U.S. patent application number 13/627880 was filed with the patent office on 2013-06-27 for composite alloy bonding wire.
The applicant listed for this patent is Jun-Der Lee. Invention is credited to Jun-Der Lee.
Application Number | 20130164169 13/627880 |
Document ID | / |
Family ID | 48654750 |
Filed Date | 2013-06-27 |
United States Patent
Application |
20130164169 |
Kind Code |
A1 |
Lee; Jun-Der |
June 27, 2013 |
COMPOSITE ALLOY BONDING WIRE
Abstract
A manufacturing method for a composite alloy bonding wire and
products thereof are provided. A primary material of Ag is melted
in a vacuum melting furnace, and then a secondary metal material of
Pd is added into the vacuum melting furnace and is co-melted with
the primary material to obtain an Ag--Pd alloy solution. The
obtained Ag--Pd alloy solution is drawn to obtain an Ag--Pd alloy
wire. The Ag--Pd alloy wire is then drawn to obtain an Ag--Pd alloy
bonding wire with a predetermined diameter.
Inventors: |
Lee; Jun-Der; (Taichung
City, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lee; Jun-Der |
Taichung City |
|
TW |
|
|
Family ID: |
48654750 |
Appl. No.: |
13/627880 |
Filed: |
September 26, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13334047 |
Dec 21, 2011 |
|
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13627880 |
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Current U.S.
Class: |
420/505 |
Current CPC
Class: |
H01L 2924/01327
20130101; B22D 11/00 20130101; H01L 2224/05624 20130101; B21C
37/047 20130101; H01L 2224/4381 20130101; H01L 2224/43848 20130101;
H01L 2224/45139 20130101; H01L 2924/01047 20130101; H01L 2924/12041
20130101; H01L 2224/45015 20130101; H01L 2924/00011 20130101; H01L
2924/01005 20130101; H01L 2924/01074 20130101; H01L 24/43 20130101;
H01L 2924/00014 20130101; H01L 2924/00015 20130101; B23K 35/40
20130101; H01L 2224/45139 20130101; B23K 35/3006 20130101; H01L
2224/45015 20130101; H01L 2924/01029 20130101; B22D 21/027
20130101; C22F 1/14 20130101; H01L 2224/45015 20130101; H01L
2224/45139 20130101; H01L 2224/45015 20130101; H01L 24/45 20130101;
H01L 2924/01033 20130101; H01L 2924/01046 20130101; H01L 2924/01023
20130101; B23K 35/0261 20130101; H01L 2924/014 20130101; B23K 35/22
20130101; H01L 2224/45015 20130101; H01L 2924/00015 20130101; H01L
2924/01012 20130101; H01L 2924/00011 20130101; H01L 2924/14
20130101; H01L 2924/00014 20130101; C22C 5/06 20130101; B23K 35/24
20130101; H01L 2924/12041 20130101; H01L 2224/745 20130101; C22C
1/02 20130101; H01L 2224/45015 20130101; H01L 2224/4321 20130101;
H01L 2224/04042 20130101; H01L 2924/00011 20130101; H01L 2924/01027
20130101; H01L 2924/01079 20130101; B21C 1/003 20130101; H01L
2924/01019 20130101; H01L 2224/43986 20130101; H01L 2924/01049
20130101; H01L 2924/20751 20130101; C22F 1/00 20130101; H01L
2924/01046 20130101; H01L 2224/45144 20130101; H01L 2924/00
20130101; H01L 2924/00 20130101; H01L 2924/01006 20130101; H01L
2924/20754 20130101; H01L 2224/48 20130101; H01L 2924/20752
20130101; H01L 2924/20755 20130101; H01L 2924/20753 20130101; H01L
2924/013 20130101 |
Class at
Publication: |
420/505 |
International
Class: |
C22C 5/06 20060101
C22C005/06 |
Claims
1. A composite alloy bonding wire, comprising: 90.00.about.99.99
wt. % Ag; and 0.01.about.10.00 wt. % but not more than 10.00 wt. %
Pd, besides unavoidable impurities, wherein the Ag and Pd are
melted to obtain a Ag--Pd alloy that excludes Mg and Al, and Ag and
Pd are essentially uniformly distributed in the alloy bonding wire,
continuous casting and drawing processes are performed on the
Ag--Pd alloy to obtain the alloy bonding wire used for packaging
processes for IC, LED or SAW, and the composite alloy bonding wire
has slender grains and annealing twins.
