U.S. patent application number 11/163425 was filed with the patent office on 2006-06-15 for method for combining components made of different materials.
Invention is credited to Yi-Chyng Fang, Chu-Wan Hong, Yeu-Lih Lin, Chang-Ting Lo, Jung-Yuan Wu, Peng-Peng Zhang.
Application Number | 20060124205 11/163425 |
Document ID | / |
Family ID | 36582402 |
Filed Date | 2006-06-15 |
United States Patent
Application |
20060124205 |
Kind Code |
A1 |
Hong; Chu-Wan ; et
al. |
June 15, 2006 |
METHOD FOR COMBINING COMPONENTS MADE OF DIFFERENT MATERIALS
Abstract
A method for combining two components together includes the
following steps: a) surface treating the two components; b) placing
them within a heating apparatus while they contact with each other,
a force being applied to the two components to push then against
each other on the contacting surfaces thereof; c) heating the two
components to a predetermined temperature which is hold for a
predetermined period time to cause the two components to diffuse at
the contacting interface to thereby combine the two components
together; d) cooling the combined two components and taking them
out of the heating apparatus.
Inventors: |
Hong; Chu-Wan; (Shenzhen,
CN) ; Lo; Chang-Ting; (Shenzhen, CN) ; Fang;
Yi-Chyng; (Shenzhen, CN) ; Wu; Jung-Yuan;
(Shenzhen, CN) ; Lin; Yeu-Lih; (Shenzhen, CN)
; Zhang; Peng-Peng; (Shenzhen, CN) |
Correspondence
Address: |
NORTH AMERICA INTELLECTUAL PROPERTY CORPORATION
P.O. BOX 506
MERRIFIELD
VA
22116
US
|
Family ID: |
36582402 |
Appl. No.: |
11/163425 |
Filed: |
October 18, 2005 |
Current U.S.
Class: |
148/512 ;
148/516 |
Current CPC
Class: |
C22F 1/00 20130101; C22F
1/08 20130101; C22F 1/04 20130101 |
Class at
Publication: |
148/512 ;
148/516 |
International
Class: |
C22F 1/00 20060101
C22F001/00; C22F 1/04 20060101 C22F001/04; C22F 1/08 20060101
C22F001/08 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 9, 2004 |
CN |
200410077431.4 |
Claims
1. A method for combining two components each having a
predetermined combining surface, the method comprising the
following steps: a) surface treating the predetermined combining
surfaces to smooth them; b) placing the two components with treated
combining surfaces within a heating apparatus with the treated
combining surfaces contacting with each other; c) heating the two
components at a predetermined temperature for a predetermined
period time to cause atoms of the two components to diffuse to each
other to form a layer of alloy at an interface of the two
components to thereby combine the two components together; d)
cooling the combined two components and taking them out of the
heating apparatus.
2. The method as described in claim 1, wherein one of the two
components is made of one of Al, the other of the two components is
made of Cu, and the alloy is Al.sub.3Cu.sub.2.
3. The method as described in claim 2, wherein at the step b) a
pair of forces is applied to the two components to induce a
pressure stress at each of the combining surfaces.
4. The method as described in claim 1, wherein the predetermined
temperature is in the range of 350-420.degree. C.
5. The method as described in claim 4, wherein the predetermined
temperature is in the range of 350-370.degree. C.
6. The method as described in claim 5, wherein the predetermined
temperature is about 360.degree. C.
7. The method as described in claim 1, wherein the predetermined
time is in the range of 2-3 hours.
8. The method as described in claim 7, wherein the predetermined
time is about 3 hours.
9. The method as described in claim 1, wherein the oven is filled
with a mixture of N.sub.2 and H.sub.2 for preventing the two
component from oxidization due to heating.
10. A product comprising first and second components made of two
different metals, respectively, and an alloy of made from diffusion
of the two metals and formed at an interface of the two components
to combine the two components together.
11. The product as described in claim 10, wherein one of the two
components is made of Al, the other of the two components is made
of Cu, and the alloy is Al.sub.3Cu.sub.2.
12. A method for combining two components together which are made
of copper and aluminum, respectively, comprising the following
steps: a) placing the two components in an oven while the two
components are subjected to a pair of forces pushing them against
each other at a combining interface of the two components; b)
heating the two components with a predetermined temperature for a
predetermined period of time until a diffusion of the two
components occurs at the combining interface to form an alloy of
the two components so that the two components are combined together
by the alloy; and c) cooling the combined two components.
13. The method of claim 12 further comprising the following step
before step a): surface treating the two components to reduce
roughness thereof.
14. The method of claim 13, wherein the surface treating step
further comprises removing oil and oxide from the two
components.
