U.S. patent application number 12/993992 was filed with the patent office on 2011-03-31 for au-ga-in brazing material.
Invention is credited to Kenichi Miyazaki, Tomohiro Shimada, Hiroyasu Taniguchi.
Application Number | 20110076183 12/993992 |
Document ID | / |
Family ID | 41570297 |
Filed Date | 2011-03-31 |
United States Patent
Application |
20110076183 |
Kind Code |
A1 |
Taniguchi; Hiroyasu ; et
al. |
March 31, 2011 |
Au-Ga-In Brazing Material
Abstract
A brazing material which can be melted at a suitable temperature
at which damage is not given to a device inside a package upon
sealing, and besides the brazing material is not remelted, e.g.,
upon mounting to a board, and which has a low temperature
difference between a liquid and a solid. The brazing material is
made of a Au--Ga--In ternary alloy, wherein weight concentrations
of the elements lie within a region of a polygon with a point A
(Au: 90%. Ga: 10%, In: 0%), a point B (Au: 70%, Ga: 30%, In: 0%), a
point C (Au: 60%. Ga: 0%. In: 40%) and a point D (Au: 80%, Ga: 0%.
In: 20%) as vertexes. excluding lines on which In and Ga become 0%,
in a Au--Ga--In ternary phase diagram.
Inventors: |
Taniguchi; Hiroyasu; (
Kanagawa, JP) ; Shimada; Tomohiro; (Kanagawa, JP)
; Miyazaki; Kenichi; (Kanagawa, JP) |
Family ID: |
41570297 |
Appl. No.: |
12/993992 |
Filed: |
July 15, 2009 |
PCT Filed: |
July 15, 2009 |
PCT NO: |
PCT/JP2009/062793 |
371 Date: |
November 22, 2010 |
Current U.S.
Class: |
420/507 |
Current CPC
Class: |
H01L 2924/0002 20130101;
B23K 35/3013 20130101; C22C 5/02 20130101; B23K 35/3006 20130101;
H01L 23/10 20130101; H01L 2924/0002 20130101; B23K 35/0227
20130101; H01L 2924/01079 20130101; H01L 2924/00 20130101 |
Class at
Publication: |
420/507 |
International
Class: |
C22C 5/02 20060101
C22C005/02; B23K 35/24 20060101 B23K035/24 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 24, 2008 |
JP |
2008-191192 |
Claims
1. A brazing material comprising a Au--Ga--In ternary alloy,
wherein weight concentrations of the elements lie within a region
of a polygon with a point A (Au: 90%, Ga: 10%, In: 0%), a point B
(Au: 70%, Ga: 30%, In: 0%), a point C (Au: 60%. Ga: 0%, In: 40%)
and a point D (Au: 80%, Ga: 0%, In: 20%) as vertexes, excluding
lines on which In and Ga become 0%, in a Au--Ga--In ternary phase
diagram.
2. The brazing material according to claim 1, wherein the weight
concentrations of the elements of the Au--Ga--In ternary alloy lie
within a region of a polygon with a point E (Au: 86%, Ga: 13%, In:
1%), a point F (Au: 81%, Ga: 17%, In: 2%), a point G (Au: 79%, Ga:
10%, In: 11%) and a point H (Au: 84%, Ga: 6%, In: 10%) as vertexes,
in the Au--Ga--In ternary phase diagram.
3. The brazing material according to claim 1, wherein the weight
concentrations of the elements of the Au--Ga--In ternary alloy lie
within a region of a polygon with a point I (Au: 85%, Ga: 10%, In:
5%), a point J (Au: 80%, Ga: 14%, In: 6%), a point G (Au: 79%. Ga:
10%, In: 11%) and a point H (Au: 84%, Ga: 6%, In: 10%) as vertexes,
in the Au--Ga--In ternary phase diagram.
4. The brazing material according to claim 1, further comprising at
least one addition element of Sn, Ge, Zn, Sb, Si, Bi and Al.
5. The brazing material according to claim 4, wherein an added
amount of the addition element is 0.001 to 3.0% by weight.
6. The brazing material according to claim 1, wherein the brazing
material has a material structure having a rapidly solidified
structure formed from a molten state.
7. A hermetic sealing member part comprising the brazing material
according to claim 1.
8. A sealing method comprising brazing components with the brazing
material according to claim 1.
