 22. Since the heat sink can be glued to the circuit
board, a common heat sink can be used for any power electronics
component.
Inventors: |
Makaran, John; (London,
CA) |
Correspondence
Address: |
Siemens Corporation
Intellectual Property Department
186 Wood Avenue South
Iselin
NJ
08830
US
|
Family ID: |
28453950 |
Appl. No.: |
10/117547 |
Filed: |
April 2, 2002 |
Current U.S.
Class: |
165/80.3 ;
165/185; 165/80.2; 165/905; 257/E23.102; 257/E23.105;
29/890.03 |
Current CPC
Class: |
H01L 2924/0002 20130101;
H01L 2924/00 20130101; H01L 23/3677 20130101; H01L 2924/0002
20130101; Y10T 29/4935 20150115; Y10T 29/49359 20150115; H01L
23/367 20130101 |
Class at
Publication: |
165/80.3 ;
165/80.2; 165/185; 165/905; 29/890.03 |
International
Class: |
F28F 007/00; B21D
053/02 |
Claims
What is claimed is:
1. A heat sink for removing heat from a component on a substrate,
the heat sink comprising: a base having a top, a bottom and
opposing sides, the top being generally planar for being adhered to
a substrate, each of the opposing sides having a cutout defining a
stepped shoulder, and a plurality of fins extending from the bottom
of the base.
2. The heat sink of claim 1, wherein the base and fins are formed
integrally.
3. The heat sink of claim 2, wherein the base and fins are an
extrusion.
4. The heat sink of claim 2, wherein the base and fins are composed
of one of aluminum and magnesium.
5. The heat sink of claim 1, further comprising locating structure
on the top of the base for locating the heat sink with respect to a
substrate.
6. The heat sink of claim 5, wherein the locating structure
includes a plurality of members of generally rectangular
cross-section extending from the top of the base.
7. A heat sink for removing heat from a component on a substrate,
the heat sink comprising: a base having a top, a bottom and
opposing sides, the top being generally planar for being adhered to
a substrate, the base including locating structure on the top
thereof for locating the heat sink with respect to a substrate, and
a plurality of fins extending from the bottom of the base.
8. The heat sink of claim 7, wherein the locating structure
includes a plurality of members of generally rectangular
cross-section extending from the top of the base.
9. A method of removing heat from a component mounted on a
substrate, the method including: providing a heat-generating
component on a top side of a substrate, providing a heat sink
having a base including a top, a bottom and opposing sides, the top
being generally planar for mounting to a circuit board, the heat
sink also including a plurality of fins extending from the bottom
of the base, and applying thermal adhesive to the bottom of the
substrate or at least a portion of the top of the heat sink and
securing the top of the heat sink to the bottom side of the
substrate so as to remove heat from the component.
10. The method of claim 9, wherein each of the opposing sides of
the heat sink has a cutout defining a stepped shoulder, the method
further comprising: providing a cover member having a top surface
and a bottom surface, and a bore there-through, at least the top
surface being generally planar, inserting the fins through the bore
with sealant, provided between the top surface of the cover member
and the shoulders, sealing the bore.
11. The method of claim 9, wherein the component provided is a
power electronics component.
12. The method of claim 11, wherein the power electronics component
is a MOSFET.
13. The method of claim 10, wherein the cover member is composed of
one of plastic and aluminum and is configured to protect the bottom
side of the substrate without contacting any portions of electrical
components on the bottom side of the substrate.
14. The method of claim 9, wherein the sealant is silicone.
15. The method of claim 9, wherein the heat sink is composed of one
of aluminum and magnesium.
16. The method of claim 9, wherein the top of the base includes
locating structure and the substrate includes locating holes
therein, the securing step including placing the locating structure
in the locating holes.
17. The method of claim 9, wherein the adhesive applied to the
portion of the top of the base.
18. A method of making a heat sink comprising: extruding material
to form a heat sink extrusion of a certain length, the heat sink
extrusion having a base including a top, a bottom and opposing
sides, the top being generally planar for mounting to a circuit
board, the heat sink extrusion also including a plurality of fins
extending from the bottom of the base, machining, at each of the
opposing sides, a cutout defining a stepped shoulder, and cutting
the extrusion across the certain length at various locations to
provide a plurality of heat sinks from the extrusion.
19. The method of claim 18, wherein the extrusion further includes
at least one rib on the top of the base extending the certain
length, after the cutting step, the method including removing a
central portion of the rib to define locating structure.