2. The composite alloy bonding wire according to claim 1, wherein
the amount of the annealing twins to all grains is above 20%.
Description
RELATED APPLICATIONS
[0001] This application is a continuation-in-part (CIP) application
of U.S. patent application Ser. No. 13/334,047, filed on Dec. 21,
2011.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention generally relates to a bonding wire
used as a packaging wire, in particular, to a bonding wire used in
the semiconductor packaging process.
[0004] 2. Description of Related Art
[0005] In semiconductor device packaging processes for IC, LED,
SAW, a wire bonding process is often performed to electrically
connect the chip to the substrate by a bonding wire which is used
as a signal and electrical current transmitting medium between the
chip and the substrate.
[0006] The primary characteristics of the bonding wire, such as the
breaking load, elongation, loop, melting point, and bondability
with IC chips depend on the materials of the bonding wire. The
performance of the packaged semiconductor device is influenced by
the characteristics of the bonding wire. According to different
types of chip and substrate, the adapted bonding wire has different
specification.
[0007] The conventional bonding wires are usually made of pure Au
material. Pure Au bonding wire has better physical properties, such
as elongation and electrical conductivity. However, pure Au bonding
wire inevitably leads to a high cost.
[0008] Therefore, the subject of the present invention is to solve
the above mentioned problem to provide a low cost bonding wire with
performance comparable to pure Au bonding wire.
[0009] German patent no. DE 3122996
"Silver-palladium-magnesium-aluminum alloy for internally oxidized
electrical contacts, e.g. spring contacts" is related to an alloy
used for electrical breaker and sliding contacts, e.g. in relays,
switches and potentiometers. The alloy has the composition (by wt.)
of 5-30% Pd, 0.1-0.5% Mg, 0.01-0.5% Al and balance Ag, which is not
suitable for making as a bonding wire used for IC, LED, SAW because
of following reasons.
[0010] 1. When wt. % of Pd is more than 10%, the hardness of the
wire will be larger than 150-200 kp/mm.sup.2. In comparison, the
hardness of the bonding wire is normal 60-90 kp/mm.sup.2. That is,
the wire made by the alloy of DE 3122996 may not be drawn to have a
diameter as or less than 0.0175 mm (0.7 mil), and a soldering
process may not be performed because it may cause cracking or
catering to the IC or LED due to the hardness of the wire.
[0011] 2. Adding Mg will increase the wear resistance and hardness
of the alloy. After adding Mg, an oxidation process may have to be
performed to obtain MgO particles in the alloy. However, MgO will
make the alloy become hard and brittle to be used as a bonding wire
for IC and LED. Besides, MgO will increase the resistance of the
alloy and decrease the conductivity of the alloy. That is also not
good for the alloy to be as a bonding wire.
[0012] 3. Adding Al will decrease the elongation of the alloy and
increase the resistance of the alloy. In addition, adding Al in Ag
will produce various configurations of Ag and Al compound in the
alloy. These are negative for the alloy to be as the bonding
wire.
[0013] 4. The resistance of the alloy of DE 3122996 is about
0.08-0.16 ohm, mm2/m which is 160-170 times of 0.00023-0.00050 ohm,
mm2/m for a general resistance of a bonding wire. The higher the
resistance of the bonding wire is, the lower the conductivity will
be. The bonding wire with high resistance will reduce the
transmission speed and the lifespan of the IC or LED.
[0014] In addition, Ag-based alloy wire such as Ag--Pd alloy wire
for a semiconductor package has disclosed in related art for
example Japanese patent application publication no. JP9275120 and
US patent application publication nos. US 2008/240975 and US
2008/230915. However, as manufacturing process of Ag--Pd alloy wire
is different, the structure of Ag--Pd alloy wire may be different.