9. The brazing material according to claim 2, wherein the weight
concentrations of the elements of the Au--Ga--In ternary alloy lie
within a region of a polygon with a point I (Au: 85%, Ga: 10%, In:
5%), a point J (Au: 80%, Ga: 14%, In: 6%), a point G (Au: 79%. Ga:
10%, In: 11%) and a point H (Au: 84%, Ga: 6%, In: 10%) as vertexes,
in the Au--Ga--In ternary phase diagram.
10. The brazing material according to claim 2, further comprising
at least one addition element of Sn, Ge, Zn, Sb, Si, Bi and Al.
11. The brazing material according to claim 3, further comprising
at least one addition element of Sn, Ge, Zn, Sb, Si, Bi and Al.
12. The brazing material according to claim 9, further comprising
at least one addition element of Sn, Ge, Zn, Sb, Si, Bi and Al.
13. The brazing material according to claim 10, wherein an added
amount of the addition element is 0.001 to 3.0% by weight.
14. The brazing material according to claim 11, wherein an added
amount of the addition element is 0.001 to 3.0% by weight.
15. The brazing material according to claim 12, wherein an added
amount of the addition element is 0.001 to 3.0% by weight.
16. The brazing material according to claim 2, wherein the brazing
material has a material structure having a rapidly solidified
structure formed from a molten state.
17. The brazing material according to claim 3, wherein the brazing
material has a material structure having a rapidly solidified
structure formed from a molten state.
18. The brazing material according to claim 4, wherein the brazing
material has a material structure having a rapidly solidified
structure formed from a molten state.
19. The brazing material according to claim 5, wherein the brazing
material has a material structure having a rapidly solidified
structure formed from a molten state.
20. The brazing material according to claim 9, wherein the brazing
material has a material structure having a rapidly solidified
structure formed from a molten state.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a brazing material and a
sealing method using the brazing material. In particular, the
present invention relates to a brazing material used for
hermetically sealing a package for various electronic components.
The present invention provides a brazing material which is not
remelted, e.g., upon mounting to a board without giving damage to a
device inside the package upon sealing and has suitable
properties.
[0003] 2. Description of the Related Art
[0004] Electronic components such as an SAW filter and a crystal
oscillator used in various types of electronic equipment such as a
cellphone are hermetically sealed in a package made of ceramics or
the like in view of protecting an internal device. A brazing
material for sealing the package has progressively been made
lead-free in view of recent environmental protection. In this view,
a Au--Sn brazing material (particularly, a Au-20 wt % Sn brazing
material having an eutectic composition) is generally used (Patent
Document 1). An advantage of the Au--Sn brazing material is that
the Au--Sn brazing material enables an efficient sealing operation
upon sealing the package since the Au--Sn brazing material has a
comparatively low melting point of about 280.degree. C.
[0005] Patent Document 1: Japanese Patent Application Laid-Open No.
2001-150182
[0006] Although the Au--Sn brazing material has preferable
properties upon the sealing operation of the package, the Au--Sn
brazing material also has a problem. The problem is caused when the
sealed package is mounted to a board. Since a temperature upon
mounting is close to the melting point of the Au--Sn brazing
material, the heat remelts the brazing material to cause peeling
and leak of the sealed part of the package. Another problem to be
concerned about, other than the case where the package is mounted
to the board, is that when the board is heated to collect damaged
parts in repairing the electronic equipment, the heat may break the
sealing of other non-damaged parts.
[0007] The remelting of the brazing material is caused by the low
melting point of the brazing material. Then, brazing materials
having some compositions have been proposed in consideration of the
problem. For example, Patent Document 2 proposes the application of
a Au--Ge brazing material, particularly a Au-12.5% Ge brazing
material. The Au--Ge brazing material has a melting point exceeding
360.degree. C. Patent Document 3 proposes a brazing material made
of a ternary alloy of Au, Ge and Sn.
[0008] Patent Document 2: Japanese Patent Application Laid-Open No.
7-151943
[0009] Patent Document 3: Japanese Patent Application Laid-Open No.
2007-160340
[0010] Both the Au--Ge brazing material and the Au--Ge--Sn brazing
material have a melting point higher than that of the Au--Sn
brazing material. The remelting of the brazing materials having a
comparatively high melting point after sealing may be reduced.
[0011] However, the Au--razing material tends to have an
excessively high melting point. Considering the melting point, a
sealing temperature must be set to 400.degree. C. or more. The
sealing performed in the high temperature atmosphere increases the
thermal damage of a device inside the package, and may possibly
damage the element.
