U.S. patent application number 13/379669 was filed with the patent office on 2012-05-24 for ultrasonic bonding tool, method for manufacturing ultrasonic bonding tool, ultrasonic bonding method, and ultrasonic bonding apparatus.
This patent application is currently assigned to TOSHIBA MITSUBISHI-ELECTRIC INDUSTRIAL. SYS. CORP.. Invention is credited to Masahisa Kogura, Akio Yoshida.
Application Number | 20120125520 13/379669 |
Document ID | / |
Family ID | 43386145 |
Filed Date | 2012-05-24 |
United States Patent
Application |
20120125520 |
Kind Code |
A1 |
Yoshida; Akio ; et
al. |
May 24, 2012 |
ULTRASONIC BONDING TOOL, METHOD FOR MANUFACTURING ULTRASONIC
BONDING TOOL, ULTRASONIC BONDING METHOD, AND ULTRASONIC BONDING
APPARATUS
Abstract
An object of the present invention is to provide an ultrasonic
bonding tool capable of bonding a lead wire, without any trouble,
even to a surface of a thin-film base having a plate thickness of 2
mm or less such as a glass substrate. In the present invention, a
surface portion of a chip portion (1c) of an ultrasonic bonding
tool (1) used in an ultrasonic bonding apparatus has a plurality of
planar portions (10) formed so as to be separated from one another,
and a plurality of concavities (11) formed between the plurality of
planar portions. Each of the plurality of planar portions (10) has
a flatness of 2 .mu.m or less.
Inventors: |
Yoshida; Akio; (Tokyo,
JP) ; Kogura; Masahisa; (Tokyo, JP) |
Assignee: |
TOSHIBA MITSUBISHI-ELECTRIC
INDUSTRIAL. SYS. CORP.
Tokyo
JP
|
Family ID: |
43386145 |
Appl. No.: |
13/379669 |
Filed: |
June 23, 2009 |
PCT Filed: |
June 23, 2009 |
PCT NO: |
PCT/JP2009/061384 |
371 Date: |
February 8, 2012 |
Current U.S.
Class: |
156/64 ;
156/580.2; 156/73.1; 451/28; 451/38 |
Current CPC
Class: |
B23K 20/22 20130101;
B24C 1/00 20130101; B24B 27/0633 20130101; H01L 2224/48456
20130101; B23K 20/106 20130101; B23K 2103/54 20180801; B24B 19/02
20130101; B24B 19/16 20130101; B24B 7/16 20130101 |
Class at
Publication: |
156/64 ;
156/580.2; 156/73.1; 451/28; 451/38 |
International
Class: |
B32B 37/10 20060101
B32B037/10; B24B 1/00 20060101 B24B001/00; B24C 1/00 20060101
B24C001/00; B32B 41/00 20060101 B32B041/00 |
Claims
1. An ultrasonic bonding tool, comprising: a chip portion at a
distal end portion of the tool, wherein the chip portion comprises
a surface portion, wherein the surface portion comprises a
plurality of planar portions and a plurality of concavities between
planar portions of the plurality of planar portions, wherein a
flatness of the plurality of planar portions is 2 .mu.m or less,
and wherein the tool is capable of applying ultrasonic
vibration.
2. The tool of claim 1, wherein an edge of an outer peripheral
portion of planar portions in the plurality of planar portions is
rounded.
3. The tool of claim 1, wherein the plurality of planar portions
has a fine unevenness with a flatness of 2 .mu.m or less.
4. The tool of claim 1, wherein the chip portion comprises: a first
layer and a second layer on the first layer as a most distal end
portion of the chip portion, and wherein the second layer is harder
than the first layer.
5. The tool of claim 1, wherein the chip portion comprises: a first
layer and a second layer on the first layer, as a most distal end
portion of the chip portion, and wherein an affinity between the
second layer and a material to be bonded is lower than an affinity
between the first layer and the material to be bonded.