The Ag--Pd alloy wire with different structure would have different
properties such as tensile strength, toughness, elongation,
hardness, electrical conductivity, thermal conductivity,
anti-oxidation, corrosion resistance and higher electro-migration
resistance.
[0015] Annealing, in metallurgy and materials science, is a heat
treatment wherein a material is altered, causing changes in its
properties such as hardness and elongation. It is a process that
produces conditions by heating to above the critical temperature,
maintaining a suitable temperature, and then cooling. Annealing is
used to induce elongation, soften material, relieve internal
stresses, refine the structure by making it homogeneous, and
improve cold working properties. Therefore, annealing process is
important for ensuring a final product with desirable physical
properties.
SUMMARY OF THE INVENTION
[0016] The present invention is to provide a low cost composite
alloy bonding wire made of silver and Palladium, capable of having
performance as good as a pure Au bonding wire.
[0017] Accordingly, a manufacturing method for a composite alloy
bonding wire is disclosed. A primary metal material of Ag is melted
in a vacuum melting furnace, and then a secondary metal material of
Pd is added into the vacuum melting furnace and is co-melted with
the primary metal material of Ag to obtain an Ag--Pd alloy
solution. The obtained Ag--Pd alloy solution is then cast and drawn
to obtain an Ag--Pd alloy wire. Finally, the obtained Ag--Pd alloy
wire is then drawn to obtain an Ag--Pd alloy bonding wire with a
predetermined diameter. An amount of cold working in the final
drawing is between 2% to 10%.
[0018] Besides, a composite alloy bonding wire made by the
abovementioned manufacturing method is provided. The composite
alloy bonding wire includes 90.00.about.99.99 wt. % Ag and
0.01.about.10.00 wt. % but no more than 10.00 wt. % Pd, besides
unavoidable impurities. The composite alloy bonding wire has
slender grains and annealing twins and the amount of the annealing
twins to all grains is above 20%.
[0019] The composite alloy bonding wire made of silver and
palladium has performance as good as a pure Au bonding wire and a
lower manufacturing cost.
BRIEF DESCRIPTION OF DRAWING
[0020] The features of the invention believed to be novel are set
forth with particularity in the appended claims. The invention
itself, however, may be best understood by reference to the
following detailed description of the invention, which describes an
exemplary embodiment of the invention, taken in conjunction with
the accompanying drawings, in which:
[0021] FIG. 1 is a flow chart for manufacturing composite alloy
bonding wire of the present invention; and
[0022] FIG. 2 shows detailed sub-steps in the flow chart of FIG.
1.
[0023] FIG. 3 schematically shows a longitudinal sectional view of
slender grains and annealing twins in the structure of composite
alloy bonding wire of the present invention.
[0024] FIG. 4 shows a photograph of slender grains and annealing
twins in the structure of composite alloy bonding wire of the
present invention.
[0025] FIG. 5 shows a photograph of the structure of composite
alloy bonding wire made by a conventional method.
DETAILED DESCRIPTION OF THE INVENTION
[0026] In cooperation with attached drawings, the technical
contents and detailed description of the present invention are
described thereinafter according to a preferable embodiment, being
not used to limit its executing scope. Any equivalent variation and
modification made according to appended claims is all covered by
the claims claimed by the present invention.
[0027] Pure Ag has good characteristics as compared to Au or Cu
(See below Table 1). However, Ag could not be used as a bonding
wire as Au or Cu because during the process of ball bonding, an
interfacial reaction will occur between Ag and Al which is in the
Al pad formed on a chip to produce the intermetallic compounds such
as Ag.sub.2Al and AgAl.sub.4 which have the hard and brittle
characteristics. Meanwhile, the difference between the diffusion
rates of Ag and Al is so significant, kirkendall voids will be
created. As a result, high electrical resistance or open circuits,
weak bond adherence or brittle bond heels will be created. The
whole integrated circuit should lose its function.