[0012] On the other hand, it can be said that the Au--Ge--Sn
brazing material minimizes the problem of the damage to the
composition upon sealing since the Au--Ge--Sn brazing material has
a melting point suppressed to a level lower than that of the Au--Ge
brazing material. However, ternary alloys such as the Au--Ge--Sn
brazing material may cause a problem of a temperature difference
between a liquidus and a solidus. How large or small the
temperature difference between the liquidus and the solidus affects
workability upon sealing the package. In Patent Document 3, the
temperature difference is set to be less than 50.degree. C.
However, it is preferable if the temperature difference is
small.
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0013] The present invention has been made against the
above-described background. The present invention provides a
brazing material which can be melted at a suitable temperature at
which damage is not given to a device inside a package upon
sealing, and besides the brazing material is not remelted, e.g.,
upon mounting to a board, and which has a small difference in
temperature between a liquidus and a solidus. Specifically, the
present invention provides a brazing material wherein the liquidus
and/or the solidus exceed 280.degree. C. and is 360.degree. C. or
less (preferably, both the liquidus and the solidus are within a
range of 300 to 340.degree. C.), and a difference between the
liquidus and the solidus is less than 45.degree. C. (preferably,
less than 40.degree. C.).
SUMMARY OF THE INVENTION
[0014] The present inventors have studied the application of a
brazing material made of Au, Ga and In as constituent elements and
made of a ternary alloy in which Au, Ga and In are alloyed, for
solving the above-mentioned problems. The present inventors have
found a brazing material having a prescribed composition range, and
have hit upon the present invention.
[0015] That is, the present invention is a brazing material
comprising a Au--Ga--In ternary alloy, wherein weight
concentrations of the elements lie within a region of a polygon
with a point A (Au: 90%, Ga: 10%, In: 0%), a point B (Au: 70%, Ga:
30%, In: 0%), a point C (Au: 60%, Ga: 0%, In: 40%) and a point D
(Au: 80%, Ga: 0%, In: 20%) as vertexes (excluding lines on which In
and Ga become 0%), in a Au--Ga--In ternary phase diagram.
[0016] The ternary phase diagram showing the composition of the
material according to the present invention is shown in FIG. 1. The
ternary alloy is applied in the present invention since the melting
point of the ternary alloy can be adjusted more effectively than a
binary Au alloy (Au--In, Au--Ga) by simultaneously adding two
elements of Ga and In to Au. The melting point (the liquidus, the
solidus) can be set within a suitable range by setting the added
amount of Ga and In to the range within the region. The composition
adjustment can also moderately reduce a temperature difference
between the liquidus and the solidus. The brazing material of the
composition range can be made suitable even in processability and
hardness.
[0017] In order to make hardness more suitable in addition to the
melting point of the brazing material, the temperature difference
between the liquidus and the solidus, and processability, it is
preferable that the weight concentrations of the elements of the
brazing material made of the Au--Ga--In ternary alloy lie within a
region of a polygon with a point E (Au: 86%, Ga: 13%, In: 1%), a
point F (Au: 81%, Ga: 17%, In: 2%), a point G (Au: 79%, Ga: 10%,
In: 11%) and a point H (Au: 84%, Ga: 6%, In: 10%) as vertexes, in
the Au--Ga--In ternary phase diagram. It is more preferable that
the weight concentrations of the elements of the Au--Ga--In ternary
alloy lie within a region of a polygon with a point I (Au: 85%, Ga:
10%, In: 5%), a point J (Au: 80%, Ga: 14%, In: 6%), a point G (Au:
79%, Ga: 10%, In: 11%) and a point H (Au: 84%, Ga: 6%, In: 10%) as
vertexes, in the Au--Ga--In ternary phase diagram. Specific
examples thereof include a brazing material lying within a range
shown in a ternary phase diagram of FIG. 2.
[0018] The ternary brazing material according to the present
invention may contain at least one addition element of Sn, Ge, Zn,
Sb, Si, Bi and Al. These addition elements are added in order to
finely adjust the melting point of the brazing material and improve
the wettability of the brazing material. The content of the
addition element is preferably 0.001 to 3.0% by weight, more
preferably 0.01 to 3.0% by weight, and still more preferably 0.1 to
3.0% by weight.