6. A method for manufacturing the tool of claim 1, comprising: (a)
preparing a tool original material comprising a distal planar
portion with a flatness of more than 2 .mu.m; (b) grinding the tool
original material to enhance the flatness of the distal planar
portion to a flatness of 2 .mu.m or less; and (c) selectively
forming the plurality of concavities by wire cutting or with a
cutting wheel, wherein the plurality of concavities separate the
distal planar portion into the plurality of planar portions.
7. The method of claim 6, further comprising: (d) shot-blasting an
edge of an outer peripheral portion of planar portions in the
plurality of planar portions, thereby rounding the edge, and (e)
forming fine unevenness having a flatness of 2 .mu.m or less in
each planar portion in the plurality of planar portions .
8. An ultrasonic bonding method for bonding a member to a thin film
base, comprising: (a) placing a lead wire of the member on a
surface of the thin-film base; and (b) applying pressure and
ultrasonic vibration to the lead wire with the tool of claim 1,
thereby bonding the lead wire onto the surface of the thin-film
base, and wherein, while applying pressure and ultrasonic
vibration, a tool width portion corresponding to a widthwise
direction of the lead wire is set smaller than a predetermined
width of formation of the lead wire.
9. The method of claim 8, further comprising: (c) detecting a
position of the chip portion with respect to the widthwise
direction of the lead wire; and (d) adjusting a relative positional
relationship between the lead wire and the chip portion based on
the position detected in (c) such that pressure can be applied to
the lead wire within a width of the lead wire while applying
pressure and ultrasonic vibration.
10. An ultrasonic bonding apparatus comprising the tool of claim
1.
11. The tool of claim 1, wherein an interval between adjacent
concavities of the plurality of concavities is 1.0 mm or less.
12. The tool of claim 1, wherein an average depth of concavities of
the plurality of concavities is 0.15 mm or less.
13. The tool of claim 1, wherein the plurality of concavities
comprises a plurality of first grooves and a plurality of second
grooves that cross the plurality of first grooves.
14. The tool of claim 1, wherein the planar portions of the
plurality of planar portions have a rectangular shape, a circular
shape, or a rhombic shape.
15. The tool of claim 4, wherein the first layer comprises a steel
material and the second layer comprises a super-steel material.
16. The tool of claim 15, wherein the super-steel material is
tungsten carbide.
17. The tool of claim 5, wherein an affinity between the second
layer and aluminum is lower than an affinity between the first
layer and aluminum.
Description
TECHNICAL FIELD
[0001] The present invention relates to an ultrasonic bonding tool
used in an ultrasonic bonding apparatus, and particularly to a
structure of a chip portion that is a distal end portion of the
ultrasonic bonding tool.
BACKGROUND ART
[0002] An ultrasonic bonding apparatus can be mentioned as an
apparatus for bonding an aluminum-based material to a steel
material that is a dissimilar metal with a high bonding strength or
as an apparatus for bonding a to-be-bonded member such as a lead
wire for external connection onto a bonding object portion of an
electronic device or the like. In ultrasonic bonding utilizing
ultrasonic vibration produced by the ultrasonic bonding apparatus,
a stress caused by vertical pressure application to a bonding
interface and a repetitive stress caused by a high vibration
acceleration in a parallel direction are given so that frictional
heat is generated in the bonding interface. Thereby, atoms of the
to-be-bonded member are diffused and thus bonding can be made. Such
an ultrasonic bonding apparatus includes an ultrasonic bonding tool
having a chip portion that is brought into contact with the
to-be-bonded member. This ultrasonic bonding tool is disclosed in ,
for example, Patent Document 1.
PRIOR-ART DOCUMENTS
Patent Documents
[0003] Patent Document 1: Japanese Patent Application Laid-Open No.
2005-254323
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0004] Here, as described above, the ultrasonic bonding apparatus
performs an ultrasonic bonding operation in which both the
application of pressure from the upper side and the application of
ultrasonic vibration are made. Thus, the bonding object portion
needs to be resistant to the ultrasonic bonding operation.
Therefore, in apparatuses including the ultrasonic bonding
apparatus disclosed in the Patent Document 1, it is not assumed
that a thin-film base, such as a glass substrate, having a
relatively small plate thickness and thus having a small resistance
is used as the bonding object portion mentioned above, and means
for bonding a lead wire onto a surface of the thin-film base has
not been considered.
