U.S. patent application number 10/172578 was filed with the patent office on 2002-12-19 for heat sink.
Invention is credited to Wong, Chee Tieng.
Application Number | 20020189790 10/172578 |
Document ID | / |
Family ID | 32986011 |
Filed Date | 2002-12-19 |
United States Patent
Application |
20020189790 |
Kind Code |
A1 |
Wong, Chee Tieng |
December 19, 2002 |
Heat sink
Abstract
A heat sink is manufactured by forming a fin 2 for dissipating
heat by separating a length of material from a substrate 1 while
leaving the proximal end attached to the substrate 1. The fins are
cut from the substrate by stamping process using the stamping
single or progressive die tooling cutting the substrate 1 along
dotted line 16. The heat sink is a unitary construction, with the
fins 2 being integrally formed with the substrate 1.
Inventors: |
Wong, Chee Tieng; (Sungai
Petani, MY) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Family ID: |
32986011 |
Appl. No.: |
10/172578 |
Filed: |
June 13, 2002 |
Current U.S.
Class: |
165/80.3 ;
165/133; 165/905; 257/E23.103; 29/890.03 |
Current CPC
Class: |
B21J 5/068 20200801;
Y10T 29/4935 20150115; H01L 23/3672 20130101; B23P 2700/10
20130101; B23P 15/26 20130101; H01L 2924/0002 20130101; F28F 3/022
20130101; Y10T 29/4913 20150115; H01L 21/4878 20130101; H01L
2924/0002 20130101; H01L 2924/00 20130101 |
Class at
Publication: |
165/80.3 ;
165/133; 165/905; 29/890.03 |
International
Class: |
F28F 007/00; F28F
013/18; F28F 019/02; B21D 053/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 15, 2001 |
MY |
PI 20012831 |
Claims
1. A method of forming a heat sink, including forming a fin for
dissipating heat by separating a length of material from a
substrate while leaving the proximal end attached to the
substrate.
2. A method according to claim 1, wherein the fin is arcuate or
planar.
3. A method according to claim 1 or 2, wherein the fin extends
generally perpendicularly to the plane of the substrate.
4. A method according to claim 1, 2 or 3, including forming a ridge
in the surface of the substrate for engagement with a cutting tool
to form the fin.
5. A method according to claim 4, wherein the ridge forms the
distal end of the fin.
6. A method according to any one of the preceding claims, wherein
the fin is formed by single or progressive stamping processes by
using the single or progressive die tooling.
7. A method according to any one of the preceding claims, including
forming a plurality of said fins on the substrate.
8. A method according to claim 7, wherein said plurality of said
fins are formed in a series of spaced apart rows.
9. A heat sink having a substrate and a plurality of fins for
dissipating heat integrally formed therewith.
10. A heat sink according to claim 9, wherein each fin is a single
layer of material extending from the substrate.
11. A heat sink according to claim 9 or 10, wherein the substrate
comprises aluminium or copper.
12. A method of forming a heat sink, substantially as hereinbefore
described with reference to any one of or combination of the
accompanying drawings.
13. A heat sink substantially as hereinbefore described with
reference to and/or substantially as illustrated in any one of or
any combination of the accompanying drawings.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to heat sinks and to a method
of forming the same. More particularly, but not exclusively, the
present invention relates to an improved method of forming heat
dissipating fins of a heat sink.
[0002] Heat sinks are well known components used, for example, for
dissipating heat from electronic circuitry, CPUs (computers) and
microprocessors in order to cool the components to enable them to
function consistently and properly. Heat sinks are often used in
conjunction with printed circuit boards which are found in
electronic equipment such as television sets and audio amplifiers
There are many types of conventional heat sinks.
[0003] One of the most widely used heat sink is extruded heat sink.
It is well know to manufacture the extruded heat sink by extruding
aluminium, through a complex shaped die to produce a section.
Extrusion limits, such as the fin height-to-gap and fin thickness,
usually dictate the flexibility in design options. Typically fin
height-to-gap aspect ratio of up to 6 and minimum fin thickness of
1.3 mm, are attainable with a standard extrusion. A 10 to 1 aspect
ratio and a fin thickness of 0.8 mm can only be achieved with
special die design features. However, as the aspect ratio
increases, the extrusion tolerance is compromised. Also, extrusion
equipment is expensive, the process slow, Further, in order that it
can be made by an extrusion process, a heat sink must be made from
aluminium, and other materials cannot be used.