20. The method of claim 19, wherein the locating structure
comprises at least one pair of locators, each locator having a
generally rectangular cross-section.
Description
FIELD OF THE INVENTION
[0001] The invention relates to heat removal from electronic
components of a circuit board and, more particularly, to a heat
sink for removing heat from a power electronics component.
BACKGROUND OF THE INVENTION
[0002] Typically, heat sinks for removing heat from power
electronics components of a circuit board are designed for the
specific component to be cooled. Development time is significant
since a thermal model and thermal stack-up need to be determined
for each heat sink. In making heat sinks, costly tooling is
required, especially if the heat sink is of the finned type.
Furthermore, rapid reconfiguration of a printed circuit board
layout is difficult and expensive since there is retooling
associated with the conventional heat sinks. This often results in
solutions that are unique to the particular packaging
embodiment.
[0003] Accordingly, there is a need to provide a heat sink to be
used for all power electronic devices.
SUMMARY OF THE INVENTION
[0004] An object of the invention is to fulfill the need referred
to above. In accordance with the principles of the present
invention, this objective is achieved by providing a heat sink for
removing heat from a component on a substrate. The heat sink
includes a base having a top, a bottom and opposing sides. The top
is generally planar for being adhered to the substrate. Locating
structure is provided on the top of the heat sink for locating the
heat sink with respect to the substrate. Each of the opposing sides
has a cutout defining a stepped shoulder. The heat sink also
includes a plurality of fins extending from the bottom of the base.
The heat sink is made preferably by an extrusion process. Since the
heat sink can be glued to the circuit board, a common heat sink can
be used for any power electronics component.
[0005] In accordance with another aspect of the invention, a method
is provided for removing heat from a component mounted on a
substrate. The method provides a heat-generating component on a top
side of the substrate. A heat sink is provided and has a base
including a top, a bottom and opposing sides. The top is generally
planar for mounting to the substrate. The heat sink also includes a
plurality of fins extending from the bottom of the base. Thermal
adhesive is applied to the bottom of the substrate or to at least a
portion of the top of the heat sink and the top of the heat sink is
secured to the bottom side of the substrate to remove heat from the
component.
[0006] In accordance with yet another aspect of the invention, a
method of making a heat sink includes extruding material to form a
heat sink extrusion of a certain length. The heat sink extrusion
has a base including a top, a bottom and opposing sides. The top is
generally planar for mounting to a circuit board. The heat sink
extrusion also includes a plurality of fins extending from the
bottom of the base. A cutout is machined at each of the opposing
sides to define stepped shoulders. The extrusion is cut across the
length at various locations to provide a plurality of heat sinks
from the extrusion.
[0007] Other objects, features and characteristics of the present
invention, as well as the methods of operation and the functions of
the related elements of the structure, the combination of parts and
economics of manufacture will become more apparent upon
consideration of the following detailed description and appended
claims with reference to the accompanying drawings, all of which
form a part of this specification.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The invention will be better understood from the following
detailed description of the preferred embodiments thereof, taken in
conjunction with the accompanying drawings, wherein like reference
numerals refer to like parts, in which:
[0009] FIG. 1 is a perspective view of a heat sink extrusion
provided in accordance with principles of the present
invention.
[0010] FIG. 2 is a perspective view of a heat sink cut from the
extrusion of FIG. 1, shown after creating shoulders in opposing
sides thereof.
[0011] FIG. 3 is a cross-sectional view of the heat sink of FIG. 2
shown mounted between a circuit board and a cover member in
accordance with the present invention.
[0012] FIG. 4 is a perspective view of a second embodiment of a
heat sink of the invention shown having locating structure on a top
thereof.
[0013] FIG. 5 is a plan view of one of the location structures of
the heat sink of FIG. 4 shown received in a through hole in a
circuit board.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT
[0014] With reference to FIG. 1, a heat sink extrusion, provided in
accordance with the invention, is shown generally indicated at 10.
Material, such as aluminum or magnesium, is extruded to form the
heat sink extrusion 10 having a certain length. The heat sink
extrusion 10 has a base 12 including a top 14, a bottom 16 and
opposing sides 18 and 20. The top 14 is generally planar for
mounting to substrate such as a printed circuit board 22 (FIG. 3).
The heat sink extrusion 10 also including a plurality of fins 24
extending from the bottom 16 of the base 12. As used herein the
term "fins" means any structure to cause heat transfer from the
base 12 to surrounding air. A cut-out is machined in each of the
sides 18 and 20 defining stepped shoulders 26 in the base 12, the
function of which will be explained below. Hence, by extrusion, the
base 12 and the fins 24 are formed integrally.