[0005] To solve the above-described problem, an object of the
present invention is to provide an ultrasonic bonding tool capable
of bonding a to-be-bonded member even to a surface of a thin-film
base having a plate thickness of 2 mm or less such as a glass
substrate or the like.
Means for Solving the Problems
[0006] An ultrasonic bonding tool according to the present
invention is an ultrasonic bonding tool used in an ultrasonic
bonding apparatus that applies pressure from an upper side to a
to-be-bonded member placed on a surface of a thin-film base and
applies ultrasonic vibration thereto to thereby bond the
to-be-bonded member onto the surface of the thin-film base, wherein
the ultrasonic bonding tool has, at a distal end portion thereof, a
chip portion that is brought into contact with the to-be-bonded
member at a time of ultrasonic bonding, a surface portion of the
chip portion which is brought into contact with the to-be-bonded
member has a plurality of planar portions formed so as to be
separated from one another and a plurality of concavities formed
between the plurality of planar portions, the plurality of planar
portions having a flatness of 2 .mu.m or less.
Effects of the Invention
[0007] In the ultrasonic bonding tool according to the present
invention, the surface portion of the chip portion which is brought
into contact with the to-be-bonded member has the plurality of
planar portions formed so as to be separated from one another and
the plurality of concavities formed between the plurality of planar
portions, and the plurality of planar portions 10 have a flatness
of 2 .mu.m or less.
[0008] Therefore, the ultrasonic bonding method using the
ultrasonic bonding apparatus having the ultrasonic bonding tool
according to the present invention provides an effect that the
to-be-bonded member can be bonded, without any trouble, even onto
the surface of the thin-film base having a plate thickness of 2 mm
or less such as a glass substrate.
[0009] These and other objects, features, aspects and advantages of
the present invention will become more apparent from the following
detailed description of the present invention when taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] [FIG. 1] A cross-sectional view schematically showing a
status of ultrasonic bonding performed by an ultrasonic bonding
tool according to an embodiment 1 of the present invention.
[0011] [FIG. 2] A cross-sectional view showing a cross-sectional
structure of a surface portion of a chip portion according to the
embodiment 1.
[0012] [FIG. 3] A perspective view schematically showing a planar
structure of the surface portion of the chip portion according to
the embodiment 1.
[0013] [FIG. 4] A cross-sectional view showing a cross-sectional
structure of a surface portion of an ordinary chip portion of an
ultrasonic bonding tool.
[0014] [FIG. 5] An explanatory diagram showing an exemplary pattern
of forming a plurality of planar portions of the chip portion
according to the embodiment 1.
[0015] [FIG. 6] A cross-sectional view showing another
cross-sectional structure of the chip portion according to the
embodiment 1.
[0016] [FIG. 7] An explanatory diagram showing a shape of a chip
portion according to an embodiment 2 of the present invention.
[0017] [FIG. 8] A cross-sectional view showing a cross-sectional
structure of a chip portion according to an embodiment 3 of the
present invention.
[0018] [FIG. 9] A cross-sectional view showing a method for
manufacturing an ultrasonic bonding tool according to an embodiment
4.
[0019] [FIG. 10] An explanatory diagram schematically showing a
planar structure with respect to an ultrasonic bonding tool and a
lead wire in an ultrasonic bonding method according to an
embodiment 5.
[0020] [FIG. 11] An explanatory diagram schematically showing a
function for adjusting a position of the lead wire, of a lead wire
guide mechanism according to an embodiment 6.
[0021] [FIG. 12] A cross-sectional view showing a cross-sectional
structure of a chip portion according to an embodiment 7 of the
present invention.
[0022] [FIG. 13] A cross-sectional view showing a cross-sectional
structure of a chip portion according to an embodiment 8 of the
present invention.
EMBODIMENT FOR CARRYING OUT THE INVENTION
Embodiment 1
[0023] FIG. 1 is a cross-sectional view schematically showing a
status of ultrasonic bonding performed by an ultrasonic bonding
tool 1 according to an embodiment 1 of the present invention.