[0004] Another conventional type o1 heat sink is folder type heat
sink that consists of a base to which a continuous corrugated fin
sheet is attached. A plurality of corrugations are formed, which
are elongate, adjacent corrugations having the appearance of
oppositely facing slots. To attach the corrugated sheet to the base
portion, square slots are formed in the corrugation. The corrugated
sheet is then slotted in to the base which is extruded so as to
have square cross section ridges which are inserted into the slot
holes. To ends of the ridges are then stamped flat to hold the
corrugated sheet on to the extruded base. The corrugations thus
form fins of the heat sink. One disadvantage of such an arrangement
is that the corrugated sheet which forms the fins forms a heat trap
between alternate pairs of fins.
[0005] In another type of conventional heat sink the fins are
formed from a numbers of separate sheets of material which are
pressed to form a U-shaped fin. The fins are then riveted to an
extruded aluminium base or sheet metal piece using two or more
rivets. Such an arrangement is disadvantageous in that the
additional manufacturing step of applying the rivets is necessary,
and further in that the rivets may work lose, reducing the
effectiveness of the heat sink.
SUMMARY OF THE INVENTION
[0006] It is an object of the present invention to provide a heat
sink which provides improved heat dissipation. It is another object
of the present invention to provide an improved method of forming
the fins to achieve maximum fin height-to-gap aspect ratio and to
reduce the fin thickness to as thin as 0.2 mm. The improved method
is less expensive, faster and more flexible, and which results in
higher cooling capacity and more reliable heat sinks.
[0007] According to a first aspect of the present invention, there
is provided a method of forming a heat sink, including forming a
fin for dissipating heat by separating a thin length of material
from a substrate while leaving the proximal end attached to the
substrate. Such a method may allow a heat sink to be formed from a
unitary sheet of material. The fins are an integral part of the
substrate and therefore do not need to be attached to a base(As the
folder type or U-fin heat sink does), so there are no joints which
could reduce conduction of heat or deteriorate with rough handling
and/or ageing. Fins may be produced by cutting thin lengths of
material from the substrate.
[0008] The fin may be arcuate in configuration.
[0009] The fin may extend generally perpendicularly to the plane of
the substrate. This may be advantageous as it allows heat to escape
from a plurality of fins as it rises between the fins.
[0010] A ridge may be formed in the surface of the substrate as a
result of the cutting process to form the fin. The ridge may form
the distal end of the fin.
[0011] The fin may be formed by the stamping process using the
single die tooling or a progressive die tooling.
[0012] The method may typically be used to form a plurality of the
very fine fins up to 0.2 mm in thickness on the substrate. A
plurality of fine fins that provide larger surface area expose to
the air stream will provide improved heat dissipation.
[0013] The plurality of fins may be formed in a series of spaced
apart rows. The space between the adjacent fins can be minimised to
achieve the maximum fin height-to-gap aspect ratio (20 to 40) thus
increase the surface area for better cooling capacity. The spacing
apart of the rows may allow improved air circulation, which may
also increase heat dissipation.
[0014] According to a second aspect of the present invention there
is provided a heat sink having a substrate and a plurality of fins
for dissipating heat integrally formed therewith. By forming the
fins integrally with the heat sink main body, a unitary structure
is formed.
[0015] Each fin may be a single thin layer of material extending
from the substrate. By forming the fins as single layers, no heat
is trapped within a single fin, and heat dissipation may be
improved.
[0016] The heat sink may comprise aluminium or copper, and may
consist of only one of aluminium and copper. With prior art
extruded heat sinks, only aluminium could be used.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] For a better understanding of the present invention,
embodiments will now be described by way of example, with reference
to the accompanying drawings, in which:
[0018] FIG. 1 shows a perspective view of a fully formed heat sink
in accordance with the present invention;
[0019] FIG. 2 shows a side plan view of a heat sink during
manufacture thereof;
[0020] FIG. 3 shows an overhead plan view of the heat sink of FIG.
1;
[0021] FIG. 4 shows a side elevational view of the heat sink of
FIG. 1 in completed form;
[0022] FIG. 5 shows a front elevational view of the heat sink of
FIG. 1 in completed form;
[0023] FIG. 6 shows a cross section taken along the line A-A of
FIG. 3;
[0024] FIG. 7 shows a front elevational view of a heat sink
according to a second embodiment of the present invention;
[0025] FIG. 8 shows a front elevational view of a heat sink
according to a third embodiment of the present invention;
[0026] FIG. 9 shows a front elevational view of a heat sink
according to a fourth embodiment of the present invention; and
[0027] FIG. 10 shows a side elevational view of the heat sink of
FIG. 9.
DESCRIPTION OF THE EMBODIMENTS
[0028] Throughout the drawings, the same reference numerals are
generally used to designate like elements.
[0029] FIGS. 1 to 6 show a first embodiment of the present
invention. The heat sink comprises a base or substrate 1, being a
block of metal such as aluminium or copper. Layers of the substrate
1 are peeled or shaved away successively in order to form heat
dissipative fins 2. The fins 2 may be formed in a series of columns
3 and rows 5. The fins 2 of each column 3 may be formed
simultaneously. The rows 5 of fins 2 are separated by a gap 6.