TABLE-US-00001 TABLE 1 Item Unit Gold Silver Copper Palladium
Atomic Symbol -- Au Ag Cu Pd Atomic Number -- 79 47 29 46 Melting
Point .degree. C. 1064.4 961.9 1083 1554 Boiling Point .degree. C.
3080 2212 2567 3140 Density, 20.degree. C. g/cm.sup.3 19.3 10.5
8.96 12.0 Resistivity, 20.degree. C. .mu..OMEGA.cm 2.3 1.63 1.69
10.8 Thermal Conductivity W/mK 316 429 401 71.8 Specific Heat J/Kg
K 130 234 386 244 Hardness Mohs -- 2.5 2.5 3.0 4.75 Hardness
Vickers MN/m.sup.2 215 215 369 461 Hardness
[0028] Nevertheless, Ag should be used as a base metal because of
its density, hardness, electrical conductivity, thermal
conductivity and the cost. The density of Ag is 10.5 g/cm.sup.3,
while in is 54.4% of Au. It is light enough to meet the weight
requirement of the electronic products. In addition, comparing the
hardness of Ag, Au, Cu and Pd, the order is Pd, Cu, Ag and Au from
high hardness to low hardness. Under either Mohs or Vickers
hardness examination, the harness of Ag is the closest to that of
Au. The hardness is critical to IC, LED and SAW because if the
material of packaging wire is too hard, it is easy to break or go
through the IC chips and destroy the IC,LED or SAW package.
[0029] Comparing the electrical resistance of Ag, Au, Cu and Pd,
the order is Pd, Au, Cu, Ag from high resistance to low resistance.
Ag has the lowest resistance and has the best conductivity.
Therefore, the alloy using Ag as a base metal is a good conductor,
which is important to IC, LED and SAW.
[0030] Comparing the thermal conductivity of Ag, Au, Cu and Pd, the
order is Ag, Cu, Au and Pd from high to low. Thermal conductivity
of Ag is the biggest and it means Ag has the best cooling capacity,
which is important to IC, LED and SAW.
[0031] Ag with the purity higher than 99.99% is easy to be broken
because its hardness is low during the wire drawing process. As a
result, during wire bonding process, partial wire arc may collapse
because of the soft material, which may cause short circuit between
the wire and cause IC, LED and SAW unable to use.
[0032] If pure Pd is used to be the base of the packaging wire, it
is not practical because of the hardness, electrical resistance and
high cost. Therefore, when Ag is used as the basic material for the
alloy, other elements must be added to change the property of Ag.
In the present application, the alloy includes Pd and excludes Mg
and Al. The advantages of adding Pd are (1) to increase the
oxidation resistant effect; (2) to increase the oxidation
resistance; (3) to decrease the diffusion rate between Ag and Al,
thus to avoid the cracking of the intermetallic compounds and the
creation of kirkendall voiding.
[0033] Refer to FIG. 1 and FIG. 2, which respectively are a flow
chart for manufacturing composite alloy bonding wire of the present
invention and a drawing showing detailed sub-steps in the flow
chart of FIG. 1.
[0034] Step 100, a primary material of Ag is provided.
[0035] Step 102, the primary material is melted in a vacuum melting
furnace (step 102a). Specific amount of a secondary metal material
of Pd is added into the vacuum melting furnace (step 102b), and
co-melted with the primary material in the vacuum melting furnace
to obtain an Ag--Pd alloy solution (step 102c). The Ag--Pd alloy
solution consists of 90.00.about.99.99 wt. % Ag and
0.01.about.10.00 wt. % but no more than 10.00 wt. % Pd, besides
unavoidable impurities.
[0036] Subsequently, continuous casting and drawing processes are
performed on the Ag--Pd alloy solution to obtain an Ag--Pd alloy
wire with diameter of 4-8 mm (step 102d). The Ag--Pd alloy wire is
rewired by a reeling machine (step 102e) and then composition
analysis (102f) is performed on the Ag--Pd alloy wire to check if
the obtained composition meets the requirement.