[0024] As shown in FIG. 1, a glass substrate 3 that is a thin-film
base having a plate thickness of about 0.7 to 2.0 mm is fixed to a
table (anvil) 5, and an aluminum-made lead wire 2 (to-be-bonded
member) for external connection having a plate thickness of about
0.1 to 0.2 mm is arranged at a predetermined position on a surface
of the glass substrate 3. Then, an ultrasonic bonding operation is
performed in which vertical pressure is applied to a bonding
surface to be bonded to the lead wire 2 via a chip portion 1 c of
the ultrasonic bonding tool 1 while the ultrasonic bonding tool 1
is ultrasonically vibrated in a horizontal direction to largely
deform the bonding surface. Thereby, the lead wire 2 and the glass
substrate 3 are solid-state bonded to each other at a bonding
interface between the lead wire 2 and the glass substrate 3.
[0025] FIG. 2 is a cross-sectional view showing a cross-sectional
structure of a surface portion of the chip portion 1c. FIG. 3 is a
perspective view schematically showing a planar structure of the
surface portion of the chip portion 1c. FIG. 2 corresponds to an
inverted version of a cross-section taken along the line A-A of
FIG. 3. As shown in FIGS. 2 and 3, on a surface of the chip portion
1c, a plurality of planar portions 10 are formed so as to be
separated from one another by a plurality of concavities 11 (in
FIG. 3, first grooves 11a and second grooves 11b).
[0026] FIG. 4 is a cross-sectional view showing a cross-sectional
structure of a surface portion of an ordinary chip portion 51c of
an ultrasonic bonding tool. As shown in FIG. 4, the chip portion
51c has a plurality of planar portions 60 formed so as to be
separated from one another by a plurality of concavities 61 through
a wire-cutting process. In general, each of the plurality of planar
portions 60 is substantially in the shape of a protrusion, and does
not maintain a high degree of flatness. Therefore, as a surface
structure of the chip portion 51c, unevenness of a few tens of pm
order is formed by the planar portions 60 and the concavities 61.
This is not a problem in the conventional method, because a large
amount of deformation in a direction of the plate thickness caused
by the ultrasonic bonding is acceptable.
[0027] On the other hand, in the chip portion 1c of the ultrasonic
bonding tool 1 according to embodiment 1, as shown in FIG. 2, a
horizontal line LH defined by a plane where surfaces of the planar
portions 10 are formed is accurately set to be 90 degrees with
respect to the vertical line LV, and the planar portions 10 are
accurately formed so as to have a flatness of 2 .mu.m or less. An
interval P1 between the concavities 11 and 11 is set to be
approximately 1.0 mm or less, and a depth D1 to the innermost of
the concavity 11 is set to be approximately 0.15 mm or less. In
this manner, the chip portion 1c of the ultrasonic bonding tool 1
according to the embodiment 1 is structured with an accuracy
completely different from the ordinary ultrasonic bonding tool 51c,
and enables the lead wire 2 to be bonded without damaging the glass
substrate 3 which is susceptible to fracture.
[0028] FIG. 3 shows an example in which the plurality of
concavities 11 of FIG. 2 are formed by a plurality of first grooves
11a and a plurality of second grooves 11b that cross each other in
the vertical direction. That is, the concavities 11 are formed in a
matrix by being separated from each other by the plurality of first
grooves 11a provided substantially in a longitudinal direction in
FIG. 3 and the second grooves 11b provided in a lateral direction
in FIG. 3, so that the plurality of planar portions 10 each having
a rectangular shape in a plan view are formed. The plurality of
planar portions 10 define a single surface having a flatness of 2
.mu.m or less.
[0029] FIG. 5 is an explanatory diagram showing an exemplary
pattern of forming the plurality of planar portions 10. In FIG. 5,
the region other than the planar portions 10 is the concavities 11,
but the concavities 11 are not shown.