Between the rows 5 of fins 2 a rib 8 is present. Between each rib 8
is a groove 10, which is formed as the fins 2 are cut from the
substrate 1.
[0030] The fins 2 are arcuate. The arc of each fin 2 illustrated
represents approximately 1/8 of a circle. The arc profile depends
on the design of the tool that forms the fins 2, and the thickness
and height of the fins 2.
[0031] FIG. 2 shows how a heat sink is formed from substrate 1.
Initially, the substrate 1 is a cuboid.
[0032] A cutting tool C of a stamping die tooling engages the
substrate 1 to form the fin 2 from the substrate 1. The substrate 1
is fed into the stamping tool C manually or by using a material
feeder (not shown). The feeding pitch corresponding to each stroke
of the press machine may vary depending on the requirements of the
tooling as well as the required thickness of the fins, fin height
and pitch between the fins of the heatsink
[0033] To facilitate the shaving/peeling process to form the fins 2
at the initial stage of the shaving process, a series of grooves 12
may be coined/formed on the surface of the substrate 1. The
substrate 1 is then progressed toward the shaving/peeling portion
of the cutting tool. Once the shaving and peeling portion of the
cutting tool C contacts the substrate 1, material will start
peeling from the surface of the substrate 1. The first few fins
will directly peel off from the substrate 1 until the proximal end
of the fins is able remain connected to the substrate 1, where the
first column of fins is formed. The subsequent columns of fins will
then be continually formed by the stamping die tool as the
substrate 1 is fed forward by a specific distance on by every
stroke of the press machine. These subsequent fins will have a
thickness corresponding to the height "h" of the ridge 12. The
ridge 12 will form the distal end of the fin 2.
[0034] The shaving/peeling advancement direction A of the cutting
tool C may vary from approximately 2.degree. to 20.degree.
depending on the required fin thickness and height as well as the
pitch between the fins. The fins will be shaved/peeled along the
dotted lines 16 separating a length "L" of substrate material from
the main body of the substrate 1 at a distance "1" from the
previously formed fins, the distance "1" determining the spacing or
pitch between adjacent fins once formed. The proximal end of the
fin 2 remains connected to the main body of the substrate 1 after
the shaving and peeling process. During the final phase of movement
of the cutting tool C, the fin 2 is peeled away from the main body
of the substrate 1 so that it lies generally perpendicular
thereto.
[0035] This process will create a long strip of substrate 1 with
the fins on the surface of the substrate 1. A cutting tool or
machine may be engaged later to cut the substrate 1 into small
piece with a specific number of columns of fins required by the
heat sink.
[0036] The pitch 18 between the columns of fins 2 is determined by
the distance 1, and is chosen according to the heat dissipation
requirements of the heat sink.
[0037] The gap 6 between the rows 5 of fins 2 is also chosen
according to the heat dissipation requirements of the heat
sink.
[0038] The thickness (corresponding to h) of each fin 2 can also be
selected according to the requirements of an individual heat
sink.
[0039] FIG. 7 shows a heat sink according to a second embodiment of
the present invention having only two rows 5' of fins 2'. The fins
2' of each row 5' are wider than the fins 2 of the first
embodiment.
[0040] FIG. 8 shows a third embodiment of the invention wherein a
single row 5" of fins 2" is formed.
[0041] FIG. 9 shows a fourth embodiment, which is small
modification of the third embodiment. In the fourth embodiment the
fins 2'" are formed across the full width of the substrate 1 rather
than leaving a rib 8 at each side, as in the first, second and
third embodiments.
[0042] FIG. 10 is a side elevational view of the heat sink of FIG.
9.
[0043] The pitch 18 of the fins 2 according to the embodiments of
the present invention and the thickness and height of the fins 2
can be varied within a larger range than is possible using a
conventional processes such as extrusion process.
[0044] Also, the process according to the embodiments produces heat
sinks faster than the processes of producing an extrusion heat
sink, folder type and bonded type heat sink according to the prior
art and at lower cost.
[0045] Further, compared with the prior art extrusion process, the
bottom surface 14 of the substrate 1 will be relatively flat,
improving heat transmission thereto. Material usage is more
efficient by forming a heat sink according to the present
embodiments. Heat sinks according to the present embodiments will
be more compact, lighter as less material is necessary to produce
them, compared with prior art heat sinks having comparable
functionality. The fins can be made thinner than is possible in the
extrusion process. Also, no rivets or other joining means are
required to connect the fins to the substrate, thereby improving
the conductivity of the heat sink and more reliable. The cost is
also lower because no additional joining process is needed.
* * * * *