[0037] Step 104, a drawing process is performed on the Ag--Pd alloy
wire; the obtained Ag--Pd alloy wire with a diameter of 4-8 mm is
drawn by a first thick drawing machine to obtain an Ag--Pd alloy
wire with a diameter of 3 mm or smaller than 3 mm (step 104a). The
Ag--Pd alloy wire with a diameter of 3 mm or smaller than 3 mm is
drawn by a second thick drawing machine to obtain an Ag--Pd alloy
wire with a predetermined diameter of 1 mm or smaller than 1 mm
(step 104b). The Ag--Pd alloy wire with diameter 1 mm or smaller
than 1 mm is drawn by a first thin drawing machine to obtain an
Ag--Pd alloy wire with a diameter of 0.5 mm or smaller than 0.5 mm
(step 104c). Then the Ag--Pd alloy wire with a diameter of 0.5 mm
or smaller than 0.5 mm is sequentially drawn by the second thin
drawing machine (step 104d), a very thin drawing machine (step
104e) and an ultra thin drawing machine (step 104f) to obtain an
ultra thin Ag--Pd alloy bonding wire with a predetermined diameter
of 0.0508 mm (2.00 mil) to 0.010 mm (0.40 mil). An amount of cold
working in step 104f is between 2% to 10%.
[0038] Step 106, the surface of the Ag--Pd alloy bonding wire is
cleaned.
[0039] Step 108, the Ag--Pd alloy bonding wire is annealed to
ensure a final product with desirable physical properties of
breaking load and elongation. The Ag--Pd alloy bonding wire is
annealed from 1200.degree. C. to 25.degree. C. for 0.3 to 5
seconds.
[0040] FIG. 3 schematically shows a longitudinal sectional view of
slender grains and annealing twins in the structure of composite
alloy bonding wire of the present invention. As shown in FIG. 3,
the slender grains 18 are adjacent to a central site of the
composite alloy bonding wire 10. Reference numerals 12, 14 and 16
respectively represent coaxial grains, high angle crystal boundary
and annealing twins.
[0041] FIG. 4 shows a photograph of slender grains and annealing
twins in the structure of composite alloy bonding wire of the
present invention. FIG. 5 shows a photograph of the structure of
composite alloy bonding wire made by a conventional method.
Referring to FIG. 4, in case of the present invention, composite
alloy bonding wire 10 has slender grains 18 and annealing twins 16
and the amount of the annealing twins 16 to all grains is above
20%. Referring to FIG. 5, in case of the conventional method,
composite alloy bonding wire 20 has none of slender grains and
annealing twins.
[0042] The Ag--Pd alloy bonding wire can be applied to packaging
process of IC, LED and SAW because the hardness of the bonding wire
is within the range of 60-90 kp/mm2, and the resistance of the
bonding wire is within the range of 0.00023-0.00050 ohm, mm2/m.
[0043] The invention is more detailed described by three
embodiments below:
Embodiment 1
[0044] A primary material of Ag is provided and is melted in a
vacuum melting furnace. Then, specific amount of a secondary metal
material of Pd is added into the vacuum melting furnace, and is
co-melted with the primary material in the vacuum melting furnace
to obtain an Ag--Pd alloy solution. The Ag--Pd alloy solution
consists of: 99.99 wt. % Ag and 0.001 wt. % Pd, besides unavoidable
impurities. The composite alloy bonding wire has slender grains and
annealing twins and the amount of the annealing twins to all grains
is above 20%.
[0045] Continuous casting and drawing processes are performed on
the Ag--Pd alloy solution to obtain an Ag--Pd alloy wire with a
diameter of 4 mm. The Ag--Pd alloy wire is rewired by a reeling
machine and then composition analysis is performed on the Ag--Pd
alloy wire to check if the obtained composition meets the
requirement.