[0030] As shown in FIG. 5(a), a plurality of planar portions 10
each having a rectangular shape in a plan view may be arranged in a
matrix (corresponding to FIG. 3), and as shown in FIG. 5(b), a
plurality of planar portions 10 each having an elongated
rectangular shape in a plan view may be arranged in parallel. As
shown in FIG. 5(c), a plurality of planar portions 10 each having a
circular shape in a plan view may be arranged in a matrix, and as
shown in FIG. 5(d), a plurality of planar portions 10 each having a
rhombic shape in a plan view may be arranged in a matrix.
[0031] FIG. 6 is a cross-sectional view showing another
cross-sectional structure of the chip portion 1c. As shown in FIG.
6, the concavity 11 may be formed such that its cross-section has
an inverted trapezoidal shape.
[0032] Hereinafter, an effect obtained by the chip portion 1c
according to the embodiment 1 will be described in comparison with
the ordinary chip portion 51c shown in FIG. 4.
[0033] In a case of the ordinary chip portion 51c, as described
above, an uneven shape of a few tens of .mu.m order is formed as
the surface structure, and therefore if the ultrasonic bonding of
FIG. 1 is performed using an ultrasonic bonding tool having the
chip portion 51c instead of the ultrasonic bonding tool 1, a
concentrated load acts on the planar portions 60 that form the
protrusions, which places the glass substrate 3 at a high risk of
cracking, to make it substantially impossible to bond the lead wire
2 without fracturing the glass substrate 3.
[0034] In the chip portion 1c of the ultrasonic bonding tool 1
according to embodiment 1, on the other hand, the plurality of
planar portions 10 have a highly accurate flatness of 2 .mu.m or
less, which can reduce the above-mentioned concentrated load in
each of the plurality of planar portions 10. Moreover, since the
plurality of planar portions 60 are formed so as to be separated
from one another, a stress is distributed among the plurality of
planar portions to thereby reduce a stress acting on one planar
portion. To further reduce a stress acting on each individual
planar portion 10, it is desirable that the planar portion 60 has a
circular shape in a plan view as shown in FIG. 5(c).
[0035] Additionally, the plurality of concavities 11 make it easy
to hold the lead wire 2 so as not to fall off during the ultrasonic
bonding operation performed by the ultrasonic bonding tool 1
(holding function) and to separate the ultrasonic bonding tool 1
from the lead wire 2 after completion of the ultrasonic bonding
operation by the ultrasonic bonding tool 1 (separating
function).
[0036] In the ultrasonic bonding tool 1 according to the embodiment
1, the surface portion of the chip portion 1 c which is brought
into contact with the lead wire 2 has the plurality of planar
portions 10 separated from one another and the plurality of
concavities 11 each formed between the plurality of planar
portions. The plurality of planar portions 10 define one plane
having a flatness of 2 .mu.m or less.
[0037] Therefore, an ultrasonic bonding method using an ultrasonic
bonding apparatus having the ultrasonic bonding tool 1 according to
the embodiment 1 provides an effect that the lead wire 2 can be
bonded without any trouble on the surface of the glass substrate 3
that is a thin-film base having a plate thickness of 2 mm or
less.
Embodiment 2
[0038] FIG. 7 is an explanatory diagram showing the shape of the
chip portion 1c according to an embodiment 2 of the present
invention. FIG. 7(a) shows a planar structure of the chip portion
1c, and FIG. 7(b) shows a cross-sectional structure of the chip
portion 1c. FIG. 7(b) corresponds to a cross-section taken along
the line B-B of FIG. 7(a).
[0039] As shown in FIG. 7(a) and (b), the chip portion 1c has a
rectangular shape in a plan view, and an acute angled end portion
(edge) of an outer peripheral portion 1ce of each of the plurality
of planar portions 10 is chamfered in both of a horizontal plane
(plane parallel to the horizontal line LH (see FIG. 2)) and a
vertical plane (plane parallel to the vertical line LV (see FIG.
2)) and rounded at a predetermined curvature radius r.
[0040] In this manner, the chip portion 1c of the ultrasonic
bonding tool 1 according to the embodiment 2 is characterized in
that the acute angled end portion (edge) of the outer peripheral
portion 1ce of each of the plurality of planar portions 10 is
chamfered and rounded.