[0015] In order to provide a plurality of heat sinks 28, generally
indicated at 28 in FIG. 2, from the extrusion 10, the extrusion 10
is cut across the length at various locations (e.g., line A of FIG.
1). Thus, many heat sinks 28 can be made from a single extrusion
10. It can be appreciated that the heat sink can be made by methods
other than extrusion, such as machining or casting.
[0016] With reference to FIG. 3, a method of removing heat from a
component mounted on a substrate such as a circuit board provides a
heat-generating component 30 mounted on a top side 31 of a circuit
board 22. The substrate is preferably of ceramic or insulated metal
material. In the illustrated embodiment, the heat-generating
component 30 is a power electronics component such as a MOSFET. The
component 30 is preferably covered with potting or conformal
coating 32. Thermal vias 34 are provided through the circuit board
22 adjacent to the component 30 and extend from the top side 31 to
a bottom side 36 of the circuit board 22. In the illustrated
embodiment, the vias 34 are bores through the circuit board that
are filled with thermally conductive material. Thus, the vias 34
provide paths for heat to be transferred from the component 30 to
the bottom side 36 of the circuit board 22. Thermal adhesive 38 is
applied to at least a portion of the top of heat sink 28 and the
top 14 of the heat sink is secured to the bottom side 36 of the
circuit board 22 adjacent to the vias 34. Of course, the adhesive
can be applied to the bottom of the circuit board instead of
applying adhesive on the heat sink. It can be appreciated that the
thermal vias are not required, but are preferred since they aid in
heat transfer.
[0017] In the illustrated embodiment, a cover member 40, preferably
of plastic or aluminum, is provided and has a top surface 42, a
bottom surface 44, and a bore 45 there-through. At least the top
surface 42 is generally planar. The cover member 40 is configured
to cover and protect the bottom side 36 of the circuit board 22
without contacting any portions of electrical components on the
bottom side 36 of the circuit board 22. In the broadest aspect of
the invention, the cover member need not be provided.
[0018] A sealant 46, such as silicone or RTV, is placed under each
shoulder 26 of the base 12 of the heat sink 28, or around the bore
45 in the cover member 40. Thereafter, the fins 24 of the heat sink
28 are inserted through the bore 45 so that the sealant 46 is
between the top surface 42 of the cover member 40 and the shoulders
26, sealing the bore 45.
[0019] With reference to FIG. 4, to aid in locating the heat sink
28' with respect to the circuit board 22, locating structure is
provided on the top 14 of the base 12. The locating structure
includes at least one pair of locators 50, of generally rectangular
cross-section, extending from the top 14 of the base. Preferably,
during extrusion of the heat sink, ribs 52 can be provided on the
top 14 of the base 12. Then, as shown in FIG. 4, the central
portions of the ribs can be removed by machining to define the
locators 50. The locators 50 can be of any cross-sectional
shape.
[0020] As shown in FIG. 5, the circuit board 22 can have plated
locating holes 54 there-through, each of which is sized to receive
an associated locator 50 of the heat sink 28 to control the X-Y
location of the heat sink 28 with respect to the circuit board
22.
[0021] Thus, in accordance with the invention, a common heat sink
can be used for all power electronic devices by simply gluing the
heat sink to the circuit board relative to the power electronics
device. Since the heat sink is a common design, rapid
reconfiguration of printed circuit board layout can be achieved.
There are no retooling costs associated with the heat sink 28. Only
the location of the bore 45 in the cover member 40 needs to be
moved during reconfiguration.
[0022] The advantages of the invention include: 1) shorter
electronics package, 2) easier to re-layout a printed circuit board
in an existing application or use in a new application because the
heat sink dimensions are common to all designs, 3) no heat sink
retooling costs, 4) ability to use finned heat sinks without the
need for expensive tooled heat sinks, 5) heat sinks are extruded
and therefore are of low cost, 6) minimize development time since
heat sink thermal model and thermal stack-up is common to all
designs, and 7) if more surface area is needed, a different
extrusion with more or longer fins can be used.
[0023] The foregoing preferred embodiments have been shown and
described for the purposes of illustrating the structural and
functional principles of the present invention, as well as
illustrating the methods of employing the preferred embodiments and
are subject to change without departing from such principles.
Therefore, this invention includes all modifications encompassed
within the spirit of the following claims.
* * * * *