15. The method of claim 12, wherein the forces applied on the two
components induces a stress of 30 Mpa at the combining
interface.
16. The method of claim 12, wherein the two components are heated
with a temperature of about 350.degree. C.-420.degree. C. for a
period of time of about 2-3 hours.
17. The method of claim 12, where the oven is filled with a mixture
of N.sub.2 and H.sub.2.
18. The method of claim 16, wherein the two components are heated
with a temperature of about 360.degree. C. for a period of time of
about 3 hours.
19. The method of claim 18, wherein the oven is filled with a
mixture of N.sub.2 and H.sub.2.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to a method for
combining components made of different materials, and more
particularly to a method for combining components made of different
metals.
DESCRIPTION OF RELATED ART
[0002] Advances in microelectronics technology have resulted in
electronic devices which process signals and data at unprecedented
high speeds. During operation of many contemporary electronic
devices such as central processing units (CPUs), large amounts of
heat are produced. The heat must be efficiently removed, to prevent
the system from becoming unstable or being damaged. Heat sinks are
frequently used for dissipating heat from these electronic
devices.
[0003] Typical heat sinks are often integrally made by extruding
aluminum (Al). However, Al has a relative low heat conductivity,
i.e., 735 KJ/(M.H.K) compared with copper (Cu), i.e., 1386
KJ/(M.H.K). Thus, conventional heat sinks made by extruding Al
cannot meet heat dissipating requirement of contemporary CPUs which
are performing tasks faster and faster and thus generating more and
more heat. Accordingly, heat sinks made by combining two components
respectively made of Al and Cu have been developed.
[0004] Nowadays, two components respectively made of Al and Cu are
generally combined via solding, screws, pressing and so on.
However, in solding, a layer of oxide i.e., Al.sub.2O.sub.3, is
inevitably formed at a predetermined combining surface of the
component made of Al, which impacts solding effective of the two
components and results in a higher thermal resistance being formed
at the interface between the two components. The method of using
screws employs heat conductive medium filled between the two
components and combines the two components with screws. The
roughness of the combining surfaces of the two components impacts
the effect of combination of the two components. Furthermore, it is
difficult to control twisting force of the screws to cause the two
components to be tightly combined together without damaging the two
components. In pressing method, a component made of Al defines a
cylindric hole and the other component made of Cu has a cylindric
configure. The diameter of the component made of Cu is slightly
larger than that of the component made of Al. The component made of
Cu is pressed into and therefore interferentially received in the
hole of the component made of Al. However, the component made of Al
is prone to be scraped by the component made of Cu at the hole in
the pressing process, which may increase the thermal resistance
between the two components.
[0005] Therefore, it is desired to design a novel method for
combining two components to overcome the aforementioned
problems.
SUMMARY OF INVENTION
[0006] A method for combining two combining surfaces of two
components together, includes the following steps: a) surface
treating the combining surfaces to reduce roughness thereof; b)
placing the two components within a heating apparatus with the
treated combining surfaces contacting with each other, wherein a
force is applied to the components to push them against each other;
c) heating the components by the heating apparatus with a
predetermined temperature which is maintained for a predetermined
period of time to cause atoms near the contacting interface of the
two components to diffuse to each other to form a layer of alloy at
the interface of the two components to thereby combine the two
components together; d) cooling the combined two components and
taking the combined two components out of the heating
apparatus.
[0007] Other advantages and novel features of the present invention
will become more apparent from the following detailed description
when taken in conjunction with the accompanying drawings, in
which:
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 is a flow chart showing combining process for two
components in accordance with a preferred embodiment of the present
invention;
[0009] FIG. 2 shows the two components combined;
[0010] FIGS. 3a-3d respectively show thermal resistances of four
sample groups A, B, C, D before and after heat treatment; and
[0011] FIG. 4 shows average thermal resistances of the four sample
groups A, B, C, D before and after heat treatment.
DETAILED DESCRIPTION
[0012] FIG. 1 shows a process of a method for combining components
in accordance with one embodiment of the present invention. In this
embodiment, two components are used. One component is made of
copper (Cu) or Cu alloy, and the other component is made of
aluminum (Al) or Al alloy. Each component has a combining surface
which is predetermined to connect with the other component. The
method comprises the following steps:
[0013] a) surface treating the combining surfaces of the two
components to reduce surface roughness thereof. In this embodiment,
the surface treatment employs firstly electrolyzing or chemically
polishing the combining surfaces; then removing oil or dirt on the
combining surfaces by cleaning the combining surfaces with alcohol
or acetone; finally removing oxidized layers on the combining
surfaces by supersonic vibration to the combining surfaces;
[0014] b) placing the two treated components within an oven (not
shown) with the combining surfaces thereof contacting to each
other. A pair of forces is exerted on the two components to push
them against each other so that a pressure stress is induced on
each of the combining surfaces as shown in FIG. 2;
[0015] c) increasing the temperature of the oven in which the two
components are received quickly until the temperature thereof gets
to 330-420.degree. C. and then maintaining the oven with the
temperature for 1-4 hours. At this step, an alloy, such as
Al.sub.3Cu.sub.2, is formed on the two combining surfaces of the
two components due to atoms diffusion between the two components.