[0041] In the ultrasonic bonding operation, the plurality of planar
portions 10 of the chip portion 1c are vibrated in a direction
parallel to the surface of the glass substrate 3 due to the
ultrasonic vibration. Accordingly, in each of the plurality of
planar portions 10, a vertical vibration of micron order occurs
back and forth, right and left, which tends to damage the lead wire
2 and the glass substrate 3 because of a concentrated load acting
thereon.
[0042] However, in the plurality of planar portions 10 of the chip
portion 1c according to the embodiment 2, the edge of the outer
peripheral portion 1ce is chamfered and rounded. Therefore, the
concentrated load on the outer peripheral portion 1ce is reduced,
and thus the effect that the lead wire 2 can be bonded without any
trouble on the surface of the glass substrate 3 is obtained more
successfully than in the embodiment 1.
Embodiment 3
[0043] FIG. 8 is a cross-sectional view showing a cross-sectional
structure of the chip portion 1c according to the embodiment 3 of
the present invention. As shown in FIG. 8, in addition to the
feature of the embodiment 2, fine unevenness in a range that
satisfies a flatness of 2 .mu.m or less is provided in a planar
portion 10a of the chip portion 1c.
[0044] In this manner, the chip portion 1 c of the ultrasonic
bonding tool 1 according to the embodiment 3 is characterized in
that the plurality of planar portions 10a have fine unevenness in a
range that satisfies a flatness of 2 .mu.m or less. Additionally,
it is also characterized in that each of the plurality of
concavities 11 has fine unevenness.
[0045] The fine unevenness of the planar portions 10a allows making
inroads into an aluminum material of the lead wire 2, and thus the
holding function of the chip portion 1c for holding the lead wire 2
increases as compared with the embodiment 1 and the embodiment 2.
Therefore, the ultrasonic bonding operation can be performed in a
state where the chip portion 1c and the lead wire 2 are more firmly
integrated with each other. Moreover, fine unevenness formed in the
plurality of concavities 11 also contributes to enhancement of the
effect that the holding function of the chip portion 1c for holding
the lead wire 2 during the ultrasonic bonding operation
increases.
[0046] As a result, an ultrasonic bonding apparatus having the
ultrasonic bonding tool 1 according to the embodiment 3 provides an
energy saving effect that the lead wire 2 can be bonded without any
trouble on the surface of the glass substrate 3 by performing an
ultrasonic bonding operation with less energy.
Embodiment 4
[0047] FIG. 9 is a cross-sectional view showing a method for
manufacturing the ultrasonic bonding tool 1 according to an
embodiment 4. In the following, details of a process for
manufacturing the ultrasonic bonding tool 1 will be described with
reference to FIG. 9.
[0048] Firstly, as shown in FIG. 7(a), in a tool original material
7 having a distal planar portion having a flatness of more than 2
.mu.m, from which the ultrasonic bonding tool 1 originates, a
grinding process and a polishing process are performed on the
distal planar portion, to increase the flatness of a planar area 8
of the tool original material 7 up to 2 .mu.m. The planar area 8
has a rectangular shape in a plan view, though not shown.
[0049] Next, as shown in FIG. 9(b), the plurality of concavities 11
are selectively formed in the planar area 8 through a grooving
process using wire cutting or a cutting wheel.
[0050] As a result, the plurality of concavities 11 separate the
planar area 8 into the plurality of planar portions 10 each still
having a flatness of 2 .mu.m. Thus, the chip portion 1c
corresponding to the embodiment 1 which includes the plurality of
planar portions 10 and the plurality of concavities 11 is
completed.
[0051] Then, as shown in FIG. 9(c), by using a shot-blasting
process in which a shooting material 16 is shot from the upper
side, the edge of the outer peripheral portion of the planar area 8
(the plurality of planar portions 10) having a rectangular shape is
rounded, and the plurality of planar portions 10a each having fine
unevenness in a range that satisfies a flatness of 2 .mu.m or less
are obtained. Consequently, the chip portion 1c according to the
embodiment 3 is obtained.