[0019] It is preferable that the brazing material according to the
present invention has a material structure having a rapidly
solidified structure formed from a molten state. It is because the
material structure having fine crystal grains formed by rapid
solidification improves wettability. The relationship between the
rapidly solidified structure and the improvement of the wettability
is not obvious. However, in this way, wetting spread tends to be
improved upon being melted without changing melting properties such
as the liquidus and the solidus. A cooling rate for obtaining the
rapidly solidified structure is preferably set to 2000 to
5000.degree. C./min.
[0020] The brazing material according to the present invention can
be used in any of plate, foil, grain, ball, powder and paste forms.
For example, in order to use the brazing material in the ball form,
the same method as that of the general brazing material can be
used. The brazing material can also be used in a window frame
shape, considering the shape of a package member to be sealed. The
brazing material according to the present invention can be
manufactured by a casting method as in a usual Au alloy without
particular difficulty. The brazing material can be processed in the
plate and foil forms by rolling and punching or the like if needed.
The obtained rolled material can be subjected to press punching and
slitting without particular difficulty. Prescribed shapes such as a
ring shape and a ribbon shape can be obtained.
[0021] Furthermore, the brazing materials of the grain and ball
forms can be manufactured from a molten state by an atomization
method, a rotating electrode method, a granulation in oil method
and a liquid droplet spraying method or the like. As described
above, in order to obtain the rapidly solidified structure for
improving the wettability of the brazing material, the brazing
materials of the plate and foil forms can be manufactured by
solidification using a cooling casting mold. The brazing materials
of the grain and ball forms can be manufactured according to
manufacturing conditions (adjustment of the diameter of a liquid
droplet, or the like).
[0022] The brazing material according to the present invention is
suitable for hermetically sealing the package member. Although the
sealing package member has a base accommodating a cap (lid) serving
as a lid body and a device, any of the cap and the base is
preferably provided with the brazing material made of the alloy
according to the present invention. When the brazing material is
fixed to the package member, the brazing material is placed on the
member, and the brazing material is melted and solidified in a
heating atmosphere to be fused. Kovar (an Fe--Ni--Co alloy) and 42
alloy (an Fe--Ni alloy) are generally used as the material of the
cap of the package member. Ceramic is used as the material of the
base. When the brazing material is fused, a fusing surface is
previously subjected to Ni plating and/or Au plating from the
object of improving the wettability of the brazing material, or the
like. The brazing material according to the present invention can
also be fused to the package member previously provided with these
plating layers.
[0023] In a method for hermetically sealing a package using the
brazing material and the package member according to the present
invention, the package member is preferably joined with a sealing
temperature being 360.degree. C. or more and less than 400.degree.
C., and preferably 380.degree. C. or less.
ADVANTAGE OF THE INVENTION
[0024] As described above, the brazing material according to the
present invention has suitable melting properties, and is suitable
for sealing the package. The brazing material has the improved
temperature difference between the liquidus and the solidus, and
has excellent workability. The brazing material according to the
present invention also has good processability, and can also be
processed into a brazing material for a package requiring
downsizing and slimming down.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a Au--Ga--In ternary phase diagram showing a
composition of a material according to the present invention;
[0026] FIG. 2 is a Au--Ga--In ternary phase diagram showing a
preferable composition and a more preferable composition of a
material according to the present invention; and
[0027] FIG. 3 is an evaluation diagram of wettability of a
Au--Ga--In ternary brazing material (Au: 82%, Ga: 10%, In: 8%).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] Hereinafter, an embodiment of the present invention and
comparative example will be described. In this embodiment, a
brazing material made of a Au--Ga--In alloy having various
compositions lying within and out of a region of FIG. 1, and a
brazing material in which Sn was added to a Au--Ga--In alloy were
manufactured. The properties of the brazing materials were
considered. In manufacture of samples, metals weighed so as to have
a prescribed composition were melted, cast, and subjected to
rolling to produce brazing materials having a thickness of 50
.mu.m.
[0029] The manufactured brazing materials were first evaluated for
hardness, processability and melting properties (liquidus,
solidus). The brazing materials were evaluated for the hardness
with a Vickers hardness meter. The processed brazing materials were
evaluated for the processability by observing the existence or
nonexistence of occurrence of break and crack of the brazing
materials with a stereoscopic microscope (10 times). The brazing
materials having no break and crack and capable of being processed
were evaluated as good. The brazing materials having observed break
or crack were evaluated as poor. The melting properties were
measured by differential thermal analysis. These results are shown
in Table 1. This evaluation was also performed for Au--Ga (15.2%)
which did not contain In for contrast (sample No. 12).