Thus, the two components are tightly combined together with a very
low thermal resistance existed at the interface thereof;
[0016] d) cooling the oven with the two combined components to the
environment temperature;
[0017] e) taking the two combined components out of the oven.
[0018] In the preferred embodiment, the thermal resistance of the
combined interface of the two components is subject to the
following factors:
[0019] a) roughness of the combining surfaces of the two
components. Lower roughness the combining surfaces of the two
components have, more tighter the two components are combined
together in the heat treatment process, which results in lower
thermal resistance being generated at the interface between the two
components.
[0020] b) forces employed to push the two components against each
other. During the heat treatment process, if a predetermined
compression stress is induced by applying forces on the combining
surfaces of the two components, Kirkendall effect on the combining
surfaces can be prevented. The Kirkendall effect is prone to
generate at the interface of the two components due to atoms
diffusing unequablely between the two components, which can
adversely increase the thermal resistance of the interface.
Generally, the stress induced by the applied forces is about 30
Mpa.
[0021] c) temperature of the heat treatment. Generally, the
temperature of the heat treatment is in the range of
330-420.degree. C., preferrably 350-370.degree. C., at which a
layer of alloy can generate at the interface between the two
components. The layer of alloy with a proper thickness is capable
of reducing interface thermal resistance between the two
components.
[0022] d) time of the heat treatment. The layer of alloy with a
thickness larger than a predetermined size may increase interface
thermal resistance between the two components. Therefore, it is
important to control the time of heat treatment in forming the
layer of alloy so that it can have a proper thickness at the
interface between the two components.
[0023] e) the percent of O.sub.2 of the gas in the oven. In order
to prevent the two components from being oxidized to form oxide
which can increase thermal resistance between the two components,
the percent of O2 of the gas in the oven should be reduced by such
as, illing the oven with a mixture of N.sub.2 and H.sub.2.
[0024] For testing the embodiment of the present invention, the
applicant takes an experiment as stated in the following.
[0025] The following Tab 1-1 shows the temperatures and periods of
time of the oven heating four groups of samples A, B, C, D. The
samples A are heated for 1 hour, the samples B are heated for 2
hours, the samples C are heated for 3 hours, and the samples D are
heated for 4 hours. The data in the Tab 1-1 shows that the heat
treatment temperatures of the samples are maintained substantially
at 360.degree. C. TABLE-US-00001 TABLE 1-1 Group of Samples Time
(min) A B C D 0 355.degree. C. 351.degree. C. 354.degree. C.
353.degree. C. 30 360.degree. C. 359.degree. C. 359.degree. C.
358.degree. C. 60 360.degree. C. 361.degree. C. 360.degree. C.
361.degree. C. 90 360.degree. C. 361.degree. C. 362.degree. C. 120
360.degree. C. 360.degree. C. 360.degree. C. 150 360.degree. C.
360.degree. C. 180 360.degree. C. 360.degree. C. 210 360.degree. C.
240 360.degree. C.
[0026] FIGS. 3a-3d show thermal resistances of the four groups of
samples A, B, C, D after heating 1, 2, 3, 4 hours respectively.
Five samples are in each group of samples. FIG. 3a shows that the
thermal resistances of the samples A after heating one hour are
higher than those before heat treatment. FIG. 3b shows that the
thermal resistances of some of the samples B after heating two
hours are higher than those before heat treatment, while the
thermal resistances of the other samples B after heating two hours
are lower than those before heat treatment. FIG. 3c shows that the
thermal resistances of the samples C after heating three hours are
lower than those before heat treatment. FIG. 3d shows that the
thermal resistances of the samples D after heating four hours are
higher than those before heat treatment. FIG. 4 shows the average
thermal resistances of the groups of samples respectively after
heat treatment and before heat treatment. FIG. 4 illustrates that
the average thermal resistance of the samples C, which are heated
for three hours, is reduced significantly in comparison with that
before heat treatment.
[0027] It is believed that the present invention and its advantages
will be understood from the foregoing description, and it will be
apparent that various changes may be made thereto without departing
from the spirit and scope of the invention or sacrificing all of
its material advantages, the examples hereinbefore described merely
being preferred or exemplary embodiments of the invention.
* * * * *