[0052] Furthermore, as shown in FIG. 9(c), if the shot-blasting
process is used, fine unevenness is also formed in each of the
plurality of concavities 11. Accordingly, the fine unevenness
formed in the plurality of concavities 11 also provides the effect
that the holding function of the chip portion 1c for holding the
lead wire 2 during the ultrasonic bonding operation increases.
[0053] In this manner, by the method for manufacturing the
ultrasonic bonding tool 1 according to the embodiment 4, the
ultrasonic bonding tool 1 having the chip portion 1c according to
the embodiment 3 can be obtained.
Embodiment 5
[0054] FIG. 10 is an explanatory diagram schematically showing a
planar structure with respect to the ultrasonic bonding tool 1 and
the lead wire 2 in an ultrasonic bonding method according to an
embodiment 5.
[0055] As shown in FIG. 10, a width Wc of formation of the planar
area of the chip portion 1c is smaller than a width WL of formation
of the lead wire 2. FIG. 10 schematically shows the chip portion 1c
in which the broken lines indicate the concavities and the rest are
the planar portions.
[0056] Accordingly, in the ultrasonic bonding method according to
the embodiment 5, a ultrasonic bonding method including the
following steps (a) and (b) can be performed by using the
ultrasonic bonding tool 1 provided with the chip portion 1c having
the width Wc of formation shown in FIG. 10.
[0057] In step (a), the lead wire 2 is placed on the surface of the
glass substrate 3. Then, in step (b), pressure is applied to the
lead wire 2 from the upper side by using the chip portion 1c of the
ultrasonic bonding tool 1, and additionally ultrasonic vibration is
applied thereto so that the lead wire 2 is bonded to the surface of
the glass substrate 3.
[0058] In the embodiment 5, during execution of the step (b), the
width Wc of formation of the chip portion 1c is set smaller than
the width WL of formation of the lead wire 2.
[0059] That is, the ultrasonic bonding method according to the
embodiment 5 is characterized by allowing the ultrasonic bonding
tool 1 to perform the ultrasonic bonding operation while the entire
planar area of the chip portion 1c is within a range of the width
WL of formation of the lead wire 2.
[0060] Since an ultrasonic bonding surface (the planar area of the
chip portion 1c) is within a range of the width WL of formation of
the lead wire 2, the lead wire 2 inevitably has a blank space 2e
where the plate thickness is not reduced after the ultrasonic
bonding operation. This can provide an effect of the strength of
the lead wire 2 can be improved.
Embodiment 6
[0061] FIG. 11 is an explanatory diagram schematically showing a
function for adjusting the position of the lead wire 2, of a lead
wire guide mechanism 21 used in an ultrasonic bonding method
according to an embodiment 6. FIG. 11(a) is a plan view, and FIG.
11(b) is a perspective view.
[0062] As shown in FIG. 11, the lead wire guide mechanism 21 is
arranged on a transport path of a transport mechanism that places
the lead wire 2 at a predetermined position on the surface of the
glass substrate 3. The lead wire guide mechanism 21 can move the
lead wire 2 in a widthwise direction D21, to thereby control a
position where the lead wire 2 is to be arranged relative to the
planar area of the chip portion 1c. In FIG. 11, two chip-marked
portions 2c marked by the chip portion 1c after the ultrasonic
bonding operation are shown.
[0063] Monitor means (not shown) such as a CCD camera for
monitoring a planar positional relationship between the chip
portion 1c and the lead wire 2 is arranged at a portion where the
chip portion 1c and the lead wire 2 are bonded to each other. A
monitoring result indicating the planar positional relationship
between the chip portion 1c and the lead wire 2 can be obtained by
image processing performed by the monitor means.
[0064] Accordingly, based on the monitoring result of the monitor
means, the lead wire guide mechanism 21 can control the planar
position of the lead wire 2 such that the center of the planar area
of the chip portion 1c can be always located in a central portion
of the lead wire 2 in a widthwise direction thereof, in other
words, such that the entire planar area can fall within the width
WL of formation of the lead wire 2 without fail.