[0046] A drawing process is performed on the Ag--Pd alloy wire; the
obtained Ag--Pd alloy wire with a diameter of 4 mm is drawn by a
first thick drawing machine to obtain an Ag--Pd alloy wire with a
diameter of 3 mm. The Ag--Pd alloy wire with a diameter of 3 mm is
drawn by a second thick drawing machine to obtain an Ag--Pd alloy
wire with a diameter of 1 mm. The Ag--Pd alloy wire with a diameter
of 1 mm is drawn by a first thin drawing machine to obtain an
Ag--Pd alloy wire with a diameter of 0.18 mm. Then the Ag--Pd alloy
wire with a diameter of 0.18 mm is sequentially drawn by the second
thin drawing machine, a very thin drawing machine and an ultra thin
drawing machine to obtain an ultra thin Ag--Pd alloy bonding wire
with a predetermined diameter of 0.050 mm to 0.010 mm. An amount of
cold working in the final drawing is between 2% to 10%.
[0047] Finally, the surface of Ag--Pd alloy bonding wire is cleaned
and is annealed. The Ag--Pd alloy bonding wire is annealed from
1200.degree. C. to 25.degree. C. for 0.3 to 5 seconds. Under the
above conditions, most of the grains inside contain annealing twin
boundary with low energies that is stable than the conventional
high angle grain boundary of grains in a wire.
Embodiment 2
[0048] A primary material of Ag is provided and is melted in a
vacuum melting furnace. Then, specific amount of a secondary metal
material of Pd is added into the vacuum melting furnace, and is
co-melted with the primary material in the vacuum melting furnace
to obtain an Ag--Pd alloy solution. The Ag--Pd alloy solution
consists of: 95.00 wt. % Ag and 5.00 wt. % Pd, besides unavoidable
impurities. The composite alloy bonding wire has slender grains and
annealing twins and the amount of the annealing twins to all grains
is above 20%.
[0049] Continuous casting and drawing processes are performed on
the Ag--Pd alloy solution to obtain an Ag--Pd alloy wire with a
diameter of 6 mm. The Ag--Pd alloy wire is rewired by a reeling
machine and then composition analysis is performed on the Ag--Pd
alloy wire to check if the obtained composition meets the
requirement.
[0050] A drawing process is performed on the Ag--Pd alloy wire; the
obtained Ag--Pd alloy wire with a diameter of 6 mm is drawn by a
first thick drawing machine to obtain an Ag--Pd alloy wire with a
diameter of 3 mm. The Ag--Pd alloy wire with a diameter of 3 mm is
drawn by a second thick drawing machine to obtain an Ag--Pd alloy
wire with a diameter of 1.0 mm. The Ag--Pd alloy wire with a
diameter of 1.0 mm is drawn by a first thin drawing machine to
obtain an Ag--Pd alloy wire with a diameter of 0.18 mm. Then the
Ag--Pd alloy wire with a diameter of 0.18 mm is sequentially drawn
by the second thin drawing machine, a very thin drawing machine and
an ultra thin drawing machine to obtain an ultra thin Ag--Pd alloy
bonding wire with a predetermined diameter of 0.050 mm to 0.010 mm.
An amount of cold working in the final drawing is between 2% to
10%.
[0051] Finally, the surface of Ag--Pd alloy bonding wire is cleaned
and is annealed. The Ag--Pd alloy bonding wire is annealed from
1200.degree. C. to 25.degree. C. for 0.3 to 5 seconds.
Embodiment 3
[0052] A primary material of Ag is provided and is melted in a
vacuum melting furnace. Then, specific amount of a secondary metal
material of Pd is added into the vacuum melting furnace, and is
co-melted with the primary material in the vacuum melting furnace
to obtain an Ag--Pd alloy solution. The Ag--Pd alloy solution
consists of: 90.00 wt. % Ag and 10.00 wt. % Pd, besides unavoidable
impurities. The composite alloy bonding wire has slender grains and
annealing twins and the amount of the annealing twins to all grains
is above 20%.
[0053] Continuous casting and drawing processes are performed on
the Ag--Pd solution to obtain an Ag--Pd alloy wire with a diameter
of 8 mm. The Ag--Pd alloy wire is rewired by a reeling machine and
then composition analysis is performed on the Ag--Pd alloy wire to
check if the obtained composition meets the requirement.