TABLE-US-00001 TABLE 1 Melting properties Difference between
liquidus and Composition (wt %) Hardness Solidus Liquidus solidus
No. Au Ga In Sn (Hv) Processability (.degree. C.) (.degree. C.)
(.degree. C.) 1 84 13 3 -- 242 good 304 317 13 2 82 10 8 -- 267
good 306 322 16 3 83 10 7 -- 290 good 306 321 15 4 81 10 9 -- 292
good 306 323 17 5 82 11 7 -- 300 good 306 324 18 6 83 9 8 -- 301
good 306 323 17 7 81.95 10.00 8.00 0.05 292 good 306 320 14 8 81.19
9.90 7.92 0.99 300 good 282 302 20 9 67 25 8 -- 180 good 390 462 72
10 65 18 17 -- 224 good 380 418 38 11 62 13 25 -- 257 good 383 408
25 12 84.8 15.2 0 -- 210 good 339 358 19
[0030] Table 1 shows that both the solidus and the liquidus of
Au--Ga--In brazing materials (samples 1 to 6) having compositions
lying within a region of FIG. 1 are within a range of 300 to
340.degree. C., and furthermore exhibit extremely excellent melting
properties since the difference between the solidus and the
liquidus is less than 20.degree. C. These brazing materials are
predicted to have a small difference with a sealing temperature
upon sealing a package. It is thought that the brazing materials
are most suitable as a brazing material for sealing the package.
Particularly, the brazing materials of the samples 2 to 6 provide a
result of having also sufficient hardness in addition to excellent
melting properties. On the other hand, Table 1 shows that samples 9
to 11 having compositions lying out of the region of FIG. 1 have a
high solidus and liquid us, and the difference between the solidus
and the liquidus is also large. Since the Au--Ga brazing material
(sample 12) which does not contain In has a composition close to an
eutectic composition, the Au--Ga brazing material has a narrow
difference between the solidus and the liquidus. However, since the
Au--Ga brazing material has a high melting point, it cannot be said
that the Au--Ga brazing material is suitable.
[0031] On the other hand, there was observed an effect of notably
reducing a melting point without extending the difference between
the liquid us and the solidus of the melting point by adding Sn
from a result of evaluating brazing materials (samples 7 and 8) to
which Sn was added as an addition element. This reduction effect of
the melting point was observed not only when Sn was added but also
when at least one addition element of Ge, Zn, Sb, Si, Bi and Al was
added.
[0032] FIG. 3 shows a result of evaluating wettability of the
ternary brazing material (Au=82%, Ga: 10%, In: 8%) of the sample 2.
The wettability was evaluated by putting a brazing material on
Kov/Ni plating/Au plating, heating the brazing material to a
temperature 20.degree. C. higher than a melting point under an
inactive atmosphere, and holding the brazing material for 2 minutes
to be melted. When the brazing material portion was wholly and
homogeneously wet-spread, the brazing material was determined as
good. When the brazing material portion was not wet-spread, the
brazing material was determined as poor. The result shows that the
brazing material portion is wholly and homogeneously wet-spread,
and the brazing material exhibits good wettability.
INDUSTRIAL APPLICABILITY
[0033] There can be provided a brazing material which can be melted
at a suitable temperature at which damage is not given to a device
inside a package upon sealing, and besides the brazing material is
not remelted, e.g., upon mounting to a board, and which has a small
temperature difference between a liquidus and a solidus.
Au--Ga---In Brazing Material
[0034] The brazing material according to the present invention is
suitable for hermetically sealing the package member. Although the
sealing package member has a base accommodating a cap (lid) serving
as a lid body and a device, any of the cap and the base is
preferably provided with the brazing material made of the alloy
according to the present invention. When the brazing material is
fixed to the package member, the brazing material is placed on the
member, and the brazing material is melted and solidified in a
heating atmosphere to be fused. Kovar (an Fe--Ni--Co alloy) and 42
alloy (an Fe--Ni alloy) are generally used as the material of the
cap of the package member pact. Ceramic is used as the material of
the base. When the brazing material is fused, a fusing surface is
previously subjected to Ni plating and/or Au plating from the
object of improving the wettability of the brazing material, or the
like. The brazing material according to the present invention can
also be fused to the package member previously provided with these
plating layers.
* * * * *