[0065] In this manner, in the ultrasonic bonding method according
to the embodiment 6, by providing the lead wire guide mechanism 21
and the monitor means, a method further including the following
steps (c) and (d) can be achieved as an improvement in the
ultrasonic bonding method according to the embodiment 5.
[0066] In step (c), the monitor means detects a position of the
chip portion 1c with respect to the widthwise direction of the lead
wire 2.
[0067] In step (d), based on the monitoring result of the step (c),
a relative positional relationship between the lead wire 2 and the
chip portion 1c is adjusted by the lead wire guide mechanism 21, in
such a manner that pressure can be applied to the lead wire 2
within the width WL of formation of the lead wire 2 during
execution of the step (b) of the embodiment 5 described above.
[0068] In this manner, the ultrasonic bonding method according to
the embodiment 6 provides an effect that the relative positional
relationship between the lead wire 2 and the chip portion 1c is
always adjusted by using the lead wire guide mechanism 21 shown in
FIG. 11, to thereby ensure that the ultrasonic bonding surface can
fall within the width WL of formation of the lead wire 2 without
fail.
Embodiment 7
[0069] FIG. 12 is a cross-sectional view showing a cross-sectional
structure of the chip portion 1c according to an embodiment 7 of
the present invention. As shown in FIG. 12, the chip portion 1c is
formed as a layered structure of a base layer 12 made of a steel
material and a front layer 13 made of a super-steel material (such
as tungsten carbide). The front layer 13 is formed by brazing the
base layer 12. The super-steel material used for the front layer 13
has a higher hardness and more excellent wearing resistance than
those of the steel material used for the base layer 12. In the chip
portion 1c of the embodiment 7, too, the features of the embodiment
1 shown in FIGS. 1 to 6 are provided.
[0070] Thus, the chip portion 1c according to the embodiment 7
includes the base layer 12 (first layer) made of a steel material,
and the front layer 13 (second layer) made of a super-steel
material that has a higher hardness (smaller degree of wear) than
that of the steel material, and the front layer 13 serves as a most
distal end portion of the chip portion 1c. This provides an effect
that the life of the chip portion 1c can be extended.
Embodiment 8
[0071] FIG. 13 is a cross-sectional view showing a cross-sectional
structure of the chip portion 1c according to an embodiment 8 of
the present invention. As shown in FIG. 13, the chip portion 1c
includes a main part 1m (first layer) made of a steel material and
having the plurality of planar portions 10 and the plurality of
concavities 11, and a DLC (Diamond Like Carbon) film 4 (second
layer) formed on the entire surface and a part of a side surface of
the main part 1m. As compared with the steel material of the main
part 1m, the DLC of the DLC film 4 has a lower affinity for
aluminum that is a material of the lead wire 2. In the chip portion
1c of the embodiment 8, too, the features of the embodiment 1 shown
in FIGS. 1 to 6 are provided.
[0072] In this manner, in the chip portion 1c of the ultrasonic
bonding tool 1 according to the embodiment 8, the DLC film 4 having
a lower affinity for aluminum that is a material of the lead wire 2
is formed on the surface, and therefore an adhesion of the lead
wire 2 to the chip portion 1c can be suppressed so that the life of
the chip portion 1c can be extended.
Others
[0073] In the above-described embodiments, a single-body structure
of the glass substrate 3 is shown as the thin-film base. However,
needless to say, similarly to the single-body of the glass
substrate 3, the present invention is also applicable to a
composite structure in which a conductive metal film layer such as
a Cr (chromium) or Mo (molybdenum) film layer, a conductive oxide
layer such as a ITO, ZnO, or SnO layer, or the like, is laminated
on the surface of the glass substrate 3.
[0074] Moreover, even in a case of, instead of the glass substrate
3, a substrate made of another material such as a silicon substrate
or a ceramic substrate, the present invention is also applicable to
the substrate serving as a thin-film base having the
above-described single-body structure or composite structure, as
long as the substrate is a thin film having a plate thickness of 2
mm or less.
[0075] While the invention has been described in detail, the
foregoing description is in all aspects illustrative and not
restrictive. It is understood that numerous other modifications and
variations not illustrated herein can be devised without departing
from the scope of the invention.
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