[0054] A drawing process is performed on the Ag--Pd alloy wire; the
obtained Ag--Pd alloy wire with a diameter of 8 mm is drawn by a
first thick drawing machine to obtain an Ag--Pd alloy wire with a
diameter of 2 mm. The Ag--Pd alloy wire with a diameter of 2 mm is
drawn by a second thick drawing machine to obtain an Ag--Pd alloy
wire with a diameter of 1.0 mm. The Ag--Pd alloy wire with a
diameter of 1.0 mm is drawn by a first thin drawing machine to
obtain an Ag--Pd alloy wire with a diameter of 0.18 mm. Then the
Ag--Pd alloy wire with a diameter of 0.18 mm is sequentially drawn
by the second thin drawing machine, a very thin drawing machine and
an ultra thin drawing machine to obtain an ultra thin Ag--Pd alloy
bonding wire with a predetermined diameter of 0.050 mm to 0.010 mm.
An amount of cold working in the final drawing is between 2% and
10%.
[0055] Finally, the surface of Ag--Pd alloy bonding wire is cleaned
and is annealed. The Ag--Pd alloy bonding wire is annealed from
1200.degree. C. to 25.degree. C. for 0.3 to 5 seconds.
[0056] More examples showing the characteristics for the Ag--Pd
alloy bonding wire with the diameter of 1.0 mil of the present are
listed as below Table 2.
TABLE-US-00002 TABLE 2 TYPE 1 2 3 4 5 6 7 Ag (Wt %) 99.45% 98.98
97.95 96.99 95.36 93.45 91.27 Pd (Wt %) 0.55 1.02 2.05 3.01 4.64
6.55 8.73 1.0-0.18 mm V V V V V V V 0.18-0.05 mm V V V V V V V
0.05-0.038 mm V V V V V V V 0.038-0.03 mm V V V V V V V 0.03-0.025
mm V V V V V V V Drawing Test V V V V V V V Break Load 11.21 12.65
13.11 13.43 13.65 14.37 16.27 (gf) Elongation 2.41 2.65 2.12 2.57
3.89 2.83 0.61 (%) Hardness 56.8 57.1 57.4 57.8 58.2 64.5 71.5 (Hv)
Resistance 1.72 1.76 1.84 2.14 3.50 4.62 5.66 (.mu..OMEGA.cm)
[0057] Specifically, the Type-6 bondability and reliability test
report is attached for reference.
[0058] Due to slender grains and annealing twins existing in the
Ag--Pd alloy bonding wire according to the present invention, it
has higher tensile strength, toughness and elongation, lower
hardness, preferred electrical conductivity, thermal conductivity,
anti-oxidation and corrosion resistance and higher
electro-migration resistance, especially having an advantage that a
hot zone is not caused when a wire bonding process is
performed.
[0059] The properties of the Ag--Pd alloy bonding wire (Ag 96 wt %
and Pd 4 wt %) according to the present invention are compared to
the Ag--Pd alloy bonding wire (Ag 96 wt % and Pd 4 wt %) made by a
conventional method shown as Table 3.
TABLE-US-00003 TABLE 3 Item Ag--Pd alloy Ag--Pd alloy bonding wire
bonding wire according to the made by a present invention
conventional method Grains slender grains none of slender and more
than grains and less 20% of annealing 10% of annealing twins to all
grains twins to all grains Breaking Load (gf) 7-12 4-10 Elongation
(%) 8-12 2-5 Elastic Modules (GPa) 19.2 18.8 Resistivity
(.mu..OMEGA.cm) 3.3 >3.7 Hardness (Hv) 56-60 65-70
Electro-migration resistance 1000 hrs pass 700 hrs fail (input dc
0.3 A) Temperature cycle test 1500 hrs pass 1000 hrs fail (TCT)
Highly accelerated stress 192 hrs pass 96 hrs fail test (HAST)
[0060] While the invention is described in by way of examples and
in terms of preferred embodiments, it is to be understood that the
invention is not limited thereto. On the contrary, the aim is to
cover all modifications, alternatives and equivalents falling
within the spirit and scope of the invention as defined by the
appended claims.
* * * * *